Rozprawy doktorskie na temat „Marine ecosystems”

The declines of fish populations in ecosystems around the globe have triggered considerable interest in marine ecosystem restoration. In addition to focusing on individual fish populations, there is increased emphasis on understanding inter-species interactions and on understanding the human relationships with the ecosystems. My thesis approaches marine restoration from (a) practical aspects of considering multispecies interactions in the ecosystem (Ecopath with Ecosim models), estimating unreported and illegal catches (influence tables) and policy that considers the concerns of multiple stakeholders (Bayesian influence diagram modeling); (b) theoretical aspects of carrying capacity and fish life history analyzed using life history parameters (Population dynamics modeling). I begin my thesis by exploring the technological, socio-economic, and political history of Raja Ampat in Eastern Indonesia (my geographical focus) to understand resource management challenges and to calculate the trends in relative misreporting of fisheries catch. The unreported fish catch exceeds the reported fish catch by a factor of 1.5. My next chapter explores the ecological benefits of establishing marine protected areas for coral reef ecosystems in Raja Ampat using Ecopath, Ecosim and Ecospace models. I estimate an ideal minimum size of no-take areas— the size of no-take area at which the biomass density of reef fish reached an asymptote—to be 16 to 25 km². Analysis of biomass density of reef fish in MPAs led to questions about ecosystem carrying capacity. To explore carrying capacity, I reconstruct ancient snapper population biomass using archaeological data obtained from fish middens using equilibrium age structure model. The results show that the ancient snapper population was about 2 to 4 times higher than the modern population biomass. To model the differing utilities of different stakeholders, in the next chapter, I develop a bayesian influence diagram model. The results indicate that restricting net fisheries and implementing 25% fisheries closure are robust scenarios favored under several combinations of the modeled variables and utility functions. The final chapter explores how the life history parameters of fish species affect the population response to restoration. It is expected that slow growing species would show a greater response to protection than fast growing species.

One of the greatest challenges for sustaining the ecosystem services that we, as a society, derive from marine ecosystems is to minimize the knowledge gap relating to marine ecosystem values. That is, identifying, eliciting and understanding the economic value of the ecosystem services that marine systems provide for societies world-wide is key to ensuring sustainable resource use and environmental management of these ecosystems. This is particularly problematic for the ecosystem services derived from the deep sea as a tremendous knowledge gap exists for the many marine ecosystems that comprise the deep sea. Addressing this gap in knowledge may, directly and indirectly, facilitate actionable strategies for successful climate change adaptation and reduce the degradation of these important marine ecosystems. Estimating values for certain types of marine ecosystem services in particular the deep sea is imperative for understanding the economic trade-offs associated with human actions and resource use of marine resources. Identifying, exploring and understanding the economic benefits and costs associated with the human resource use of marine systems is also crucial for circumventing irreversible damage to ecosystems, and for addressing the growing problem of ecosystem degradation of marine ecosystems. However, a knowledge gap remains in terms of eliciting and understanding how vulnerable marine ecosystems, such as coral reefs and the deep-sea, generate economic value to local economies, and for societies on a global scale. By employing a variety of quantitative and qualitative methodologies, this thesis explores the economic value of the ecosystems of coral reefs and the deep-sea, respectively. The thesis investigates various aspects of the economic contribution of these ecosystems, namely: (i) the local economic contribution of ) Fiji's coral reefs to tourism; and ii) the economic value of the deep- sea's ecosystems to human societies, globally. Moreover, it discusses the importance of exploring the social and non-monetary value of coral reefs to human well-being in the South Pacific Island Countries (SPICs). The research of this thesis therefore constitutes a genuine contribution to understanding how changes in these marine ecosystems impact on economies and human well-being, now and in the future. Although the full extent to which ecosystem degradation of marine ecosystems will impact economies and societies globally remains uncertain, its impacts are already being witnessed, e.g. through ocean acidification, sea-level rise, reduced fish stocks and changing environmental conditions. In turn, these impacts affect human survival and well-being by negatively impacting fishery incomes, food security and coastal protection in many countries around the world. Action and investment plans for reducing the ecosystem degradation of marine systems are urgently needed to protect the value of those ecosystem services to human societies. Deepening our understanding of marine ecosystems' economic contributions constitutes a crucial component of facilitating action plans and investments for sustainable resource use and development. Valuation of vulnerable marine ecosystems is important for several reasons. First, valuation of an ecosystem's contribution to society demonstrates the importance of that ecosystem for social stability, economic growth and human well-being, thereby improving public awareness of that ecosystem's significance. Second, ecosystem valuation can inform policy and decision-making for future conservation programs and legislation pertaining to the human use of marine resources. Third, ecosystem valuation creates important incentives to invest in the protection of marine systems as it outlines the connection between the ecological functioning of marine systems on the one hand, and economic output and stability on the other hand. Fourth, ecosystem valuation can also raise awareness about the importance of protecting biodiversity. Finally, ecosystem valuation of marine ecosystems is especially important for supporting decision-making related to the resource-use of marine ecosystems for which very limited information exists on their economic contribution. The thesis starts with an introduction and a literature review of the main themes and concepts along with the problems, challenges and opportunities associated with the ecosystem valuation of coral reefs and the deep-sea. Subsequently, the research studies of this thesis, which constitutes chapters 2, 3, 4 and 5 are presented. Specifically, chapter 2 explores the economic impacts of future (hypothetical) deep-sea mining activities on Fiji's tourism industry, through a contingent behaviour study; chapter 3 discusses the need for developing non-monetary and social ecosystem valuation methodology in order to elicit marine ecosystems' importance for human well-being in the SPICs; chapter 4 explores current knowledge about the deep-sea's economic value through a systematic review and meta-analysis; and chapter 5 identifies the four main priorities for future ecosystem valuation, policy-making and research pertaining to the deep-sea. This thesis makes a small but significant contribution to the knowledge base of the economic value of the ecosystems of coral reefs and the deep-sea, respectively, and to developing future ecosystem valuation by means of introducing the social willingness-to commit (Social WTCommit) technique. Finally, this thesis can contribute to policy-making, decision-making and legislation pertaining to the deep-sea and coral reefs, locally and globally.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Dept Account,Finance & Econ
Griffith Business School
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Gli ecosistemi marini sono sottoposti a diversi fattori di stress di origine antropica, i cui effetti non sono ancora del tutto noti. Questo gap conoscitivo rappresenta un punto cruciale, in quanto, la conoscenza degli effetti delle attività umane è essenziale per l’applicazione di piani di monitoraggio e di adeguate strategie di mitigazione. Di conseguenza, in questa tesi, sono stati selezionati e studiati quattro diversi tipi di pressioni antropiche; allo scopo di aumentare le conoscenze disponibili come richiesto dalla MSFD. La prima fonte di impatto selezionata sono gli impianti di desalinizzazione, per i quali è stato studiato l’impatto sulla comunità macrobentonica. I risultati ottenuti suggeriscono che non sono causa di alterazioni distinguibili dalla naturale variabilità spaziale della macrofauna. Ciò può essere messo in relazione alle piccole dimensioni degli impianti. Risultati simili sono stati ottenuti per la seconda pressione antropica studiata, cioè ripascimento e (ri)stenditura della sabbia sugli arenili, i quali, non hanno alterato la naturale variazione spaziale e temporale della macro e meiofauna. Anche in questo caso, la mancanza di un impatto significativo è da attribuire alla piccola scala dell’intervento. Il terzo caso di studio riguardava l’analisi dell’estensione (m2) di una prateria di fanerogame nell’arco di 40 anni. I risultati indicano, come i due declini riscontrati fossero correlati a due diversi fattori, quali urbanizzazione e aumento della temperatura, i quali hanno agito non solo sull’estensione della prateria, ma anche sulla composizione tassonomica. Infine, è stato analizzato il potenziale impatto della pesca con draghe idrauliche, particolarmente intensa nel Mare Adriatico. Più specificatamente, è stato studiato il potenziale effetto della diminuzione dello sforzo di pesca (di circa il 50%) imposto dall’emergenza sanitaria del SARS-CoV-2 sulle comunità macrobentoniche. I risultati evidenziano un aumento significativo dei bivalvi, che porta ad una comunità macrobentonica significativamente diversa rispetto a quella presente prima del lockdown. In conclusione, dall’analisi questi casi di studio è emerso come la “scala” della pressione antropica giochi un ruolo cruciale nel determinare l’eventuale impatto. Inoltre, è stato evidenziato come diversi ecosistemi mostrino una apprezzabile resilienza quando le pressioni antropiche diminuiscono in maniera significativa.
Multiple stressors affect coastal marine ecosystems, whose effects are often largely unknown. This represents a crucial point, since the knowledge about the impacts caused by human activities are essential to apply adequate monitoring plans and mitigation strategy. Consequently, in this thesis four different human pressures were selected and investigated, in order to increase the available information. The first impact source selected is represented by desalination plants, for which the impact on macrobenthic assemblage was investigated. The results suggest that they do not cause alterations superimposed to the natural spatial variability of the macrofauna assemblage. This has been related to the small sizes of the plants. Similar results were obtained for the second stressor investigated (i.e., beach nourishment and beach re-profiling), which did not alter the spatial-temporal trend of the macro-meiofauna assemblage. Again, the lack of a significant impact was associated to the small size of the interventions. The third case study investigated the long term (40 years) changes (in m2) of seagrass meadow extension in the North Adriatic Sea. The results indicated that the two declines recorded were mainly correlated with two different drivers: urbanization and positive thermal anomalies respectively, which affected not only the meadow extension but also the species composition. Finally, the last pressure analyzed is the fishing with hydraulic dredging, which is extremely intensive in the Adriatic Sea. Specifically, here the effects of the decrease of fishing effort (of about 50%) imposed by the SARS-CoV-2 sanitary emergency was studied. From the results, it is evident a significant increase of bivalves, making the entire macrofauna assemblage significantly different from that present before the 2020. Overall, from these case studies, it is clear as a crucial role is played by the “size” of the human pressure. In addition, it is clear that in different ecosystems, when there is a noticeably decrease of human pressures, an appreciable partial recovery is possible.

An ecosystem-based approach to the management of marine ecosystems is the goal of the recent European Integrated Maritime Policy, known as the Blue Book (2007), shortly followed by the new Marine Strategy Framework Directive (2008/56/EC). It is recognized that management should take into account the processes taking place within, and the interactions between ecological, social and economic systems to be effective and sustainable. Yet a quantitative knowledge about such processes and the interactions between marine ecosystems and socio-economic systems is often weak or lacking. The goal of this thesis is to explore how pressures exerted on large-scale marine ecosystems translate into state changes. The focus is on multiple pressures, and on both populations and ecosystems, i.e. on the integrated functioning of marine ecosystems. Both anthropogenic pressures, such as fishing or nutrient enrichment, and natural ones, such as climate and environmental variability, are taken into account, mainly based on the Northern Adriatic Sea case study. The Northern Adriatic Sea is a data-rich Mediterranean basin, eutrophic, heavily fished, strongly influenced by climate, and with a long history of human pressures acting on it. Different methodologies are used in a complementary manner, such as conceptual models, ecological network analysis applied to a static trophic network model, timeseries analysis, population models, review of historical data, and meta-analysis of macroecological patterns. Case studies include species of commercial importance such as small pelagics or crabs, or charismatic predators such as sharks and skates. Based on the study of the functioning of marine ecosystems from many different points of view, the main conclusion of this work is that an ecosystem-based approach is indeed necessary to manage marine ecosystems. The reason is that multiple interacting factors, including but not limited to external pressures, can and do influence ecosystem functioning “bottom up”, “top down”, as well as from the middle of the system.
Un approccio ecosistemico alla gestione degli ecosistemi marini è l’obiettivo della recente Politica Marittima Integrata per l’Unione Europea, nota come Blue Book (2007), seguita a breve dalla nuova Direttiva Quadro sulla Strategia per l’Ambiente Marino (2008/56/EC). Vi si riconosce che, per esercitare una gestione efficace e sostenibile, si devono considerare i processi che si svolgono all’interno dei sistemi ecologici, sociali ed economici, e le interazioni fra tali sistemi. Tuttavia, una conoscenza quantitativa di tali processi e delle interazioni fra gli ecosistemi marini e i sistemi socio-economici è spesso scarsa, se non del tutto mancante. Lo scopo di questa tesi è comprendere meglio come le pressioni agenti su ecosistemi marini a larga scala portino a cambiamenti di stato. Ci si è concentrati su pressioni multiple, e sia su popolazioni che ecosistemi, ovvero sul funzionamento integrato degli ecosistemi marini. Sono state considerate sia pressioni di origine antropica come pesca ed apporti di nutrienti, che naturali come la variabilità climatica ed ambientale, basandosi principalmente sul caso di studio dell’Adriatico Settentrionale. L’Adriatico Settentrionale è un bacino del Mar Mediterraneo caratterizzato da abbondanza di dati utilizzabili a scopo scientifico, ed è un ecosistema eutrofico, intensamente sfruttato dalla pesca, fortemente influenzato dal clima, ed è sottoposto a pressioni antropiche da lungo tempo. Si sono utilizzate in maniera complementare differenti metodiche, fra cui modelli concettuali, l’analisi di reti ecologiche (Ecological Network Analysis) applicata ad un modello statico di rete trofica, l’analisi di serie temporali, modelli di popolazione, rassegna di dati storici, e meta-analisi di regolarità macro-ecologiche. I casi di studio includono specie di importanza commerciale come pesce azzurro o granchi, e predatori famosi come squali e razze. La principale conclusione di questo lavoro, basata sullo studio del funzionamento degli ecosistemi marini da molti punti di vista diversi, è che un approccio ecosistemico è realmente necessario nella gestione degli ecosistemi marini. Il motivo è che il funzionamento degli ecosistemi può essere ed è effettivamente influenzato da fattori multipli interagenti fra di loro, che includono (senza essere limitati ad esse) le pressioni esterne, e che agiscono sia dal basso (cioè dai livelli gerarchici inferiori) verso l’alto, che dall’alto (cioè dai livelli gerarchici superiori) verso il basso, ed a partire dall’interno (ovvero, dalle gerarchie intermedie) del sistema.

