Dissertations / Theses on the topic 'Subtidal communities'

This thesis is concerned with the contrasting communities that occur in the subtidal zones of two closely situated islands in Saldanha Bay on the west coast of South Africa: Both are guano islands, supporting substantial populations of seabirds. They have a similar bottom topography and experience similar physical conditions. Despite these similarities their subtidal benthic communities are however, radically different. Marcus Island has prolific beds of the black mussel Choromytilus meridionalis, accompanied by a large number of other species, notably the sea urchin Parechinus angulosus, the holothurians Pentacta doliolum, Thyone aurea and Trachythyone insolens, large population of whelks, mostly Burnupena spp. and the barnacles Austromegabalanus cylindricus and Notomegabalanus algicola. In contrast, Malgas Island is dominated by a large population of the rock lobster Jasus lalandii together with a dense seaweed flora, and has small numbers of the ribbed mussel Aulacomya ater and the whelks Argobuccinum pustulosum and Burnupena papyracea.

Includes bibliographical references (leaves 50-57).
The South African abalone Haliotis midae is a commercially exploited species that is seriously threatened by overfishing and poaching. This not only affects the species itself but also the integrity and functionng of the ecosystem through associated changes in community structure. I assessed the influence of abalone on the ecosystem by a combination of (a) dietary studies, (b) comparisons of communities living on shell versus surrounding rock substratum, and (c) removal experiments using field exclusion/inclusion plots.

Thesis (Ph.D.)--University of Massachusetts Boston, 2005.
Title from PDF title page. Available through UMI ProQuest Digital Dissertations. Includes bibliographical references (p. 82-102). Also issued in print.

Includes bibliographical references (leaves 84-92).
Several aspects of seaweed ecology are poorly studied and documented in South Africa, especially the subtidal algal communities along the south coast. This study aims to investigate these communities where few other studies have been conducted. Sampling of shallow subtidal seaweed communities was undertaken at eleven sites along the south coast of South Africa from Still Bay to Mzamba. At each site a number of quadrats were placed within the shallow subtidal zone ranging in depth from O.3m to 2.5m. Within these quadrats all algae were destructively sampled (excluding encrusting algae), invertebrate grazers present were counted, and environmental measurements were taken. These environmental measurements included depth and slope, with temperature data supplied from a previous study. The biogeographical communities of this area were investigated using Detrended Correspondence Analysis, Canonical Correspondence Analysis and cluster analysis, in order to compare them with previous studies on the marine biogeography of the area. In the 85 quadrats that were sampled, 97 species of Chlorophyta, Phaeophyta and Rhodophyta were found. Articulated (or geniculate) coralline red algae were very abundant in the samples, with 17 species that contributed over 44 of the biomass. There was a high number of other red algal species (54 species) but they represented only 10 of the total biomass. Green algal species were not very common (there were only 12 species) but they contributed 42 to the biomass. There were a similar number of brown algal species (14), although they only contributed 2 of the total biomass.

Sessile marine invertebrate larvae can recognize suitable settlement substrata by using various environmental cues, including organic/microbial "biofilms". In laboratory assays the effect of biofilm age on the settlement of a range of fouling species was assessed: the species included barnacle, bryozoan, spirorbin and ascidian larvae. The larvae of most species responded differentially to films of varying ages. A general trend of reversal of the effect of filming on the settlement response of the barnacle Balanus amphitrite amphitrite- from inhibitory to facilitatory - was noted with increasing film age. The settlement of the solitary ascidian Ciona intestinalis clearly was facilitated on filmed substrata of all ages. The larvae of the arborescent bryozoan Bugula flabellata generally were inhibited by biofilming (irrespective of film age), and the settlement of the polychaete Spirorbis spirorbis was found to be enhanced on "older" (12d) films only. In a series of manipulative panel experiments in a tidal rapid on the west coast of Scotland the effects of biofilming on subsequent larval settlement in the field were quantified. Inhibitory and facilitatory responses to biofilming were noted and these varied markedly between species and between two local habitats of contrasting flow regimes. The larvae of certain year-round settling species were found to vary in their response to biofilmed substrata depending on the season. Quantitative data were obtained for biofilms on artificial substrata by enumerating bacteria, diatoms, protozoans, fungi and the percent cover of microbial exopolymeric substances. These permitted comparisons of biofilms both in field and laboratory experiments. The results of the present study emphasize the importance of microbial surface film cues in explaining recruitment patterns of macrofouling assemblages during the first stages of substratum colonization.

