Tesi sul tema "Marine invertebrates – North Sea"

Differential compaction occurs within many sedimentary settings, such as alluvial and deltaic deposition, but it is within the submarine fan environment where the process is most effective due to the very high depositional porosities of the muds found there. Additionally the grain size of siliciclastic sediments within the submarine fan environment varies rapidly both horizontally and vertically, and hence the effect of differential compaction control on the depositional geometry and arrangement needs to be examined and modelled. It is also important to ascertain the rate at which sediments compact when buried, and whether compaction is complete at the end of deposition or whether it requires additional time to achieve this state. Sea- floor topography can be created if the latter case is true, and could influence subsequent deposition. Alternatively, if sea-floor topography is not created, the major control upon subsequent deposition may be the compatibility of the underlying section. Both controls will favour deposition of successive coarse clastic units above areas of fine-grained sediments, i.e. sand above shale rather than sand above sand. The Palaeocene sediments of the Central North Sea In the Montrose - Arbroath area (Blocks 22/17 and 22/18) combined with outcrop studies In southern California and New Mexico, have been used to assess the control of differential compaction on sediment distribution in a deep-sea fan setting. Differential compaction affects the Montrose - Arbroath area on a variety of scales. Firstly, differential compaction of the entire Palaeocene section across the underlying Forties - Montrose High induces structure. At a smaller scale, differential compaction may form a considerable control upon the spatial distribution of submarine fan channels and lobes that form the reservoir section throughout the area, and therefore the areal distribution of the oilfields themselves. Finally differential compaction may effect the distribution pattern of individual turbidites within such channel systems, thus forming a fine control upon the distribution of sands and shales within the reservoir. Fieldwork on submarine fan deposits in southern California has highlighted further complications to differential compaction that need to be addressed during the modelling process. Sedimentary processes such as basal loading and slumping are highly common in such deposits, and both can effect the compactional process to differing degrees. Results obtained from the modelling of stratal patterns observed in New Mexico provide information on the timing of differential compaction. It is suggested that compaction of sediments, even during early burial, requires a time interval often greater than the period of deposition, resulting in post-depositional compaction and the production of near-surface overpressure.

For decades, humans have impacted marine ecosystems in a variety of ways including contamination by pollution, fishing, and physical destruction of habitats. Global change has, and will, lead to alterations in in a number of abiotic factors of our ocean in particular reduced oxygen saturation, salinity changes, elevated temperature (ocean warming or OW) and elevated carbon dioxide (ocean acidification or OA). Now and in the future, OA and OW will operate together with local anthropogenic drivers such as oil pollution. And yet, at present, very little is known about their potential combined interactive effects on physiological performance and tolerance of marine organisms. Therefore, multiple driver experiments are required if we are to understand and predict future vulnerability of species, populations and ecosystems. Early life stages of invertebrates are generally considered most vulnerable to environmental stress. However, few studies consider the combined effects OA and OW on survival and growth during early development of marine invertebrates, and to our knowledge, there is no information on the additional effects of oil pollution. Therefore, the aim of this thesis was to investigate the effects of combined exposure to OA, OW, and incorporating local drivers such as oil pollution on the development, morphology and physiology of three economically and ecologically important marine invertebrates. These are Northern shrimp Pandalus borealis, Northern krill Meganyctiphanes norvegica, and the green sea urchin Strongylocentrotus droebachiensis. All are cold-water species, assumed to have a narrower tolerance than more temperate species, and so could be particular sensitive to combined stressor affects. Both Northern krill and to a lesser extent Northern shrimp larvae survived experimental conditions, mirroring those predicted under a future global change scenario (combined OA and OW exposure). Neither was hatching success affected. Both shrimp and krill larvae exhibited accelerated developmental rates and incurred greater maintenance costs as a result of exposure to these stressors. Shrimp larvae showed accelerated developmental rates (-9 days), increased metabolic rates (+20 %), and increased feeding rates (+20 %), but reduced growth (- 9 %) when exposed to OW compared with the control. OA increased development rate but only at the control temperature. Although juvenile mortality of krill was not affected by predicted OA/OW conditions, metabolic rate increased significantly (+ 36 %), as did larval developmental rate, while number of moults, feeding rate and growth (- 67 %) decreased significantly (- 67 %, - 60 % and -8 % respectively). Accelerated development was accompanied by greater maintenance costs possibly due to experience a mismatch between energy supply and demand. Both species had an excess of food, and so growth reduction was more likely to be associated with higher metabolic demands in the future global change treatments. Food shortage in situ, due to variable food availability in the sea and/or mismatch with key prey species (algae and zooplankton) could result in more negative effects on growth and ultimately survival. Green sea urchins were also able to survive OA exposure, without detectable effects on hatching success. However, at day 44 post-fertilization, larval body length in the OA treatment was 9 % lower compared to the control. Furthermore, there was a significant tendency of urchin larvae to increase swimming activity in the OA conditions that might indicate compensatory feeding. Elevated maintenance and repair costs as a result of exposure to multi-stressors affected the energy budget of all the three species studied here resulting in reduced growth. Global drivers (OA and OW) resulted in trade-offs with more energy reallocated to swimming activity and metabolism, rather than growth. Exposure to oil reduced the acquisition of energy by reduced feeding which in turn resulted in less energy being available for growth. Both shrimp and sea urchin larvae showed reduced activity and feeding when exposed to oil. It is possible that the reduced swimming activity observed may be due to a narcotic effect of the oil. Furthermore, early stage sea urchin larvae showed increased mortality when exposed to oil while the older larvae did not, indicating a stage specific toxicity to oil for sea urchin larvae. The combination of global drivers and oil pollution acted additively on growth for both sea urchin and shrimp larvae. The impact of combined drivers on the size of shrimp larvae was equal the sum of the negative impacts observed for each driver: a 5 % reduction when exposed to OA and OW, a 9 % reduction when exposed to oil, and a cumulative 15 % reduction when exposed to all stressors. Similarly, the impact of combined drivers on the size of sea urchin larvae was equal to the sum of the negative impacts observed for each driver: a 14 % reduction when exposed to OA, a 9 % reduction when exposed to oil, and a 21 % reduction when exposed to all drivers. Therefore, the study demonstrated the additive physiological effects of OA, OW and a contaminant, and indicated that larval (sea urchin and shrimp) resilience to future changes (i.e. pollution) could be greatly reduced if larvae were already energy limited and severely stressed (reduced development) as a result of exposure to the global drivers. This study therefore shows the importance that the effective management of local drivers such as oil pollution could have against the backdrop of OA and OW, and emphasises that it is important to study impacts of toxicants, such as an oil pollution, in the context of predicted changes in the environment, as OW and OA are becoming major concerns. Finally, the fact that some local and global drivers seem to act additively should encourage local managers to act on local driver regulations, to obtain positive effects on local populations and environment and thereby rendering them more resilient to the negative impacts of future global drivers.