La valeur esthétique des paysages et des espèces est un élément central de la conservation de la biodiversité, puisqu’elle fait intervenir les dimensions affectives et émotionnelles de notre rapport à la nature. Le lien entre biodiversité et perception esthétique demeure cependant peu étudié dans le cadre des services écosystémiques.Suite à un premier travail de synthèse ayant permis de poser les bases conceptuelles et méthodologiques de l’esthétique des paysages, trois études menées sur des systèmes sous-marins à différentes échelles ont permis de mieux comprendre et de quantifier le lien entre les différentes facettes de la biodiversité et la perception esthétique.Les résultats ont permis de mettre en évidence que la nature du lien entre biodiversité et préférences esthétique est dépendante de l’échelle de perception : à une échelle multi-spécifique, la biodiversité et la composition en espèces ont un effet positif sur les préférences esthétiques, tandis que les préférences à l’échelle spécifiques sont déconnectées du fonctionnement écologique des écosystèmes.Ces résultats confirment l’importance de la valeur esthétique dans notre perception de la biodiversité, qui pourrait avoir des conséquences majeures sur la façon dont nous protégeons notre environnement. L’approche fonctionnaliste de l’expérience esthétique est proposée et décrite afin de promouvoir une perception esthétique basée sur la compréhension et la reconnaissance des processus écologiques. Des pistes d’éducation à la biodiversité basée sur une expérience esthétique engagée sont également proposées afin de reconnecter les besoins écologiques et les préférences esthétiques
The aesthetic value of landscapes and species is a central element for the conservation of biodiversity, since it involves the emotional and emotional dimensions of our relationship to nature. However, the links between biodiversity and aesthetic perception remains poorly studied and recognized within the ecosystem services framework.Following a first critical review, that described the conceptual and methodological bases of landscape aesthetics, three studies on underwater systems at different scales have been computed in order to better understand the link between the different facets of biodiversity and aesthetic perception.The results revealed that the link between biodiversity and aesthetic preferences is dependent on the scale of perception: at a multi-specific scale, biodiversity and species composition have a positive effect on aesthetic preferences, while preferences at a specific scale are disconnected to the ecological functioning of ecosystems.These results confirm the importance of aesthetic value in our perception of biodiversity, which could have major consequences in the way we protect our environment. The aesthetic experience based on the understanding of ecological functioning is proposed and described in order to promote an aesthetic perception relevant to ecological processes. Education to biodiversity based on engaged aesthetic is also proposed, in order to reconnect ecological needs and aesthetic preferences

Although there are various indications and claims that jellyfish have been increasing at a global scale in recent decades, a rigorous demonstration to this effect has never been presented. As this is mainly due to scarcity of quantitative time series of jellyfish abundance from scientific surveys, an attempt is presented here to complement such data with non-conventional information from other sources. This was accomplished using the analytical framework of fuzzy logic, which allows the combination of information with variable degrees of cardinality, reliability, and temporal and spatial coverage. Data were aggregated and analysed at the scale of Large Marine Ecosystem (LME). Of the 66 LMEs defined thus far, which cover the world’s coastal waters and seas, trends of jellyfish abundance (increasing, decreasing, or stable/variable) were identified (occurring after 1950) for 45, with variable degrees of confidence. Of these 45 LMEs, the overwhelming majority (31 or 69%) showed increasing trends. Recent evidence also suggests that the observed increases in jellyfish populations may be due to the effects of human activities, such as overfishing, global warming, pollution, and coastal development. Changing jellyfish populations were tested for links with anthropogenic impacts at the LME scale, using a variety of indicators and a generalized additive model. Significant correlations were found with several indicators of ecosystem health, as well as marine aquaculture production, suggesting that the observed increases in jellyfish populations are indeed due to human activities and the continued degradation of the marine environment.

In this thesis, the stochastic advection-reaction-diffusion models are analyzed to obtain the vertical stationary spatial distributions of the main groups of picophytoplankton, which account about for 80% of total chlorophyll on average in Mediterranean Sea. In Chapter 1 we give a short presentation of the experimental and phytoplanktonic data collected during different oceanographic surveys in Mediterranean Sea. In Chapter 2 we introduce the deterministic and stochastic approaches (one-population model) adopted to describe the picoeukaryotes dynamics in Sicily Channel. Moreover, numerical results for the biomass concentration are compared with experimental data by using chi-squared goodness-of-fit test. In Chapter 3 we modify the previous one-population model to study the population dynamics of two picophytoplankton groups, i.e. picoeukaryotes and picoprokaryotes (Prochlorococcus). The agreement between theoretical results and experimental findings is checked by using two comparative methods: chi-squared goodness-of-fit test and Kolmogorov-Smirnov (K-S) test. In Chapter 4 we introduce a deterministic model used to perform the spatio-temporal analysis of five picophytoplankton species sampled in a site of the Tyrrhenian Sea: numerical results are compared with experimental data acquired during different oceanographic surveys in the period from 24 November 2006 to 9 June 2007. The models investigated in the chapters 2, 3 and 4, show that real distributions are well reproduced by theoretical profiles. Specifically, position, shape and magnitude of the theoretical deep chlorophyll maximum exhibit a good agreement with the experimental values. Finally, conclusions and future prospects of this thesis are discussed.

Water motion has been shown to influence almost every aspect of the ecology of seagrass communities; seagrass communities have likewise been shown to significantly influence water movement around them. This thesis examines the important role of water motion on seagrass ecosystems by integrating field and laboratory studies of several aspects of seagrass ecology influenced by water motion. To facilitate the study of hydrodynamics of seagrass ecosystems, a solid state electronic current meter was designed and developed, using thermistors as flow sensing devices. Important characteristics of the meters include: no moving parts, compact size, high sensitivity (resolution better than ± 0.5 cm s-1), and high sampling rate (greater than 0.2 Hz). Deployment of the meters in field measurements provided reliable and meaningful results of flow conditions through seagrass canopies, and they show great potential for use in many studies of marine ecology. Field studies of water velocity profiles revealed significant differences between the shapes of profiles of different seagrass species, particularly between species of Posidonia and Amphibolis. Of particular note is the observation of a region of high water velocity beneath the leafy canopy of Amphibolis, which was not present in the Posidonia plants. Water velocity profile measurements, sediment grain size analyses and standing stock measurements were conducted across an exposure gradient in a Posidonia sinuosa meadow. These studies revealed that, while the exposed location experienced a higher ambient water velocity than the sheltered site, the baffling influence of the seagrass canopy reduced the water velocity to approximately the same at both sites, within the meadow, although the effects varied seasonally. It was also observed that the seagrass meadow produced apparent skimming flow under the low flow conditions measured at the sheltered location; this phenomenon reflects the capacity for flow redirection over the canopy, and has important implications for the sub-canopy ecosystem and the protective role of seagrasses on the seabed. Field and laboratory studies on the role of seagrass density on the hydrodynamic nature of seagrass ecosystems revealed that water velocity profiles through meadows of reduced densities, and different shoot arrangements, were markedly different to “natural” profiles, implying the existence of a “critical density” (approximately 25 % of natural meadow density) with regard to canopy hydraulics. The role of water motion at an individual leaf scale was investigated with a series of laboratory flume studies of photosynthetic rates of seagrass and algae. The results show that the response of photosynthetic rate to water velocity depends very much on the plant species, with the algae markedly more productive (on a unit chlorophyll basis) than the seagrasses tested. Increases in photosynthetic rate were observed at water velocities above approximately 2.5 cm s-1; negligible photosynthetic activity was observed below this velocity. Calculation of P v. I curves indicated that the Posidonia species had high Ik values at low velocities (1360 :mol quanta m-2 s-1 for P. australis and 250.8 :mol quanta m-2 s-1 for P. sinuosa at 1.58 cm s-1), which decreased with increasing water velocity (to 138.9 and 24.77 :mol quanta m-2 s-1 for P. australis and P. sinuosa respectively), while the algal species had relatively constant values of Ik across all water velocities (85.42 to 312.7 :mol quanta m-2 s-1 for Ulva lactuca and 169.7 to 573.9 :mol quanta m-2 s-1 for Laurencia cruciata). Dye visualization studies showed that the algae remained quite rigid at all the velocities tested, while the seagrass leaves compressed as velocity increased. This resulted in an increased rate of turbulence creation by the algae, which is believed to enhance photosynthetic rates, through improved nutrient exchange rates across the boundary layer adjacent to the thallus. Further dye visualization studies revealed the significance of blade morphology on the creation of microscale turbulence at the surface of seagrass leaves. Epiphytic growth on seagrass leaves was observed to play an important role in breaking up water flow across the leaf surface, thereby enhancing the creation of microscale turbulence. From these studies, it is clear that water motion influences all aspects of the functioning of all components of seagrass communities, playing a role in nutrient supply, reproduction, physical stability, temperature and metabolic functions. The influence of seagrass meadows on coastal hydrodynamics is also apparent, with potential impacts on sediment stability, recruitment of benthic species and coastal erosion. This thesis has clearly demonstrated that water motion is an important parameter in seagrass ecology, and requires serious consideration in seagrass research, conservation and rehabilitation programmes.