Includes bibliographical references (p. 209-274).
The biogeography and ecology of benthic shallow subtidal reef communities in the western Indian Ocean is poorly known, particularly in north-eastern South Africa and southern Mozambique. This thesis uses quantitative information to resolve biogeographic patterns, define reef community types, elucidate potential abiotic determinants of community composition, and evaluate whether subsidies of riverine-derived particulate organic matter (POM) support filter-feeder biomass and drive biogeographic patterns. A large-scale biogeographic analysis was conducted using quantitative biomass data derived from 55 shallow subtidal reefs spanning five countries in the western Indian Ocean. Two statistically distinct marine provinces, Tropical Indo-West Pacific and Subtropical Natal, were recognised by differences in community composition and separated by a biogeographic break in the vicinity of Cape Vidal, South Africa. The biogeographic break took the form of a transitional or overlap area corresponding in location to the Delagoa Bioregion, one of three bioregions also revealed by post-hoc analyses. Significant differences in total average biomass and trophic structure were evident among bioregions, with a number of inter-bioregional trends in trophic groups being apparent. In total, 12 reef community types were recognised, based on similarity profile permutation tests. Most reefs in the Subtropical Natal Bioregion were dominated by a community type characterised by a high biomass of the filter-feeding ascidian Pyura stolonifera and various species of articulated coralline algae. In the Delagoa Overlap Bioregion, a comparatively high diversity of community types was defined, many dominated by algal turf, P. stoloniferaand various Alcyonacea and Scleractinia. Further north, P. stolonifera diminished and the contributions of Scleractinia, especially Porites spp., Pocilloporaspp. and Galaxea spp. increased. Many of these community types are not represented within protected area networks, particularly those in southern Mozambique. When the biomass data were correlated with nine abiotic variables, likely determinants of community composition emerged at both inter- and intra-regional scales. Sea surface temperature, significant wave height, chlorophyll-a and suspended inorganic sediment were the variables highly correlated with community composition and therefore most likely to drive biogeographic differences. Within each bioregion, different sets of abiotic variables were found to be important in driving community differences among sites, including turbidity, chlorophyll-a, reef susceptibility to sand inundation, reef heterogeneity and sea surface temperature. Striking differences in the oceanographic conditions of bioregions were evident, especially between Subtropical Natal and Delagoa Overlap bioregions. In particular, the strong influence of wave height emerged as a novel and unexpected correlate at a biogeographic scale. These differences initiated a trophic study conducted in the Subtropical Natal Bioregion, aimed at determining the importance of riverine-derived POM subsidies in supporting the high filter-feeder biomass in this bioregion. Using carbon, nitrogen and sulphur isotopes and a three-source Bayesian mixing model to calculate proportional contributions, I determined that marine-derived POM formed the bulk of the diets of four species of filter-feeders, but the assimilation of riverine-derived POM was nevertheless notable, ranging from 8 to 33 %. I concluded that riverine POM is likely to play an important but secondary role to factors such as increased levels of turbidity and productivity in explaining the high filter-feeder biomass in the Subtropical Natal Bioregion. These findings provide the first evidence of riverine-inshore-pelagic coupling in filterfeeder communities in this bioregion, and throw light on the factors linked to large-scale biogeographic patterns.

Shallow subtidal epibenthic communities worldwide are under threat from exploitation, pollution, eutrophication, acidification, climate change, and invasive species, with implications for ecosystem diversity, productivity, function, and services. Subtidal ecosystems in the Gulf of Maine are particularly impacted, making it crucial to understand these habitats so that our impacts can be predicted and mitigated. I investigated the basic ecological forces that structure shallow subtidal epibenthic communities in this region, and how invasive species integrate themselves into these communities. I used community phylogenetic and functional trait analyses to investigate if invertebrate communities in the rocky subtidal are assembled via deterministic or random forces, experimental manipulations to quantify how macroalgae might influence sessile invertebrates on subtidal surfaces, and measurements of life history traits of Botrylloides violaceus, an invasive colonial ascidian, to estimate whether growth of this species differs among man-made versus natural habitats. Based on community phylogenetic analyses, rocky subtidal invertebrate communities appear to be structured by deterministic forces, with evidence for both competitive exclusion and environmental filtering operating at different spatial scales. These findings support existing studies that show that competition structures communities at local scales, and also expand our knowledge of the processes that act regionally, i.e. environmental filtering. On shallow sunlit experimental surfaces suspended from floating docks, macroalgae had little effect on invertebrate abundance or diversity, contrary to findings from experiments in the rocky subtidal. Macroalgae did influence composition as well as enhance invertebrate colonization in the early stages of community assembly. Different factors appear to influence the balance between heterotrophs and autotrophs in floating dock and rocky subtidal systems with implications for community structure, function and productivity. In different habitats, colonies of the invasive ascidian B. violaceus exhibited differences in life history traits. It grew faster and attained larger sizes in man-made floating dock versus natural rocky subtidal and eelgrass bed habitats. Again, differences among habitats appear to influence invasion success. In conclusion, competitive exclusion, facilitation, and environmental filtering play key roles in controlling the structure, composition, and function of shallow subtidal communities. Invasive species have the potential to disrupt these forces as they integrate themselves into man-made and subsequently natural habitats.

[Truncated abstract] The ecological effects of marine protected areas (MPAs) in temperate ecosystems are poorly understood relative to their tropical counterparts. The limited number of rigorous empirical studies supporting existing theoretical models, increasing public awareness of the importance of marine conservation strategies and legislative requirements to review management effectiveness provide further impetus to study temperate MPAs. Investigations should consider confounding effects of natural variability if MPA effects are to be clearly demonstrated. This research helps to address these needs by investigating the short term effects of sanctuary zones (no-take MPAs where fishing is prohibited) and wave exposure at Marmion Marine Park, Western Australia. The three sanctuary zones at Marmion Marine Park are extremely small (0.061 0.279 km2) compared to most reported in the literature. The sanctuary zones are nested within a larger, fished zone (94.95 km2). The sanctuary zones have been protected from fishing since the year 2000. A post-hoc, asymmetrical sampling design was used in this study and involved surveys of fishes, mobile invertebrates and macroalgae at one sanctuary zone and two fished sites (controls) at each of three successive, subtidal reef lines. The three reef lines are exposed to a gradient in wave energy. The size structure and abundance of the heavily exploited Panulirus cygnus (Western Rock Lobster) were positively affected by protection from fishing in sanctuary zones, despite the highly mobile nature of this migratory species. The mean abundance of legal size lobsters was higher in sanctuary zones compared to fished sites during an interannual study (2003, 2005 and 2006). The total abundance of lobsters and the mean abundance of legal size lobsters were higher at inshore and offshore sanctuary zones compared to fished control sites during a 2005/2006 fishing season study. These zoning effects did not vary with the time of survey. ... Furthermore, the abundance of large lobsters in sanctuary zones decreased with the duration of the 2005/2006 fishing season. Similarly, it is likely that sanctuary zones are too small relative to the movement of fishes to adequately protect stocks of some targeted species. The small sanctuary zones at Marmion are unlikely to offer protection to highly mobile species over the long term. And finally, ecological assemblages within each level of wave exposure are distinct. Consequently for each assemblage type, the current reserve design does not include replication of sanctuary zones and does not offer any 'insurance' in the event of isolated impacts affecting a particular zone. This study has identified the benefits and deficiencies of the design and function of small no-take temperate MPAs in Western Australia. An increase in the size and number of sanctuary zones within each wave exposure level will help to address the v shortfalls of the zoning scheme and enhance the conservation benefits of management at Marmion Marine Park. More generally, this study demonstrates that the mobility of the species to be protected from fishing should be considered when designing MPAs. Lessons learned from this work will be beneficial for the future management and conservation of resources in the region and elsewhere.