Ostracods were obtained from two cores in the southern North Sea area: the Sand Hole and Swarte Bank Formations of Tappin (1991) in BGS borehole 81/52A, cored from the Inner Silver Pit, southern North Sea, and a core from Shoeburyness in Essex, borehole S 1. The faunal assemblages in 131-181/52A were dominated by Sarsicytheridea punctillata, Elo/sonella concinna and Acanthocvthereis clunelmnensis. The assemblages recovered reflect a transition from glacio-marine conditions in the Swarte Bank Formation up into a cold-temperate marine environment in the Sand Hole Formation with deteriorating temperatures indicated at the top of the interval studied. In BHSI a freshwater to brackish transition occurred in the core, the freshwater section being dominated by Darwinula slevensoni and llyocypris spp., and the brackish section by Cyprideis torosa and C ytheromor pha fiiscata. The palaeoecology of the ostracod assemblages recovered is compared to other palaeoecological data from the same sections in each core and to ostracod data from other Hoxnian/l lolsteinian sites in north western Europe. These data are also discussed in the light of evidence indicating that there was a barrier across the southern North Sea when the sediments examined were deposited. Sarsicytheridea spp. and (yprideis terosa were used for trace element (Mg: Ca, Sr: Ca) and stable isotope (cS'"O, ö'3C) analyses. A calibration equation for the calculation of temperature from Mg: Ca ratio was successfully established from analysis of modern Sarsicytheridea. Modern Sr: Ca data could not be used to establish a calibration for salinity since there was too much scatter in the data. (' prideis torosa has been used for trace element and stable isotope work by other authors who have published relationships between ('yprideis and the water chemistry. Ostracods were also analysed down core to examine the changing ratios of Mg and Sr as a proxy for temperature and salinity changes in the I-loxnian of the southern North Sea. In BH81/52A, Mg: Ca data indicated a deterioration in temperature from 36.20 m to the top of the section studied of 9°C. Oxygen stable isotopic analyses from the same species, measured through the same core intervals, did not exhibit a trend, but their values were indicative of normal marine salinities. Carbon stable isotope analyses, performed at the same time as the oxygen analyses, indicate that there may have been high productivity in the region of deposition of the Sand Hole Formation, implying deposition in a region of freshwater influence. However, C/N analyses indicated that the sediments in the Inner Silver Pit were deposited under fully marine conditions. In III ISI, both the Mg: Ca and Sr: Ca data suggested that salinity had increased upcore. Ilowever, there was a lot of scatter in the data, indicating that the estuarine environment, under which the palaeoecology suggests the sediments were deposited, was a highly fluctuating one. These data compare favourably with previously published records. Published partition coefficients were used to compare the trace element data obtained to mean river and seawater values.

Le modèle biogéochimique de résolution complexe MIRO a été développé pour étudier la dynamique des efflorescences de Phaeocystis en zone côtière belge (BCZ) en réponse aux apports de nutriments anthropiques délivrés directement par l’Escaut et indirectement par la Seine via les eaux atlantiques entrantes. Le modèle MIRO décrit les cycles du carbone (C), de l’azote (N), du phosphore (P) et de la silice (Si) au travers de 38 compartiments chimiques, planctoniques et benthiques clés de l’écosystème côtier dominé par Phaeocystis. Il a été validé dans une configuration multi boite simple en utilisant des forçages climatologiques pour la période 1989-1999 et sur base d’une comparaison visuelle des simulations de nutriments et des variables planctoniques avec les données récoltées durant cette même période.

