Dissertations / Theses on the topic 'Invasive marine species'

Marine biological invasions have increased significantly in recent years due to global trade, transport and tourism. Invasions occur when species get transported from one region to another and establish themselves in the new habitat. These species compete for space and resources, displacing native species and changing, populations and communities. Invasive non-native species are the number one threat to Galapagos ecosystems and although many preventive and corrective measures have been applied to terrestrial problems, the impacts of invasive non-native species in the marine environment has received relatively little attention to date. The marine ecosystems of Galapagos harbour distinctive biological communities given a unique confluence of currents in the Eastern Tropical Pacific (ETP). They sustain a high incidence of endemic species, which are regularly subjected to extreme climate variability through El Niño–Southern Oscillation (ENSO) events. This research examines the negative impacts that marine non-native species can have on the biodiversity, ecosystem services and the health of the Galapagos Marine Reserve (GMR). Baseline surveys revealed nine marine non-native species present in the GMR at this time and the potential for the impacts of high-risk species for the GMR examined. Furthermore international marine traffic was analysed resulting in Panama and Guayaquil being identified as the hotspots for the translocation of marine no-native species to the Galapagos. A species based exposure model produced a list of 469 high-risk species that could have arrived in the GMR during 2013 from 14 different regions worldwide. Additionally, natural vectors were assessed as well as natural processes enhanced by anthropogenic activity. These results reflect the considerable risk that these vectors pose in the translocation of marine non-native species, furthermore ENSO events and global climate change were identified as major threats to the marine ecosystems of the GMR due to the increase in SST. Species distribution models are presented for 19 high-risk non-native species and the open niche scenario is described as the biggest threat the GMR is facing with the arrival of non-native species regardless as to how these species arrive through anthropogenic or natural vectors. Several risk assessments are presented and discussed in order to provide management strategies for decision makers in the GMR.

In the context of biological invasions, ship transport plays an important role in the transference of species around the world. During this process organisms are exposed to several stressful conditions, which do not prevent them to arrive in areas where they did not occur before. The marine invertebrates Carcinus maenas and Mytilus galloprovincialis natives in Portugal, have already established stable invasive populations in several regions worldwide. This study exposed organisms of both species to stress conditions similar to what occurs in ballast tanks and on ship hulls. Results showed a high survival of pre-stressed Mytilus galloprovincialis individuals when compared to non pre-stressed organisms when exposed to air exposure, hyposalinity and heat events. However when Carcinus maenas was exposed to heat stress, there was no significant difference between groups with a different stress history. These findings suggest that transport on ships is not only a vector of dispersal but also a vector capable to increase the resistance to stress conditions in potential species invaders by selection of resistant individual; Resumo: "Transporte marítimo de espécies marinhas invasoras e sua resistência ao stress" No contexto das invasões biológicas, o transporte marítimo desempenha um papel importante contribuindo para a transferência de espécies em todo o mundo. Durante este processo os organismos são expostos a variadas condições de stress que não os impede de chegar a áreas onde não ocorriam anteriormente. Os invertebrados marinhos Carcinus maenas e Mytilus galloprovincialis nativos em Portugal, já estabeleceram populações invasoras estáveis em várias regiões do mundo. Neste estudo, submeteram-se organismos de Carcinus maenas e Mytilus galloprovincialis a condições de stress semelhante ao que ocorre em tanques de água de lastro e em cascos de navios. Os resultados mostram uma maior sobrevivência dos indivíduos Mytilus galloprovincialis pré – expostos a condições de stress quando comparado com organismos sem uma prévia exposição a esses eventos de stress, quando expostos ao ar, baixa salinidade e altas temperaturas. No entanto, quando Carcinus maenas foi exposto a temperaturas mais altas, não houve diferença significativa entre os grupos com diferentes exposições ao stress aplicado. Estes resultados sugerem que o transporte marítimo não é apenas um vetor de dispersão mas também um vector capaz de aumentar a resistência a condições de stress em potenciais espécies invasoras, nomeadamente através da seleção dos indivíduos mais resistentes.

Anthropogenic climate change is one of the main challenges affecting the globe, with particular implications for the oceans. Marine climate change research has moved forward rapidly in recent years, and a range of physical model outputs are available that can be used by ecologists to help predict how species might be affected into the future. Policy makers require a level of understanding of how certain species and their ranges might change so that they can respond with sustainable management actions. This thesis aims to make use of a number of modelling techniques to explore implications of past and future conditions for marine species, and to appraise those tools that can be used under differing circumstances. Policy questions are answered relating to changes in the abundance and distribution of marine species. The links between historical climatic conditions and Barents Sea cod abundance are explored using Generalised Additive Models using data collected in the middle of the 20th century. This valuable historical data indicated that cod have temperature preferences and expand and shift their distributions based on environmental conditions. A simpler modelling technique is used to examine how oxygen conditions have changed in recent decades in the North Sea, how they might change in the future, and what implications this has for commercial fish species. The models show that oxygen conditions have improved recently and that they will not decrease to levels that result in large negative effects in the coming century. Species distribution modelling using a combination of global and downscaled model outputs shows that the UK will become more suitable for some non-native and harmful algal species in the 21st century, and less suitable for others. The model outputs contribute to the understanding of climate change effects and development of management tools to ensure the resilience of marine ecosystems into the future.

Biofouling on recreational yachts is an important vector for marine invasive alien species (MIAS) in many countries. There are various characteristics of a vessel that make it more susceptible to hull fouling. Yachts in three Western Cape marinas were surveyed to assess extent of fouling, hull maintenance patterns, travel history and yacht-owner awareness of MIAS issues.

Introduction and spread of non-indigenous species is a significant threat to the preservation of global biodiversity. Human-mediated vectors are responsible for transporting potentially invasive species to new habitats throughout the world. This research investigates the role of recreational boating movements as a vector for introduction and spread of invasive species. A baseline survey of subtidal fouling communities was conducted using artificial substrates in marinas of the southern Strait of Georgia, British Columbia. There was both a high presence of non-indigenous species and high non-indigenous species fouling cover in some marinas, indicating a likely negative impact on native communities. A dive survey which examined the species present on the underwater surfaces of recreational boats in marinas throughout British Columbia showed that more than two-thirds of boats examined had macrofouling present and one-quarter had one or more known non-indigenous species. In combination, a boater questionnaire was used to describe the movements and behaviours of the boaters themselves and behaviour patterns indicated a risk of non-indigenous species transport. The results of the dive survey and boater questionnaire were then used to develop a model that predicts the presence of fouling on boats based on three variables (age of antifouling paint, time in water and incidence of long trips). The biomechanical properties of non-indigenous species were compared to native species and non-indigenous species had both stronger attachment and lower drag than similar native species, indicating they have the ability to remain attached to fast-moving marine vessels. Finally, a statistical analysis was conducted comparing environmental, demographic and vector variables in explaining the spatial distribution of non-native species. The results showed that recreational boating played a stronger role in the distribution of subtidal non-native species than the original introduction vectors, aquaculture and shipping. This body of research demonstrates that recreational boating is a significant vector for the introduction and spread of invasive species in this region and around the world. It is the first comprehensive study of the recreational boating vector in Canadian marine waters and the results have important implications for the prevention of new introductions and the preservation of biodiversity.