The subtidal seaweed communities of the KwaZulu-Natal coast are poorly understood. A recent collaborative research project between Belgian and South African phycologists, however, is currently investigating the diversity and biogeographical affinities of the marine benthic algal flora of this region. The newest leg of the project is focusing on correlating biogeographic patterns with abiotic factors in the area between the St. Lucia estuary and Sodwana Bay, where it has become evident that there is a huge turnover in species composition. The present study examines seaweed community change along a depth gradient (1-30 m depth) at Sodwana Bay on the KwaZulu-Natal (KZN) coast, South Africa. All seaweed cover within 25 x 25 cm quadrats was collected, identified and weighed. The environmental variables, depth and % sand cover, were also measured. Both biomass and presence/absence data were ordinated to show community differentiation related to the environmental variables. The seaweed communities are largely red turfs, with a total of 82 Rhodophyte, 14 Chlorophyte, and 8 Phaeophyte taxa recorded. These turf communities showed exceptional diversity with 105 taxa (>25 % of recorded KZN flora) occurring in the total sample area of 1.56m². Seaweed communities clearly change with depth, but the biggest change occurs between the shallow subtidal zone (approx 1 m depth) and deeper waters (>5 m depth), mostly likely due to the effects of wave action; thereafter communities do change with depth, but the effects are less pronounced. Biomass (p=0.049, significant) and seaweed diversity (p=0.078, not significant) were both shown to decrease, and % bare (seaweed-free) cover (p=0.002, significant) increased, with increasing depth. It is likely that these changes with increased depth can be attributed to the effects of increased light attenuation on ecological functioning in the subtidal communities. Sand inundation patterns are shown to be important in determining seaweed community structure, but do not appear to be predictable along a depth gradient (p=0.544, not significant).

A variabilidade espacial de densidade e composição de comunidades subtidais de meiofauna e nemátodes de vida livre foi estudada em dois estuários portugueses, Mira (costa sudoeste) e Mondego (costa oeste), sujeitos a diferentes pressões antropogénicas, ao longo do gradiente de salinidade (de <0.5 até> 3Opsu). Em ambos os estuários, os taxa Nematoda, Copepoda e Polychaeta dominaram as comunidades de meiofauna. Os padrões espaciais de densidade e composição das comunidades de meiofauna e nematodes refletiram o gradiente de salinidade, sendo influenciados por este fator de stress natural. Para além da salinidade, as propriedades do sedimento também influenciaram as comunidades e a diferença entre as respostas das comunidades ao stress antropogénico e natural não foram distinguidas. No entanto, a diferente composição trófica das comunidades de nematodes do Mira e Mondego está relacionada com a diferente pressão antropogénica sentida neste dois sistemas, que se sobrepôs ao efeito da salinidade, tendo sido possível detetar o efeito do stress antropogénico nestes estuários. Abstract: The spatial variations in density and composition of subtidal meiofauna and free-living Nematoda communities were analysed in two Portuguese estuaries, Mira (southwestern coast) and Mondego (western coast), that are subjected to different anthropogenic pressures, along the salinity gradients (from <0.5 to >30psu). ln both estuaries, meiofauna communities were characterized by the dominance of the taxa Nematoda, Copepoda and Polychaeta. The spatial paflems of density and composition of both meiofauna and Nematoda communities reflected the salinity gradient, being these assemblages structured and influenced by this natural stressor. Besides salinity, sediment properties also influenced the communities and the responses of the communities to both anthropogenic and natural stress could not be easily differentiated. Nevertheless, different patterns of the trophic nematode structure assemblages between Mira and Mondego overlapped the salinity effects and the feeding guilds and their response could detect the anthropogenical-induced stress in these estuaries.