Le modèle validé a ensuite été utilisé pour étudier le fonctionnement de l’écosystème et les cycles biogéochimiques associés. Plus précisément, les bilans de carbone et de nutriments réalisés sur base des flux biologiques modélisés ont montré que l’écosystème de la BCZ, dominé par les efflorescences de Phaeocystis, se caractérise par une faible efficience trophique, une faible capacité de rétention/élimination des apports de nutriments d’origine anthropique et une faible capacité d’absorption du CO2 atmosphérique. Des scénarios annulant tour à tour l’activité biologique et les apports de carbone par les rivières ont permis de déterminer les rôles respectifs de la température, des processus biologiques et des apports de nutriments et de carbone par les rivières dans l’évolution saisonnière de la pCO2 des eaux de surface.

L’effet combiné des apports anthropiques de nutriments et des conditions météorologiques locales (débit, vent, température) a été étudié sur base d’une simulation effectuée pour la période contemporaine (1989-2003) en utilisant les forçages réels mesurés. La comparaison visuelle des simulations et des observations montre que, si le modèle est parfaitement capable de reproduire les successions phytoplanctoniques, il est par contre moins performant en ce qui concerne la reproduction des signaux extrêmes. Il apparaît donc que l’échelle de temps (mensuelle) utilisée pour décrire la variabilité des forçages est trop longue et ne permet pas de capter les variations hydrologiques à court terme résultant du vent et de la marée.

De manière à mieux comprendre le lien entre les activités humaines sur le bassin versant et l’eutrophisation des zones côtières, le modèle MIRO a été couplé aux sorties du modèle de rivière RIVERSTRAHLER appliqué à la Seine et à l’Escaut sur une période de 50 ans (1950-1998). Les résultats obtenus montrent que l’importance des efflorescences de diatomées est conditionnée par les apports de PO4, alors que l’importance des Phaeocystis est directement liée à l’importance des apports de NO3. Un bilan établi pour la BCZ montre que plus de 50% des apports annuels de N et 60% des apports annuels de P proviennent des eaux Atlantiques et pointe l‘importance des apports de la Seine pour l’enrichissement de la BCZ.

Différents scénarios de réduction des apports de nutriments provenant des rivières ont été réalisés afin de cibler le ou les nutriments à diminuer prioritairement pour réduire les efflorescences de Phaeocystis. Les résultats montrent que, dans les conditions actuelles, seule une réduction des apports de NO3 prédit une diminution des efflorescences de Phaeocystis. De plus, pour avoir un abattement significatif de ces efflorescences, il est nécessaire d’agir de manière conjointe sur les apports de la Seine et de l’Escaut.

En vue de l’implémentation du code MIRO dans un modèle 3D hydrodynamique et pour tenir compte de la variabilité spatiale des sédiments dans la zone étudiée, une paramétrisation des flux de nutriments à l’interface eau-sédiment a été recherchée sur base des résultats obtenus avec un modèle diagénétique analytique décrivant la dégradation de la matière organique et les cycles de l’azote et du phosphore dans les sédiments.

Doctorat en sciences, Spécialisation biologie animale
info:eu-repo/semantics/nonPublished

Microplastics represent persistent and highly dispersal pollutants in the marine environment. The knowledge about ingestion and relative effects in large marine vertebrates, such as sea turtles, is still fragmentary. To date, studies on MP accumulation in these animals were based on the analysis of gastrointestinal tracts obtained after necropsy. In this study, we developed a protocol that allows the study of the MP through faecal material from alive turtles, that can be used in rescue centres in several locations. Specifically, faecal samples from 45 specimens of Caretta caretta, rescued along the coast of Emilia-Romagna and Marche (Italy) from 2016 to 2019 were assessed for MP content through different hospitalization periods. A unique sample was collected from 24 animals, while for 21 specimens two samples were obtained. This allowed us to quantify and characterize the MPs and to evaluate putative differences in the excreted particles during the hospitalization period. All individuals showed MPs in the faeces, for an average value of 6 ± 6.09 particles/animal. The maximum number of particles found in a single individual is 34 MPs. Filamentous particles were the most represented shape and transparent/white and red colours prevailed over the other colours. Analyses of data about first sampling show a significant negative correlation between MP number and turtle’s size. This could be due to the different feeding behaviours that occur in these animals according to their life stage. The absence of significant differences between classes and categories of shape and colours particles could be due to the high contamination of the preys in the Adriatic Sea. The absence of significant differences between the first and second sampling (where available), suggests that during the hospitalization period there might have been external influences that affected the results, including MP intake with diet, which would be considered in future studies.