Les activités anthropiques causent des invasions biologiques qui sont devenues un problème mondial susceptible de causer des dommages écologiques (p. ex., sur la biodiversité et l’habitat), économiques (sur les industries) et sociaux (sur le bien-être humain). La prévention et la détection précoce des nouvelles invasions sont des éléments essentiels pour la gestion des risques et des impacts sur les écosystèmes et les économies. Bien sûr, la prévention est préférable, mais la détection précoce est une étape cruciale pour enrayer la propagation ultérieure des espèces envahissantes, car elle offre la possibilité de les éradiquer avant les phases d’établissement de la population et de propagation. Bien qu’il s’agisse d’une option de gestion efficace en matière de coût et de temps, la détection précoce exige un effort d’échantillonnage considérable pour détecter les populations envahissantes aux tout premiers stades de leur invasion. En utilisant le système benthique marin comme modèle, quatre études interdépendantes ont été menées pour identifier des stratégies d’échantillonnage susceptibles d’améliorer notre capacité à détecter des populations envahissantes rares et à comprendre les patrons et processus écologiques de recrutement benthique à multiples échelles spatiales et temporelles. Plus précisément, ces études expérimentales sur le terrain visaient à (1) évaluer la relation entre l’approvisionnement en larves et la fixation dans une population envahissante isolée, (2) déterminer la durée de l’échantillonnage et de la fréquence à l’aide de plaques de fixation pour la détection d’espèces rares, (3) déterminer l’importance relative aux sources de variations spatiales et temporelles du recrutement benthique, et (4) examiner l’effet de l’échelle spatiale de l’échantillonnage sur la détection des espèces en analysant les patrons de recrutement à de multiples échelles sur quatre ordres de grandeur allant de la dizaine de mètres à la dizaine de kilomètres. Première étude : contrairement à l’hypothèse originale d’une relation étroite entre l’approvisionnement et la fixation initiale, l’approvisionnement en larves était plutôt un facteur déterminant de la fixation aux échelles moyennes. Ces résultats suggèrent que la force de cette relation s’affaiblit avec l’augmentation de l’échelle spatiale des observations de terrain. Néanmoins, un quart de la variation de la fixation à moyenne échelle peut encore être expliqué par l’approvisionnement sur des courtes échelles de temps (une semaine). Par conséquent, cette relation confirme l’utilité des plaques de fixation en tant qu’outil efficace pour la détection précoce aux échelles moyennes dans une marina, car une faible densité de recrutement sur les plaques correspond à une faible abondance de propagules envahissantes dans la colonne d’eau...
Les activités anthropiques causent des invasions biologiques qui sont devenues un problème mondial susceptible de causer des dommages écologiques (p. ex., sur la biodiversité et l’habitat), économiques (sur les industries) et sociaux (sur le bien-être humain). La prévention et la détection précoce des nouvelles invasions sont des éléments essentiels pour la gestion des risques et des impacts sur les écosystèmes et les économies. Bien sûr, la prévention est préférable, mais la détection précoce est une étape cruciale pour enrayer la propagation ultérieure des espèces envahissantes, car elle offre la possibilité de les éradiquer avant les phases d’établissement de la population et de propagation. Bien qu’il s’agisse d’une option de gestion efficace en matière de coût et de temps, la détection précoce exige un effort d’échantillonnage considérable pour détecter les populations envahissantes aux tout premiers stades de leur invasion. En utilisant le système benthique marin comme modèle, quatre études interdépendantes ont été menées pour identifier des stratégies d’échantillonnage susceptibles d’améliorer notre capacité à détecter des populations envahissantes rares et à comprendre les patrons et processus écologiques de recrutement benthique à multiples échelles spatiales et temporelles. Plus précisément, ces études expérimentales sur le terrain visaient à (1) évaluer la relation entre l’approvisionnement en larves et la fixation dans une population envahissante isolée, (2) déterminer la durée de l’échantillonnage et de la fréquence à l’aide de plaques de fixation pour la détection d’espèces rares, (3) déterminer l’importance relative aux sources de variations spatiales et temporelles du recrutement benthique, et (4) examiner l’effet de l’échelle spatiale de l’échantillonnage sur la détection des espèces en analysant les patrons de recrutement à de multiples échelles sur quatre ordres de grandeur allant de la dizaine de mètres à la dizaine de kilomètres. Première étude : contrairement à l’hypothèse originale d’une relation étroite entre l’approvisionnement et la fixation initiale, l’approvisionnement en larves était plutôt un facteur déterminant de la fixation aux échelles moyennes. Ces résultats suggèrent que la force de cette relation s’affaiblit avec l’augmentation de l’échelle spatiale des observations de terrain. Néanmoins, un quart de la variation de la fixation à moyenne échelle peut encore être expliqué par l’approvisionnement sur des courtes échelles de temps (une semaine). Par conséquent, cette relation confirme l’utilité des plaques de fixation en tant qu’outil efficace pour la détection précoce aux échelles moyennes dans une marina, car une faible densité de recrutement sur les plaques correspond à une faible abondance de propagules envahissantes dans la colonne d’eau...
Les activités anthropiques causent des invasions biologiques qui sont devenues un problème mondial susceptible de causer des dommages écologiques (p. ex., sur la biodiversité et l’habitat), économiques (sur les industries) et sociaux (sur le bien-être humain). La prévention et la détection précoce des nouvelles invasions sont des éléments essentiels pour la gestion des risques et des impacts sur les écosystèmes et les économies. Bien sûr, la prévention est préférable, mais la détection précoce est une étape cruciale pour enrayer la propagation ultérieure des espèces envahissantes, car elle offre la possibilité de les éradiquer avant les phases d’établissement de la population et de propagation. Bien qu’il s’agisse d’une option de gestion efficace en matière de coût et de temps, la détection précoce exige un effort d’échantillonnage considérable pour détecter les populations envahissantes aux tout premiers stades de leur invasion. En utilisant le système benthique marin comme modèle, quatre études interdépendantes ont été menées pour identifier des stratégies d’échantillonnage susceptibles d’améliorer notre capacité à détecter des populations envahissantes rares et à comprendre les patrons et processus écologiques de recrutement benthique à multiples échelles spatiales et temporelles. Plus précisément, ces études expérimentales sur le terrain visaient à (1) évaluer la relation entre l’approvisionnement en larves et la fixation dans une population envahissante isolée, (2) déterminer la durée de l’échantillonnage et de la fréquence à l’aide de plaques de fixation pour la détection d’espèces rares, (3) déterminer l’importance relative aux sources de variations spatiales et temporelles du recrutement benthique, et (4) examiner l’effet de l’échelle spatiale de l’échantillonnage sur la détection des espèces en analysant les patrons de recrutement à de multiples échelles sur quatre ordres de grandeur allant de la dizaine de mètres à la dizaine de kilomètres. Première étude : contrairement à l’hypothèse originale d’une relation étroite entre l’approvisionnement et la fixation initiale, l’approvisionnement en larves était plutôt un facteur déterminant de la fixation aux échelles moyennes. Ces résultats suggèrent que la force de cette relation s’affaiblit avec l’augmentation de l’échelle spatiale des observations de terrain. Néanmoins, un quart de la variation de la fixation à moyenne échelle peut encore être expliqué par l’approvisionnement sur des courtes échelles de temps (une semaine). Par conséquent, cette relation confirme l’utilité des plaques de fixation en tant qu’outil efficace pour la détection précoce aux échelles moyennes dans une marina, car une faible densité de recrutement sur les plaques correspond à une faible abondance de propagules envahissantes dans la colonne d’eau. Deuxième étude : des durées d’échantillonnage intermédiaires d’une à deux semaines (l’échelle des traitements allant d’un jour à un mois) étaient la durée optimale de déploiement de la plaque de fixation pour la détection des espèces « rares » (c’est-à-dire, des le début du recrutement). Une analyse au niveau de l’assemblage montre toutefois que l’augmentation de la durée et de la fréquence de l’échantillonnage augmentait logarithmiquement le nombre total d’espèces rares observées. Ces résultats espèce par espèce et au niveau de l’assemblage démontrent que la modification des éléments temporels de l’échantillonnage, tels que la durée et la fréquence, peut affecter considérablement la détection d’espèces. Troisième étude : après avoir évalué plusieurs sources spatiales et temporelles (le site, la région, la saison, et l’année), le moment choisi pour le déploiement des plaques est apparu comme étant la plus grande source de variabilité du recrutement benthique d’espèces rares. En particulier, le moment optimal pour la détection précoce serait en automne (a) lorsque le recrutement saisonnier d’espèces envahissantes établies tend à atteindre un pic et (b) lorsque la détection au niveau du site d’espèces envahissantes rares tend à se produire. Quatrième étude : l’échelle spatiale dominante dans le recrutement d’espèces rares est la plus petite (centaine de mètres). Cette échelle dominante peut être interprétée comme étant la bonne échelle spatiale pour la détection d’espèces rares. Une analyse plus poussée a montré que si l’échantillonnage a été structuré de manière aléatoire, l’échantillonnage à des échelles intermédiaires (millier de mètres) devient l’échelle optimale pour la détection d’espèces rares. Ces résultats élucident les différences de variabilité naturelle de la population benthique entre multiples échelles d’espace et de temps pour des espèces rares et communes. Ces études écologiques font partie d’une boîte à outils de détection précoce nécessaire à la gestion des espèces envahissantes marines en renseignant sur la manière dont l’échantillonnage des espèces rares doit être faite à multiples échelles spatio-temporelles. Des expériences de terrain similaires optimisant la détection d’espèces rares (au-delà de l’utilisation de plaques de fixation pour détecter les organismes benthiques dans les provinces Maritimes canadiennes) devraient être réalisées pour d’autres taxons, régions, t outils d’échantillonnage—en particulier, les envahisseurs à haut risque prévus, les invasions futures, et les outils récemment développés.
Les activités anthropiques causent des invasions biologiques qui sont devenues un problème mondial susceptible de causer des dommages écologiques (p. ex., sur la biodiversité et l’habitat), économiques (sur les industries) et sociaux (sur le bien-être humain). La prévention et la détection précoce des nouvelles invasions sont des éléments essentiels pour la gestion des risques et des impacts sur les écosystèmes et les économies. Bien sûr, la prévention est préférable, mais la détection précoce est une étape cruciale pour enrayer la propagation ultérieure des espèces envahissantes, car elle offre la possibilité de les éradiquer avant les phases d’établissement de la population et de propagation. Bien qu’il s’agisse d’une option de gestion efficace en matière de coût et de temps, la détection précoce exige un effort d’échantillonnage considérable pour détecter les populations envahissantes aux tout premiers stades de leur invasion. En utilisant le système benthique marin comme modèle, quatre études interdépendantes ont été menées pour identifier des stratégies d’échantillonnage susceptibles d’améliorer notre capacité à détecter des populations envahissantes rares et à comprendre les patrons et processus écologiques de recrutement benthique à multiples échelles spatiales et temporelles. Plus précisément, ces études expérimentales sur le terrain visaient à (1) évaluer la relation entre l’approvisionnement en larves et la fixation dans une population envahissante isolée, (2) déterminer la durée de l’échantillonnage et de la fréquence à l’aide de plaques de fixation pour la détection d’espèces rares, (3) déterminer l’importance relative aux sources de variations spatiales et temporelles du recrutement benthique, et (4) examiner l’effet de l’échelle spatiale de l’échantillonnage sur la détection des espèces en analysant les patrons de recrutement à de multiples échelles sur quatre ordres de grandeur allant de la dizaine de mètres à la dizaine de kilomètres. Première étude : contrairement à l’hypothèse originale d’une relation étroite entre l’approvisionnement et la fixation initiale, l’approvisionnement en larves était plutôt un facteur déterminant de la fixation aux échelles moyennes. Ces résultats suggèrent que la force de cette relation s’affaiblit avec l’augmentation de l’échelle spatiale des observations de terrain. Néanmoins, un quart de la variation de la fixation à moyenne échelle peut encore être expliqué par l’approvisionnement sur des courtes échelles de temps (une semaine). Par conséquent, cette relation confirme l’utilité des plaques de fixation en tant qu’outil efficace pour la détection précoce aux échelles moyennes dans une marina, car une faible densité de recrutement sur les plaques correspond à une faible abondance de propagules envahissantes dans la colonne d’eau. Deuxième étude : des durées d’échantillonnage intermédiaires d’une à deux semaines (l’échelle des traitements allant d’un jour à un mois) étaient la durée optimale de déploiement de la plaque de fixation pour la détection des espèces « rares » (c’est-à-dire, des le début du recrutement). Une analyse au niveau de l’assemblage montre toutefois que l’augmentation de la durée et de la fréquence de l’échantillonnage augmentait logarithmiquement le nombre total d’espèces rares observées. Ces résultats espèce par espèce et au niveau de l’assemblage démontrent que la modification des éléments temporels de l’échantillonnage, tels que la durée et la fréquence, peut affecter considérablement la détection d’espèces. Troisième étude : après avoir évalué plusieurs sources spatiales et temporelles (le site, la région, la saison, et l’année), le moment choisi pour le déploiement des plaques est apparu comme étant la plus grande source de variabilité du recrutement benthique d’espèces rares. En particulier, le moment optimal pour la détection précoce serait en automne (a) lorsque le recrutement saisonnier d’espèces envahissantes établies tend à atteindre un pic et (b) lorsque la détection au niveau du site d’espèces envahissantes rares tend à se produire. Quatrième étude : l’échelle spatiale dominante dans le recrutement d’espèces rares est la plus petite (centaine de mètres). Cette échelle dominante peut être interprétée comme étant la bonne échelle spatiale pour la détection d’espèces rares. Une analyse plus poussée a montré que si l’échantillonnage a été structuré de manière aléatoire, l’échantillonnage à des échelles intermédiaires (millier de mètres) devient l’échelle optimale pour la détection d’espèces rares. Ces résultats élucident les différences de variabilité naturelle de la population benthique entre multiples échelles d’espace et de temps pour des espèces rares et communes. Ces études écologiques font partie d’une boîte à outils de détection précoce nécessaire à la gestion des espèces envahissantes marines en renseignant sur la manière dont l’échantillonnage des espèces rares doit être faite à multiples échelles spatio-temporelles. Des expériences de terrain similaires optimisant la détection d’espèces rares (au-delà de l’utilisation de plaques de fixation pour détecter les organismes benthiques dans les provinces Maritimes canadiennes) devraient être réalisées pour d’autres taxons, régions, t outils d’échantillonnage—en particulier, les envahisseurs à haut risque prévus, les invasions futures, et les outils récemment développés.
As a consequence of anthropogenic activities, biological invasions have become a global problem that can cause ecological (e.g., biodiversity and habitat), economic (industries), and social (human wellbeing) harm. Prevention and early detection of new invasions are vital components of managing risks and impacts to ecosystems and economies. Prevention is, of course, preferred but early detection is a critical step that can ultimately stop future spread of invasive species because it provides an opportunity for eradication before population growth and spread. Despite being a cost- and time-effective management option, early detection requires considerably high sampling effort to detect incipient invasive populations at the early stages of their invasion. Using the marine benthic system as a model, four inter-related studies were carried out to identify sampling strategies that could enhance our ability to detect rare invasive populations and to understand ecological patterns and processes of benthic recruitment across multiple scales of space and time. Specifically, these experimental field studies aimed to (1) evaluate the relationship between propagule supply and settlement in a closed invasive population, (2) determine the optimal sampling duration and frequency using settlement plates to detect rare species, (3) ascertain the relative importance of spatial and temporal sources of variation in benthic recruitment, and (4) examine how the spatial scale of sampling affects species detection by analyzing recruitment patterns at multiple scales across four orders of magnitudes ranging from tens of metres to tens of kilometres. First study: Contrary to the expectation of a strong relationship between supply and initial settlement, larval supply was instead a limited determinant of settlement at mesoscales. This finding suggests that the strength of this relationship weakens as the spatial scale increased from previously reported small-scale field observations to mesoscales of the present study. Nonetheless, a quarter of the variation in settlement can still be explained by supply over short timescales (one week). Therefore, this relationship supports the utility of settlement plates as an effective tool for early detection at mesoscales within a marina because low densities of recruitment on plates correspond to low abundances of invasive propagules in the water column...
As a consequence of anthropogenic activities, biological invasions have become a global problem that can cause ecological (e.g., biodiversity and habitat), economic (industries), and social (human wellbeing) harm. Prevention and early detection of new invasions are vital components of managing risks and impacts to ecosystems and economies. Prevention is, of course, preferred but early detection is a critical step that can ultimately stop future spread of invasive species because it provides an opportunity for eradication before population growth and spread. Despite being a cost- and time-effective management option, early detection requires considerably high sampling effort to detect incipient invasive populations at the early stages of their invasion. Using the marine benthic system as a model, four inter-related studies were carried out to identify sampling strategies that could enhance our ability to detect rare invasive populations and to understand ecological patterns and processes of benthic recruitment across multiple scales of space and time. Specifically, these experimental field studies aimed to (1) evaluate the relationship between propagule supply and settlement in a closed invasive population, (2) determine the optimal sampling duration and frequency using settlement plates to detect rare species, (3) ascertain the relative importance of spatial and temporal sources of variation in benthic recruitment, and (4) examine how the spatial scale of sampling affects species detection by analyzing recruitment patterns at multiple scales across four orders of magnitudes ranging from tens of metres to tens of kilometres. First study: Contrary to the expectation of a strong relationship between supply and initial settlement, larval supply was instead a limited determinant of settlement at mesoscales. This finding suggests that the strength of this relationship weakens as the spatial scale increased from previously reported small-scale field observations to mesoscales of the present study. Nonetheless, a quarter of the variation in settlement can still be explained by supply over short timescales (one week). Therefore, this relationship supports the utility of settlement plates as an effective tool for early detection at mesoscales within a marina because low densities of recruitment on plates correspond to low abundances of invasive propagules in the water column...

Although the process by which fertilization occurs in bryozoans is well described, the ability to self-fertilize and the subsequent ecological consequences are poorly understood. Culturing experiments were conducted examining the effects of selfing on offspring survival and reproduction in the simultaneous hermaphrodite Bugula stolonifera collected from Eel Pond, Woods Hole, MA. Results from these experiments document significant decreases in survival and fecundity of selfed offspring, compared to outcrossed controls, suggesting that these animals are not routinely self-fertilizing in Eel Pond. How these arborescent colonies minimize selfing remains unclear, but it is hypothesized that conspecific aggregations could serve to minimize the chances that a colony utilizes its own sperm for fertilization. The genetic composition of these aggregations was investigated using a newly developed microsatellite library. As larvae routinely metamorphose on conspecific colonies, the possibility that larvae select or avoid their maternal colony was also investigated. Analyses of genetic structure document homogeneity throughout these aggregations on extremely small spatial scales, suggesting high amounts of larval dispersal within aggregations. When combined with results from parentage-exclusion and kinship analyses, these results indicate that a colony's nearest neighbors are not composed of siblings, potentially minimizing inbreeding. Molecular analyses were then used to determine if the high larval dispersal within aggregations resulted in high mixing between aggregations. Sites within Eel Pond separated by 100-300 m were routinely sampled from 2009 to 2011, and analyses were conducted to investigate potential inter- and intra-annual genotypic differentiation within and between aggregations. Results document that although low levels of mixing could result in increased homogeneity between some aggregations, barriers to genetic exchange prevent mixing between most sites. Further, inter-annual comparisons within sites document that significant differentiation can occur between reproductive seasons. Hence, any potential homogeneity achieved between sites during one reproductive season will likely be lost by the beginning of the next reproductive season. Additionally, while sampling in Eel Pond in 2010, I document the first occurrence from the western Atlantic Ocean of another aggregating arborescent bryozoan, Tricellaria inopinata. The growth and reproductive biology of these animals was monitored throughout 2011; results suggest that this introduction is likely to persist.