The removal of marine species through fishing has impacted marine ecosystems for thousands of years. The pressure of exploitation on marine ecosystems has now reached a point at which there is serious concern over ecosystem well-being on a global scale. There has, therefore, been a global move towards an ecosystem approach to fisheries management. The objective of this study was to develop a decision tree framework to assess the status of exploited marine ecosystems, which could be successfully applied to numerous ecosystems and guide decision support under changing conditions. This work was based on that of the IndiSeas project, which makes use of indicators designed to detect the impacts of fishing on marine ecosystem around the world. A suite of indicators, selected from those utilised in the IndiSeas project, was divided into ecological and fishing pressure indicators. Ecosystem specific suites of environmental indicators were also included, allowing the framework to ascertain the impacts of environmental variability on ecosystem components. This is an important addition as currently many assessments of the impacts of fisheries do not account for the influence of the environment. The framework was developed for the Southern Benguela ecosystem and then applied, with minor adjustments to account for ecosystem-specific characteristics, to the South Catalan Sea and North Sea. Indicator time series were analysed making use of linear regressions, resulting in the assignment of a score between one and five, depending on the direction and significance of trends. Data series were divided into distinct periods based on known environmental changes or shifts within ecosystems. Careful consideration was given as to whether fishing and environmental indicator trends could explain the observed trends in ecological indicators. A method of score adjustment was then developed to account for the impacts of both fishing and environmental variability on ecological indicators. Correlations were conducted to detect potential redundancies of ecological indicators and weightings were applied to decrease the contribution of correlated indicators to overall ecosystem trends. However, as correlations differed between indicators and amongst ecosystems, it was necessary to adjust the applied weightings for individual ecosystems. Results for the Southern Benguela classified the ecosystem as neither improving nor deteriorating during Period 1 (1978-1993) and Period 2 (1994-2003). During Period 3 (2004-2010) the ecosystem was classified as possibly improving. The South Catalan Sea was classified as possibly deteriorating during Period 1 (1978-1990) and neither improving nor deteriorating during Period 2 (1991-2010). The North Sea ecosystem was classified as neither improving nor deteriorating during Period 1 (1983-1992). During the second (1993-2003) and third (2004-2010) periods the ecosystem was categorised as possibly improving. When assessing fisheries impacts at an ecosystem scale there are typically high levels of uncertainty. However, this thesisoncluded that the development of a scoring and weighting system, alongside the addition of environmental drivers and the inclusion of expert knowledge throughout the applications of this framework, has allowed the developed decision tree framework to successfully categorise the three ecosystems. It is anticipated that the knowledge that this framework will add to current methods of generating advice for fisheries management will aid future decision support within these ecosystems.

Marine ecosystems are undergoing rapid change from a suite of human-induced stressors including overexploitation of resources, habitat fragmentation and loss, reduced habitat quality and changes to ecosystem functioning. Reserves are implemented and designed to reduce these influences, by preserving biodiversity, conserving marine habitats, increasing resilience of biota to disturbances, enhancing productivity, and facilitating the recovery of exploited fishery species. Although marine reserves can alter the structure and functioning of ecosystems, other factors such as seascape context and temporal variability can influence fish communities, ultimately determining the effectiveness of marine reserves. Ecosystem processes, abundances of harvested species and the spatial use of marine reserves can be largely influenced by the spatial properties that make up an ecosystem and other environmental factors such as climate. Although there is growing recognition of these processes, many of the key ecological characteristics that occur in protected seagrass ecosystems remain hitherto unstudied. I, therefore, aim to assess the influence of seascape context and temporal variability relative to the effectiveness of marine reserves for the protection of harvested seagrass fish species and the functions they provide. Ultimately, this thesis aims to determine the most suitable form of management of fish communities within seagrass ecosystems.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Environment
Science, Environment, Engineering and Technology
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Amb aquest treball es preté comprovar la universalitat de la relació estequiomètrica de Redfield i recercar patrons consistents de les desviacions d'aquesta raó promig en ambients oligotrofics. Per tal de dur a terme aquest propòsit s'han desenvolupat relacions estequiomètriques en el compartiment particulat i dissolt orgànic i inorgànic per el C, N, P i Si.
La estequiometria dels nutrients a l'oceà s'ha examinat al Mar Mediterrani i a l'Oceà Atlàntic subtropical, mentre que la zona costenera del Mar Mediterrani ha servit per estudiar aquestes relacions sota l'influència d'aports terrestres.
En el segon capítol de la tesi es descriuen patrons meridionals del fluxe de nitrogen i fósfor vers la capa biogènica de l'Oceà Atlàntic Central. La raó promig entre el fluxe difusiu del nitrogen inorgànic dissolt (DIN) i del fósfor (DIP) es mostra similar a la raó de Redfield al llarg de l'Oceà Atlàntic Central, però tendeix a valors per sota dels establerts per Redfield a la part sud del trajecte i superiors a la raó de Redfield al centre del gir sudtropical. La raó N:P del fluxe difusiu i la raó N:P dels nutrients dissolts inorgànics en la capa biogènica es troben fortament correlacionats, mentre que no existeix cap correlació amb els valors de la raó N:P de les aigües intermitges. Els resultats trobats en aquest capítol de la tesi indiquen que la recirculació vertical de nutrients a la capa biogènica de l'oceà Atlàntic Central és capaç d'operar amb raons estequimètriques que difereixen de Redfield i per tant els components biogènics i biolítics s'adapten a les variacions locals de la raó de Redfield. La hipòtesis que existeixen raons estequiomètriques previsibles en la reserva oceànica de material dissolt orgànic que es troben en equilibri amb la reserva del material particulat orgànic i dissolt inorgànic, es corrobora en el tercer capítol d'aquesta tesi. La majoria del carboni orgànic present en aigües oligotrofiques del Mediterrani estratificat es troba en forma d'orgànic dissolt, mentre que el POC (carboni orgànic particulat) representa un percentatge menor. El nitrogen i fósfor orgànic dissolt que comprenen el 50-80% del "pool" total de P i N a la capa biogènica, decreix en percentarge a la capa biolítica. S'ha comprovat una distribució uniforme del nitrogen disolt total (TDN). L'increment en el percentatge de N inorgànic disolt i el decreixement en percentatge de N orgànic dissolt amb la fondària, és un indicador clar de l'equilibri dinàmic que existeix entre les reaccions bioquímiques entre les reserves oceàniques. Mitjançant un sistema de balanços, s'estableix un intercanvi de nutrients (exportació-importació) entre els pools dissolt orgànic i dissolt inorgànic en el sistema. S'ha comprovat que el fluxe de nitrogen orgànic dissolt (DON) excedeix al fluxe difusiu de nitrogen inorgànic i per tant els aports atmosfèrics i terrestres són importants en aquesta regió.
En el quart capítol de la tesi es descriu el lligam existent entre el component pelàgic i els component del bentos d'una àrea litoral del Mar Mediterrani, és a dir un compartiment anabolic que produeix matèria orgànica i un de catabolic que actúa com agent oxidant de la reserva de matèria orgànica del sistema. El compartiment pelàgic es mostra heterotrofic. Al mateix temps, existeix una contribució important de material terrestre als sediments. Per contra, el compartiment bentònic és autotrofic on el dèficit en la producció grossa es compensa amb l'excés de producció neta del sistema. Mitjançant la quantificació simultànea dels fluxes anuals de sedimentació per al C, N, P i Si així com dels fluxes sediment-aigua de les espècies orgàniques i inorgàniques dissoltes, s'ha establert un sistema de balanços de matèria del sistema. El compartiment bentonic es configura com a sumider o exportador de matèria orgànica, degut als aports terrestres de carboni en el sistema.
Els patrons de distribució de nutrients derivats dels resultats dels capítols anteriors es comproven mitjançant un experiment d'addició de nutrients. En el capítol cinquè d'aquesta tesi s'estudien els canvis en la distribució de nutrients en les diferents reserves nutricionals d'un sistema quan es troba sotmès a aports controlats de nutrients. S'ha comprovat que, mentre el tamany relatiu de la reserva de nutrients inorgànics dissolts no varia amb l'increment de nutrients en el medi. Hi ha una tendència a l'increment del tamany relatiu de la reserva del material particulat, paral.lela a un decreixement simultani de la reserva de material dissolt orgànic. Aquest experiment contribueix a verificar el paper del DOM (matèria dissolta orgànica) com a principal reserva nutricional en sistemes oliogotròfics.
The stoichiometric ratios are powerful tools to model basic biogeochemical patterns of the sea when the fluxes of a single element are known. It is, therefore essential to understand the full implications of variable stoichiometries to predict the effect of the living components of the ocean on biogeochemical processes. Here, the stoichiometry between C, N, P and Si in different chemical pools (particulate and dissolved organic and dissolved inorganic matter) were examined in contrasting oceanic and littoral ecosystems, and the changes in nutrient partitioning in response to nutrient inputs was tested through experimental research.
In the Central Atlantic Ocean, the average ratio between dissolved inorganic nitrogen and phosphorus in the estimated vertical diffusive fluxes was similar to the Redfield ratio, but tended to be above the Redfield ratio at the center of the South subtropical gyre. The N:P supply ratio and the N:P ratio of dissolved inorganic nutrients in the biogenic layer were strongly correlated, but were not positively correlated to that in the intermediate waters. The vertical nutrient conveyor belt of nutrients in the upper waters operates relatively independently of the underlying waters in the Central Atlantic, so that both the biogenic and the biolythic components should be able to adapt to local variation about the Redfield ratio.
In the stratified NW Mediterranean Sea, the stoichiometry between dissolved inorganic, organic and particulate organic matter pools indicated an excess nitrogen relative to phosphorus, particularly in the biolythic layer, as well as a general silicate deficiency relative to both N and P. Most (> 80 %) of the organic carbon was present as dissolved organic carbon, with POC representing a minor percent of total organic C throughout the water column. The increasing C/N ratio of DOM with depth indicates that N is recycled faster than C in the DOM. There exists a dynamic equilibrium between the biological transformations between these pools with depth, with a dominance of DON production in surface waters and remineralization in the underlying layers, from which dissolved inorganic nitrogen is re-supplied to the biogenic layer.
Alocthonous N inputs must be important in the region since the downward DON flux exceeded the diffusive DIN supply.
The coupling between anabolic and catabolic compartments of a littoral area in the NW Mediterranean Sea are characterized. The pelagic compartment was heterotrophic, supported by significant allochthonous inputs of land material, whereas the benthic compartment was autotrophic, with the excess net benthic community production balancing the deficit in pelagic community production, leading to a system in metabolic equilibrium. Sedimentary inputs of phosphorus and silicon were compensated by sediment release of phosphate and silicate, whereas nitrogen was lost or accumulated in the sediment compartment. Carbon inputs to the benthic compartment also exceeded requirements, due to the allocthonous subsidies to the system, so that the benthic compartment stored or exported organic carbon.
Experimental nutrient additions lead to a parabolic change in C/N and C/P ratios in the dissolved organic matter with increasing nutrient inputs. The relative size of the dissolved inorganic nutrient pools did not vary, but there was a tendency towards an increase in the relative size of the particulate pool at the expense of a decrease in the relative importance of DOM as a reservoir of N, P and C, with increasing nutrient inputs.
The relative importance of different nitrogen pools was examined in relation to the total nutrient stoichiometry of the oligotrophic system. The ratio of dissolved inorganic nutrients reported in the research presented is indicative of a general deficiency in nitrogen compared to the global ratios reported in literature. The dissolved organic matter was highly depleted in P relative to N and C at all locations investigated and the resulting POC:PON ratio (11.7) of this study in the particulate pool deviates greatly from the literature values which approximates Redfield value (5.5-6). The shift of the dominance of DON towards PON at TOC/TN values higher than 20 on the oligothrophic areas of the study, gives evidence of increasing carbon export fluxes in a system dominated by particulate pool and points to the effect of the biota on the gradient-driven export to sinking carbon fluxes in the ocean.

Southeast Florida’s continual urban expansion will potentially increase anthropogenic pollution in adjacent coastal marine systems. Furthermore, increased nutrient loads could have detrimental effects on the already threatened Florida Reef Tract. The present study uses a stable isotopic approach to determine the sources and the impact of nutrients on the Florida Reef Tract. δ13C and δ15N analysis of macroalgae, sponges, and sediment were analyzed in order to determine nutrient inputs in this region. While δ13C data did not display any significant trends spatially, δ15N values of the majority of biota exhibited a strong East to West gradient with more enriched values close to shore. Relative enrichment in δ15N values were measured for sediments sampled along the Florida Reef Tract in comparison to a pristine Marquesas Keys sediment core. The δ15N data also implies that shoreline anthropogenic nutrients have more nutrient loading implications on reefs than major point sources.

Over the past decades technological developments have both changed and increased human in influence on the marine environment. We now have greater potential than ever before to introduce disturbance and deplete marine resources. Two of the issues currently under public scrutiny are the exploitation of fish stocks worldwide and levels of anthropogenic noise in the marine environment. The aim of this thesis is to investigate and develop novel analyses and simulations to provide additional insight into some of the challenges facing the marine ecosystem today. These methodologies will improve the management of these risks to marine ecosystems. This thesis first addresses the issue of competition between humans and grey seals (Halichoerus grypus) for marine resources, providing compelling evidence that a substantial proportion of the sandeels consumed by grey seals in the North Sea are in fact H. lanceolatus, which is not commercially exploited, rather than the commercially important A. marinus. In addition, we present quantitative results regarding sources of bias when estimating the total biomass of sandeels consumed by grey seals. Secondly, we investigate spatially adaptive 2-dimensional smoothing to improve the prediction of both the presence and density of marine species, information that is often key in the management of marine ecosystems. Particularly, we demonstrate the benefits of such methods in the prediction of sandeel occurrence. Lastly this thesis provides a quantitative assessment of the protocols for real-time monitoring of marine mammal presence, which require that acoustic operations cease when an animal is detected within a certain distance (i.e. the "monitoring zone") of the sound source. We assess monitoring zones of different sizes with regards to their effectiveness in reducing the risks of temporary and permanent damage to the animals' hearing, and demonstrate that a monitoring zone of 2 km is generally recommendable.