Under the growing demand for marine fish resources, and the apparent and expected impacts of global climate change, there is a need to conduct long-term monitoring (LTM) to ensure effective management of resources and conservation of biodiversity. However LTM programmes often suffer from design deficiencies and fail to achieve their objectives. These deficiencies stem from the fact that insufficient consideration is afforded to the design phase, with programmes selecting methods that are not suitable to address the objectives, or are not cost-efficient, compromising the sustainability of the LTM. To facilitate the establishment of LTM programmes along the southern coast of South Africa, background research needed to be conducted to identify which methods were most appropriate for LTM of reef fish. This study presents a detailed field-based assessment of the suitability and cost-efficiency of monitoring methods for long-term monitoring of reef fish in the Agulhas Ecoregion of South Africa. The approach adopted to identify the method, or suite of methods most suited for LTM, involved (i) the selection of methods considered suitable for LTM, (ii) the individual assessment and optimisation of method performance, and (iii) the comparative assessment of the fish community sampled by the different methods. The most suited method(s) were then identified as those that provide the most comprehensive assessment of the fish community and had the highest cost-efficiency. The research was conducted between January 2008 and 2011 in the Tsitsikamma and Table Mountain National Park (TNP and TMNP, respectively) marine protected areas (MPAs) within the Agulhas Ecoregion. The methods selected included fish traps (FT), controlled angling (CA), underwater visual census (UVC), remote underwater video (RUV), baited RUV (BRUV) and remotely operated vehicles (ROV). The individual assessment and optimisation was conducted with the FT, UVC, RUV and BRUV methods. The assessment of the FT method aimed to identify the optimal soak time, and whether or not the size of the funnel entrance to the trap affected the catch. The results identified that larger funnel entrances caught more fish and soak times of 80 minutes produced the highest catches per unit effort. However the data were highly variable and the method detected few of the species typical of the region. Fish traps were also associated with high levels of mortality of fish post-release. The assessment of UVC strip transect method involved directly comparing the precision of data collected by researchers and volunteers using a novel double-observer technique (paired-transects). The results showed considerable error in both the volunteers and researchers data, however the researchers produced significantly higher precision data, compared to the volunteers. The distinction between researchers and volunteers was not evident in the data for the dominant species of fish. For all observers, the abundance of a species in the sample had a significant influence on its detectability, with locally scarce or rare species poorly detected. UVC was able to sample the majority of species typical of reefs in the region, however it appeared plagued by observer and detectability biases. The assessments of RUV and BRUV were conducted simultaneously which enabled the assessment of the effect of bait on the observed fish community. In addition the optimal deployment time for both methods to maximise species richness and abundance was determined. The results showed that BRUV, and to a lesser degree RUV, were able to effectively survey the reef fish community for the region with a 50 minute and 35 minute deployment time, respectively. Baited remote underwater video was especially good at detecting the invertebrate and generalist carnivores, and cartilaginous species. On the other hand, RUV was more effective at surveying the microinvertebrate carnivores. Remote underwater video was characterised by higher data variability, compared to BRUV, and was ultimately considered a less cost-efficient monitoring method. Comparative methods assessments were conducted during two field experiments with the FT, UVC and BRUV methods in the TMNP MPA, and the FT, CA, UVC, RUV, BRUV and ROV methods compared in the TNP MPA. The objectives of the comparison were to investigate differences in the fish communities observed with the different methods, and to determine the power of the data to detect an annual 10% growth in the fish populations over a period of five years. The results from the method comparison were in turn used to conduct the cost-benefit analysis to determine the efficiency of the different methods at achieving monitoring objectives requiring population data from multiple trophic and functional groups with the community, and from species of fisheries importance. The results indicated that FT, CA and ROV were ineffective at monitoring the reef fish community, although CA appeared to provide valuable data for the dominant fisheries species. Both CA and FT required minimal initial investment however, the variability in the data translated into high annual monitoring costs, as the required sampling effort was great. The ROV required the highest initial investment and was identified as the least cost-efficient method. Underwater visual census was able to adequately survey the bony fish within the community, however it did not detect the cartilaginous species. Underwater visual census required a large initial investment and was not cost-efficient, as a many samples were required to account for the variability in the data. Remote underwater video provided a comprehensive assessment of the reef fish community, however it too was associated with high levels of variability in the data, compared to BRUV, reducing its cost-efficiency. BRUV provided the most comprehensive assessment of the reef fish community and was associated with the highest cost-efficiency to address the community and fisheries species monitoring objectives. During the course of this research stereo-BRUV has gained considerable support as an effective reef fish monitoring method. Although not tested during this research, stereo-BRUV is preferred to BRUV as it provides accurate data on the size of fish. However, the initial investment of stereo-BRUV is over three times that required for the BRUV. Although it is recommended that a baited video technique be used for LTM in the Agulhas Ecoregion, the choice between BRUV and stereo-BRUV will depend on the specific objectives of the programme and the available budget at the implementing agency.