Invasive species are becoming more common as human interactions within coastal waters and the aquarium trade continues to increase. The establishment of the invasive lionfish complex Pterois volitans and P. miles from the Indo-Pacific to the Western Atlantic, Gulf of Mexico, and the Caribbean Sea has had significant negative effects on reef fish biodiversity and economically important species. Their rapid colonization and success has been attributed to their biological and ecological life history traits as well as their absence of predation. Past research has highlighted these characteristics; however, there is a knowledge gap in lionfish parasitism. This research explored the enemy release hypothesis as a key success factor in rapid establishment in the invaded range on a biogeographical scale. The diversity of lionfish parasitism was compared among 15 geographically diverse sites within the invaded range, incorporating the time of introduction at each site. Eight new parasites are described for the first time in the invasive lionfish: (1) a Cymothoid isopod: Rocinela stignata, (2) four nematodes: Raphidascais sp., Contraceacum sp., Paracuria adunca and Hysterothylaceum sp., (3) one digenean: Tergestia sp., (4) two acanthacephalans: Serracentis sp. and Dollfusentis sp., and (5) two cestodes: Nybelinia sp. and Tentacularia sp. Lionfish from the east coast of Florida exhibited the highest abundance in parasite fauna while other invaded areas yielded low abundance and diversity. Comparisons between lionfish parasitism from the past native range studies and the invaded range suggest that vectors of time, life history traits, and trophic interactions structure the lionfish parasite community. Lionfish in the Western Atlantic and Caribbean were found to be host for generalists parasite species within the coastal ecosystem. Consequently, lionfish have relatively low parasite abundance, supporting the enemy release hypothesis and its direct relation to their invasion success.

Humans have caused grave ecological and economic damage worldwide through the introduction of invasive species. Understanding the factors that influence community susceptibility to invasion are important for controlling further spread of invasive species. Predators have been found to provide biotic resistance to invasion in both terrestrial and marine systems. However, predators can also have the opposite effect, and facilitate invasion. Therefore, recovery or expansion of native predators could facilitate the spread of invasive species. Needles et al. (2015) demonstrated that the threatened southern sea otter (Enhydra lutris nereis) facilitated the invasion of an exotic bryozoan, Watersipora subatra. However, the underlying mechanism was not fully understood. We tested the hypothesis that sea otter predation on Romaleon antennarium crabs indirectly facilitated the abundance of W. subatra. To do this, we collected weekly data on sea otter foraging and quantified the abundance of crabs in the sea otter diet. We also conducted a caging experiment, where we experimentally manipulated crab densities and limited otter access using exclusion cages on pier pilings in Morro Bay, CA. We used photoQuad image processing software to calculate the abundance of W. subatra on PVC panels within each treatment group. We found that crabs were the second most abundant prey item in Morro Bay, comprising 25.1% of the otter diet. Through the caging experiment, we found that W. subatra abundance significantly increased as crab densities decreased. Our results indicated that sea otters indirectly facilitated the invasion of W. subatra by reducing R. antennarium crab densities and sizes. Removal of crabs may release W. subatra from the disturbance caused by crab foraging behavior. Understanding the impacts of top predators in invaded ecosystems has important management implications, as recovery of predator populations could unintentionally benefit some non-native species. Therefore, management should focus first on prevention and second on early detection and eradication of invasive species likely to benefit from predator recovery.

Aquatic invasive species (AIS) are biological pollutants that cause detrimental ecological, economic, and sociological effects on non-native communities. With increasing globalization through maritime trade, coastal ports are vulnerable to AIS introductions transported by commercial vessels. As Cuba’s Port Mariel becomes a competitive transshipment hub within the Caribbean, it is essential to identify the potential threat that AIS may pose with a likely increase in shipping activity. It is equally important to understand the status of established AIS in Cuba and control measures presently being implemented by the country. This information can provide guidance for establishing or improving Cuban AIS preventative and remedial actions. For this study, publically accessible information was used to conduct threat assessments of present and potential AIS in Cuba and to identify feasible international donors of AIS due to trade with Port Mariel. Fifteen species were identified as established Cuban AIS, eight of which were associated with harmful impacts to the environment, economy, and human health. Only one established AIS, Perna viridis (the Asian green mussel), was recorded as having repeated, negative influences in Cuba. Regional trade partners of Port Mariel were identified as the most likely donors of AIS due to ecological similarity and minimal voyage duration between countries. These trade partners also represented the busiest ports and transshipment hubs in the wider Caribbean region and, therefore, could expose Port Mariel to ‘stepping-stone’ invasions. Five species associated with international trade partners were identified as potentially detrimental to Cuba if introduced into Port Mariel. There were no significant differences between the salinity and temperature tolerances of the AIS already established in Cuba and the possible AIS of concern, suggesting that these potential invaders could survive the environmental conditions of Port Mariel and subsequently become established throughout Cuba. The results presented herein are a preliminary assessment of AIS threats in Cuba and emphasize the importance of prioritizing AIS prevention and management. This study also establishes a baseline inventory of potential AIS in Cuba and a methodology that can be followed for future analyses outside of the study region.

Non-indigenous seaweeds impact natural communities worldwide, affecting biodiversity, ecosystem functioning, and ecosystem services, resulting in significant economic and social consequences. Among major impacts are the displacement of native species, a threat to endangered species, and effects on ecological and evolutionary processes within the invaded communities. While critical to predict the fate of introduced species, understanding the mechanisms of acclimation and adaptation following introduction represents a great challenge in seaweeds. In this thesis, we investigated some acclimation processes, with an emphasis on the role of associated microbiota, and examined their effects with Sargassum muticum as a model species. This brown seaweed native to Asia, is an emblematic invader among seaweeds, with a distribution now ranging from Mexico to Alaska in America and from Morocco to Norway in Europe. We first reviewed the competitive advantages and traits that may contribute to its invasiveness. In addition, we provided an overview of putative underlying mechanisms of acclimation and adaptation and highlighted their role in seaweed invasions. We then examined the effects of ocean acidification on the microbiome of S. muticum and revealed that it does not have significant effects on the seaweed-associated microbiota despite certain changes in the microbial community. We further investigated the seasonal changes in the seaweed-associated microbiota and revealed significant differences between seasons and geographic locations. Finally, we applied ecological niche modelling, but innovatively accounting for phenology, to project the distribution of S. muticum under two future climate change scenarios. According to our projections, by 2100 the distribution of S. muticum is expected to shift northwards along its European, North American and Asian distributions with a partial retreat from the currently occupied areas.
As algas não indígenas afetam comunidades naturais em todo o mundo, afetando a biodiversidade, o funcionamento dos ecossistemas e os seus serviços, com consequências económicas e sociais significativas. Entre os principais impactos estão deslocamento de espécies nativas e espécies ameaçadas e efeitos sobre processos ecológicos e evolutivos nas comunidades invadidas. A compreensão dos mecanismos de aclimatação e adaptação após a introdução representa um grande desafio nas algas marinhas. Nesta tese investigamos alguns processos de aclimatação, com ênfase no papel dos microorganismos associados e examinamos os seus efeitos usando Sargassum muticum como espécie modelo. Esta alga marinha nativa da Ásia é uma importante invasora, com uma distribuição atual do México ao Alasca na América e de Marrocos à Noruega na Europa. Primeiro analisamos as vantagens e características competitivas que podem contribuir para sua invasibilidade. Além disso, fornecemos uma visão geral dos mecanismos de aclimatação e adaptação subjacentes e destacamos seu papel nas invasões de algas marinhas. Em seguida, examinamos os efeitos da acidificação dos oceanos no microbioma de S. muticum e revelamos que não tem efeitos significativos sobre a comunidade microbiana das algas marinhas apesar de causar algumas mudanças na comunidade. No estudo das mudanças sazonais na microbiota associada às algas marinhas revelamos diferenças significativas entre as estações e os locais geográficos. Finalmente, realizamos modelação de nicho ecológico de forma inovadora para a fenologia, para projetar a distribuição de S. muticum em dois cenários futuros de mudança climática. De acordo com nossas projeções, até 2100, a distribuição de S. muticum deverá expandir-se para norte ao longo das suas distribuições européia, norte-americana e asiática, com retração parcial das áreas atualmente ocupadas.

Precise descriptions and comprehensive taxonomies of species and their ecology are essential in monitoring changes in marine biodiversity at multiple spatial scales. A currently undescribed species of commensal amphipod in the genus Leucothoe is reported from New Zealand, collected from the endemic tunicate Cnemidocarpa bicornuta. This species differs from others in the genus in having a one-articulate first maxilla palp and an apically produced tuberculate lobe on the inner margin of the outer plate of the maxilliped. Previous taxonomic surveys in New Zealand waters did not document this species, indicating that it may be a recent arrival. This research highlights the importance of biodiversity monitoring and taxonomic surveys to record occurrences of undescribed or recently-arrived taxa.

The development of offshore wind farms and marine renewable energy devices in the Mediterranean is central to both national, and international, energy strategies for countries bordering the Mediterranean Sea. The ecological impacts of marine renewable energy development in the Mediterranean region, although essential for policy makers, are as yet unknown. The Northern Adriatic is identified as a plausible site for offshore wind farm development. Using the wider region (Adriatic and Northern Ionian) as a case study, this thesis examines the likely impact to the marine environment if an offshore wind farm is established. Site suitability, based on wind speed, bathymetry, and larvae connectivity levels are investigated along with the plausibility of the turbines operating as artificial reefs in the area. As offshore wind farms may alter the larval connectivity and supply dynamics of benthic populations, a connectivity map was constructed to identify areas of high and low connectivity in the Adriatic Sea. The Puglia coast of Italy is a likely larval sink, and displays some of the highest connectivity within the region, suggesting potential inputs of genetic materials from surrounding populations. Considering offshore wind farms could operate as artificial reefs, an in-situ pilot project was established to simulate the presence of wind turbines. Macroinvertebrates colonized the new substrata within the first few months but were lower in abundance when compared to a natural hard substrata environment. Time, turbine location, and the material used for turbine construction all affected the macro-invertebrate communities. In addition, fish abundances, and diversity were lower around the simulated OWF foundations in comparison to a natural hard substrata environment, and no increases in fish abundance occurred around the simulated turbines when compared to reference sites of soft substrata. This observation was validated with the use of an ecosystem modelling software (Ecopath with Ecosim), which simulated the overall ecosystem level impacts that would occur if 50 offshore monopile wind turbines were introduced to the Northern Ionian and colonized by macroinvertebrate communities. When compared to the baseline scenario (no simulated introduction of an OWF), the introduction of new habitat had no discernible impacts to the structure or functioning of the marine ecosystem. Noticeable changes to the ecosystem were only apparent if fishing restrictions were enforced in parallel with the simulated offshore wind farm; the ecosystem appears to become more structured by top down predation. In addition seabirds are also impacted by the reduction of fishing discards as a food source. These results are the first attempt to quantify the suspected benefits of offshore wind farms operating as de-facto marine protected areas.