International agreements like the Convention on Biodiversity are soliciting the development of transboundary networks of Marine Protected Areas (MPAs) in order to improve the protection of natural resources and the individual ecological relevance of MPAs. Together with ecosystem based criteria, environmental governance plays a key role in the management of marine and coastal areas in particularly at transboundary scale. Therefore this research focuses on two study cases relevant for transboundary governance for MPAs. The first case study is the North Adriatic, regarding the analysis of the network of MPAs in the North Adriatic Sea at a transboundary level among Italy, Slovenia and Croatia. The second case study regards the analysis of the governance of the Wadden sea trilateral cooperation for the management of the area that started in 1978. One of the objectives of this work was the identification and analysis of the figure of the policy entrepreneur and the strategies used to bring about a policy change in the environmental conservation strategies in the two case studies. Policy entrepreneurs are defined as those individuals or organisations that thanks to their perseverance, ingenuity, and willingness to spend time and resources for an idea, can help bringing about a policy change. Moreover, in the North Adriatic case the research applied also social network analysis methods to identify the main actors involved (e.g. managers of MPAs, NGOs, governmental agencies and other actors relevant for MPAs), their roles and relations within the system of governance of MPAs in the North Adriatic. Focus interviews were also used to investigates possible ways to improve the efficiency of MPAs and the existing constraints that can slow the process. From the analysis of the role of policy entrepreneurs, in both case studies these were found among organizations out of the government. In both cases, individual stakeholders were supported by a staff of an organization or a company and they applied a number of strategies such as the so called “window of opportunity” and “venue shopping”. In the North Adriatic case the analysis of the governance of MPAs let emerge the need to enhance collaboration among MPAs in order to exchange expertise, enhance the protection of the coastal and marine resources and gain more political influence in order to cope with the lack of interest of national governments towards the issue.

The impacts of two strains of the dinoflagellate Alexandrium tamarense, differing in lytic activity, on the abundance and the composition of microbial communities (<150 μm) were studied in North Sea water during spring with Phaeocystis globosa as a dominant species. Cell-free suspensions (supernatant) of exponentially growing lytic and non-lytic Alexandrium culture were added at different concentrations to natural microbial communities under nutrient rich conditions. The non-lytic strain had a positive impact on diatoms whereas the lytic strain suppressed phytoplankton growth in comparison to the control. P. globosa, present as single cells in the initial community, increased in abundance and formed colonies in all treatments. However, total abundance and number of colonies was low with lytic Alexandriumadditions, whereas shape of the colonies, but not abundance of cells, was affected by non-lytic Alexandrium additions. During the 4-day experiment, bacterial abundance was constantly higher with high lytic additions (highest concentration equivalent to 1000 cells ml−1) whereas nanoflagellate abundance in the same treatments was found to be lower at the end of the experiment. Initial bacterial community composition differed significantly among lytic Alexandrium, non-lyticAlexandrium and North Sea water. However, neither bacterial activity nor composition was significantly affected by the supernatants after 96 h. Our results indicated that Alexandrium allelochemicals do not inhibit growth and production of bacteria in seawater collected during spring in the North Sea.
Allelopathy among phytoplankton - a structuring force among phytoplankton