Orientadora: Profa. Dra. Natalia Pirani Ghilardi-Lopes
Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Evolução e Diversidade, São Bernardo do Campo, 2018.
Apesar da importância do monitoramento das unidades de conservação (UCs) marinhas, problemas logísticos e orçamentários dificultam sua realização e, consequentemente, a gestão efetiva dessas áreas. Por isso, é necessária a busca por alternativas de baixo custo que possam auxiliar nessas questões. A abordagem por biótopos associada à ciência cidadã mostra-se adequada para o monitoramento de comunidades marinhas bentônicas por possibilitar extensa amostragem em curto período de tempo e com baixo custo, além de integrar cidadãos ativamente em produções de conhecimento. Essa pode ser uma ferramenta interessante para o monitoramento de UCs marinhas; porém, é importante que a elaboração do protocolo de monitoramento e sua validação sejam realizadas considerando-se as recomendações da literatura. Nesse sentido, este trabalho se propôs a (1) avaliar o status dos protocolos de ciência cidadã para bentos marinho e costeiro no mundo e (2) a propor, aplicar e validar o uso da ciência cidadã associada à abordagem por biótopos como uma ferramenta para o monitoramento de comunidades bentônicas em UCs marinhas. Para isso, realizamos o levantamento e comparação da estrutura de protocolos de ciência cidadã para bentos costeiro e marinho, incluindo o protocolo proposto no presente estudo. Apesar da maioria dos projetos encontrados apresentarem várias das características recomendadas pela literatura, seus principais interesses são a coleta de dados e os resultados oriundos destes, ficando a educação dos CCs, sua inclusão no processo de desenvolvimento do protocolo e sua avaliação em segundo plano. Sugerimos que os protocolos considerem a educação científica e ambiental dos CCs como um objetivo a ser atingido, e nosso protocolo leva tais ideias em consideração. Para embasar a elaboração do nosso protocolo, realizamos um levantamento prévio dos biótopos de um trecho do infralitoral consolidado da Ilha das Palmas (Estação Ecológica Tupinambás, Ubatuba/SP). Nesse levantamento, foram identificados 20 biótopos e três animais vágeis associados em apenas um mergulho. Também foram detectados organismos invasores e a dominância de tapetes na área de estudo. Isso é um demonstrativo de que a caracterização de comunidades marinhas bentônicas utilizando o método visual por biótopos pode agilizar a identificação de possíveis impactos negativos e a realização de planos de prevenção ou mitigação dos mesmos. Cientistas cidadãos (CCs) voluntários foram capacitados no uso do protocolo, que foi dividido em duas etapas: (1) a coleta de dados, que consistiu de registros fotográficos padronizados do costão rochoso; e (2) o processamento das fotografias, que consistiu da identificação (ID) dos biótopos nas fotos em um curso presencial. As fotos obtidas durante a Etapa 1 estão disponíveis na plataforma Zooniverse, através do projeto Monitore Tupinambás (https://www.zooniverse.org/projects/larissakawabe/monitore-tupinambas), no qual qualquer voluntário pode contribuir com as análises, seguindo o tutorial disponível. A avaliação educacional da pesquisa, realizada através de questionários pré e pós-atividade, mostrou principalmente que houve mudanças de percepção dos CCs em relação ao ambiente estudado. Para a validação dos dados da Etapa 2, comparamos as IDs dos biótopos realizadas pelas pesquisadoras (grupo controle) e CCs (grupo experimental), analisando a precisão e acurácia das respostas. Apesar das limitações inerentes do método utilizado (ID por foto) e das necessidades de modificação do protocolo identificadas por CCs e pesquisadoras; os resultados de acurácia e precisão foram comparáveis aos de outros trabalhos similares, demonstrando que esse protocolo, o primeiro a ser desenvolvido com foco em bentos marinho no Brasil, é uma ferramenta promissora para o monitoramento participativo e de longo prazo das UCs marinhas do país, auxiliando na gestão dessas áreas e na educação ambiental e científica dos cidadãos participantes.
Despite the importance of monitoring the marine protected areas (MPAs), logistical and budgetary problems make it difficult to carry out and, consequently, affect the effective management of these areas. Therefore, it is necessary to search for low-cost alternatives that could help with these issues. The biotope approach associated with citizen science could be interesting for the monitoring of marine benthic communities because it allows extensive sampling in a relatively short period of time and at low cost. At the same time, citizens are integrated as active contributors in the knowledge production. This can be an interesting tool for the MPA monitoring; however, it is important that the elaboration of the monitoring protocol and its validation consider the literature recommendations. In this sense, this work aimed to (1) evaluate the status of citizen science protocols for marine and coastal benthos in the world and (2) to propose, apply and validate the use of citizen science associated with the biotope approach as a tool for monitoring benthic communities in MPAs. For this, we conducted a survey and comparison of the structure of citizen science protocols for coastal and marine benthos, including the protocol proposed in the present study. Although most of the projects found present several of the characteristics recommended by the literature, their main interests are the data collection and their results, being the education of citizen scientists, their inclusion in the protocol development process and their evaluation in the background. We suggest that the protocols consider the scientific and environmental education of citizen scientists as a goal to be achieved, and our protocol takes such ideas into account. To support the elaboration of our protocol, we carried out a preliminary biotopes survey of a consolidated subtidal section of the Ilha das Palmas (Tupinambás Ecological Station, Ubatuba/SP). In this survey, 20 biotopes and three associated animals were identified in only one dive. Invasive organisms and carpet dominance were also detected in the study area. This is a demonstration that the benthic marine communities characterization using the biotope visual method can speed up the identification of possible negative impacts and the implementation of prevention or mitigation plans. Volunteer citizen scientists were trained in the use of the protocol, which was divided into two steps: (1) data collection, which consisted of standardized photographic records of the rocky reef; and (2) the processing of the photographs, which consisted of identification (ID) of the biotopes in the photos in a classroom course. The photos obtained during Stage 1 are available on the Zooniverse platform through the Monitore Tupinambás project (https://www.zooniverse.org/projects/larissakawabe/monitore-tupinambas), in which any volunteer can contribute to the analyzes, following the tutorial available. The educational evaluation of the research, performed through pre and post-activity questionnaires, showed mainly that there were changes in perception of citizen scientists in relation to the studied environment. For the data validation of Stage 2, we compared the biotope IDs performed by the researchers (control group) and citizen scientists (experimental group), analyzing their accuracy and precision. Despite the inherent limitations of the method used (ID per photo) and the identification by citizen scientists and researchers of protocol modification needs; the results of accuracy and precision were comparable to those of other similar studies, demonstrating that this protocol, the first developed with a focus on marine benthos in Brazil, is a promising tool for the participatory and long-term monitoring of the country's MPA, assisting in the management of these areas and in the environmental and scientific education of the citizens scientists.

The British Columbian (BC) coast spans a 1000 km range of complex coastal geographic and oceanographic conditions that include thousands of islands, glacial carved fjords, exposed rocky coastline, and warm inlands seas. Very little is known about invertebrate fouling communities along the BC coast as studies are usually localised, focused in ports, or are conducted in the intertidal environment. This study provides the first high resolution study of invertebrate fouling communities of the BC coast by describing the identity, richness, diversity, and community composition of invertebrate fouling communities. Studying fouling communities on artificial surfaces was useful because the limiting resource (space) was defined, the researcher could control the timeframe, the samples were easily transported long distances, and the system can be easily replicated. Settlement structures were deployed in the spring of 2007 from the floating structures of marinas, docks, and aquaculture facilities. The deployment sites spanned a range of coastal environments from the Alaskan border to the southern tip of Vancouver Island, and included the Queen Charlotte Islands and Vancouver Island. The settlement arrays were collected roughly five months following deployment. Samples were transported back to the laboratory where all organisms present on the settlement arrays were identified to the lowest taxonomic level possible and their relative abundance recorded. The invertebrate fouling community was very species rich with 171 species identified and an additional 34 categories of unresolved taxa. This high richness may be attributed to the fact that the settlement arrays sampled the community as a whole, including motile and rare species. The richness per sample ranged from 1 to 29 species with the average being 12 species, of which more than one (1.25) was introduced to the BC coast. This invertebrate fouling community was dominated by relatively few species. Only 20% of the sessile species had an average cover over 1% and only 13% of the motile species had an average count over 0.5 individuals per sample. Of the sessile species, the Mytilus sp. complex was the most common with an average coverage of 35%. The Mytilus sp. complex was also found in 78% (126/162) of all samples. There were eleven introduced and twelve cryptogenic species identified in this study. Introduced species represented 30% of the dominant (=most abundant) sessile species and 20% of the dominant motile species study. The introduced and cryptogenic species were more abundant than native species when comparing abundance based on their distributions in the samples. The prominence and abundance of the introduced species in these communities may be an artefact of studying anthropogenic sites. However, it underscores the fact that the establishment and spread of non-native species are continuing along our coast, and that the strong competitive ability of a number of these species may have negative ecological and economic impacts. There were strong similarities in community composition across all geographic areas of the BC (Strait of Georgia-SOG, Juan de Fuca Strait- JFS, west coast of Vancouver Island-WCVI, Johnstone Strait-JS, and the north coast of the mainland-NC). The most common species assemblage was the Mytilus sp. complex and its associated species. The species assemblages observed across numerous geographic areas included species that were strong space competitors, had ranges that included the length of our study area, had key reproductive periods during the sampling period, and were able to recruit to artificial substrates. Anthropogenic structures may also be partially responsible for the strong similarities in community composition along the coast as we may be sampling species that are best adapted to these environments. Additionally, anthropogenic structures and activities may serve as vectors of species dispersal. Pairwise comparisons showed that the WCVI differed from the JFS and QCI in community composition in that the WCVI was strongly influenced by the Mytilus sp. community but the JFS and QCI were influenced by introduced and cryptogenic species. This study is the first to examine fouling communities that span the length of the BC coast. The data collected can be used as a baseline of comparison for future studies on subjects such as climate change, human mediated species introductions, and anthropogenic disasters.
Graduate