Biological invasions threaten the ecological integrity of natural ecosystems. Anthropogenic introductions of non-native species can displace native flora and fauna, altering community compositions and disrupting ecosystem services. One often-overlooked vector for such introductions is the release of aquarium organisms into aquatic ecosystems. Following detrimental aquarium-release invasions by the “killer alga” Caulerpa taxifolia, aquarium hobbyists and professions began promoting the use of other genera of macroalgae as “safe” alternatives. The most popular of these marine aquarium macroalgae, the genus Chaetomorpha, is analyzed here for invasion risk. Mitigation strategies are also evaluated. I found that the propensity for reproduction by vegetative fragmentation displayed by aquarium strains of Chaetomorpha poses a significant invasion threat—fragments of aquarium Chaetomorpha are able to survive from sizes as small as 0.5 mm in length, or one intact, live cell. Fragments of this size and larger are generated in large quantities in online and retail purchases of Chaetomorpha, and introduction of these fragments would likely result in viable individuals for establishment in a variety of geographic and seasonal environmental conditions. Mitigation of invasion risk was assessed in two ways—rapid response to a potential introduction by chemical eradication and prevention through safe hobbyist disposal. I tested the effectiveness of five chemicals used as algicides and found that acetic acid was highly effective at limiting survival and growth of aquarium Chaetomorpha. Chlorine bleach, copper sulfate and rock salt were effective at limiting growth but were inconsistent or ineffective in reducing survival of algal fragments. The algicide Sonar limited neither survival nor growth. If aquarium strains of Chaetomorpha are released, chemical eradication presents a viable management strategy, particularly through the use of acetic acid. A more cost-effective strategy, however, would be preventing introductions; thus safe alternatives to release were determined for hobbyist disposal of unwanted or excess aquarium Chaetomorpha. Here I present the minimum exposure durations necessary to induce full mortality of aquarium Chaetomorpha through boiling, microwaving, freezing, desiccation and exposure to freshwater. Hobbyist disposal by any of these methods would constitute safe alternatives to introduction of the alga into natural environments. Such preventative measures will inform outreach campaigns in order to limit the potential for aquarium-release introduction.
M.S.
Masters
Biology
Sciences
Biology

Les espèces exotiques envahissantes sont un sujet de préoccupation grandissant, mais sont-elles,pour le droit international, un objet comme un autre ? Une espèce exotique envahissante a comme particularité d’être une espèce vivante qui, par sa seule présence dans un écosystème qui lui est étranger, va engendrer des effets délétères alors qu’elle n’en aurait causé aucun dans son écosystème d’origine. Le droit de la mer est-il armé pour répondre à cette menace ? La question de la qualification de leur atteinte en droit international et plus précisément en droit de la mer est autant novatrice que capitale. Le traitement juridique des espèces exotiques envahissantes a consisté, jusqu’à maintenant, à les rattacher de facto à la lutte pour la conservation de la diversité biologique sans même que soit posée la question, en amont, de leur qualification. Et si les espèces exotiques envahissantes étaient considérées comme une pollution ? Envisager cette hypothèse implique de procéder à une étude de fond tant des instruments de droit international, et de droit de la mer en particulier, que de la pollution marine. S’il est permis de reconnaître les espèces exotiques envahissantes comme étant une source de pollution, elle n’en reste pas moins une nouvelle forme de pollution encore jamais reconnue par les instruments de droit international : une pollution biologique. Cette pollution, autonome de celles déjà existant en droit international,impliquant la nécessité de repenser la définition de la pollution marine
Alien invasive species are a growing concern, but are they an object as any other in international law ? An invasive alien species is a living species which, by its mere presence in an ecosystem outside its natural range, causes deleterious effects which is not the case in its native ecosystem. Is the law of the sea equipped to meet this new threat ? The classification of its effects in international law, and more specifically the law of the sea, is as innovative as capital. The legal treatment of invasive alien species so far has been tied to the struggle for the conservation of biological diversity without wondering, in advance, what its classification is. What if alien invasive species are considered pollution ? Considering this hypothesis means studying instruments of international law, and more precisely those of the law of the sea, as well as marine pollution. If one can allow to identify invasive alien species as a source of pollution, it remains a new form of pollution that has never been recognized before by the instruments of international law : a biological pollution. This pollution, independent of those already existing in international law, implies the need to rethink the definition of marine pollution

Les écosystèmes marins sont bouleversés par de nombreux phénomènes tels que la surpêche, la pollution, le changement climatique et les espèces invasives, dont les impacts conjugués affectent négativement leurs structures et fonctionnements. Il est urgent d’évaluer le rôle de la navigation de plaisance comme facilitateur des invasions biologiques, et particulièrement pour la mer Méditerranée qui accueille deux tiers du trafic mondial de bateaux affrétés, et constitue le point chaud de la problématique des espèces non indigènes. Cette thèse se propose de combler ce besoin en accomplissant la première étude du rôle de la navigation de plaisance dans la propagation des ENI, par le bio-encrassement des marinas et coques de bateaux, à l’échelle du bassin méditerranéen. Une recherche minutieuse d’ENI a été conduite dans 34 marinas à travers la Méditerranée (s’étalant de l’Espagne à la Turquie), en ciblant les macro-invertébrés pour déterminer si les marinas constituaient bien des points chauds en ENI. Puis, des entretiens ont été conduits avec des propriétaires et/ou capitaines sur les caractéristiques de leurs bateaux, dont les opérations de nettoyage de la coque, les peintures, et leurs historiques de trajets récents. Des échantillons biologiques de bio-encrassement ont ensuite été collectés sur environ 600 bateaux, pour lesquels le capitaine/propriétaire avait été interrogé, afin de corréler les deux sources d’information. Les résultats de cette évaluation des marinas à l’échelle de la Méditerranée ont ensuite été combinés avec des données existantes sur les ENI présents dans les marinas italiennes, portant le nombre de marinas échantillonnées à 50. L’ensemble de ces données a été utilisé dans des analyses statistiques multivariées afin d’identifier les principaux facteurs abiotiques contribuant à la richesse en ENI et les similarités entre les différentes marinas
Many stressors, such as climate change, overfishing, pollution and biological invasions, are currently devastating the marine domain. The role of recreational boating in facilitating marine bioinvasions urgently necessitated a proper evaluation, especially in the Mediterranean Sea which hosts 2/3 of global charter boat traffic and is also the global hotspot for alien species. This study addresses this shortfall by completing the firstever Mediterranean basin-wide study investigating the influence of recreational boats in the transfer of NIS from biofouling both in marinas and from boat-hulls. First, a thorough investigation of NIS was conducted in 34 marinas across the Mediterranean (spanning from Spain to Turkey), targeting benthic macroinvertebrates. All marinas were found to host NIS, ranging from 2 to 27 per marina. This first output of this research provides a massive update of new NIS records and updated species distributions for the Mediterranean, and presents three new species in the Mediterranean basin, 51 new NIS country records and 20 new subregional records, which can now be fed into models and databases to gain a better comprehension of the composition and scale of NIS colonizing marina habitats. it was realized that almost 80% of sampled fouled vessels were found to host at least 1 NIS, while 11 was the maximum NIS found on one boat-hull. It was also found that recreational vessels visiting new marinas sometimes carry NIS not yet present neither in that marina nor in the country in which they are visiting, thus providing ample evidence of recreational boating supplying new NIS to marinas. The results of this large-scale Mediterranean marina assessment were combined with other existing data on NIS in Italian marinas for a total sample size of 50 marinas, which were then used to feed both univariate and multivariate statistical tests aimed at identifying which abiotic factors mainly contribute to total species richness of NIS in marinas and also which factors contribute to similar NIS assemblages between marinas. The results revealed that a higher species richness of NIS in Mediterranean marinas was influenced by the following factors: water temperatures above 25°C, a higher number of berths, absence of floating pontoons, proximity to the Suez Canal and proximity to commercial harbours. Whereas the similarities between NIS assemblages amongst marinas were more influenced by environmental factors such as temperature, biogeographical region, climate type, primary productivity and again proximity to the Suez Canal. The significance of the Suez Canal as a prominent factor in both analyses coincides with the general trend of higher total NIS found in the Eastern Mediterranean strongly influencing NIS distributions. The results presented within this thesis, adding to those marinas surveyed from around the world, form a robust case that recreational boating provides an extremely important pathway in facilitating primary NIS introduction events and their associated secondary spread to other coastal areas as ‘stepping stone’ habitats

With the majority of Earth’s population living in coastal areas, estuarine ecosystems have been particularly affected by anthropogenic disturbances. My dissertation research focused on three interrelated types of human disturbance that affect estuaries: Anthropogenic alteration of freshwater inflow, the introduction of invasive species, and habitat alteration. Using the LoxahatcheeRiver(Jupiter, FL) as a model system, my goal was to understand how these disturbances affect estuarine organisms, particularly fishes. One of the most ecologically harmful disturbances affecting estuaries is anthropogenic alteration of freshwater inflow (and resulting changes in salinity patterns). To identify effects of freshwater inflow on the behavior of an ecologically and economically important fish (common snook Centropomus undecimalis), I conducted a 19-month acoustic telemetry study. Common snook were more abundant and made more frequent upstream migrations during the wet season, but freshwater inflow did not appear to be the proximate cause for these behaviors. Increased estuarine salinity resulting from anthropogenic flow alteration may have facilitated the second type of disturbance that I address in this dissertation; the invasion of non-native Indo-Pacific lionfish into estuarine habitats. During the course of my dissertation research, I documented the first ever estuarine invasion by non-native lionfish. Using mark-recapture, I identified high site fidelity in lionfish, a trait that may aid future control efforts. The extremely low minimum salinity tolerance that I identified in lionfish appears to have allowed the species to colonize far upriver in estuaries with anthropogenically modified salinity patterns. Anthropogenic salinity alteration has also led to a severe degradation of oyster reef habitats in theLoxahatcheeRiver. As a foundation species, oysters provide food, shelter, and nursery habitat for a wide variety of estuarine organisms, including many ecologically and economically important fishes. Increasingly, degraded oyster reef habitats have been the focus of restoration efforts. I identified a relatively rapid (< 2 years) convergence between restored and natural oyster reef communities, and documented the importance of vertical relief in restoration success. My dissertation research is critical for the management and conservation of coastal rivers inFlorida, while more broadly informing restoration and management decisions in many other estuarine and coastal ecosystems.

The Nile monitor (Varanus niloticus) is a large, carnivorous lizard that has become a notorious invasive species in Florida, USA. Initially released in the 1980s from the pet trade, the species has since established at least three breeding populations and spread throughout much of southern Florida. While current control efforts have failed to eradicate V. niloticus, it is important to attain a better understanding of its invasive dynamics to guide and inform better control strategies. In this study, available georeferenced records of V. niloticus in Florida were compiled and linked to a habitat classification map to evaluate ecotype preferences. Factored with bioclimatic data, the regional spread of V. niloticus was modelled for contemporary and projected (i.e., in the year 2050) presence using Maxent and Mahalanobis Distance models. Study results indicate that V. niloticus maintains a strong presence in eastern Lee County on the southwestern coast. Populations in Palm Beach and Miami-Dade counties on the southeastern coast may be interconnected, contrary to current descriptions that they are separated from each another. Model forecasts of conditions for the year 2050 identify widespread expansion of V. niloticus in Florida, particularly northward with the establishment of a new population center in Pasco County in the western central peninsula. This is the first known modelling study of V. niloticus in Florida and identifies regions at greater risk for future population expansion.

Predator satiation and prey-size preference were determined for locally caught lionfish, schoolmaster, and graysby, all co-occurring predatory fishes in the Florida coral reef ecosystem. Individuals were evaluated by exposing them to wild-caught killifish over a gradient of four size classes (20 mm to 60 mm, in 10 mm increments). Preference trials extended over a 2 hr time period and were filmed to determine the order in which each prey item was consumed. Satiation was evaluated by exposing the predators to an equal number of excess prey items for 24 hrs and evaluating consumed prey weight. Lionfish and schoolmaster showed a significant preference for the smallest size class (20-30 mm) while the graysby preferred the largest (50-60 mm) and smallest equally. Graysby were shown to consume the least amount of food per gram by biomass (0.034g/gram predator-1) while lionfish consumed the most (0.079g/gram predator-1). A significant difference was also found between consumption rates of lionfish and schoolmaster (0.053g/gram predator-1). If consumption is compared by length between species, lionfish ( = 0.051g/mm predator-1) and schoolmaster ( = 0.061g/mm predator-1) consumption was not significantly different. These results suggest that lionfish success may stem from its ability to target prey sizes not preferred by the graysby while able to outcompete schoolmaster for the same prey size class. However, if the lionfish is compared on an individual level to schoolmaster by individual or length, consumption is similar, suggesting lionfish consumption is not significantly greater on the reef than the native species on an individual basis.

Les algues non-indigènes ont des impacts sur les communautés naturelles à une échelle mondiale: elles affectent la biodiversité et le fonctionnement des écosystèmes ainsi que les services écosystémiques, avec des conséquences économiques et sociales. Parmi les conséquences de ces introductions sont le déplacement d'espèces indigènes, des compétitions avec des espèces en danger et des effets sur les trajectoires éco-évolutives des espèces des communautés envahies. Bien que crucial pour anticiper le devenir des espèces non-indigènes, comprendre les mécanismes d'acclimatation et d'adaptation agissant post-introduction reste un challenge chez les algues. Au cours de cette thèse, nous avons étudié certains processus d'acclimatation, en particulier le rôle des bactéries associées, et leurs effets, en utilisant comme modèle d'étude Sargassum muticum. Cette algue brune originaire d'Asie, est une espèce emblématique parmi les algues introduites avec une présence du Mexique à l'Alaska en Amérique et du Maroc à la Norvège en Europe. Nous avons effectué une analyse bibliographique des traits et caractéristiques écologiques qui pourraient expliquer son succès. Nous avons ensuite montré que l'acidification n'a pas d'effets significatifs sur les bacteries associées, bien que des changements saisonniers du microbiome aient été observés. Enfin, nous avons utilisé un modèle de niche écologique, intégrant la phénologie, pour prédire la distribution de S. muticum sous deux scénarios de changement climatique. Selon nos résultats, d'ici 2100, la distribution de S. muticum devrait se déplacer vers le nord dans l'hémisphère nord avec des régressions dans certaines zones actuellement occupées
Non-indigenous seaweeds impact natural communities worldwide, affecting biodiversity, ecosystem functioning, and ecosystem services, resulting in significant economic and social consequences. Among major impacts are the displacement of native species, a threat to endangered species, and effects on ecological and evolutionary processes within the invaded communities. While critical to predict the fate of introduced species, understanding the mechanisms of acclimation and adaptation following introduction represents a great challenge in seaweeds. In this thesis, we investigated some acclimation processes, with an emphasis on the role of associated microbiota, and examined their effects with Sargassum muticum as a model species. This brown seaweed native to Asia, is an emblematic invader among seaweeds, with a distribution now ranging from Mexico to Alaska in America and from Morocco to Norway in Europe. We first reviewed the competitive advantages and traits that may contribute to its invasiveness. We then showed that acidification has no significant effects on associated bacteria, although seasonal changes in the microbiome have been observed. Finally, we applied ecological niche modelling, but innovatively accounting for phenology, to project the distribution of S. muticum under two future climate change scenarios. According to our projections, by 2100 the distribution of S. muticum is expected to shift northwards along its European, North American and Asian distributions with partial retreat from the currently occupied areas

Pterois volitans and Pterois miles, two species of lionfish from the South Pacific and Indian Ocean, have become prolific invaders of reef, hard bottom, mangrove, and sea grass habitats along the United States Atlantic coast and Caribbean. Their route and timing of introduction is poorly understood. However, historical sightings and captures have been robustly documented since their introduction. This study presents an in-depth analysis of these records based on spatial location, dates of arrival, and physical factors present at capture sights. A stage map was created showing the progression of the invasion as a series of current-driven and proximity-based recruitment periods based on the observed invasion pattern. Using a model that was developed for this study, the relationship between depth, salinity, temperature, and current was examined, finding the latter to be the most influential parameter for transport to new areas. Temperature and extreme depth are perceived as the only limiting factors in the invasion. This predictive model can be applied to other species and locations.