Il progetto di dottorato è stato principalmente focalizzato sull’implementazione delle tecniche di riproduzione controllata nel genere Patella. Le specie oggetto di studio sono state P. caerulea e più in particolare P. ferruginea, specie protetta e in via di estinzione, il cui ripopolamento è oggetto del progetto europeo ReLife (LIFE15 NAT/IT/000771). Essendo P. ferruginea una specie protetta, inizialmente abbiamo preferito testare i trattamenti di induzione non letale su una specie cogenerica, P. caerulea, comune e abbondante lungo le coste italiane. I vari trattamenti testati hanno dato ottimi risultati, e il trattamento del “bubbling” è risultato il migliore, sia in termini di tempo di risposta alla stimolazione degli esemplari, sia perché si tratta di un metodo poco costoso e facilmente ripetibile. È stato possibile stilare un protocollo di spawning non letale, ed effettuare una fecondazione artificiale con successivo sviluppo larvale e insediamento dei giovanili (Ferranti et al., 2018). Inoltre, sono stati condotti dei monitoraggi lungo la costa ligure, che hanno permesso di riportare la presenza di esemplari di P. ferruginea, considerata estinta lungo queste coste (Espinosa et al., 2014). La distribuzione di P. ferruginea, lungo le coste liguri, è estremamente scarsa e frammentata, infatti la specie è stata rinvenuta come esemplari isolati o piccoli gruppi, come nell'AMP delle Cinque Terre. Questi ritrovamenti hanno però permesso di ampliare la mappatura della presenza di P. ferruginea lungo le coste del Mediterraneo (Ferranti et al., 2019). Inoltre, per comprendere meglio il ciclo riproduttivo e i tempi di rilascio dei gameti in P. ferruginea alle nostre latitudini, abbiamo posizionato degli esemplari in mare per la maturazione in condizioni naturali, fino all’inizio del periodo riproduttivo. Gli esemplari successivamente sono stati sottoposti a biopsia della gonade sia prima di essere messi in mare per determinare il sesso (Guallart et al., 2013a), che all'inizio del periodo riproduttivo previsto per comprendere lo stadio di maturazione. L’osservazione del materiale ottenuto tramite biopsia ha permesso di determinare che gli esemplari avevano raggiunto la maturazione gonadica e che uno di loro aveva effettuato il cambio di sesso, evento noto in letteratura, ma osservato qui per la prima volta alla latitudine del Mediterraneo nord-occidentale (Ferranti et al., 2021). Tali risultati implicano che la specie può completare il suo ciclo riproduttivo lungo le coste liguri. Sempre al fine di comprendere meglio i tempi di maturazione delle gonadi, abbiamo applicato le tecniche della Risonanza Magnetica su esemplari di patelle. La Risonanza Magnetica, attraverso un approccio non invasivo, ha permesso di osservare lo spessore della gonade e anche di capire se un esemplare avesse rilasciato o meno gameti, al fine di applicare eventualmente tecniche di stimolazione al rilascio dei gameti solo al momento giusto. I risultati indicano che la risonanza magnetica può essere molto utile come strumento aggiuntivo, sia per valutare la maturità sessuale di P. ferruginea, che per ridurre al minimo il numero di prove di induzione per ogni esemplare, e di conseguenza lo stress (Guallart et al., 2020). Ancora più rilevante è l'aver fornito l’evidenza, per la prima volta, che l’emissione delle uova può essere indotta in P. ferruginea e dimostrare che è possibile ottenere giovanili, in condizioni controllate, attraverso metodi non invasivi. Questi risultati hanno permesso di elaborare un protocollo preliminare sull'induzione all’emissione spontanea dei gameti da parte di P. ferruginea, senza sacrificare i riproduttori di una specie protetta. Inoltre, questo ci ha permesso di effettuare una fecondazione artificiale che ha portato allo sviluppo, insediamento, metamorfosi e crescita larvale di un numero piuttosto elevato di individui giovanili di P. ferruginea (Ferranti et al., in prep.). Di conseguenza, sapendo che la specie è presente lungo la costa ligure, che riesce a raggiungere la maturità anche a queste latitudini e che è possibile riprodurre P. ferruginea in condizioni controllate fino allo stadio giovanile, possiamo affermare che esiste la possibilità di ripopolamento e reintroduzione in ambiente naturale di esemplari di P. ferruginea, recuperando questa specie nell’area in oggetto, come previsto dal progetto ReLife. Inoltre, la reintroduzione realizzata da esemplari ottenuti mediante tecniche di acquacoltura, senza influenzare sostanzialmente le popolazioni donatrici, è anche in accordo con la strategia spagnola per la conservazione della specie (MMAMRM, 2008), e in generale, le azioni di ripopolamento attraverso la riproduzione controllata, potrebbero consentire in futuro di ripopolare altre aree costiere, dove le popolazioni di P. ferruginea sono scomparse e/o in regressione, per un recupero della specie a livello globale.
The PhD project was mainly focused on the implementation of controlled reproduction techniques in the Patella genus. The species considered were P. caerulea and more particularly P. ferruginea, a protected and endangered species, whose repopulation is the subject of the European ReLife project (LIFE15 NAT/IT/000771). Being P. ferruginea a protected species, we initially preferred to test the non-lethal induction treatments on a cogeneric species, P. caerulea, common and abundant along the Italian coasts. The various treatments tested have provided excellent results, and the “bubbling” treatment was the best, both in terms of time of response to stimulation of the specimens and of replicability and ease of use. The results obtained made it possible to draw up a non-lethal spawning protocol, and to carry out artificial fertilization with subsequent larval development and settlement of the juveniles (Ferranti et al., 2018). In addition, monitoring was carried out along the Ligurian coast, which allowed reporting the presence of P. ferruginea, considered extinct along these coasts (Espinosa et al., 2014). P. ferruginea distribution, along the Ligurian coasts, is extremely scarce and fragmented; in fact the species has been found as isolated specimens or small groups, such as in the Cinque Terre MPA. However, these findings permitted to expand the mapping of the presence of P. ferruginea along the Mediterranean coasts (Ferranti et al., 2019). Furthermore, to better understand the reproductive cycle and the timing of P. ferruginea natural spawning at our latitudes, we placed specimens at sea for maturation in natural conditions, up to the beginning of the expected reproductive period. Specimens were later subjected to a biopsy of the gonad, both before being placed in the sea to determine sex (Guallart et al., 2013a), and at the beginning of the expected reproductive period to understand the stage of maturation. The observation of the material obtained through biopsy made it possible to determine that the specimens had reached gonadal maturation and that one of them had performed sex change, an event known in the literature, but observed here for the first time at the north-western Mediterranean latitude (Ferranti et al., 2021). This implies that the species can complete its reproductive cycle along the Ligurian coasts. Always in view of a better understanding of the timing of gonad maturation, we applied the Magnetic Resonance Imaging (MRI) techniques on limpets. MRI, through a non-invasive approach, allowed to observe the thickness of the gonad and also to understand whether or not a specimen had released gametes, in order to eventually apply stimulation techniques to spawning only at the right time, reducing stress on specimens. The results indicated that MRI can be very useful as an additional tool, both in evaluating the sexual maturity of P. ferruginea and in minimizing the number of induction trials for each specimen, and consequently the stress (Guallart et al., 2020). Even more relevant is having provided evidence, for the first time, that spawning can be induced in P. ferruginea and demonstrated the feasibility of obtaining juveniles, under controlled conditions through low-invasive methods. These results allowed drawing up a preliminary protocol on the induction of spawning of P. ferruginea, which allows for the spontaneous release of gametes, without sacrificing the broodstock of a protected species. Furthermore, this allowed us to carry out an artificial fertilization that led to larval development, settlement, metamorphosis and growth of a pretty large number of P. ferruginea juveniles (Ferranti et al., in prep.). Consequently, knowing that the species is present along the Ligurian coast, that it manages to reach maturity even at these latitudes, and that it is possible to reproduce P. ferruginea under controlled conditions until it reaches the juvenile stage, we provide evidence of the feasibility of P. ferruginea restocking and reintroduction in the natural environment, recovering this species in this area, as expected from the ReLife project. Moreover, the reintroduction made from specimens obtained through aquaculture techniques, without substantially affecting donor populations, is also in accordance with the Spanish strategy for the conservation of the species (MMAMRM, 2008), and generally, repopulation actions through controlled reproduction, could allow in the future to repopulate other coastal areas, where populations of P. ferruginea are disappeared and/or in regression, for the recovery of the species at a global level.