Coral reefs are the iconic ecosystem of tropical seas and yet they are under increasing pressure as a result of multiple climatic stressors. This thesis uses observations and models to further understanding of environmental impacts on coral reefs. In particular it examines the impact of rising Sea Surface Temperature (SST) and ocean acidification on coral growth and the frequency of coral bleaching events. UK ocean biogeochemical models are assessed for implementation in the next UK Earth System Model. This analysis finds little evidence that more complex ocean biogeochemical models provide better simulations of large scale biogeochemical features. An established wavelet-based spatial comparison technique is used to analyse the spatial scales that Earth System Models can skillfully simulate patterns of SSTs. It is shown that in coral regions, current models cannot skilfully simulate patterns of historical SST anomalies at sub-regional (<32◦) scales. These findings are used in combination with SST and aragonite saturation state outputs from Earth System Models to show that historical Caribbean coral growth has been influenced by anthropogenic aerosol emissions over the 20th Century. Earth System Model outputs are also used to make projections of global coral bleaching throughout the 21st Century. It is shown that under even the most extreme conventional mitigation scenarios the majority of the world’s coral reefs are projected to experience levels of thermal stress induced bleaching that cause reef degradation throughout the 21st Century. Geoengeering scenarios involving the injection of SO2 into the stratosphere can reduce the projected thermal stress on coral reefs relative to conventional mitigation scenarios but such benefits are shown to be highly dependent on the sensitivity of coral bleaching thresholds to ocean acidification.

Our world is subjected to a panoply of drivers of change. In this context, the understanding on how our biosphere resists, absorbs or is altered by the changes, appears as a hot question in ecology. In this respect, two ecological concepts appear as essential, resilience and biotic interactions. Resilience is related to how ecosystems persist under stress or suffering disturbances. Interactions among species are to a large part responsible for the delivery of ecosystem functions, and form the architecture of biodiversity. Moreover, a substantial part of ecosystem resilience is founded on species interactions. This thesis is an attempt to shed some light on these issues through the deep exploration of specific case studies in seagrass ecosystems, in particular how seagrasses respond to external drivers (or how resilient they are), how these responses affect species interactions and which mechanisms allow coexistence of species linked by positive and negative interactions. Our approach is based upon field observations and field manipulative experiments. Chapter 1 shows how an increase of organic matter in sediment weakens the mutualism between the bivalve Loripes lucinalis and the seagrass Cymodocea nodosa. The mechanism implied is the effect of this increase (and, probably, the resulting anoxia) on seagrass root morphology (plant trait), which results in a lower provision of habitat for the bivalves, whose abundance decreases. The weakening of the mutualism can potentially decrease the resilience of these ecosystems to eutrophication and, therefore, compromise their persistence. Chapter 2 describes a facilitative cascade in which the seagrass C. nodosa favors the abundance of the pen shell Pinna nobilis, which positively affects the sea urchin Paracentrotus lividus, which in turn consumes the seagrass. We suggest that the persistence of this three-species assemblage rests on the very local impact of sea urchins on the seagrass, likely driven by behavioural and denso-dependent processes. Chapter 3 and 4 show that fast-growing species such as C. nodosa are highly resilient to stress or disturbances when affecting only the aboveground parts, recovering fast (within two weeks) from a single event of disturbance. C. nodosa shows several mechanisms of tolerance, such as compensatory growth, reallocation of internal resources and enhancement of the formation of new modules, when coping to repeated defoliation simulating herbivory. However, when the belowground parts are lost by disturbances, recovery is highly delayed up to two years and is dependent on the characteristics of the disturbance such as size and timing. Overall, this research has contributed to increase our understanding on how ecosystems respond to changes and how species interactions are maintained and disrupted. We have shown that environmental changes can alter the functioning of seagrass ecosystems at least in two directions. Firstly, by altering fundamental biological interactions, such as the seagrass-lucinid mutualism and, secondly, by affecting the resilience of ecosystems dominated by a foundation species, which promote species coexistence. Advances in the two complementary and interlinked directions will be crucial to better manage and preserve ecosystems and prevent their potential collapse under the increasing human-induced change the world is submitted to.
El nostre món està sotmès a un ampli ventall de forces que tendeixen a provocar canvis. En aquest context, entendre com la biosfera resisteix, absorbeix o és alterada per aquestes forces resulta una qüestió candent, especialment per l'ecologia. Al respecte, dos conceptes ecològics esdevenen essencials: la resiliència i les interaccions biològiques. La resiliència és la capacitat de persistència o recuperació que tenen els ecosistemes sotmesos a estrès o pertorbacions. Les interaccions entre espècies (efectes de l'existència d'una espècie sobre la fitness d'una altra) contribueixen al manteniment de les funcions ecosistèmiques i, en un cert sentit, constitueixen l'arquitectura de la biodiversitat. A més, la resiliència dels ecosistemes depèn , en gran part, d’aquestes interaccions. Aquesta tesi és un intent d’aprofundir en els aspectes esmentats a través d'una sèrie de casos d’estudi en ecosistemes d’angiospermes marines. Concretament, el que fem és estudiar com els ecosistemes d’angiospermes marines responen a les forces causants de canvis, com aquestes respostes vénen mitjançades per canvis en la interacció entre espècies, i provar d'esbrinar els mecanismes que permeten la coexistència d’espècies que es troben vinculades per interaccions positives i negatives. La nostra aproximació es basa tant en observacions com en experiments en el camp. El Capítol 1 mostra com un increment de matèria orgànica en el sediment debilita el mutualisme entre el bivalve Loripes lucinalis i l’angiosperma marina Cymodocea nodosa. El mecanisme implicat que es proposa per explicar-ho està relacionat amb la plasticitat morfològica de la planta. Així, un increment en la matèria orgànica del sediment (i, probablement, l’anòxia que se'n segueix), fa que la planta modifiqui la morfologia de les seves arrels, que esdevenen molt menys ramificades i fan disminuir per tant la disponibilitat d'hàbitat per als bivalves. Una debilitació del mutualisme pot, potencialment, disminuir la resiliència d’aquests ecosistemes a l’eutrofització i, per tant, comprometre la seva persistència. El Capítol 2 descriu una cascada de facilitació en la qual l’angiosperma marina C. nodosa afavoreix l’abundància del gran bivalve Pinna nobilis, que ajuda a incrementar l'abundància de la garota Paracentrotus lividus, que al seu torn consumeix l’angiosperma. Suggerim que la persistència d’aquest sistema de tres espècies, aparentment inestable (tres interaccions concatenades circularment, dues de positives i una de negativa) es basa en què la interacció negativa (l’efecte de les garotes sobre l’angiosperma) té un abast molt limitat, probablement degut tant al seu comportament alimentari com a les defenses de la planta enfront de l'herbivorisme. Els Capítols 3 i 4 mostren que les espècies de creixement ràpid, com ara C. nodosa, són altament resilients a l'estrès o a les pertorbacions quan aquestes afecten només les parts aèries de les plantes (defoliació parcial o total), recuperant-se ràpidament (dues setmanes) després d'una pertorbació puntual en el temps. C. nodosa mostra diversos mecanismes de tolerància a la defoliació, com ara el creixement compensatori, la reassignació de recursos interns i l’increment en la taxa de formació de nous mòduls. Tanmateix, quan les pertorbacions provoquen la pèrdua de les parts subterrànies (rizomes i arrels), la recuperació és molt més lenta, i triga fins a dos anys. A més, aquesta recuperació depèn de les característiques de la pertorbació com ara la mida de l'àrea afectada i l’època de l'any en què es produeix. En general, aquesta tesi ha contribuït a comprendre millor les respostes dels ecosistemes als canvis. Hem pogut documentar alguns processos que permeten la coexistència entre espècies, així com mecanismes de resiliència específics que esdevenen ecosistèmics quan es manifesten en espècies fundadores d'hàbitat. També hem demostrat com els canvis, més enllà d'afectar espècies individuals més o menys emblemàtiques, poden provocar alteracions de formes més subtils, com ara erosionant la seva resiliència mitjançant la modificació d’interaccions biològiques. Els avenços en totes aquestes direccions complementàries i interrelacionades són crucials per a gestionar i preservar els ecosistemes i evitar el seu possible col·lapse.

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

The importance of Trait Mediated Indirect Interactions (TMII) is increasingly being recognized. TMII are interactions between two species via a change in trait (behavioural, morphological, but not numerical) over a third one, which together cause ecological dynamics. Marine food webs have complex interactions, but TMII have not yet received great appreciation or application in marine conservation and management models. This article is a review about the different ways in which TMII can affect marine ecological dynamics. I summarize known examples of Behaviourally Mediated Indirect Interactions, Physiologically Mediated Indirect Interactions, and other types of indirect interactions such as initiated or mediated by parasites, in order to provide a better understanding about their functioning. I found that TMII are omnipresent in marine ecosystems and occur at all trophic levels, spanning from macro- to microorganisms. Furthermore, it includes many different taxa and guilds, and the mechanisms are highly diverse. Some of them enhance Density Mediated Effects, while others counteract them. Sometimes this results in the effects opposite of those expected, and often they extend further in the food web. Understanding of TMII is likely to be beneficial for marine conservation and management, due to the role of humans causing them or suffering its effects.

Marine environments play a central role for the planet, yet an understanding of how climate change is affecting marine ecosystems has been poorly developed. There is now growing evidence that human activities are driving rapid changes from local to global scale. In last decades, the rates of change is accelerating and may exceed the potential tolerance of many organisms to adapt. Ecological systems and marine organisms have evolved under different regimes of stress and disturbances both of natural and anthropic origin and intrinsically connected. No ecosystem is unaffected and marine coastal habitats are particularly sensitive due to the convergence of multiple stressors. The present work attempts to investigate how variable patterns of stress and disturbance influence the change in marine ecosystems, looking at two iconic coastal habitats: seagrass beds and coral reefs. Effects due to the anthropogenic pressure and a severe storm are here investigated as stress and disturbance respectively, on the endemic Mediterranean seagrass Posidonia oceanica. Thermal anomalies causing repeated coral bleaching events are considered as disturbances on Maldivian coral reefs, while the reduced pH environment that is created at shallow hydrothermal vents of North Sulawesi (Indonesia) is seen as a stress simulating climate and human impact on benthic habitats. The study of change in coastal ecosystems has been carried out by means of several approaches including the comparison with long-time series, the use of indicators able to return a value of ecological status, retrospective analyses and modelling. The present work confirms the complexity of the interactions between stresses and disturbances, different in scale and intensity, operating on a same ecosystem. The increase in seawater temperature starting from the 1980-90s can be identified as a common driver of change in both seagrass meadows and coral reefs ecosystems. In P. oceanica meadows of the Ligurian Sea, anthropic pressures remain the primary causes of impact, although, high intensity, pulse disturbances demonstrated that a single event is able to cause the same loss resulting from hundreds of years of chronic stress. Benthic habitats in close proximity to hydrothermal vents at tropical latitudes seem not negatively affected by the reduced pH as a chronic stress, while, in Maldivian coral reefs, the ability to cope with thermal disturbances seems to be dependent on coral genera. Benthic ecosystems could develop a certain adjustment capacity to chronic stress to the detriment of an enhanced sensitivity towards disturbances but this is of concerns regarding the predicted increase of high intensity disturbances due to climate change. Moreover, chronic stress and disturbances invariably co-occur, so it becomes difficult to assess which may be the proximate cause of ecosystem change. Data on benthic communities suggest that marine habitats are experiencing phase-shifts toward alternative and unknown states. Consequently, future marine habitats will likely lose their original features acquiring a new different shape. Continuing studies and long-term series of data will remain the most effective tool to validate these predictions and evaluate temporal patterns.