Aquatic sediments are, by surface, the largest habitat on Earth. A wide diversity of organisms inhabit these sediments and by their actions they have a large influence on and also mediate many ecosystem processes. Several of these processes, such as decomposition and remineralisation of organic matter are important on a global scale and are essential to sustain life on Earth. The main aim of this thesis was to use an experimental ecosystem ecology approach in order to study some of these ecosystem processes in marine sediments and how they are linked to biodiversity. Paper I and II found that an increased species richness of sediment deposit feeders increases the processing of organic matter from phytoplankton settled on the sea-floor, and that species-rich communities have a more efficient resource utilization of deposited organic matter. The results in paper IV and V also suggest that there is a link between microbial diversity in sediments and the degradation of organic contaminants. Paper V also shows that antibiotic pollution is a potential threat to natural microbial diversity and microbially mediated ecosystem services. The introduction of invasive species to ecosystems is another major threat to biodiversity and was studied in Paper II and III, by investigating the ecology of Marenzelleria arctia, a polychaete worm recently introduced in the Baltic Sea. Paper II suggests that M. arctia mainly utilize food resources not used by native deposit feeders, thus potentially increasing the benthic production in the Baltic Sea by increasing resource use efficiency. Paper III, however, show that M. arctia is protected from predation by the native benthic invertebrate predators, due to its ability to burrow deep in the sediment, suggesting that predation on M. arctia by higher trophic levels is restricted, thereby limiting trophic transfer. In conclusion, this thesis gives some examples of the importance of marine biodiversity for the generation of a few key ecosystem processes, such as organic matter processing and the degradation of harmful contaminants.
At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 3: Manuscript. Paper 4: In press.

Human-mediated introductions of non-indigenous species now threaten to homogenize the biota of the Globe, causing huge economic and ecological damage. This thesis studies the ecological role of 3 invasive planktonic crustaceans, the omnivorous copepod Acartia tonsa (western Atlantic and Indo-Pacific) and the predatory cladocerans, Cercopagis pengoi (Ponto-Caspian) and Bythotrephes longimanus (Eurasian). B. longimanus invaded the North American Great Lakes in 1982, C. pengoi the Baltic in 1992 and the Great Lakes in 1999, while A. tonsa has an extensive invasion history that includes the Baltic. We review current knowledge on feeding biology of the predatory cladocerans. A study of stable C and N isotope ratios indicated mesozooplankton as the main food source of C. pengoi in the northern Baltic Sea proper, with young C. pengoi also eating microzooplankton, such as rotifers. Young-of-the-year herring did eat C. pengoi and herring trophic position shifted from 2.6 before the invasion to 3.4 after, indicating that C. pengoi had been “sandwiched” into the modified food web between mesozooplankton and fish. Salinity tolerance experiments on Acartia tonsa and co-occurring Acartia clausi showed the formers euryhaline character and high grazing potential. Energy partitioning between ingestion, production and respiration was rather constant over the tested salinity range of 2 to 33, with small differences in gross growth efficiency and cost of growth, but maximum ingestion at 10-20. Egg hatching in A. tonsa was only reduced at the lowest salinity. Extreme changes in salinity were needed to cause significant mortality of A. tonsa in the field, but its feeding activity could be severely reduced by salinity changes likely to occur in estuaries. A study of a hypertrophic estuary showed that A. tonsa can sustain a population despite very high mortality rates, caused by predation, high pH and low oxygen, helping explain the success of A. tonsa as an invader of estuaries.

Thesis: Ph. D., Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Department of Biology; and the Woods Hole Oceanographic Institution), 2017.
Cataloged from PDF version of thesis.
Includes bibliographical references.
Every genome tells a story. This dissertation contains four such stories, focused on shared themes of marine population dynamics and rapid change, with an emphasis on invasive marine species. Biological invasions are often characterized by a range expansion, during which strong genetic drift is hypothesized to result in decreased genetic diversity with increased distance from the center of the historic range, or the point of invasion. In this dissertation, population genetic and genomic tools are used to approach complex and previously intractable fundamental questions pertaining to the non-equilibrium dynamics of species invasions and rapid range expansions in two invasive marine species: the lionfish, Pterois volitans; and the shrimp, Palaemon macrodactylus. Using thousands of loci sequenced with restriction enzyme associated DNA sequencing in these two systems, this research tests theoretical predictions of the genomic signatures of range expansions. Additionally, the first chapter elucidates patterns of population genetic connectivity for deep-sea invertebrates in the New Zealand region demonstrating intimate relationships between genetics, oceanographic currents, and life history traits. Invasive shrimp results extend our understanding of marine population connectivity to suggest that human-mediated dispersal may be as important - if not more important - than oceanographic and life history considerations in determining genetic connectivity during specific phases of marine invasions. In invasive populations of lionfish, measures of genomic diversity, including a difference between observed and expected heterozygosity, were found to correlate with distance from the point of introduction, even in the absence of spatial metapopulation genetic structure. These results indicate a signal of rapid range expansion. The final study in this dissertation uses an innovative temporal approach to explore observed genomic patterns in the lionfish. In all, this dissertation provides a broad perspective through the study of multiple species undergoing superficially parallel processes that, under more intense scrutiny, are found to be mechanistically unique. It is only through comparative approaches that predictable patterns of population dynamics will emerge.
by Eleanor Kathleen Bors.
Ph. D.

Predicting the locations of new biological invasions has become a high priority for biologists as well as trying to predict if newly introduced species will become damaging to native ecosystems. Reefs of the eastern oyster Crassostrea virginica in Mosquito Lagoon, Florida have been highly disturbed in recent years resulting in dead reefs (piles of dead, disarticulated shells) some of which have been restored. I conducted oyster reef surveys for non-native invertebrates to determine if disturbance on these oyster reefs might assist invasion by two species, Mytella charruana and Perna viridis, recently introduced to the southeastern coast of the United States. Next, I investigated if M. charruana's temperature and aerial exposure tolerance limits may allow for it to establish permanently on intertidal oyster reefs. Temperature and aerial exposure tolerance experiments were conducted and oyster reef temperatures were collected. Oyster reef surveys could not predict if reef disturbance is assisting in the invasion process because only two non-native individuals (P.viridis) were found, one on a restored reef and one on a natural (reference) reef. Tolerance experiments showed that some Mytella charruana survived even after 7 days of 8??C temperatures if the mussels are exposed to air for 4 hours or less per day. Mytella charruana had near 0% survival after 4 hours of 44??C. However, only disturbed reefs reached this temperature in the field. It is likely that M. charruana could survive in the low intertidal zone on restored or reference reefs. This information is important for understanding the introduction of M. charruana in Mosquito Lagoon and also provides a data set of temperature tolerances for better understanding of whether the species might be able to invade other areas.
ID: 029809008; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (M.S.)--University of Central Florida, 2011.; Includes bibliographical references (p. 64-67).
M.S.
Masters
Biology
Sciences

Biological invasions pose a serious threat to biodiversity world-wide. Through various means, such as competition or predation, invaders can radically change species composition and the functioning of native ecosystems. Even though our understanding of the mechanisms underlying invasion success is improving, there is still a lack of knowledge on the response of native species under pressure from invasion. This study adds to existing knowledge on the responses of a native species to invasion by non-indigenous species. Pyura pachydermatina is a native ascidian in the southeast coast of New Zealand currently under pressure from increased urbanisation and invasion by other ascidian species. The reproductive strategies employed by P. pachydermatina are investigated and the role of these strategies to increase its resistance to invasion are assessed. A population study on the status of P. pachydermatina around the Banks Peninsula was carried out in Camp Bay, Pigeon Bay, and Wainui. Spawning experiments using P. pachydermatina and gonad histology were done regularly during the one year study period to assess its ability to self-fertilise and determine its reproductive period. In addition, predation experiments were carried out to assess the susceptibility of P. pachydermatina early life stages to two amphipod predators. The surveys indicated that the populations of P. pachydermatina in the three sites are different from one another. Wainui has on average the largest individuals of P. pachydermatina and Camp Bay, the smallest. Abundance of P. pachydermatina was highest in Pigeon Bay and lowest in Wainui. The three life stages of Pyura pachydermatina; recruits, juveniles, and adults, were present in all sites at all seasons. The spawning experiments confirmed the species’ ability to self-fertilise and that it has a year-round spawning period. The two amphipod predators, Jassa marmorata and Caprella mutica, were efficient in consuming the egg and larval stages of P. pachydermatina, but did not feed on the settlers. Year-round reproduction and the ability to self-fertilise potentially give P. pachydermatina increased resistance to the effects of urbanisation and invasion. This population study suggested that the species is thriving around the Banks Peninsula. This, combined with previous studies on the non-indigenous ascidian Styela clava that stated the static or declining populations of the potential invaders, gives a positive outlook for the native species for the future. I suggest the use of genetic techniques to assess, in more detail, the population structure and dispersal potential of this native species. I also suggest constant monitoring of native species is required to keep up to date with the current status of the species, which will in turn help management decisions should regional spread of the Lyttelton S. clava invasion occur in the future.

Species invasion has been recognized as a major threat to biodiversity. Knowledge of the factors that limit the establishment and spread of non-indigenous species (NIS), such as biotic resistance and unfavourable environmental conditions, are important to their effective management. To test the biotic resistance and environmental favourability hypotheses in the fouling communities of British Columbia (BC), 22 locations were compared using settlement tiles in a large-scale survey. Biotic resistance is believed to be stronger in more diverse communities, therefore NIS richness and abundance were compared to native species richness and environmental conditions to investigate their importance using generalized and linear mixed models. Invader taxonomic group may influence biotic resistance, and environmental tolerances vary by species, therefore factors that affected Botrylloides violaceus presence and abundance were investigated as a case study. The biotic resistance hypothesis was not supported for NIS richness or NIS abundance, but could not be fully discounted due to a trend toward a negative slope between native species richness and B. violaceus presence and abundance, and the absence of predator data. Environmental variables affected NIS: salinity had a positive influence on NIS richness, NIS abundance, and B. violaceus presence, and temperature had a positive effect on B. violaceus presence and abundance. Salinity had a positive impact on native species richness as well, supporting the environmental favourability hypothesis. This suggests that knowledge of relevant environmental conditions is more important for the management of invasive species than the species richness of vulnerable communities. Environmental conditions are not static, so species invasion must be considered in the context of climate change. To understand how climate change may influence species invasion, B. violaceus presence and abundance in BC were compared to a range of abiotic conditions. This comparison informed a GAMLSS model that used linear trends from historical shore station data to project potential abundance in BC forward 50 years. Overall, the abundance of B. violaceus in BC was projected to increase. A larger increase in B. violaceus abundance was forecast for locations where conditions increased into the range favourable for growth. If temperature and salinity become more favourable for B. violaceus, as projected, climate change could intensify the invasion.

Marine seaweeds constitute one of the most productive plant systems known on Earth and a rich fauna including juvenile fish and crustaceans is dependent on the habitats they form. Human influence on marine costal ecosystems has resulted in large scale changes to the abundance and distribution of species, where species introductions constitute an obvious part. The aims of this thesis were to 1) explore how non-native seaweeds impact on ecosystem functions (primary production and decomposition), and 2) study how interactions between non-native seaweeds and native communities affect invasion success. I used a combination of laboratory assays, outdoor mesocosms and field experiments. Paper I and II revealed that the impact on ecosystem functions were substantially different depending on the identity of the invader. The highly successful non-native red alga Heterosiphonia japonica had a large effect on community productivity. Due to the rapid growth of the invader, the primary production increased by more than four times in mixed species communities with the invader compared to  communities with only native species. In contrast, the morphologically similar and equally successful non-native red alga Bonnemaisonia hamifera grew slowly and had no effect on community production. But B. hamifera produces a potent defense compound that deters native herbivores and reduces the growth of micro-organisms. As a direct or indirect effect of this chemical defense, the litter from B. hamifera decomposed considerably slower compared to native seaweed litter. Rapid growth and defense against predation are likely important in explaining how the two invaders have become successful in the invaded range. These results show that traits related to invasion success may determine impacts on native communities. Paper III shows that the rapidly growing invader H. japonica is avoided as food by native herbivores, which likely enables the invader to survive during colder seasons with sub-optimal growth conditions.  In paper IV I found that competition from the native brown alga Fucus vesiculosus decreased growth of the non-native congener Fucus evanescens. Native herbivores caused more damage to the native competitor but it did not relieve F. evanescens from competitive pressure. Several native brown algae grow in the niche of F. evanescens, which may explain why the species only is growing sparingly in the invaded range. The results indicate that competition with native seaweeds have potential to reduce the success of non-native seaweeds in the new range. In summary, this thesis shows that non-native seaweeds differ strongly in their effect on ecosystem functions. Knowledge of which traits are present among abundant non-native species and how these traits relates to different effects may enable us to gain a better understanding of invasion impacts on native communities. The thesis also highlights that competitive interactions can be of importance for invasion success in seaweed communities.