Stable isotope methods offer a powerful means of investigating trophic interactions, allowing assessment of the relative importance of multiple nutrient sources to biological assemblages, as well as estimation of the trophic positions of consumers. Differences in the isotope ratios of consumers between habitats can thus indicate differences in the structures of food webs, or the contributions of different food sources to those food webs. Isotope methods were used to compare the food web of an artificial reef located off the south coast of England with that of a nearby natural reef system, revealing a similarly complex food web, with similar trophic structure, and similar inputs from the available food sources. Isotope methods should be incorporated into more artificial reef studies, where they have been seldom applied. Offshore oil and gas platforms in the North Sea are artificial reefs, hosting substantial assemblages of sessile invertebrates and other associated fauna, and attracting large numbers of fish and motile invertebrates. Structural survey footage provided by the oil and gas industry allowed the investigation of the marine life associated with several of these structures, of varied ages and in various locations in the North Sea. At least thirty‐six taxa of motile invertebrates and fish were observed in association with the structures, most of which were present on all platforms surveyed. While most reef‐associated fish were observed around the base of the larger platforms, many thousands of fish were also observed in the water column around these structures at other depths. A small number of sessile taxa dominated the fouling assemblages, in places achieving total coverage of the available surfaces. Fouling composition changed with depth, but this pattern was not identical on all platforms. Platform age and location both affected the fouling assemblages present, but these two factors did not fully explain all the variation.

The sedimentological character and stratigraphic architecture of shallow-marine reservoirs are strongly controlled by the interplay of physical processes that occur at and near the shoreline (e.g. wave- vs. tide- vs. fluvial-dominated). These aspects can be further complicated by the interplay of tectonics in rift basins through fault block rotation, uplift, and subsidence. This thesis presents a subsurface case study from the Middle-to-Upper Jurassic 'syn-rift' Krossfjord and Fensfjord formations, Horda Platform, offshore western Norway. The distribution, geometry, and connectivity of these sandbodies are poorly understood, as they have not been the focus of previous work. However, the formations form a significant oil and gas reservoir in the Troll and Brage fields, and a prospective reservoir in the Gjøa Field. Analysis of core and wireline-log data from the Krossfjord and Fensfjord formations identified wave- and tide-dominated deltaic, shoreline and shelf depositional environments. The integration of biostratigraphic data enabled subdivision of the formations into 'series' bound by maximum flooding surfaces. The integration of 3D seismic data defined the gross stratigraphic architecture, specifically the stacking patterns of clinoform sets, and enabled further subdivision of the 'series'. Seismic geomorphological analysis of clinoforms, calibrated using forward seismic models of outcrop analogues, aided interpretation of the shoreline process regime (e.g. relative influence of waves, tides and river-mouth processes) in the context of shoreline trajectories. Palaeogeographic reconstructions illustrate that a subaqueous delta was located over the Troll Field fronting a wave- and current-driven southerly-directed spit during Middle to Late Jurassic times. In conclusion, a robust understanding of the Krossfjord and Fensfjord formations is established in order to drive future exploration in these, and coeval, reservoirs. In addition, the novel forward seismic modelling methodology described herein has wide applications and the results are directly applicable to many other shallow-marine reservoir sandstones, for which the outcrops studied are considered to be sedimentological analogues.

PCBs are among the most problematic marine contaminants. Converging towards the oceans via the rivers and the atmosphere, they concentrate in sediments where they become a permanent threat to organisms living at their contact. PCBs are extremely resistant, bioaccumulated and some congeners are considered as highly toxic. The North Sea is considered as a highly contaminated area ;however little information is available regarding the impact of PCBs on key benthic organisms of this region.

Ubiquist, abundant and generally recognized as a good bioindicator species, the common NE Atlantic sea star Asterias rubens (L.) is an ecosystem-structuring species in the North Sea and was chosen as an experimental model. The present study focused on the characterization of PCB bioaccumulation in A. rubens exposed through different routes (seawater, food, sediments) and on subsequent biological responses, at immune and sucellular levels. The considered responses were respectively (i) the production of reactive oxyggen species (ROS) by sea stars amoebocytes, which constitutes the main line of defence of echinoderms against pathogenic challenges and (ii) the induction of a cytochrome P450 immunopositive protein (CYP1A IPP) which, in vertebrates, is involved in PCB detoxification.

Experimental exposures carried out have shown that A. rubens efficiently accumulates PCBs. Exposure concentrations were always adjusted to match those encountered in the field. PCB concentrations reached in sea stars during the experiments matched the values reported in field studies ;therefore our experimental protocol was found to accurately simulate actual field situations. Uptake kinetics were related to the planar conformation of the considered congeners :non-coplanar PCB uptake was described using saturation models, whereas coplanar PCBs (c-PCBs) were bioaccumulated according to bell-shaped kinetics. Non-coplanar congeners generally reached saturation concentrations whithin a few days or a few weeks, which means that sea stars can be used to pinpoint PCB contamination shortly after occurrence. On the other hand, c-PCB concentrations reached a peak followed by a sudden drop, indicating the probable occurrence of c-PCB-targeted metabolization processes in sea stars. Our experimental studies also demonstrated that seawater was by far the most efficient route for PCB uptake in sea stars and that even if PCB levels in seawater are extremely low compared to sediment-associated concentrations, seawater constitutes a non-negligible route for PCB uptake in marine invertebrates. Among the different body compartments, bodywall displayed the highest bioaccumulative potency and can therefore be considered as particularly interesting for field biomonitoring applications. Rectal caeca, which play a central role in digestion and excretion processes in sea stars, have also rised particular interest as results suggest these organs could be involved in the elimination of PCB 77 degradation products.