Hydrocarbon (HC) pollution is a worldwide threat to marine natural ecosystems due to the increasing exploitation of underground marine petroleum deposits in several areas and to the high traffic of oil tankers and the presence of submarine pipes that are main transport routes for crude oil and refined products. HCs spread in the marine environment is mainly due to accidental oil spills or inadequate practices and their release affects marine ecosystems causing severe ecological and economical damages. The Mediterranean Sea is particularly endangered by hydrocarbon pollution because of its physical nature – it is an enclosed basin with a slow water exchange – and because it hosts about 20% of the global oil tanker traffic in its waters and tens of oil-related sites along its coastline. The conventional remediation strategies, comprising chemical and physical methods, are extremely expensive and invasive, therefore the development of cheaper and eco-friendly approaches is crucial to preserve human and ecosystem health. In this perspective, bioremediation (i.e. the use of living organisms to remove pollutants from a contaminated area) is a promising technology which, taking advantage of microbes’ metabolic potential to degrade a wide range of pollutants, can both reduce the costs and may represent a permanent solution. Nevertheless, there is still a scarce knowledge of the processes and the microorganisms involved in the clean-up of hydrocarbons from marine environments, hence some problems still exist concerning the in-field application of bioremediation. The aim of the present PhD thesis was to: i) investigate the overall prokaryotic diversity of pristine and oil polluted sites across the whole Mediterranean Sea; ii) depict the phylogenetic and functional diversity of hydrocarbonoclastic bacteria inhabiting pristine and polluted sites; iii) establish a large collection of bacteria showing degrading activities toward hydrocarbon compounds; iv) set up microcosm experiments to investigate the potential of bacterial bioaugmentation in bioremediation processes under laboratory scale conditions, v) test the degrading potential of selected bacterial strains and consortia under different pressure values, simulating different depths along the water column. The diversity of planktonic bacterial communities in the Mediterranean Sea was firstly evaluated on open seawater samples collected at different depths in a transect covering the main oil tanker route across the whole basin, from the Levantine Sea to the Gibraltar strait. Automated Ribosomal Intergenic Spacer Analysis (ARISA) showed that the microbiome inhabiting deep and surface water samples were sharply separated. Furthermore, the composition of the bacterial communities described in the surface layers of the water columns at different sampling stations has been significantly correlated, beside to their geographical position and depth, to the temperature and salinity values recorded for each sample. Denaturing Gradient Gel Electrophoresis (DGGE) and ARISA fingerprinting were also applied to depict the bacterial composition of highly polluted sediments collected at the Ancona harbor (Italy) and El-Max district (Egypt), showing the significant influence of the different pollutants’ concentration (i.e. hydrocarbons, heavy metals) in the selection of peculiar bacterial assemblages . This molecular approach led to the identification of bacterial species potentially useful for site-tailored bioremediation purposes. A large collection of hydrocarbon degrading bacterial strains was hence established from enrichments using contaminated sediments as inoculum and diesel, crude oil and naphthalene as unique carbon sources. The cultivation approaches adopted to enrich and isolate hydrocarbonoclastic bacteria from chronically polluted area, like the Ancona harbor, permitted to evaluate the influence of different hydrocarbon pollutants used as single carbon source in the selection of specific marine bacteria populations. The results obtained taking advantage of DGGE fingerprinting and 16S rRNA pyrosequencing applied on the enrichments showed that, under laboratory conditions, the supply of different hydrocarbon compounds led to the selection of different, and specialized, bacterial communities. A total of 248 bacterial strains have been isolated from open sea surface water collected along oil tanker routes and the chronically polluted sediments, and have been identified by 16S rRNA gene sequencing. Alcanivorax and Marinobacter, two ubiquitous marine hydrocarbonoclastic genera, were the most abundant within the established collection, representing respectively 67% and 23% of the isolates. Due to the great importance of the Alcanivorax genus for hydrocarbon remediation of marine polluted sites, all the isolates belonging to this genus were investigated at a finer level in terms of phylogenetic and functional diversity. This sub-collection, comprising 179 isolates belonging to the 4 species A. borkumensis, A. jadensis, A. venustensis and A. dieselolei, were genotyped using two different fingerprinting techniques: Internal Transcribed Spacer (ITS)-PCR and BOX-PCR. The combination of the applied techniques allowed the identification of 85 genotypes, distributed among the different sites investigated, showing clear evidence of geographic divergence. The functional diversity of these strains was furthermore investigated through the PCR amplification of the alkB gene, encoding for an alkane monooxigenase involved in the first step of hydrocarbons degradation, and subsequent Restriction Fragment Length Polymorphism (RFLP) analysis of the amplicons, allowing the identification of 16 different polymorphisms. The results demostrated the existence of a high degree of geographical divergence within the Alcanivorax genus, suggesting a potentially high metabolic diversity that could be exploited for site-tailored bioremediation interventions. Recently, the Deepwater Horizon break in the Gulf of Mexico (2010) and the subsequent huge oil spill occurred at a depth of 1500 meters, highlighted the need to get more insight on bioremediation processes occurring at high depth. This accident represents a milestone and shed a light on the importance to investigate the effect of pressure, an environmental parameter that might hamper the activity of oil-degrading strains, on growth and degradation capabilities. The capability of selected hydrocarbonoclastic strains, belonging to the species A. jadensis, A. dieselolei and M. hydrocarbonoclasticus, to adapt and degrade a model alkane molecule (dodecane) at high pressure was therefore tested. The growth of the strains at increasing hydrostatic pressure and their physiologic activities were evaluated, comparing the results with the type strain A. borkumensis SK2. Overall, the results showed a detrimental effect of pressure for all the strains in terms of growth rates, O2 consumption and CO2 production. The potential adaptation of A. borkumensis and A.dieselolei was evaluated also with less recalcitrant carbon source than alkanes (pyruvate), without showing substantial differences, except for the higher consumption of pyruvate by A. borkumensis SK2. This investigation pinpointed that the tested bacteria can survive at high hydrostatic pressures, even though both their growth and degradation capability were mostly inhibited with the increase in hydrostatic pressure. Moreover, aiming to create a baseline for future transcriptomic analyses, the complete genome of this 4 strains was sequenced and annotated: all the strains owned multiple copies of the genes involved in the degradation of hydrocarbons (alkane monoossigenase, alk and cytochrome p450, cyp450), apparently belonging to different families, highlighting the great functional potential of these strains. A second sub-collection of hydrocarbonoclastic bacteria, isolated from chronically polluted sediments, was screened for the presence of functional genes involved in the degradation/detoxification of specific pollutants (alkanes and heavy metals), the ability to grow on different HCs and the ability to produce biosurfactant and from biofilm. The results showed that several isolates, mainly belonging to the Marinobacter genus, were positive for the investigated traits, hence they could be potentially exploited for autochthonous bioaugmentation (ABA) purposes in the sites of provenience. Finally, the bacterial community response in a biodegradation process based on an ex-situ landfarming set-up was evaluated. Landfarming was performed, using a combination of biostimulation and bioaugmentation, to remediate oil-polluted sediment collected at Elefsina bay (Greece). This work was realized to determine the effect of bioaugmentation by four allochthonous oil-degrading bacterial consortia, previously isolated from 4 polluted areas located in the Southern Mediterranean, in relation to the degradation efficiency of the indigenous community. DGGE fingerprinting analysis allowed the characterization of the bacterial community dynamics, evaluating the dominant taxa through time and at each treatment. The results showed that the added allochthonous bacteria quickly perished and were rarely detected, furthermore their addition induced minimal shifts in the community structure. These data, together with the measurement of HC degradation over the experimental time, suggested that, during the landfarming, biodegradation was mostly performed by the autochthonous populations rather than by the allochthonous ones. Furthermore, biostimulation, in contrast to bioaugmentation, was proved to enhance the HCs degradation when compared to the control treatment. To conclude, the results obtained this Ph.D. project emphasized the high bacterial diversity of the Mediterranean Sea in both pristine and polluted sites and the occurrence of distribution patterns which were significantly related to several environmental parameters, including the concentration of hydrocarbons and heavy metals. Moreover, this study confirmed the great potential of the Mediterranean Sea as a source of bacterial strains harbouring degradation capabilities toward different hydrocarbon molecules and, through the ex-situ application of different bioremediation strategies (bioaugmentation and biostimulation), it demonstrated the great importance of autochthonous microbial community in remediating polluted environments.

The potential for life to control its environment was first suggested by Lovelock (1972). Charlson et al (1987) proposed a role for marine planktonic ecosystems in global climate regulation via the production and ventilation to the atmosphere of dimethylsulphide (DMS), a by-product of phytoplankton metabolism. Once in the atmosphere DMS contributes to the formation of cloud condensation nuclei, and increases the amount and brightness of cloud. This affects the albedo of the planet, reflecting more incident sunlight back into space, and cooling the earth. In common with many other 'hypotheses' regarding complex adaptive systems, the hypothesis proposed by Charlson et al (1987) is not experimentally testable. The production and ventilation to the atmosphere of DMS is the result of complex interactions between biological, chemical and physical processes. Consequently, increasing use is being made of mathematical models that simulate these processes to advance understanding of it (Archer et al. 2002). This study examines one of the fundamental mechanisms proposed by the Charlson et al (1987) hypothesis, that increasing global temperatures will lead to increased ventilation of DMS from the ocean to the atmosphere. The study develops one-dimensional biogeochemical models of DMS production by upper ocean ecosystems, based on the model proposed by Gabric et al. (1993b). The models are examined to elucidate their fundamental mathematical properties, and are subjected to sensitivity analysis to identify important processes and parameters. These investigations identify a simpler model that can reproduce the predictions of the Gabric et al. (1993b) model. Predictions derived from model simulations forced by climatologies of measured physical data are compared to a global database of measurements of sea surface DMS concentrations, and to observed depth profiles of DMS in the upper ocean. These comparisons confirm that all models are in good qualitative agreement with measured data. The fifteen global climate prediction models currently in use around the globe all predict substantial warming effects from the ventilation of anthropogenic carbon dioxide to the atmosphere. A simplified DMS model is calibrated to climatologies of Antarctic chlorophyll and DMS data and reproduces the data with great precision. The calibrated model is applied in global warming scenarios to 'test' the efficacy of the mechanism proposed by the Charlson et al (1987) hypothesis. This simulation provides evidence that the response predicted by the hypothesis is indeed feasible, and that substantial increases (up to 45%) in the ventilation of DMS to the atmosphere could be possible in some circumstances. The results of the modelling study provide impetus for further examination of field data. If couplings between marine biota and atmosphere are feasible, then they may be operating contemporarily, and may be detectable. Atmospheric DMS is oxidised to form aerosols (Miller et al. 2002) that influence the aerosol optical depth of the atmosphere. Archives of remote sensed ocean chlorophyll a concentration and aerosol optical depth are examined for evidence of the biologically mediated couplings. A clear coupling between aeolian dust and marine phytoplankton is evident from this analysis, suggesting that the deposition of dust from the atmosphere is a major factor controlling phytoplankton growth in many parts of the ocean. A second coupling between marine phytoplankton and atmospheric aerosols is also detected. This coupling is apparently not related to dust and is symmetrical about the equator, despite the substantial differences in the atmospheres and oceans of each hemisphere. It is speculated that this coupling may reflect the influence of the ventilation of DMS produced by marine phytoplankton on the atmosphere. This thesis provides new evidence supporting the important role of marine ecosystems in global climate regulation by the production of DMS. This evidence is principally obtained from a biogeochemical modelling approach, but is supported by analyses of empirical data. The concordance of results obtained from different approaches suggests that the contribution of marine ecosystems to global climate regulation is real, important and currently active.