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 3: Manuscript. Paper 4: Manuscript.

Alien-native trophic interactions: consequences for invasion success and ecosystem effects of invasions

Les conditions environnementales définissent la distribution des espèces marines à l’échelle globale. Celles-ci seront potentiellement altérées par le changement climatique, impactant l’exploitation des ressources halieutiques et l’équilibre des écosystèmes. Dans ce contexte, cette thèse identifie les espèces et les zones géographiques qui seront potentiellement impactées par le changement climatique, en se focalisant sur certaines espèces, indigènes ou non-indigènes, d’intérêt commercial en Méditerranée.Basée sur le concept de niche écologique, qui définit la distribution potentielle d’une espèce en fonction des conditions environnementales dans lesquelles elle a été observée, nous avons développé une procédure de modélisation de la distribution actuelle et future des espèces marines. Cette procédure s’appuie sur un ensemble d’algorithmes statistiques, de modèles climatiques et de scénarios futurs. Elle permet de projeter un ensemble de distributions futures, à large échelle spatiale et temporelle, tout en proposant des réponses aux principales limitations des modèles de niche écologique. Successivement appliquée aux petits poissons pélagiques et aux céphalopodes, nous avons identifié des impacts majeurs du changement climatique en Méditerranée à l’horizon 2100, notamment des extinctions locales de plusieurs espèces de petits poissons pélagiques dans son bassin Sud-Est. Au contraire, la mer du Nord, les côtes norvégiennes et la mer Baltique pourraient bénéficier d’une expansion de l’aire de distribution de ces espèces. A l’échelle du golfe du Lion, les conséquences théoriques d’un changement de distribution des petits poissons pélagiques impacteraient indirectement leur exploitation ainsi que la productivité des bas niveaux trophiques. Les effets conjugués du réchauffement de la Méditerranée et de l’agrandissement du canal de Suez sont à l’origine d’invasions biologiques, notamment dans son bassin Sud-Est. Parmi ces espèces non-indigènes de Méditerranée, certaines présentent un intérêt commercial ou pourraient faire l’objet d’une exploitation future. Nous avons quantifié le potentiel invasif de plusieurs espèces non-indigènes, en fonction de leurs traits fonctionnels et écologiques, puis estimé leur expansion future à l’aide de notre procédure de modélisation de niche écologique. L’ensemble de la Méditerranée pourrait voir l’arrivée de ces espèces à l’horizon 2100, en particulier pour un réchauffement supérieur à 2°C.Cette thèse révèle la sensibilité particulière de la Méditerranée au réchauffement climatique tout en proposant des perspectives d’adaptation ou de conservation des espèces et des écosystèmes face aux tendances climatiques du 21ème siècle
Environmental conditions are shaping the spatial distribution of marine species worldwide. However, climate change may alter their future distribution, impacting marine resources exploitation and ecosystems balance. In this context, this PhD identifies climate induced impacts in species and geographical areas, by focusing on some species, indigenous or non-indigenous, of commercial interest in the Mediterranean.Based on the ecological niche concept, that defines the potential distribution of a species according to the environmental conditions in which it is observed, we developed a contemporary and future distribution modelling procedure for marine species. This procedure includes an ensemble of statistical algorithms, future climate models and scenarios while accounting for common ecological niche modelling limitations. Applied to small pelagic fish and cephalopods, we projected major climate induced impacts in the Mediterranean Sea by 2100, including local extinctions in its south-eastern basin. Conversely, we projected a distributional range expansion of most of the studied species towards the North, Norwegian and Baltic seas. In the Gulf of Lion, the small pelagic fish distributional range shifts may indirectly impact their harvesting capacity as well as the productivity of low trophic levels. The combined effects of climate warming and the opening of the Suez Canal induced biological invasions, especially in the South-East Mediterranean. These non-indigenous Mediterranean species may be of commercial interest subject to future harvesting. After quantifying the invasive potential of several non-native Mediterranean marine species, according to their functional and ecological traits, we applied our modelling procedure to estimate their future distributional range expansion. We projected a major distributional range expansion of non-native species in the whole Mediterranean Sea by 2100, especially for warming exceeding 2°C.This work highlights the sensitivity of the Mediterranean Sea to climate change while proposing adaptation and conservation perspective of species and ecosystems facing the upcoming climate trends of the 21st century

In this thesis I review how Sargassum muticum (Yendo) Fensholt, an invasive alga from Asia, has spread globally due to human activities and describe how this species can affect seagrass ecosystems. Abiotic factors such as nutrient and substratum availability may facilitate the spread of S. muticum into Zostera marina L. meadows, but analyses of seawater nutrients, and sediment particle size and % organic content revealed no significant differences between experimental quadrats in seagrass meadows either with, or without the presence of S. muticum. Phenolic compounds were examined because they form the basis of defensive mechanisms in plants and algae, therefore any change in phenolic content may affect the ability of Z. marina to protect itself from disease, herbivory and invasive species through allelopathic interactions. Results from a four year field study and multiple annual laboratory experiments showed significant reductions (p = 0.034 and p = 0.002, respectively) in the caffeic and tannic acids equivalents content of Z. marina when in the presence of S. muticum. As the abundance of S. muticum increases, other changes in the physiology of Z. marina may occur including variations in growth rates, nutrient partitioning and chlorophyll fluorescence, but data from multiple laboratory experiments illustrated no significant differences in growth. Chlorophyll fluorescence analyses revealed significant differences between treatments with and without S. muticum (p = 0.008), but pairwise comparisons indicated these differences only occurred in 2008 (p < 0.001). Significant differences were also found in nutrient partitioning amongst functional regions of the shoots (p = 0.024), but pairwise comparisons detected these differences between a biomass control treatment (ZZ: Zostera + Zostera) and the ZS (with S. muticum) and ZM (Z. marina on its own at a lower biomass per replicate) treatments (p = 0.013 and p = 0.019, respectively), but not between ZS and ZM. Previous in situ research has found negative effects of S. muticum presence on densities of kelp and other algae. Results from the long-term field study indicated significantly lower mean in situ Z. marina densities within the ZS treatment (p < 0.001). Epibiota found living on the blades of Z. marina provide food for organisms within seagrass ecosystems and also create microhabitats for other species to occupy. Alterations in the abundances of epibiota and microhabitats formed could further modify seagrass ecosystems through shifts in timing of food availability, food preferences and microhabitats created. The long-term field study data revealed significantly lower epibiota abundances within the ZS treatment (p = 0.019), but differences in biomass between treatments were not detected. Changes in the biochemistry, physiology, vegetative physiognomy and epibiota assemblages of Z. marina revealed during experimental manipulations are presented and considered within the context of long-term seagrass survival in light of increasing S. muticum invasion.

The spread of exotic species is considered to be one of the most significant threats to ecosystems and emphasises the need for appropriate management interventions. The majority of marine non-indigenous species (NIS) are believed to have been introduced via ship biofouling and their domestic spread continues to take place via this mechanism. In some countries, biosecurity systems have been developed to prevent the introduction of NIS through biofouling. However, implementing biosecurity strategies is difficult due to the challenges around identifying high-risk vectors. Reliable predictors of risk have remained elusive, in part due to a lack of scientific knowledge. Nonetheless, invasion ecology is an active scientific field that aims to build this knowledge. Propagule pressure is of particular interest in invasion ecology as it describes the quantity and quality of the propagules introduced into a recipient region and is considered to be an important determinant in the successful establishment of NIS. Environmental history affects health and reproductive output of an organism and, therefore, it is beneficial to examine this experimentally in the context of biofouling and propagule pressure. The aim of this thesis was to examine how voyage characteristics influence biofouling recruitment, survivorship, growth, reproduction and offspring performance through the ship invasion pathway. This was to provide fundamental knowledge to assist managers with identifying high-risk vessels that are likely to facilitate the introduction or domestic spread of NIS, and to understand the processes affecting biofouling organisms during long-distance dispersal events. Chapter One provides an introduction to the issues addressed in this thesis. Each data chapter (Chapters Two – Five) then focused on a stage of the invasion process and included field experiments using a model organism, Bugula neritina. Finally, Chapter Six provides a summary of key findings, discussion and the implications to biosecurity management. Throughout this thesis, the effect of donor port residency period on the success of recruits was highlighted. Chapter Two focused on recruitment in the donor region. As expected, recruitment increased with residency period. Importantly, recruitment occurred every day on vulnerable surfaces, therefore, periods as short as only a few days are able to entrain recruits to a vessel hull. The study presented in Chapter Three showed that there was high survivorship of B. neritina recruits during 12 translocation scenarios tested. In particular, the juvenile short-residency recruits (1-8 days) survived voyages of 8 days at a speed of 18 knots; the longest and fastest voyage simulated. Interestingly, variation in voyage speed and voyage duration had no effect on the survivorship of recruits, but did have legacy effects on post-voyage growth. Again, B. neritina which recruited over very short residency periods of 1 day continued to perform well after translocation and had the highest level of reproductive output after the voyage scenarios (Chapter Four). Recruits that were older (32-days) and reproductively mature at the commencement of the scenarios failed to release any propagules. Even though the number of ‘at sea’ and ‘port residency’ days were equal, reproductive output was higher after short and frequent voyages than after long and infrequent voyages. Finally, the study presented in Chapter Five examined transgenerational effects of B. nertina. Results showed that although the environmental history of the parent colony had a carry-over effect on offspring performance, it was the offspring environment that was a stronger determinant of success (measured by reproductive output and growth). Although cross-vector spread is possible (i.e. parent and offspring both fouling an active vessel), offspring released from a hull fouling parent into a recipient environment will perform better. In combination, these studies have provided new insights into NIS transport via vessel biofouling. Although shipping pathways are dynamic and complex, these results suggest that juvenile stages that recruit over short residency periods and are then translocated on short voyages, may pose a higher risk for NIS introduction than originally assumed. This has implications for marine biosecurity management as short residency periods are common and short, frequent voyages are typical of domestic vessel movements which are largely unmanaged.

Dissertação de Mestrado em Ecologia apresentada à Faculdade de Ciências e Tecnologia
Non-indigenous species (NIS) can be defined as species that colonized new geographical areas where they were not present previously. Their increasing appearance has been causing considerable ecological and economic problems globally. Under this scope, biological invasion and invaders’ success has been an important topic during the last decades. Hundreds of marine NIS have been introduced around the world and seaweeds (marine macroalgae) are a significant part of them. Studies conducted worldwide in the last decade have been reporting around 250 species of introduced seaweeds. The northeast part of the Atlantic is especially known to be home to many introduced species and more than 100 introduced species of seaweeds are reported in Europe. This thesis will go through the processes of seaweeds invasion, from their introduction stage and their introduction vectors, to their invasive success, focusing on the main NIS of seaweeds that can be currently found at the northwest of the Iberian Peninsula. Particularly, six NIS of seaweeds (Sargassum muticum, Grateloupia turuturu, Asparagopsis armata (including Falkenbergia rufolanosa stage), Undaria pinnatifida, Codium fragile spp. fragile and Colpomenia peregrina) were previously selected and sampled – based on DAFOR (Dominant, Abundant, Frequent, Occasional or Rare) cover ranges scale – along intertidal sites located within the northwest of the Iberian Peninsula. As a result of the sampling, the distribution of those seaweeds has been updated for the area, producing a hotspot map of their presence and relative abundance. Furthermore, the environmental management of NIS was addressed, as well as their potential uses such as biofertilizers, bioactivities, feed and food, aiming to show how these species, which are jeopardizing the ecosystem, can be an excellent environmental resource of bioactive compounds with high industrial potential and high socio-economic revenue.
As espécies não nativas (ENN) podem ser definidas como espécies que colonizaram novas áreas geográficas onde não estavam presentes anteriormente. O seu crescente aparecimento tem causado consideráveis problemas ecológicos e económicos a nível mundial. Neste âmbito, a invasão biológica e o sucesso dessas invasões tem sido um tema importante nas últimas décadas. Centenas de ENN marinhas têm sido introduzidas em todo o mundo e macroalgas marinhas são uma parte significativa delas. Estudos realizados em todo o mundo na última década têm relatado cerca de 250 espécies de macroalgas introduzidas. O nordeste do Oceano Atlântico é especialmente conhecido por albergar muitas espécies introduzidas e mais de 100 espécies de macroalgas introduzidas são relatadas na Europa. Esta tese considerará os processos de invasão de macroalgas, desde a fase de introdução e de seus vectores de introdução, ao seu sucesso invasivo, com foco nas principais ENN de macroalgas que podem ser encontradas no noroeste da Península Ibérica. Particularmente, seis ENN de macroalgas (Sargassum muticum, Grateloupia turuturu, Asparagopsis armata (incluindo a sua fase Falkenbergia rufolanosa), Undaria pinnatifida, Codium fragile spp. fragile e Colpomenia peregrina) foram previamente seleccionadas e amostradas - com base na escala de cobertura DAFOR (Dominante, Abundante, Frequente, Ocasional ou Rara) – no espaço entre marés e ao longo de praias localizadas no noroeste da Península Ibérica. Como resultado da amostragem, a distribuição dessas macroalgas foi atualizada para a área de estudo, produzindo um mapa da sua presença e abundância relativa. Além disso, a gestão ambiental das ENN foi abordada, bem como seus potenciais usos, nomeadamente como biofertilizantes, alimentos, rações, compostos bioactivos, com o objectivo de mostrar como essas espécies, que estão comprometendo o ecossistema, podem ser um excelente recurso ambiental de compostos bioativos com alta potencial industrial e alta receita socioeconómica.