The field work carried out during the present study showed that PCB concentrations measured in A. rubens tissues reflect environmental levels of certain congeners. As it was the case in experimental conditions, A. rubens differentially accumulated PCB congeners according to their planarity. Strong relationships were found between concentrations measured in sediments and those determined in sea stars body wall for certain non-coplanar congeners (e.g. 118 and 138), thus allowing to consider A. rubens as a suitable bioindicator species for medium-chlorinated PCB congeners. On the other hand, sea stars appeared to be able to regulate -to a certain extent- their content in coplanar PCBs. This implies that (i) A. rubens cannot be strictly considered as an indicator organism for c-PCBs and (ii) c-PCBs probably affect essential aspects of sea star biology, potentially leading to deleterious effects.

The present study addressed effects of PCB exposure on A. rubens biology, in both experimental and field conditions. In experimental conditions, PCBs were found to significantly alter ROS production by sea stars amoebocytes. This alteration also occurred in a congener-specific way :c-PCBs were found to significantly affect, and probably impair sea stars immune system, whereas non-coplanar congeners had no effect. In the field, the PCB contribution to immunotoxicity could not be determined because none of our studies considered ROS production along with c-PCB concentration measurements. However, the levels of ROS production by sea stars amoebocytes measured in field and experimental conditions were found to potentially lead to altered immunity, and therefore to impair sea stars defence against pathogenic agents.

A specially designed ELISA was used to measure CYP1A IPP in experimental and field conditions. Experimental work has shown that the induction of this protein was related to PCB exposure in a congener-specific fashion :c-PCBs alone were found to strongly induce the production of CYP1A IPP according to a dose-dependent relationship. These results have highlighted many similarities between the dioxin-like responsiveness of CYP1A IPP induction in sea stars and that occurring in vertebrates. This strongly suggests similarities in the toxicity-triggering mechanism of dioxins and c-PCBs. In the field, CYP1A IPP induction was found to be significantly related to PCB levels determined in bottom sediments. It can thus be considered as a valuable biomarker. Further research is however needed to better characterize the influence of physico-chemical and physiological parameters on CYP1A induction to refine the interpretation of the information gathered via this biomarker.

Results obtained in our study have lead to questionning international regulations applying to PCB biomonitoring in the marine environment. For instance, we strongly suggest that the selection of congeners to be systematically considered should be revised to include c-PCBs. Indeed, in our experiments PCB toxicity was almost always attributable to the sole c-congeners. Historically, determination of c-PCB concentrations was extremely difficult due to analytical limitations ;however, nowadays, these problems have been overcome and do no more justify their exclusion from monitoring studies.

Although A. rubens appeared to be quite resistant to PCB contamination, levels measured in sea stars from the southern North Sea can possibly affect their immune and endocrine systems in a subtle way, but with relatively low risk for this species at the short-term. However, this does not mean that other species in this region undergo similarly low risks, or that sea star-structured ecosystems may not become affected in the long-term

Doctorat en sciences, Spécialisation biologie animale
info:eu-repo/semantics/nonPublished

The evolution of the lower course and estuary of the river Ribble (Lancashire, U.K.) during the Holocene is the object of study, along with the history of sediment fluxes in them and their influence on past human settlements. Investigation of the valley floor geomorphology and terrace fill stratigraphy and sedimentology, as well as palaeoecological analysis and a number of 14C essays, allowed the reconstruction of Late Pleistocene and Holocene alluvial history and chronology of a reach at the transition point between fluvial and estuarine influences; the archaeological evidence is evaluated in this context. Alluviation and incision cycles led to the formation of four river terraces. The oldest terrace, rich in coarse-grained materials, seems to be of Pleistocene age. 14C dating on the second terrace would point to an Earliest Holocene or Younger Dryas age; the fill, however, comprises abundant fine-grained overbank sediments. Large parts of the unit were reworked during a phase of lateral channel activity that occurred prior to ca. 8900 cal BP; between then and ca. 6900 cal BP the river underwent meander cut-offs, after which limited lateral activity occurred. New alluviation occurred around 4700 cal BP, possibly related to the aggradation of the third terrace, though its fill is only certainly known, from archaeological evidence, to be of pre-Roman age. Channel size increase occurred by the time the terrace was deposited. The fill features abundant clayey sediments; it was incised at or after the end of the Roman period. The last terrace was deposited in the late first millennium AD mainly as overbank silts, and has since been incised again. Fluvial response appears mainly related to climate changes, river activity corresponding to shifts to wetter, cooler climate. Human action likely enhanced fluvial response in the historical period, leading to post-Roman incision and deposition. There seems to be a good connection between sediment production in the catchment and deposition downstream. Local factors also show a major importance in determining river response. Early Holocene fluvial history finds no match in other Northern English rivers; a different response to the same climate changes is apparent, possibly related to differences in sediment supply conditions. No clear evidence is found supporting an influence of sea-level change on river processes. On the other hand, it appears plausible river sediment input has a driving influence in enhancing or causing minor regressions recorded on the estuary. The conditions existing in Roman times could have allowed access from the sea to the Roman sites at the upper end of the Ribble estuary and by its North shore; a relative sea-level minimum could have caused a shift of focus in naval traffic from the former to the latter site.