The potential for life to control its environment was first suggested by Lovelock (1972). Charlson et al (1987) proposed a role for marine planktonic ecosystems in global climate regulation via the production and ventilation to the atmosphere of dimethylsulphide (DMS), a by-product of phytoplankton metabolism. Once in the atmosphere DMS contributes to the formation of cloud condensation nuclei, and increases the amount and brightness of cloud. This affects the albedo of the planet, reflecting more incident sunlight back into space, and cooling the earth. In common with many other 'hypotheses' regarding complex adaptive systems, the hypothesis proposed by Charlson et al (1987) is not experimentally testable. The production and ventilation to the atmosphere of DMS is the result of complex interactions between biological, chemical and physical processes. Consequently, increasing use is being made of mathematical models that simulate these processes to advance understanding of it (Archer et al. 2002). This study examines one of the fundamental mechanisms proposed by the Charlson et al (1987) hypothesis, that increasing global temperatures will lead to increased ventilation of DMS from the ocean to the atmosphere. The study develops one-dimensional biogeochemical models of DMS production by upper ocean ecosystems, based on the model proposed by Gabric et al. (1993b). The models are examined to elucidate their fundamental mathematical properties, and are subjected to sensitivity analysis to identify important processes and parameters. These investigations identify a simpler model that can reproduce the predictions of the Gabric et al. (1993b) model. Predictions derived from model simulations forced by climatologies of measured physical data are compared to a global database of measurements of sea surface DMS concentrations, and to observed depth profiles of DMS in the upper ocean. These comparisons confirm that all models are in good qualitative agreement with measured data. The fifteen global climate prediction models currently in use around the globe all predict substantial warming effects from the ventilation of anthropogenic carbon dioxide to the atmosphere. A simplified DMS model is calibrated to climatologies of Antarctic chlorophyll and DMS data and reproduces the data with great precision. The calibrated model is applied in global warming scenarios to 'test' the efficacy of the mechanism proposed by the Charlson et al (1987) hypothesis. This simulation provides evidence that the response predicted by the hypothesis is indeed feasible, and that substantial increases (up to 45%) in the ventilation of DMS to the atmosphere could be possible in some circumstances. The results of the modelling study provide impetus for further examination of field data. If couplings between marine biota and atmosphere are feasible, then they may be operating contemporarily, and may be detectable. Atmospheric DMS is oxidised to form aerosols (Miller et al. 2002) that influence the aerosol optical depth of the atmosphere. Archives of remote sensed ocean chlorophyll a concentration and aerosol optical depth are examined for evidence of the biologically mediated couplings. A clear coupling between aeolian dust and marine phytoplankton is evident from this analysis, suggesting that the deposition of dust from the atmosphere is a major factor controlling phytoplankton growth in many parts of the ocean. A second coupling between marine phytoplankton and atmospheric aerosols is also detected. This coupling is apparently not related to dust and is symmetrical about the equator, despite the substantial differences in the atmospheres and oceans of each hemisphere. It is speculated that this coupling may reflect the influence of the ventilation of DMS produced by marine phytoplankton on the atmosphere. This thesis provides new evidence supporting the important role of marine ecosystems in global climate regulation by the production of DMS. This evidence is principally obtained from a biogeochemical modelling approach, but is supported by analyses of empirical data. The concordance of results obtained from different approaches suggests that the contribution of marine ecosystems to global climate regulation is real, important and currently active.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Australian School of Environmental Studies
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Investigations on the biodiversity in relation to conservative and non-conservative parameters in the Mangalavanam mangrove ecosystem, located in the northern fringes of Cochin City have been carried out from January to June 2002. The mangrove ecosystem is regularly under tidal influence and hence submergence and emergence of land takes place depending on the tidal amplitude. The average dissolved oxygen of the water was found to be 3.5ml/l despite the fact, phytoplankton was abundant in the ecosystem. It reveals that respiratory demand of the aquatic biota has exceeded the photosynthetic oxygen production. The indirect relationship exhibited by the quantity of phytoplankton and oxygen is attributed to anthropogenic activities, which resulted in to the eutrophication of the mangrove ecosystem. The general nutrient load was at a higher level. The macrophytic vegetation was dominated by A^icennia marina, Rhizdphora mucronata and Acanthus ilicifolius. The presence of Avicennia and Acanthus in majority of the area that showed decrease in salinity and more freshwater influx. The phytoplankton community was dominated by djatoms represented Naviculaceae followed by Coscinodisceae, which Is evidenced by the presence of high quantity of silicate. The Zooplankton was dominated by copepods. Benthic community is dominated by the infauna such as polychaetes and decapods. Juveniles of common brackish water fishes. Chanos spp., Liza spp., Etroplus spp., Silago spp., Lethrinus spp. and Lutjanus spp., and species of crustaceans like Penaeus spp., Metapenaeus spp., Macrobrachium spp., Acetes spp., Metaplex spp., Sesarma spp., Uca spp., and Scylla spp., have been found to be the residents of the mangrove ecosystem. Avian fauna comprises mostly little cormorants (Phalactocorax niger) and black crowned night heron (Nycticorax nycticorax). Other arboreal fauna is dominated by Indian flying fox (Pteropus giganteus). An evaluation on the biodiversity of the mangrove ecosystem in the light of the present investigations reveals that species diversity Is less, but moderate population density of available species could be observed. To put It In a nutshell, human interventions on the environment has been detrimental and a general degradation of the ecosystem has been evidenced by the emergence of terrestrial vegetation and shrinking of the true mangrove areas.

The conservation of marine ecosystem structure and functioning is a priority target within the context of the environmental management. This is especially important in oligotrophic systems such as the Balearic Sea, where food availability is a limiting factor. For such a target is fundamental to know the array of predator-prey interactions as a basis to understand the food web trophodynamics. In this Thesis, the trophic structure of the pelagic and benthic habitats off the Balearic Islands and the feeding ecology of three taxonomic groups (cephalopods, elasmobranchs and mesopelagic fishes) playing a key role in marine ecosystems, were investigated A relatively large food web (89 species) encompassing both the pelagic and the benthic habitats were analysed. The food webs extended up to 4 trophic levels in both habitats, and most species occupied intermediate trophic levels. A high partitioning rate of trophic resources was found, which might be related to the reduction of competition for food. The energy link between the pelagic and benthic communities (benthopelagic coupling; BPC) was stronger on the shelf break, where higher hydrodinamism mix the water column and associated nutrients, than on the slope. The geographical variability of oceanographic drivers (i.e. eddies, currents) influenced the strength of the BPC. Regarding species trophic interactions, stomach contents provided evidence of mesopelagic prey coupling pelagic and benthic habitats, especially down the shelf break. Rays from the shelf consumed mainly decapod crustaceans and teleosts, whereas sharks from the slope fed primarily upon mesopelagic prey (i.e myctophids, euphausiids). Sharks and rays variation in diet was driven by species specific ontogenetic stages and habitat use. The diet of the two squid Loligo vulgaris and L. forbesii, examined for the first time in the Mediterranean, showed their highly piscivorous habits. Their prey composition revealed a lack of diet overlap as a result of their bathymetric segregation. Both squids showed shifts in diet related to size and their reproduction period. The squid L. vulgaris feed on small benthic prey until they reach a size threshold and feed on benthopelagic fish thereafter. Seasonal changes in diet in both squid species, likely related to reproduction, might help improving their individual body condition. During this period, L. vulgaris increased the consumption of highly nutritive polychaetes, whereas the adults of L. forbesii carried out movements to deeper waters to feed on lipid-rich mesopelagic prey. Mesopelagic prey are important food resources for demersal species in the Balearic Sea and, as a result of their nycthemeral movements, they have important implications for the transport of mass and energy through the water column. The trophodynamics of this group revealed that food sources (δ13C) varied little over the spatial scales sampled (location and depth) but showed high seasonality, reflecting intra-annual changes in the species composition of the phytoplankton community. By contrast, spatio-temporal variations of mesopelagic trophic interactions (δ15N) were minimal. Important niche segregation was observed between the non-migratory stomiiforms and some of the extensive migratory myctophids. Finally, the comparative analysis of the trophic ecology of deep-sea cephalopods and elasmobranchs showed that they displayed different feeding strategies with a clear resource partitioning between and within taxa. Segregation of the isotopic space indicated a contrasting food source gradient (δ13C) stretching from pelagic (squids and cuttlefishes) to nektobenthic (octopuses and elasmobranchs) sources. However, deep-sea sharks off the Balearic Islands frequently preyed on mesopelagic species, as did squids and cuttlefishes. Cephalopods, in turn, constituted an important food resource for deep-sea sharks. Squid and shark species identified as benthopelagic feeders, play a key role in the transport of energy from midwater regions to the benthic community.

Plastic pollution has been recognised as one of the major global threats for marine ecosystems. In the Mediterranean basin, plastic debris are present at concentrations comparable to the subtropical ocean gyres. Microplastics (< 5 mm) also reached the most remote environment on Earth, being reported in Antarctic surface waters and sediments. The limited knowledge on the biological impacts of the smallest fraction of plastic debris, defined as nanoplastics (< 1 μm), is of primary concern, due to their high surface reactivity and nanometric size that allow to easily interact with biological surfaces at the cellular level. Within this thesis, the bioaccumulation and toxicity of nanoplastics in Mediterranean and Antarctic marine organisms have been investigated. Polystyrene nanoparticles (PS NPs), having a nominal diameter of approx. 50 nm and different surface charge, were adopted as nanoplastics as anionic carboxylated (PS-COOH) and cationic amino-modified (PS-NH2). The characterization of their behaviour in natural sea water media was combined with cellular/whole-animal bioassays in order to define uptake, disposition and mechanisms of action under controlled laboratory conditions. The four chapters of the thesis report findings on model organisms including zooplanktonic and benthic species from the Mediterranean Sea and Southern Ocean around Antarctica, as sea urchin embryos (Paracentrotus lividus), green microalga (Dunaliella tertiolecta), brine shrimp (Artemia franciscana) and Antarctic sea urchin (Sterechinus neumayeri) and krill (Euphausia superba) respectively. Overall, we proved that NP surface charge (anionic vs cationic) drives the behaviour of PS NPs in natural sea water in terms of stability and aggregation, which differs in Mediterranean and Antarctic sea waters. Anionic PS-COOH formed large micro-sized aggregates whereas cationic PS-NH2 resulted better dispersed in Mediterranean sea waters. In Antarctic sea waters, such difference in aggregation was reduced, with PS-COOH reaching nano-sized aggregates and PS-NH2 approaching the nominal size. A similar pattern of biodistribution and toxicity was observed in marine organisms from Mediterranean Sea and Antarctica, with respect to NP surface charge. Anionic PS-COOH were mostly ingested, accumulated and excreted with no or limited effect, while PS-NH2 revealed a less clear disposition but cause high toxicity, hinder embryo development and larval growth, disrupt physiology and organism’s survival. For this latter NP, several markers of stress, were identified through up-regulation of apoptotic-related genes (caspase8, hsp60, hsp70 and p-38 mapk) in Mediterranean sea urchin embryos and moulting-related genes (clap, cstb and cb6) in brine shrimp larvae and Antarctic krill juveniles. In Antarctic sea urchin coelomocytes, both PS NPs were able to reduce the cellular phagocytic capacity, with PS-COOH inducing the strongest gene modulation in contrast to a threshold in cell defence ability upon PS-NH2 exposure. Overall, ecotoxicological data constitute a comprehensive baseline on the biological effects of nanoplastics in Mediterranean and Antarctic marine species, motivating future research using more realistic exposure scenarios towards environmental-like conditions and more specific NP-biological interactions (i.e. eco and bio-coronas).