An average of three to five billion tons of ballast water (BW) is transported globally per year; 79 million tons of which is released into U. S. waters. Ballast water is necessary for large ships to maintain balance and stability while loading and unloading cargo as well as during transit. As a ship unloads it’s cargo at a port, it takes on ballast water and then when it loads cargo at the next port, it discharges the ballast water, thus transferring water from port to port. Aquatic organisms are transported around the globe via ballast water. These organisms can potentially cause serious environmental and human health impacts. Historically, transfer of macro-organisms such as fish, snails, and vascular plants via ballast water have been the focus of ballast water research. More recently, microorganisms such as toxin producing dinoflagellates and diatoms i.e. ‘harmful algal blooms’ and pathogenic bacteria (e.g. Vibrio cholerae), have been found to survive in ballast tanks for several weeks. These organisms have moved to the forefront of ballast water management (BWM) trepidations because they compose serious threats to human health as well as Marine Protected Area (MPA) ecosystems such as coral reefs. Ballasting activities of ships calling at the Port of Houston were used as a model for other major ports in U.S. Gulf States. Ballast water management reports, submitted to the U.S. Coast Guard by all overseas vessels calling at the Port of Houston in 2010 were examined for the ballast management strategies utilized prior to docking. Currently, all “coastwise” ships are not required to conduct ballast water exchanges (BWE) if they do not transit beyond the 200nm EEZ. Close inspection of BW management report forms for “overseas” ships determined that the degree of completeness was variable. By comparing the frequency of vessels entering the Port of Houston, ballast water capacities, the management types utilized, and the locations of ballast water exchanges and discharges, it can be concluded that larger vessels present the highest risk of bacterial transfer to coral reefs. Five coral diseases were discovered to be prevalent throughout the ballast management areas their presence has significantly increased in these areas over the past thirty years. The combination of this disease growth along with an increase in shipping and ballast exchanges suggests that the vector at which pathogens are being displaced must lie within the shipping lanes.

The simultaneous increase in biological invasions and habitat alteration through the building of coastal infrastructure is playing an important role in reshaping the composition and functioning of nearshore marine ecosystems. This thesis examined patterns of marine invasions across anthropogenic and natural habitats and explored some of the processes that influence establishment and spread of invaders. The goals of this thesis were four-fold. First, I examined the habitat distribution of marine nonindigenous species (NIS) spanning several taxonomic groups and geographical regions. Second, I conducted systematic subtidal surveys in anthropogenic and natural habitats and investigated the distribution of nonindigenous ascidians on Southern Vancouver Island, British Columbia, Canada. Third, I tested methods for in-situ larval inoculations and utilized these techniques to manipulate propagule supply and assess post-settlement mortality of ascidians across habitat types. Fourth, I investigated the role of biotic resistance, through predation by native species, on the survival of ascidian colonies in anthropogenic and natural habitats. Results from this research showed that anthropogenic habitats are hubs for marine invasions and may provide beachheads for the infiltration of nearby natural sites. Specifically, a literature review of global scope showed that most NIS are associated with anthropogenic habitats, but this pattern varied by taxonomic group. Most algal and mobile invertebrate NIS were reported from natural habitats, while most sessile NIS were reported from artificial structures. Subtidal field surveys across both anthropogenic and natural habitats showed that nonindigenous ascidians were restricted largely to artificial structures on Southern Vancouver Island and that this pattern is consistent across their global introduced ranges. Field manipulations using the ascidian Botrylloides violaceus as a model organism, showed that post-settlement mortality is high and that large numbers of larvae or frequent introduction events may be needed for successful initial invasion and successful infiltration of natural habitats. Experiments also showed that predation by native species can limit the survival of B. violaceus in anthropogenic and natural habitats. This dissertation contributes knowledge about the patterns and processes associated with habitat invisibility; provides insight into factors affecting colonization; and supplies valuable information for predicting and managing invasions.
Graduate
0329

Chondrichthyans—sharks, rays, skates, and chimaeras—influence top down control of food webs and connect disparate ecosystems, yet populations of many species around the world have experienced sharp declines in abundance. Marine protected areas (MPAs) have a long history of conserving marine biodiversity, but their effectiveness to protect representative and critical habitat for threatened species on a global scale is controversial and hindered by a lack of biological and ecological data for the majority of chondrichthyan species. In this thesis, I use non-invasive baited remote underwater video (BRUV) and citizen science diver data to explore diverse chondrichthyan communities in two countries, South Africa and Costa Rica, with data-poor chondrichthyan fisheries and limit conservation funding, and the relationships of these chondrichthyans to biotic and abiotic factors in their habitats in and around MPAs. First, through a literature review, I find substantial taxonomic and geographic biases in understanding of reef shark biology, ecology, and conservation, which impair ability to implement effective conservation measures for these species. After identifying these research gaps, I used BRUVs to explore the diversity of a chondrichthyan hotspot in South Africa, finding many poorly understood endemic chondrichthyans. I discovered strong associations of the chondricthyan community to different habitat types (sand versus reef and kelp habitat), which resulted in poor diversity within one of the region’s larger MPAs—a whale sanctuary whose focus on large charismatic whales left mostly poorer quality sand habitat protected. However, a high occurrence of chondrichthyans within a neighbouring MPA suggested even small MPAs can conserve a high abundance of smaller species, especially if residency can be demonstrated. I then used the BRUV data to examine the relationships amongst these chondrichthyans and the community of other marine animals within the region, finding strong co-occurrence patterns that suggest chondrichthyans, particularly the endemic catsharks, could serve as effective ‘umbrella’ species for conservation in this region where little other information is available for conservation planning and monitoring. Finally, at Cocos Island, an MPA off Costa Rica, I discovered similarly strong, species-specific associations to another aspect of habitat: temperature. I found significant and species-specific responses to the El Niño–Southern Oscillation (ENSO). For example, the scalloped hammerhead Sphryna lewini counts declined by 224.7% during strong El Niño conditions and by 14.7% with just a 1°C rise in SST, while the benthic whitetip reef shark Triaenodon obesus had a weaker response, dropping by only 7.9% and 4.4%, respectively. In general, strong El Niño events reduced sightings within the MPA, providing some of the first indications of how a rising frequency and intensity of these events will impact the spatial distribution of both chondrichthyans and their habitat in the Eastern Tropical Pacific. Overall, this thesis provides insight into the factors influencing chondrichthyan abundance and diversity, demonstrating the importance of considering both biotic and abiotic factors during MPA design and the need to study these factors across diverse taxonomic groups and ecosystems.
Graduate
2021-05-08

Marine invasive species are widely recognized as one of the worst threats to marine ecosystems integrity, unbalancing native communities, which may lead to paramount ecological and economic impacts. Within seaweeds, Sargassum muticum and Asparagopsis armata are recognized as successful invaders in Europe and America. Despite several attempts to control the spread of marine invaders, until now, all have proven to be elusive, and therefore, alternative strategies should be embraced. Worldwide, seaweeds have been increasingly explored due to their ability to produce bioactive compounds. However, one of the main problems associated with the production/extraction of these bioactive compounds for new products development, is the scarce availability of target species and the potential negative environmental consequences of their exploitation. Accordingly, the use of invasive species to obtain natural bioactive compounds presents us with a two-folded opportunity - high availability of the biological material for the extraction of unique bioactive compounds for new products development, and through specimen collection, the mitigation of the negative effects caused by alien species, contributing to ecosystem integrity and sustainability. Within this framework, the present work aimed to evaluate the antioxidant, antimicrobial, and antifouling properties of these seaweed extracts, as well as the concentration of the bioactive compounds by chromatographic and spectroscopic means. In addition, the mechanisms of action possibly involved in the most potent antioxidant and antimicrobial activities were also studied. The antioxidant capacity was estimated through the quantification of the total phenolic content (TPC) and by evaluating the scavenging properties through the 1,1-diphenyl-2-picryl-hydrazyl (DPPH) and oxygen radical absorbance capacity (ORAC) assays. The antimicrobial potential was evaluated on Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans, Escherichia coli, and Salmonella enteritidis through growth inhibition analysis. The antifouling properties of both seaweed was evaluated on the growth inhibition of nine microalgae growth, namely Tetraselmis suecica, Tetraselmis chui, Thalassiosira weissflogii, Chaetoceros calcitrans, Cylindrotheca closterium, Nannochloropsis oculata, Phaeodactylum tricornutum, Isocrysis galbana, Nannochloropsis gaditana, and 5 marine microorganisms, namely Vibrio anguillarum, Photobacterium damselae ssp. piscicida, Aeromonas hydrophila, Aeromonas aquariorum, and Edwardsiella tarda. The biofilm inhibitory capacity was tested on Vibrio parahaemolyticus and Bacillus subtilis. Within this framework a new model to evaluate the anti-adherence properties of seaweed extracts on the marine invertebrates Aurelia aurita and Phyllorhiza punctata polyps is also proposed. Sargassum muticum revealed to contain compounds with high antioxidant potential exhibiting cytoprotective properties in oxidative stress conditions, which can be related with the reduction of hydrogen peroxide production and apoptosis blocking. A. armata revealed to produce compounds with high antimicrobial potential with a broad-spectrum activity and with potential to interfere in bacterial biofilms development. Results suggest that the antimicrobial activity may be linked to microorganisms cytoplasmatic membrane damage and DNA damage. Both, Sargassum muticum and Asparagopis armata presented relevant antifouling potential. This property was the most expressive on both seaweed crude extracts, which revealed high anti-algae effects, antibacterial and anti-adherence properties. The present work shows that the potential of both seaweeds to provide valuable compounds is enormous, pointing therefore to an opportunity for sustainable development with high economic benefits. In marine natural products research and development, one of the main bottlenecks for further industrial applications is the scarcity of the biological target and the negative impact that is associated with its collection from the ecosystem. Since Asparagopsis armata and Sargassum muticum are successful invaders and occur in great amount in Portugal and many other coasts of the world, their collection could contribute for marine ecosystem restoration and equilibrium by means of profitable harvesting for a high revenue industry, turning a threat into a major socio-economic opportunity.
As espécies invasoras marinhas são uma das principais ameaças à integridade dos ecossistemas marinhos, promovendo um desequilíbrio nas comunidades nativas, resultando em sérios impactos ecológicos e económicos. Entre as algas marinhas, a Sargassum muticum e a Asparagopsis armata são reconhecidas como invasoras de sucesso na Europa e América. Apesar de já terem sido efetuadas várias tentativas para controlar o avanço de invasores marinhos, nenhuma provou ser efetivamente eficaz, sendo, portanto, necessário desenvolver estratégias alternativas. Nas últimas décadas as algas marinhas têm sido estudadas devido às suas múltiplas propriedades biológicas. No entanto, um dos principais problemas associados à exploração destes componentes bioativos prende-se com a abundância de matéria prima que, na maioria dos casos, é escassa e sazonal, resultando a sua exploração em sérios danos ecológicos. Neste contexto, a exploração de organismos invasores marinhos oferece-nos uma dupla oportunidade – elevada disponibilidade do material biológico para extração de compostos bioativos com características únicas com vista ao desenvolvimento de novos produtos, e, por outro lado, através da sua recolha, a mitigação dos efeitos negativos provocados pela sua invasão, contribuindo deste modo para a integridade e sustentabilidade do ecossistema marinho. Neste contexto, o presente trabalho pretendeu avaliar o potencial antioxidante, antimicrobiano e anti-incrustante de extratos destas duas algas invasoras, bem como a quantificação e caracterização química dos compostos bioativos através de técnicas cromatográficas e espetroscópicas. Em acréscimo, foram também estudados os mecanismos de ação envolvidos nas bioatividades mais potentes. As propriedades antioxidantes foram avaliadas através da determinação do conteúdo total em polifenóis (TPC), da capacidade de destoxificação do radical 1,1-difenil-2-picril-hidrazil (DPPH) e da avaliação da capacidade de absorção do radical oxigénio (ORAC). A atividade antimicrobiana foi avaliada em Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans, Escherichia coli e Salmonella enteritidis, através da análise da inibição do seu crescimento. Neste âmbito, foi também avaliado o potencial de inibição de produção de biofilmes em Pseudomonas aeruginosa. As propriedades anti-incrustantes foram avaliadas através da análise da capacidade de inibição do crescimento de nove microalgas, nomeadamente Tetraselmis suecica, Tetraselmis chui, Thalassiosira weissflogii, Chaetoceros calcitrans, Cylindrotheca closterium, Nannochloropsis oculata, Phaeodactylum tricornutum, Isocrysis galbana, Nannochloropsis gaditana e em cinco microrganismos marinhos, nomeadamente Vibrio anguillarum, Photobacterium damselae ssp. piscicida, Aeromonas hydrophila, Aeromonas aquariorum e Edwardsiella tarda. Foi também testado o potencial dos extratos e das frações de ambas as algas na inibição da produção de biofilmes nos microorganismos Vibrio parahaemolyticus e Bacillus subtilis. Também no âmbito do potencial anti-incrustante foi proposto um novo modelo para avaliar as propriedades de anti-aderência dos extratos em pólipos de medusas, nomeadamente de Aurelia aurita e Phyllorhiza punctata. De uma forma geral, Sargassum muticum revelou ser a alga com maior potencial antioxidante, revelando propriedades citoprotetoras em condições de stress oxidativo que poderão estar relacionadas com a redução da produção de peróxido de hidrogénio e com bloqueio do processo apoptótico. Por outro lado, a alga Asparagopsis armata revelou o maior potencial antimicrobiano com um largo-espectro de atividade e com capacidade para inibir o desenvolvimento de biofilmes bacterianos. A ação antimicrobiana parece estar relacionada com danos na membrana citoplasmática e danos no ADN. Ambas as algas apresentam potencial anti-incrustante. Esta bioatividade foi mais evidente nos extratos brutos de ambas as algas, tendo-se verificado propriedades anti-algais, anti-bacterianas e de anti-aderência. Demonstra-se nesta investigação que ambas as algas apresentam propriedades bioativas relevantes com elevado potencial para serem usadas no desenvolvimento sustentável de novos produtos, resultando em benefícios económicos importantes. Por outro lado, na pesquisa de produtos naturais marinhos, um dos principais obstáculos para o desenvolvimento industrial de novos produtos prende-se com a escassez da matéria prima e os impactos ambientais negativos inerentes à recolha do material biológico. Neste contexto, as algas Sargassum muticum e Asparagopsis armata são invasores que ocorrem em abundância, não só na costa Portuguesa, mas em praticamente todo o mundo e, portanto, a sua recolha do meio ambiente para a exploração industrial dos seus compostos bioativos contribuirá para a restauração e equilíbrio do ecossistema marinho, transformando uma ameaça ambiental numa grande oportunidade sócio-económica.
Programa Doutoral em Ciência, Tecnologia e Gestão do Mar