This body of work examines the influence of land use on nearshore water quality, and how this can drive changes to algal and invertebrate communities along Australia's southern coastline. The overall aim of the thesis was to investigate links between increasing coastal water-column nitrogen concentrations (derived from terrestrial inputs) and the expansion of turf-forming habitats that can alter the structure and function of subtidal ecosystems. I initially tested whether human activities in coastal catchments can increase subsidies of nitrogen to open rocky coasts. I identified landscape-scale variation in the supply of Dissolved Inorganic Nitrogen (DIN) to coastal waters adjacent to natural, agricultural and urban catchments. Compared to natural catchments, subsidies of DIN were 8 - 407 times greater in urban catchments, and 1 - 63 times greater in agricultural catchments. Subsidies of nitrogen from urban catchments were attributed to the release of sewage effluent, as delineated by δ¹ ⁵N isotopic values of transplanted algae. Having made this link, I then assessed whether catchment-scale variation in nitrogen subsidies may predict patterns of subtidal habitat structure, particularly as related to theories of regime shifts from forested landscapes to structurally depauperate turf-forming habitats. I validated this hypothesis, demonstrating that both relative covers and patch-sizes of turfed habitat were greater where the ratio of terrestrial nitrogen inputs to ambient coastal resources was large. An important realisation was that loss of forests may be more strongly related to the size of subsidy (i.e. the relative increases in water column nitrogen concentrations along urban coasts) rather than the size of coastal populations. Together, these data link coastal development with modified land-to-sea subsidies, and indirectly support the model that ecological effects may be proportional to the disparity between donor and recipient resources. Having demonstrated a link between nitrogen subsidies and subtidal habitat change, I then investigated factors likely to initiate and maintain such shifts. My results demonstrate that nutrient elevation can alter the natural phenology of turfs, sustaining dense covers throughout periods of natural senescence (winter). Perennial turf covers are able to accumulate large volumes of sediment; a synergy can impede the winter recruitment of canopy-forming species (kelps and fucoid algae). My observations of reduced forest recovery along urban coasts serve to highlight the complex interaction between elevated nutrients, persistent turf covers and increased sediment accumulation, which can reduce the resilience of coastal ecosystems to disturbance. In recognition that regime shifts are likely to have consequences for higher trophic levels, I compared the diet of invertebrate herbivores from healthy and degraded coastlines using stable isotope analysis (δ¹³C and δ¹⁵N). Dietary modelling showed that turfs contributed more to the diet of consumers along degraded coastlines where turfed landscapes have replaced extensive covers of macroalgal forest. Additionally, there were strong correlations between covers of turfed habitat, herbivore diet and relative densities. Changes to ambient food quality associated with regime shift may be an important aspect of nutrient-driven change along human-dominated coastlines. The final component of my thesis redressed some of the uncertainty about restoration initiatives for urban coasts by demonstrating that regime shifts are not necessarily permanent. I showed that turf removal can facilitate the recovery of degraded forests. Future restoration, therefore, is a possible outcome of polices that aim to decouple the link between nutrient inputs and recalcitrant turfed habitats that prevent forest recovery. Initiatives that reduce nutrient discharge to coastal waters (e.g., wastewater recycling) are likely to restore the resilience of nearshore marine ecosystems and promote their rehabilitation.
http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1473469
Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2009

As human activity along coastlines increase, degradation and destruction of coastal marine ecosystems around the globe will increase at an alarming rate. In an effort to mitigate degradation and destruction of coastal marine ecosystems, artificial reefs have been used in restoration and enhancement projects. As artificial reefs are the main method of restoring diversity to a degraded area, it is important to know the mechanisms that drive marine community assembly and diversity on those reefs. Understanding community assembly patterns of foundational species, in particular, may provide insight to community assembly patterns at higher trophic levels. Subtidal macroalgae are commonly seen as foundational species in marine environments and both deterministic and stochastic processes play a role in their assembly. Environmental gradients, which are deterministic processes, play a significant role in structuring subtidal macroalgae communities. Depth, which is negatively correlated with light, is the main driver structuring subtidal macroalgal communities, however, other gradients such as water flow, and distance to a propagule source also impact their assembly. This study sought to determine which environmental gradients play a prominent role in subtidal macroalgal community assembly. To study subtidal macroalgal community assembly, 92 artificial reef units called Reef Balls were deployed east of the Ogden Point Breakwater in Victoria, BC in June 2009. Two years passed to allow for macroalgal growth and early successional processes to occur prior to sampling the communities on thirty Reef Balls via underwater collection in July 2011. Algae were sorted by genus and dry weight was measured. To determine effects of environmental gradients on community assembly light, depth, water flow, distance to the nearest Reef Ball and distance to the breakwater were measured at each Reef Ball. A redundancy analysis revealed that depth was the most significant environmental gradient shaping algae communities and had the greatest effect on upper canopy algae. Spatial plots reveal a depth and coastline zonation of algae genera comprising the canopy. While depth was found to significantly structure algae genera found in the canopy, there was a high degree of unexplained variation in the model. This suggests that unmeasured variables such as colonization and priority effects may be driving algal community structure in the lower canopy. Differences in community structure between upper and lower canopy reveal that multiple mechanisms are responsible for shaping subtidal algal communities. Further study is required to determine the importance of stochastic colonization events and priority effects.
Graduate
0329
vmucciar@uvic.ca