In this thesis is presented the development of different analytical methodologies for the analysis of marine biotoxins in seawater. The objectives were the development of the methods and the application to study the biotoxins in marine environments as well as to use it as early warning tools able to detect the presence of the biotoxins at low concentrations previous to an algal bloom development. The analytical development has been carried out evaluating the precision, accuracy, selectivity and sensibility of the methods. Due to the diverse physic-chemical properties between the different groups of toxins, three different methodologies have been created. First step of the methods consisted in a sample pre-treatment to eliminate the possible interferences in the sample that could difficult the instrumental analysis. For this reason, the biotoxins were extracted from seawater and concentrated to achieve better sensibility. Then, the seawater was filtered and the particulate and filtrate portions were separated, treated and analysed separately. The extraction of the biotoxins form the particulate was carried out with methanol and assisted with ultrasounds. For the filtrate portion solid phase extraction was employed at different conditions conditioned by the different groups of biotoxins. The analysis of the extracts was performed by high performance liquid chromatography coupled to high resolution mass spectrometry through the ionization by electrospray. The chromatographic separation was carried out by hydrophilic interaction and reversed phase modes. The acquisition mode for the mass spectrometry was the combination of full scan at high resolution with tandem mass. After being validated, the three methodologies were applied to study the occurrence of the different biotoxins in the Mediterranean Sea. In the Catalan’s littoral, okadaic acid was found in concentrations ranging from 2 ng/L to 9.5 µg/L. Domoic acid was also present in the study of Ebro delta, reaching the highest concentration of 69.5 ng/L during summer. Also, the most hydrophilic marine toxins were studied in Mar Menor, Murcia, but any of the toxins was detected. Finally, one of the methods was used to validate an immunoassay capable to detect and quantify five pollutants in seawater, being one of them domoic acid.
La tesis doctoral presenta el desarrollo de diversas metodologías analíticas para el análisis de biotoxinas marinas en agua de mar. Las técnicas utilizadas son la cromatografía líquida de alta eficacia acoplada a la espectrometría de masas de alta resolución. El objetivo de estos métodos de análisis es su utilización en el estudio de las biotoxinas marinas en el medio marino, así como su aplicación para la temprana detección de estos compuestos cuando están a bajas concentraciones, con el fin de anticiparse a la posible formación de eventos de floraciones algares nocivas donde la concentración de las biotoxinas podría ser muy elevada y provocar impactos negativos en el ecosistema y en las actividades de maricultura. El desarrollo analítico se ha realizado evaluando la precisión, exactitud, selectividad y sensibilidad de los métodos. Dado que las propiedades físico-químicas de los diferentes grupos de biotoxinas son muy diversas, se han tenido de desarrollar tres metodologías diferentes. La primera etapa para todas consiste en un tratamiento de muestra ya que es esencial eliminar posibles interferencias en la muestra para su posterior análisis mediante las dichas técnicas instrumentales, por lo que las biotoxinas fueron extraídas del agua de mar y concentradas. Primeramente, se filtra el agua de mar y se separa la porción de materia en suspensión y la parte del filtrado para ser tratadas y analizadas por separado. La extracción de las biotoxinas de la porción de materia en suspensión se realiza con metanol y se asiste con ultrasonidos. La fracción del filtrado se somete a una extracción en fase sólida en diferentes condiciones dependiendo del grupo de toxinas. El análisis de los extractos, se realiza mediante cromatografía liquida de alta eficacia acoplada a espectrometría de masas de alta resolución mediante la ionización por electroespray. La separación de los compuestos más polares, se realizó mediante cromatografía líquida de interacción hidrofílica mientras que para los más apolares fue de tipo fase inversa. La adquisición utilizada en la espectrometría de masas fue mediante la combinación de un barrido completo en alta resolución y la fragmentación de los iones precursores, tipo tándem de masas, para cada una de las toxinas a resolución más baja. Una vez validadas, las tres metodologías se emplearon en el estudio de biotoxinas en el mar Mediterráneo, concretamente en el litoral catalán y murciano. Las biotoxinas más apolares se investigaron a lo largo de la costa catalana, mediante muestras recolectadas en playas públicas y puestos deportivos en diferentes localidades. El 88 % de esas muestras había una de las toxinas más frecuentemente hallada en el mar Mediterráneo, el ácido okadaico, el cual estaba en rangos de concentración de entre 2 ng/L y 9,5 µg/L. Por otro lado, el ácido domoico, se estudió en la zona de la desembocadura del rio Ebro, que consta de una zona de humedales y dos bahías donde se llevan a cabo actividades de maricultura. Su presencia destacó en las bahías especialmente en las muestras colectadas en verano, aunque la concentración más alta llegó a los 69,5 ng/L. Finalmente, las biotoxinas más polares se analizaron en aguas de la laguna salada del Mar Menor, en Murcia. Sin embargo, no se detectó la presencia de ninguna. Por otro lado, una de los métodos se utilizó para la validación de un inmunoensayo previamente desarrollado, capaz de detectar y cuantificar cinco grupos de contaminantes en agua de mar, siendo uno de ellos una biotoxina, el ácido domoico. Al immunoensayo se le añadió una etapa de tratamiento de muestra en que se pudieron concentrar los diferentes compuestos y conseguir así una detectabilidad a concentraciones muy bajas, del rango de los ng/L. Para concluir, se podría decir que los métodos desarrollados proporcionan mucha sensibilidad y selectividad en el análisis de biotoxinas marinas en agua de mar y que además, gracias a la alta resolución de las técnicas instrumentales, se podría estudiar la caracterización de compuestos nuevos.

Coastal marine ecosystems are among the most impacted globally, attributable to individual and cumulative effects of human disturbance. Anthropogenic nutrient loading is one stressor that commonly affects nearshore ecosystems, including seagrass beds, and has positive and negative effects on the structure and function of coastal systems. An additional, previously unexplored mechanistic pathway through which nutrients may indirectly influence nearshore systems is by driving blooms of benthic jellyfish. My dissertation research, conducted on Abaco Island, Bahamas, focused on elucidating the role that benthic jellyfish have in structuring systems in which they are common (i.e., seagrass beds), and explored mechanistic processes that may drive blooms of this taxa. To establish that human disturbances (e.g., elevated nutrient availability) may drive increased abundance and size of benthic jellyfish, Cassiopea spp., I conducted surveys in human-impacted and unimpacted coastal sites. Jellyfish were more abundant (and larger) from human-impacted areas, positively correlated to elevated nutrient availability. In order to elucidate mechanisms linking Cassiopea spp. with elevated nutrients, I evaluated whether zooxanthellae from Cassiopea were higher from human-disturbed systems, and whether Cassiopea exhibited increased size following nutrient input. I demonstrated that zooxanthellae population densities were elevated in human-impacted sites, and that nutrients led to positive jellyfish growth. As heightened densities of Cassiopea jellyfish may exert top-down and bottom-up controls on flora and fauna in impacted seagrass beds, I sought to examine ecological responses to Cassiopea. I evaluated whether there was a relationship between high Cassiopea densities and lower benthic fauna abundance and diversity in shallow seagrass beds. I found that Cassiopea have subtle effects on benthic fauna. However, through an experiment conducted in a seagrass bed in which nutrients and Cassiopea were added, I demonstrated that Cassiopea can result in seagrass habitat modification, with negative consequences for benthic fauna. My dissertation research demonstrates that increased human-driven benthic jellyfish densities may have indirect and direct effects on flora and fauna of coastal marine systems. This knowledge will advance our understanding of how human disturbances shift species interactions in coastal ecosystems, and will be critical for effective management of jellyfish blooms.

Coastal ecosystems, including estuaries, provide a range of services to humans, mediated by the species within these ecosystems. Microphytobenthos (MPB) play a vital role in many key processes within estuarine ecosystems, and provide a food source for higher trophic levels. Anthropogenic activity is already causing changes to ecosystems, through pollution, overexploitation and, more recently, climate change. Increasing temperature and carbon dioxide levels, and altered biodiversity, are likely to affect species, and their interactions, within these ecosystems. Much ecological research has focused on the effects of a single stressor on specific species or ecosystems, with relatively little work examining the effects of multiple stressors. The research in this thesis investigates the effects of altered environmental variables (light, tidal regime, temperature and carbon dioxide) and different macrofaunal diversity on primary production (MPB biomass) through a series of manipulative lab- based mesocosm experiments. This work also examines the temporal variability of environmental stressors on species across two trophic levels. Results demonstrate how multiple environmental stressors interact in a complex and non-additive way to determine an ecosystem response (MPB biomass, nutrient concentration), and the effects of altered biodiversity were underpinned by strong species effects. Temporal variation of stressors had a strong effect on ecosystem response. In marine coastal ecosystems, environmental changes through ocean acidification will have economic and social repercussions, directly impacting the human services and livelihoods that these systems provide. As such, future research should be focused on identifying and mitigating the inevitable multiple effects that future global change may have on coastal ecosystems.

A Work Project, presented as part of the requirements for the Award of a Masters Degree in Economics from the NOVA – School of Business and Economics
The main objective of this work project is to highlight the progress made in the field of ecological-economic modeling of marine and coastal ecosystems, in particular, by stressing the need to incorporate more realistic biology as well as the spatial dimension in integrated models for sustainable coastal management. The discussion undertaken is based on a recent application of an integrated ecological-economic model that is spatially explicit by Altman et al. (2012), and should provide guidance to the GOI’s research project to the Peniche-Nazaré study site in the Portuguese coast.

Consortium for International Earth Science Information Network (CIESIN) initiated a series of nine human dimensions of global change pilot projects in 1991, to better understand how physical, biological, and social scientists must interact in order to address problems of importance to decision -makers. There is also a need to develop methodologies for merging data sets which differ on spatial and temporal scales, and indeed, to ascertain whether or not data are generally available to address specific, highly complex earth and social science. Because there has been virtually no research on the use of remotely sensed data in the social sciences of global change, this is a component of each pilot project. Pilot projects need to show how the results would be transferred to decision makers. All these elements of the pilots are to be used to inform the design of the CIESIN Data and Research Center. One of the CIESIN human dimensions of global change pilot projects is situated on the north coast of the Dominican Republic in Buen Hombre.

La réglementation actuelle, reposant sur la loi de 1976 sur la protection de la nature, impose aux maîtres d’ouvrage de respecter le principe « éviter – réduire – compenser » lors de la conception de les projets d’exploitation et d’aménagement. Lorsqu’un projet n’a pu ni éviter ni réduire les impacts environnementaux, il est nécessaire de définir des mesures compensatoires pour les impacts résiduels qualifiés de significatifs. Concernant les écosystèmes marins, ces mesures font appel à des actions écologiques ainsi qu’à des mesures de gestion et d’amélioration des connaissances sur le milieu marin. Alors que le développement de l’activité économique maritime est encouragé, en particulier, suite aux appels à la croissance bleue (e.g. tourisme maritime, EMR, pêche, aquaculture, ressources minérales marines, biotechnologies, transport maritime, construction navale), il est primordial de questionner nos capacités à prendre en compte les impacts de ces activités. A partir d’un état des lieux de la compensation sur le milieu marin en France, il s’agit d’identifier les limites du système actuel et de proposer des pistes d’amélioration. Ces dernières peuvent être méthodologiques et techniques, liées à la prise en compte de nouvelles approches ou à l’émergence de nouveaux systèmes de gouvernance. A travers l’analyse d’une cinquantaine d’études d’impacts françaises, les pressions et impacts générés par différents projets d’aménagements (infrastructures portuaires, dragages, extractions de granulats, prises et rejets d’eau, etc.) sont examinés et la pertinence des mesures ERC proposées est discutée. Ensuite, en se basant sur une revue bibliographique, la faisabilité et l’efficacité des techniques d’ingénierie écologique (écoconceptions portuaires, bio-remédiation et techniques de restauration des herbiers, macro-algues, récifs coralliens, populations d’ichtyofaune et bivalves) sont évaluées au regard des exigences de la séquence ERC. Cette analyse permet de discuter de la notion d’équivalence écologique et de proposer un arbre de décision original. D’autre part, constatant que les mesures compensatoires proposées dans les études d’impact ne sont que très rarement dimensionnées, une méthode opérationnelle permettant d’évaluer les besoins compensatoires est élaborée. Cette méthode associe une analyse multicritère de l’état de l’environnement inspirée de l’Unified Mitigation Assessment Method (UMAM, méthode utilisée en Floride pour les impacts autorisés) et une évaluation plus fine à l’échelle d’un indicateur empruntée à l’Habitat Equivalency Analysis (HEA, développée par la NOAA pour la compensation des dommages accidentels). Il s’agit ensuite d’examiner l’utilisation actuelle de l’approche par les services écosystémiques dans la compensation à travers la réglementation, les standards internationaux et la littérature scientifique. L’objectif est d’étudier en quoi cette approche permettrait d’améliorer la mise en place de la compensation mais aussi d’en souligner les limites. Enfin, l’approche sociologique de l’acteur-réseau (Callon, Latour) permet d’analyser les différents types organisationnels ayant émergé autour de la compensation en Californie. L’objectif est de critiquer, à partir de situations constatées en France et aux Etats-Unis, les réponses formulées en termes de gouvernance par ces deux sociétés côtières exigeant un principe de compensation. Ce travail souligne la nécessité de mettre en place des mesures ambitieuses et efficaces de compensation afin que le développement économique maritime cesse de contribuer à l’érosion de la biodiversité
My research topic is multidisciplinary combining geography, ecology and economics and addressing the efficiency of current marine offset practice. Building on a state of the art of current practice, I am working on a more prospective approach (compared to current research on mitigation targeting terrestrial ecosystems). By offset, I am referring to legal mitigation that consists in avoiding – reducing – offsetting adverse impacts of development projects such as dredging, port infrastructure, oil exploration, marine aggregate extraction, beach nourishment, etc. on marine and coastal ecosystems. Based on a review of around fifty French marine Environmental Impact Assessments (EIAs), I analyzed the assessment of impacts, the use of offset sizing methods (robust method to assess ecological losses due to development projects and ecological gains created by offset measures) and the kind of measures proposed. Within these EIAs, sizing methods were seldom used and the very few measures suggested to offset residual impacts could be questioned in terms of equivalency and appropriateness. These measures were either ecological engineering techniques (such as seagrass or coral restoration), management measures (used to reduce pressure on the impacted ecosystems through the funding of management measures in Marine Protected Areas for example) or even knowledge acquisition. Thus, I am also looking at the efficiency of ecological engineering techniques on marine and coastal ecosystems. My research mainly focuses on the offset of authorized impacts but could also deals with some aspects of the offset of accidental damages