The introduction of invasive species has been increasing with globalization and is recognized as one of the main threats to the oceans and the second cause of biodiversity loss. The red alga Asparagopsis armata exhibits a strong invasive behavior inducing significant changes in the invaded community. The study of the impact of this invasive on ecologically relevant species is crucial for risk assessment. Assessing sub-organismal endpoints may therefore provide early indicators of A. armata exposure and their possible impacts on natural populations. The results emphasize the importance of considering specific (biomarkers) as well as more generalized and ecologically related in situ responses to identify and evaluate biological effects of A. armata in the field. To validate the fatty acid profile (FAP) tool, the marine snail G. umbilicalis was exposed to three metals: cadmium, nickel and mercury, and the total lipid content, lipid peroxidation and FAP were measured. The FAP analysis suggested a change in fatty acid metabolism and indicated a link between exposure to metals and homeoviscous adaptation and immune response. In particular, five fatty acids (palmitic, eicosatrienoic, arachidonic, eicosapentaenoic, and docosahexaenoic acids) proved to be good indicators of the responses of G. umbilicalis to the metals used, thus having the potential to be used as biomarkers for contamination by metals in this species. In the continued use of this species, there was also a need to characterize it biochemically. To assess the different enzymatic forms present in the sea snail, different substrates and selective inhibitors were used. Additionally, in vitro and in vivo effects of the pesticide chlorpyrifos (CPF) on AChE activity were investigated, along with effects on snails' behaviour. The results obtained showed that G. umbilicalis has cholinesterases with characteristics of AChE. In addition, CPF inhibited AChE activity both in vitro and in vivo conditions, and AChE inhibition was positively correlated with flipping test. To understand the mechanisms of toxicity of the invasive A. armata, lethal and sublethal effects of A. armata were investigated and biochemical biomarkers responses associated with energy metabolism were analyzed.Results showed invertebrates’ physiological status impairment after exposure to this algae exudate. Highest concentrations of exudate significantly increased lipid content in both organisms. In the shrimp, protein content, ETS, and LDH were also significantly increased. On the contrary, these parameters were significantly decreased in G. umbilicalis. Behavioural impairments were observed in G. umbilicalis exposed to A. armata exudate, with reduction in feeding consumption and increased flipping time. Antioxidant defences, oxidative damage and neuronal parameter as well as the fatty acid profile were evaluated after exposure to A. armata exudate. Results revealed different metabolic responses between species, indicating that A. armata exudate affected the organisms through different pathways. Despite previous studies indicating that the exudate effected G. umbilicalis’ survival and behaviour, this does not seem to result from oxidative stress or addressed neurotoxicity. For P. elegans, an inhibition of AChE and the decrease of antioxidant capacity with the increase of LPO, suggests neurotoxicity and oxidative stress as mechanisms of exudate toxicity for this species. For fatty acids, there were differences more pronounced for P. elegans with a general increase in PUFA, which commonly means a defence mechanism protecting from membrane disruption. Omega-3 PUFAs ARA and DPA were increased in both invertebrates. To evaluate the effects of this invasive in a more realistic scenario, Variations on native intertidal seaweed and macroinvertebrate assemblages inhabiting rock pools with and without the presence of the invasive macroalgae A. armata were assess. Results showed different patterns in the macroalgae composition of assemblages but not for the macrobenthic communities. Ellisolandia elongata was the main algal species affected by the invasion of A. armata. Invaded pools tended to show less species richness, showing a more constant and conservative structure, with lower variation of its taxonomic composition than the pools not containing A. armata. This work relied on the ecotoxicological and ecological information to provide insight in how A. armata affects specific invertebrates and in general coastal communities, embracing methods at different biological organization levels which prepare the way for various hypotheses testing in assessing Asparagopsis armata exudates toxicity. The analyses of biochemical biomarkers contribute to the knowledge of the sub lethal effects and ecological impacts on communities. Thus, aiding the comprehensive understanding of the mechanisms that lead to higher level responses.
A introdução de espécies invasoras tem aumentado com a globalização e é reconhecida como uma das principais ameaças aos oceanos e a segunda causa da perda de biodiversidade. A alga vermelha Asparagopsis armata exibe um forte comportamento invasor induzindo mudanças significativas na comunidade invadida. O estudo do impacto desta invasora em espécies ecologicamente relevantes é crucial para a avaliação de risco. A avaliação de parâmetros ao nível suborganismal pode, portanto, fornecer indicadores precoces da exposição de A. armata e seus possíveis impactos nas populações naturais. Os resultados enfatizam a importância de se considerar respostas específicas in situ (biomarcadores), bem como respostas mais generalizadas e ecologicamente relacionadas, para identificar e avaliar os efeitos biológicos de A. armata no campo. Para validar a ferramenta de perfil de ácidos gordos (PAG), o caracol marinho G. umbilicalis foi exposto a três metais: cádmio, níquel e mercúrio, e mediu-se o teor de lipídios totais, peroxidação lipídica e PAG. A análise PAG sugeriu uma mudança no metabolismo dos ácidos gordos e indicou uma ligação entre a exposição a metais e adaptação homeoviscosa e resposta imune. Em particular, cinco ácidos gordos (ácidos palmítico, eicosatrienóico, araquidónico, eicosapentaenóico e docosahexaenóico) mostraram-se bons indicadores das respostas de G. umbilicalis aos metais utilizados, tendo, portanto, potencial para serem utilizados como biomarcadores de contaminação por metais em esta espécie. No uso continuado desta espécie, houve também a necessidade de a caracterizar bioquimicamente. Para avaliar as diferentes formas enzimáticas presentes no caracol marinho, foram utilizados diferentes substratos e inibidores seletivos. Além disso, os efeitos in vitro e in vivo do pesticida clorpirifos (CPF) sobre a atividade da AChE foram investigados, juntamente com os efeitos sobre o comportamento de caracóis. Os resultados obtidos mostraram que G. umbilicalis possui colinesterases com características de AChE. Além disso, o CPF inibiu a atividade da AChE tanto in vitro quanto in vivo, e a inibição da AChE foi positivamente correlacionada com o teste de viragem. Para compreender os mecanismos de toxicidade da invasora A. armata, os efeitos letais e subletais de A. armata foram investigados e as respostas de biomarcadores bioquímicos associadas ao metabolismo energético foram analisadas. Os resultados mostraram comprometimento do estado fisiológico dos invertebrados após a exposição a este exsuda do de algas. As concentrações mais altas de exsuda do aumentaram significativamente o conteúdo de l í pidos em ambos os organismos. No camarão, o teor de proteína, ETS e LDH também aumentaram significativamente. Ao contrário, esses parâmetros diminuíram significativamente em G. umbilicalis. Efeitos comportamentais foram observados em G. umbilicalis exposto ao exsuda do de A. armata, com redução no consumo de alimento e aumento do tempo de viragem. As defesas antioxidantes, dano oxidativo e parâmetro neuronal, bem como o perfil de ácidos gordos foram avaliados após exposição ao exsuda do de A. armata. Os resultados revelaram diferentes respostas metabólicas entre as espécies, indicando que o exsuda do de A. armata afetou os organismos por diferentes vias. Apesar de estudos anteriores indicarem que o exsuda do afetou a sobrevivência e o comportamento de G. umbilicalis, isso não parece resultar de stress oxidativo ou neurotoxicidade direcionada. Para P. elegans, a inibição da AChE e a diminuição da capacidade antioxidante com o aumento da LPO, sugere neurotoxicidade e stress oxidativo como mecanismos de toxicidade do exsudado para esta espécie. Para os ácidos gordos, houve diferenças mais pronunciadas para P. elegans com um aumento geral de PUFA, o que comumente significa um mecanismo de defesa que protege da ruptura da membrana. PUFAs ómega -3 ARA e DPA foram aumentados em ambos os invertebrados. Para avaliar os efeitos desse invasor em um cenário mais realista, foram avaliadas as variações nas comunidades nativas de algas marinhas intertidais e macroinvertebrados habitando poças rochosas com e sem a presença da macroalga invasora A. armata. Os resultados mostraram diferentes padrões na composição de macroalgas das comunidades, mas não para as comunidades macrobentónicas. Ellisolandia elongata foi a principal espécie de algas afetada pela invasão de A. armata. As poças invadid as tenderam a apresentar menor riqueza de espécies, apresentando uma estrutura mais constante e conservadora, com menor variação de sua composição taxonómica do que as poças sem A. armata. Este trabalho baseou -se na informação ecotoxicológica e ecológica para fornecer uma visão de como A. armata afeta invertebrados específicos e em comunidades costeiras no geral, abrangendo métodos em diferentes níveis de organização biológica que preparam o caminho para o teste de várias hipóteses na avaliação da toxicidade do exsudado de Asparagopsis armata. As análises de biomarcadores bioquímicos contribuem para o conhecimento dos efeitos subletais e impactos ecológicos nas comunidades. Auxiliando assim na compreensão abrangente dos mecanismos que levam a respostas de nível superior.
Programa Doutoral em Ciência, Tecnologia e Gestão do Mar

This thesis examines the contribution of a non-indigenous red alga, Mazzaella japonica, to wrack subsidies in Baynes Sound, British Columbia, and the effects of its removal by a commercial beach-cast harvest. Field and laboratory work was conducted to determine: 1) How large wrack inputs are in terms of biomass and spatial extent within the harvest region, and what proportion of this is comprised of M. japonica; 2) how wrack characteristics influence associated macrofauna communities; 3) if there is any detectable effect of beach-cast harvesting on either the wrack characteristics or macrofauna communities; and 4) if M. japonica provides a food source for native invertebrate consumers within the subtidal and supralittoral zones. Field surveys conducted from November 2014 through March 2015 found that wrack biomass within the harvest region could reach as much as 853 kg (±173 SD) per meter of shoreline, and cover up to 35 m2 (± 3 SD) of beach surface within this area. The macrophyte composition of the wrack was dominated by M. japonica, which accounted for 90% of the identifiable macrophyte biomass on average. Wrack in the later stages of decomposition hosted the most speciose and diverse assemblages of macrofauna, though community composition also differed among collection sites and with depth of the wrack. Though we were limited in our ability to disentangle the effects of beach-cast harvesting due to a concentration of effort at one site, we failed to detect any large influence on wrack biomass or macrofauna communities. Harvesting does, however, appear to be associated with a greater area of wrack cover and decreased mean depth. Stable isotope mixing models estimated that M. japonica contributed no more than 22% and 17% on average to the diets of supralittoral and subtidal consumers respectively, despite its overwhelming dominance in both environments. These results suggest that the non-indigenous red alga may experience a reprieve from herbivory within the subtidal environment. A lack of consumption within the supralittoral zone could influence nutrient cycling on recipient beaches and increase propagule pressure in the surrounding regions. Results from these studies are intended to help inform the management of M. japonica and its commercial harvesting. Combined, they indicate that this non-indigenous seaweed does not provide a substantial subsidy in the form of food provision for resident invertebrates. Furthermore, the commercial removal of M. japonica is small compared to the total biomass available, and had no detectable effect on the wrack-associated macrofauna communities examined.
Graduate
2017-08-19
jjulin.holden@gmail.com