Two subtidal reef communities characterised by sponges were examined to assess two distinct aspects of marine benthic community ecology which have not previously received much attention. The first study focused on the role of settlement events in the origin and maintenance of community structure and involved investigation of factors affecting dispersion, settlement and recruitment of sponge propagules. The second examined how natural gradients in ambient physical conditions, in the absence of disturbance, affected size structure and species interactions within the community. Settlement events were examined on a reef flat which was covered by a shallow sediment overlayer. The distribution and abundance of established sponges was found to be highly correlated with sediment regimes. The sponge community was shown to be stable over time and able to resist disturbance by storms because of the presence of turfing algae. Sponge settlement was inhibited by the sediment overlayer. Established sponges were found clumped into oblong groups orientated east-west and there were many instances where sponges were found closely associated. Adjacent areas were characterised by deeper unstable sediments and fewer sponges. Storms contoured sediments into ripples and scoured oblong east-west orientated patches of basal rock. Sediments were also sorted during storms such that particles of large grain size were left around the edges of ripples and over the scoured rock patches. The basal reef of both the stable and unstable areas was covered in a mosaic of encrusting algal and sponge species which tolerated the sediment overlayer. This assemblage was also exposed during storms. Sponges reproduced in a number of ways, but asexual propagules were the most successful. Sponges from several orders produced buds which developed in a complex manner. Buds adhered to rock and shell fragments of large size which acted as anchors, or attached to other buds irrespective of genotype. The change in weight and shape increased the likelihood that buds would gravitate into the scoured patches of basal rock. Bud loss off the reef was minimal. Buds were able to settle onto the basal rock patches and did so almost exclusively onto bare rock. A high degree of 'selectivity' of settlement site by buds was imparted by altering developmental rate during the settlement process in response to the substrate type. Polymastia granulosa buds exhibited an additional developmental sequence not previously reported for any colonial organism. Buds either settled directly in suitable conditions, or developed further along a different pathway. Buds which did not come into contact with basal rock elongated and appeared to be capable of digging into sediments. The elongated bud then broke up along its length into smaller particles, termed 'beads', which were capable of movement and invariably settled onto gravel fragments. Sponges were shown to settle onto scoured rock patches during storms and were eventually covered by sediments. Subsequent survivorship and recruitment depended species specifically on sediment depth and quality. Settlement patterns matched the observed dispersion patterns of established sponges and suggested a mechanism whereby the community had originated and how structure was maintained. These hypotheses were tested experimentally in situ and in the laboratory. The importance of asexual modes of reproduction, and settlement mediated by physical disturbance appears to be a common formula for recruitment by colonial marine organisms. Recruitment events were found to explain the distributional patterns of the established population. The structure of populations of thin encrusting species on vertical reef walls was examined in a novel manner whereby the mean size and density of individuals was quantified and related to gradients in the ambient physical environment. This was achieved by examining the benthic communities on a range of subtidal reef walls of uniform slope and aspect, but which were subject to natural gradients in physical conditions. The species composition of each of the six reefs studied was similar but the size structure of communties changed within each reef system in response to gradients in light intensity and water movement. Fish and urchin disturbance was shown to be unimportant and there was no indication that storms disrupted communities. The implications of changes in size structure of populations on interactions between component species in different ambient conditions were examined. The eastern wall of two cave, archway and open reef systems was surveyed according to a stratified sampling design where each reef was divided by depth and distance along the wall. Different taxonomic/morphological groups were found at particular positions on reef walls. Thin encrusting algal species were found to be one of the most abundant groups. It was assumed that the individual size of encrusting species at each wall position reflected long term ambient environmental conditions as well as the ability of each species to maintain itself against overgrowth by neighbours. By relating the population size structure of different taxa with indices for light intensity and water movement recorded at each wall position within each reef, it was shown that community structure varied markedly on the same reef wall as a function of ambient physical conditions. Changes in proportional species composition, notably from thin encrusting algal dominated assemblages to sponge characterised assemblages, with decreasing light intensity were accompanied by changes in the individual size structure of populations. At each wall position all species exhibited similar individual size. Individual size decreased and density of individuals of all species increased with decreasing light intensity. In conditions where light levels were not sufficient to support algae, individual size of encrusting fauna increased with increasing water movement. The implications of these observations on competitive interactions between encrusting species was examined. The outcome of competitive interactions between the same species was found to vary depending on wall position.