Globally, ecosystems are experiencing increasing pressure from anthropogenic stressors. Human population growth is responsible for overexploitation of natural resources, pollution, land alteration and climate change. A change in landscape connectivity, may not only reduce the habitable space for species, but may also affect their movement and population dynamics. These changes potentially reduce the resilience of ecosystems against other stressors. Reserves are a common method to protect areas from overexploitation and habitat destruction and help to safeguard ecosystem functioning. Reserve size, location and configuration influence the effect of reserves and the optimal design of protected areas is a field of ongoing research. Connectivity is a guiding principle in protected area planning but the explicit incorporation of connections remains a challenge. Reasons can be found in the scarcity of quantitative data on connectivity and a lack of agreement on connectivity measures. Currently, connections in marine landscapes are less studied than on land. The aim of this thesis was to examine the relationship between connectivity and ecosystem processes, and to test methods for modelling and incorporating quantitative data on connectivity in the design of marine protected areas.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Grifffith School of Environment
Science, Environment, Engineering and Technology
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Evidence from modern oceanography, climate simulations of future conditions, and paleoceanographic archives motivates the need to reconstruct Oxygen Minimum Zone (OMZ) changes during past events of abrupt climate warming and carbon system perturbation. This dissertation focuses on the loss of oxygen in the Eastern Pacific Ocean through the most recent deglaciation event, in order to understand the spatial magnitude of oceanic deoxygenation and to quantify disturbance and recovery dynamics in seafloor biodiversity. New evidence from a shallow post-glacial sediment core (MV0811-15JC) from Santa Barbara Basin, California, USA, demonstrates the remarkable shallowness of OMZ influence to within ~300 meters from the ocean surface during the recent deglaciation. This site confirms that paleoceanographic reconstructions of hypoxia from Santa Barbara Basin are a product of regional expansions and contractions of the OMZ. Microfossil archives of seafloor metazoans (Echinodermata, Arthropoda and Mollusca; >5,350 individuals) from site MV0811-15JC demonstrate the extreme sensitivity of seafloor metazoan communities to abrupt (<100 year) deoxygenation of the Eastern Pacific, and expand known timescales of biological recovery by one order of magnitude, from <100 years to >1,000 years. Molluscan communities provide a complex interpretive window with which to understand environmental change through the deglaciation. Chemosynthetic and symbiotic molluscs numerically dominate the faunal record, yet these extremophiles do not strongly co-occur, indicating the development of heterogeneous extreme environments as a result of hydrographic regimes and the development of sulfur oxidizing bacterial mats. These analyses reveal that previous deoxygenation events dwarf modern scales of ecological disturbance, and illustrate the role that climate and oceanographic change have in driving long-term successional oscillations in ocean ecosystems. More broadly, the global inventory of deglacial and post-glacial sediment records exhibits remarkable synchrony in reconstructing subsurface hypoxia, and reveals that OMZs across the entire Eastern Pacific margin expanded and intensified concurrently. Most strikingly, these results uncover the capacity for large contiguous swaths of the ocean interior to rapidly lose dissolved oxygen, resulting in the expansion of OMZ ecosystems and the compression of surface ocean oxygenated ecosystems. Climate-forced changes to ocean systems introduce a scale of environmental disturbance that only has analogue in the rapid warming events of past climates. These critical analogues serve to illustrate the scale and ecological consequences of climate-forced deoxygenation.

Because of its geographical location, the Arctic environment is considered as pristine. However, expanding industrial activities in the Arctic require assessment of the toxicity of chemicals at low temperature. Biomarkers defined as "biological responses to a chemical or chemicals that give a measure of exposure or toxic effect" were shown to be relevant to measure in situ impact of oil discharges. Most biomarker studies have been performed with temperate organisms. The Arctic is characterised by low stable temperature, strong seasonality in light, resulting in a short primary production in Spring. Therefore, indigenous organisms have developed specific adaptations to live with a hmited food supply in water near freezing point. Conversely, physical properties of petroleum hydrocarbons are affected by low temperature (i.e. reduced solubility). Consequently, the biological adaptation of cold-water organisms together with the altered oil behaviour, may affect typical biomarker responses. Because oil compounds are strongly prooxidant, the research strategy of this work was based on oxidative stress. The antioxidant defences were investigated by measuring the total oxyradical scavenging capacity (TOSC). The impact of reactive oxygen species was investigated by measuring the stability of the cell membranes. Finally, the physiology of the organisms was considered by looking at heart and respiration rates. Invertebrates were selected for study owing to their abundance in the polar ecosystem. They were sampled using dredges and Scuba diving from the research vessel Jan Mayen (University of Tromso) in May and August 1999, and during May and September 2000 in the l^ords of Svalbard and in Antarctica as well in January 2000. In the Arctic, two bivalves, Mya tnincata and Chlamys islandicus, and two crustaceans, Hyas araneus and Sclerocrangon boreas were selected. In this work, the ecophysiology of Arctic and Antarctic marine invertebrates was investigated and compared to temperate organisms. Polar marine invertebrates are characterised by low respiration and heart rates and a high TOSC. The elevated level of antioxidant defences is thought to reflect the oxidative pressure of the polar marine ecosystem; however, it suggested that a high TOSC may help to protect biomolecules from oxidative damage as repair mechanisms are limited due to the lack of food for 9 months. Organisms were exposed to poly aromatic hydrocarbons either dissolved, dispersed injected or via sediment. TOSC, cell membrane stabiHty and heart rate were valid biomarkers to monitor the impact of poly aromatic hydrocarbons in Arctic marine organisms. The biomarker responses obtained in this study provide essential background information for monitoring the potential impact of oil and gas activities in the Arctic.

Glacier runoff (i.e., meltwater and rainwater discharged at the glacier terminus) provides about half of the freshwater discharge into coastal margins of the Gulf of Alaska, where contemporary glacier melting rates are among the highest in the world. Roughly 410 billion metric tons of glacier runoff enter the Gulf of Alaska each year. With freshwater discharge volumes of that magnitude, I hypothesized that glacier runoff has both direct and indirect effects on the receiving coastal marine ecosystems that support rich food webs, abundant and diverse marine communities, commercial fisheries and tourism industries. To examine the influence of glacier runoff on coastal marine ecosystems, I focused on three questions: 1) How does the marine food web respond to physical and biological gradients induced by glacier runoff? 2) What is the contribution of riverine organic matter (OM) and ancient carbon resources in glacier runoff to marine food webs from plankton to seabirds? and 3) How does the influence of glaciers on coastal marine ecosystems differ at small to large spatial and temporal scales? I measured physical, chemical and biological indices within four fjord systems along the eastern Gulf of Alaska coast. In chapter one I used geostatistics as well as parametric and non-parametric models to demonstrate a strong influence of glacier runoff on ocean conditions and coastal food webs across all the fjord systems. In chapter two I used isotopes (δ ²H, δ¹³C, δ¹⁵N, and δ ¹⁴C) to trace riverine OM and ancient carbon resources into the marine food web. This work included the development of a novel multi-trophic level 3-isotope Bayesian mixing model to estimate the proportion of allochthonous resources in animal tissues. Mean estimates from 14 species groups spanning copepods to seabirds ranged from 12–45 % riverine OM source assimilation in coastal fjords, but ancient carbon use by marine food webs was low. In the third chapter I synthesized information on the scale-dependent influence of glaciers on lower-trophic level productivity, predator-prey interactions and ways that humans may be affected by anticipated changes in glacier coverage. This contemporary understanding of glacier influence on coastal ecosystems aligns with paleoenvironmental evidence suggesting that over geological time scales glaciers have and will continue to shape marine ecosystems in the Gulf of Alaska.

Free-living or host-associated marine microbiomes play a determinant role in supporting the functioning and biodiversity of marine ecosystems, providing essential ecological services, and promoting the health of the entire biosphere. Currently, the fast and restless increase of World’s human population strongly impacts life on Earth in the forms of ocean pollution, coastal zone destruction, overexploitation of marine resources, and climate change. Thanks to their phylogenetic, metabolic, and functional diversity, marine microbiomes represent the Earth’s biggest reservoir of solutions against the major threats that are now impacting marine ecosystems, possibly providing valuable insights for biotechnological applications to preserve the health of the ocean ecosystems. Microbial-based mitigation strategies heavily rely on the available knowledge on the specific role and composition of holobionts associated microbial communities, thus highlighting the importance of pioneer studies on microbial-mediated adaptive mechanisms in the marine habitats. In this context, we propose different models representing ecologically important, widely distributed, and habitat-forming organisms, to further investigate the ability of marine holobionts to dynamically adapt to natural environmental variations, as well as to anthropogenic stress factors. In this PhD thesis, we were able to supply the characterization of the microbial community associated with the model anthozoan cnidaria Corynactis viridis throughout a seasonal gradient, to provide critical insights into microbiome-host interactions in a biomonitoring perspective. We also dissected in details the microbial-derived mitigation strategies implemented by the benthonic anthozoan Anemonia viridis and the gastropod Patella caerulea as models of adaptation to anthropogenic stressors, in the context of bioremediation of human-impacted habitats and for the monitoring and preservation of coastal marine ecosystems, respectively. Finally, we provided a functional model of adaptation to future ocean acidification conditions by characterizing the microbial community associated with the temperate coral Balanophyllia europaea naturally living at low pH conditions, to implement microbial based actions to mitigate climate change.

This thesis assessed the current prospect for implementing an ecosystem-based management for fisheries (EBFM) in the Bay of Bengal Large Marine Ecosystem from national and regional level perspectives. A central result of the study is that the governance concept had been defined and used imprecisely in the literature. The way the different elements constitute EBFM revealed that both Bay of Bengal LME countries and existing regional fisheries organisations are unlikely to satisfy all the elements on the EBM checklist. The study also observes that the Bay of Bengal countries do not share a common understanding of EBFM.

Continental shelves cover less than 5% of the global ocean, but play a crucial role in marine biogeochemical cycling, since they account for 30% of primary production, 80% of organic matter burial, 50% of marine denitrification. Coastal waters biogeochemical cycling is subject to multiscale anthropogenic pressures ranging from climate change to nutrient loading input. The processes connecting the pelagic and benthic realms define the benthic– pelagic coupling (BPC) and comprises the physically, biologically and chemically mediated two-way exchange of matter (particulate and dissolved). Despite the importance of the benthic domain and the enhancement of models resolution, BPC is mostly approximated through a closure term. Moreover, data focusing on the BPC dynamics are sparse, hampering model parameterization and validation. The objectives of this study are: develop a parametrized numerical model addressing BPC and assess the skills of the 1DNEMO-BFM model in simulating the BPC in marine areas with different climatic characteristics. The benthic sub-model is based on two crucial parameters: the sinking velocity of particulate matter and the diffusion of inorganic matter at the benthic-pelagic interface. Beyond the apparent simplicity, the benthic sub-model has been calibrated considering a complex pelagic food web and for the main ecological and physical characteristic. The model has been implemented in three different sites: Gulf of Trieste, St Helena Bay (South Africa), Svinoy Fyr (Norway). For all the station, model results have been compared with observational data. Sensitivity tests have been performed, to statistically investigate the response of the benthic sub-model in changing