Cerastoderma edule, the edible cockle, is a dominant and widely distributed bivalve of the northeast Atlantic coast. This bivalve is a highly exploited species in many countries, displaying an important socio-economic role and playing crucial services for ecosystem functioning. This bivalve is host of several trematode species, the most prevalent clade of macroparasites in coastal waters, that display a complex life cycle commonly including three host species. Trematodes are able to modulate cockles population dynamics, exerting devastating impacts depending on abundance, life-cycle stage or combination with abiotic factors. However, the patterns by which they govern are still poorly understood. The present thesis aimed to recognize environmental patterns that could regulate trematode population dynamics, identifying the major factors implicated in infection rate variability. In the first instance, an extensive spatial sampling of cockles was performed from north Portugal to south Morocco in order to identify large scale drivers of parasite community structure and to analyse, for the first time, cockles south of 31 °N. Most of the 12 identified trematode species were observed along the whole latitudinal gradient demonstrating the high dispersal ability of these parasites. Results suggested that temperature was the most important trigger to predict parasite infection, with coastal upwelling system operating for Portugal as a shield against trematode infection. Nonetheless, hosts geographical distribution, second intermediate host tidal position and the oceanic influence also seemed to affect trematode abundance. Following these results, the effect of host vertical position (intertidal vs. subtidal) and hydrodynamics on trematode infection rate was assessed at a small-scale. For this, cockles were collected in intertidal and subtidal sites of downstream and upstream areas of the Ria de Aveiro coastal lagoon (Portugal). Cockle density, trematode infection and sediment and water physico-chemical features were assessed. To characterize the lagoon hydrodynamics, simulation with the numerical model Mohid were performed. Intertidal cockles displayed significantly higher individual infection than those from subtidal sites, highlighting that the host vertical position represent an important driver of trematode infection success, possibly due to shorted distance from the first intermediate host (often intertidal gastropods) or lower capacity of cercariae (trematode free-living stage emerging from the first intermediate host to infect second intermediate host) to find their suitable host in a subtidal environment and then to complete the life cycle. Overall, the downstream areas (= higher hydrodynamics) presented higher trematode abundance suggesting a positive influence of water dynamics in the ecological quality of these areas, increasing the dispersion of trematode freeliving stages that promotes contact with the second intermediate host and consequent infection success. The influence of water current on trematodes infection was corroborated through experimental approach. Lastly, and pursuing the track of some of the obtained results (namely the infection between intertidal and subtidal sites), the effect of light on cercariae transmission success, using the trematode Himasthla elongata was assessed. Through experimental approach, this study aimed to observe the influence of light (no light vs. light exposure) on the cercariae behaviour. Nevertheless, cockles under dark conditions presented higher levels of infection compared to cockles exposed to light. These differences were explained by the influence of light on the cercariae swimming activity, which navigation showed to be guided by the light position and not by the presence and/ or filtering capacity, since that cockles respiration rate was similar regardless light conditions. This thesis findings demonstrated the importance of abiotic factors on the transmission success of trematode parasites. The outcomes of this study can be used for a more efficient management of cockles stocks by helping to predict areas or periods of higher probability of a trematode abundance outbreak.
O berbigão, Cerastoderma edule, é uma espécie de bivalve amplamente distribuída pela costa nordeste do Atlântico. Este bivalve é altamente explorado em vários países, inclusive Portugal, tendo uma alta relevância socioeconómica e um papel importante em serviços cruciais para o funcionamento do ecossistema. Este bivalve é hospedeiro de várias espécies de trematodes, os macroparasitas mais prevalentes em águas costeiras, que exibem um ciclo de vida complexo e que geralmente usam três espécies diferentes de hospedeiros. Os trematodes são capazes de modular a dinâmica populacional dos berbigões, exercendo sobre eles impactos devastadores dependendo da abundância, fase do ciclo de vida ou da combinação com fatores abióticos. No entanto, os padrões pelos quais estes parasitas se governam ainda são pouco compreendidos. Assim, esta tese teve como objetivo principal, reconhecer padrões ambientais que podem regular a população de trematodes, identificando os principais fatores implicados na variabilidade da taxa de infeção. Num primeiro momento, foi realizada uma extensa amostragem espacial de berbigão, desde o norte de Portugal até ao sul de Marrocos, de forma a identificar fatores que influenciam, em larga escala, a comunidade dos parasitas e que permitiu analisar, pela primeira vez, berbigões a sul de 31 °N. Das 12 espécies de trematodes identificadas, várias foram observadas em todo o gradiente latitudinal demonstrando a grande capacidade de dispersão destes parasitas. Os resultados sugeriram que a temperatura foi o fator mais importante para despoletar a infeção por trematodes, com o sistema de upwelling da costa Portuguesa a funcionar como proteção contra a infeção por trematodes. No entanto, a distribuição geográfica dos hospedeiros, a posição de maré do segundo hospedeiro e a influência oceânica também pareceram ter efeito na abundância dos trematodes. No seguimento destes resultados, avaliou-se os efeitos, em pequena escala, da posição vertical (intertidal ou subtidal) e do hidrodinamismo na taxa de infeção por trematodes. Para isso, foi recolhido berbigão em zonas intertidais e subtidais de uma área a montante e a jusante da Ria de Aveiro. Foram analisados a densidade de berbigão, a infeção por trematodes e os parâmetros físicoquímicos do sedimento e da água. Para caracterizar o hidrodinamismo da Ria procedeu-se a várias simulações através do modelo Mohid. Berbigão da zona intertidal demonstrou maiores níveis de infeção, destacando a importância da posição vertical do hospedeiro no sucesso da infeção pelos trematodes, possivelmente devido a uma distância mais curta ao primeiro hospedeiro (geralmente gastrópodes intertidais) ou a uma menor capacidade das cercariae (estado de vida livre dos trematodes que emerge do primeiro hospedeiro e infeta o segundo) para encontrar o seu hospedeiro num ambiente subtidal e completar o ciclo de vida. No geral, as áreas a jusante (maior hidrodinamismo) apresentaram níveis de infeção mais altos, sugerindo uma influência positiva da dinâmica da água na qualidade ecológica destes habitats, aumentando a dispersão das cercariae promovendo, desta forma, o contacto com os seus hospedeiros e consequentemente, aumentando o sucesso da infeção. A influência da corrente da água na infeção de trematodes foi corroborada por uma experiência laboratorial. Por último, e seguindo alguns dos resultados obtidos (principalmente a diferença de infeção entre a zona intertidal e subtidal), foi testado o efeito da luz no sucesso da transmissão pela cercaria da espécie de trematode Himasthla elongata. Através duma experiência laboratorial, pretendeu-se observar o efeito da luz (ausência vs. presença de luz) no comportamento das cercariae. Berbigões sob a ausência de luz demonstraram ficar mais parasitados do que os que se encontravam expostos à luz. As diferenças foram explicadas pela influência da luz na atividade natatória das cercariae e não pela presença ou capacidade filtradora dos berbigões, uma vez que, estes não demonstraram diferenças na taxa de respiração, qualquer que fosse a exposição luminosa. Esta tese demonstrou a importância dos fatores abióticos no sucesso de transmissão dos trematodes entre hospedeiros. Os resultados deste estudo podem ser utilizados de modo a controlar e a melhor gerir as populações de berbigão, ajudando a prever áreas ou períodos de maior probabilidade de surtos de abundância de trematodes.
Mestrado em Biologia Aplicada