The occurrence of regime shifts in large marine ecosystems is unproven and controversial. Despite this, a number of marine regime shifts are reported to have occurred during the last century. These shifts have been largely attributed to overfishing and climate change, and have had important consequences for marine ecosystem structure and function. Understanding the relationships between ecosystem pressures and responses is a critical step towards an effective ecosystem approach to management. Ecosystem models are a useful way of investigating how ecosystems respond to changes in pressures at the component and system level. This thesis aims to (i) define a set of quantitative thresholds for defining large-scale changes in marine ecosystem components in historical data and model simulations, (ii) characterise changes in the Irish Sea marine ecosystem that were observed between 1973 and 2002, and (iii) investigate whether 3 UK Ecosim models are capable of simulating the observed ecosystem level changes in response to trends in fishing and climate. System-level changes are measured using 12 model-based indicators of ecosystem state. Marine ecological regime shifts are defined as changes in marine community structure that occur over a 1-7 year period with an amplitude of at least 46% of the largest difference in indicator value. They persist on a decadal to multi-decadal scale and are associated with changes in biological communities spanning over at least 3 trophic levels. The criteria are used to diagnose an ecological regime shift in the Irish Sea in the late 1980s. Despite the inherent uncertainties associated with ecosystem models, all 3 models show that they are able to provide insights into the ecosystem responses to fishing and climate pressures, and that other factors are likely to have been important in explaining observed changes in the UK's marine ecosystem state. This suggests that they will be useful tools for "end-to-end" ecosystem analysis, which will be important in understanding the relationships between ecosystem pressures and responses.

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

The Wilson’s Plover (Charadrius wilsonia) is a species of concern in most southeastern U.S. coastal states, where it breeds and winters. The U.S. Shorebird Conservation Plan listed this species as a Species of High Concern (Prioritization Category 4), and the U.S. Fish and Wildlife Service has designated it as a Bird of Conservation Concern (BCC). Despite its conservation status, Wilson’s Plover population trends are poorly understood and little research has been conducted examining habitat factors affecting this species’ breeding and foraging ecology. I collected Wilson’s Plover demographic data and explored which habitat characteristics influenced breeding success and foraging site selection among three coastal habitat types (i.e. fiddler crab (Uca spp.) mud flats, beach front, and interdune sand flats) at Onslow Beach, Marine Corps Base Camp Lejeune, North Carolina, 2008-2009. I observed little difference between years in nest success (≥ 1 egg hatched), failure, and overall nest survival. The majority of nest failures were caused by mammalian predators. For those nests that hatched successfully, greater proportions were located in clumped vegetation than on bare ground or sparsely vegetated areas. In-season chick survival for both years was higher for nests that hatched earlier in the season, and for nests farthest from the broods’ final foraging territory. Productivity estimates (chicks fledged per breeding pair) were not significantly different between years (0.88 ± 0.26 fledged/pair in 2008, 1.00 ± 0.25 fledged/pair in 2009) despite a shift in foraging behavior, possibly related to habitat alterations and availability in 2009. My findings indicate that Wilson’s Plover adults and broods were flexible in establishing final foraging territories; in 2008 all final brood foraging territories were on fiddler flats while in 2009, final foraging territories were sometimes split between fiddler flats, beach front, and interdune sand flats. For those Wilson’s Plovers establishing territories on fiddler flats, area of the flat was the most important feature explaining use versus non-use of a particular flat; area ≥ 1250 m² was preferred. Close proximity to water and vegetative cover were also important habitat features in foraging site selection on fiddler crab mud flats, and in all habitat types combined. My findings will directly contribute to population and habitat research goals outlined in the U.S. Shorebird Plan and will supplement limited data about foraging and habitat use related to Wilson’s Plover breeding ecology.
Master of Science

Waterfowl are known to be capable of influencing wetland ecology in a number of ways, sometimes to the detriment of other species that also inhabit this type of environment. Western Golden Bay including Farewell Spit is one of the largest areas of intertidal sand flat habitat in New Zealand and supports a wide array of species including internationally important populations of bar-tailed godwits (Limosa lapponica) and red knot (Calidris canutus). These species, particularly red knot, have declined in number over the last the 25 years at this site. Another numerous species at this site, the black swan (Cygnus atratus), has been suggested as a possible contributor to the observed decline in wader numbers through their impact on the habitat. This thesis presents the findings of a research project on the role of black swans in the tidal seagrass (Zostera muelleri) ecosystem in western Golden Bay carried out between October 2007 and October 2008. In an effort create a clear picture of what role the black swans play in this environment the project focused on four major aspects of swan-ecosystem interactions. The first of these looked at the activity patterns of black swan. This showed the swans’ activity is largely dictated by the tidal cycle with foraging occurring during the intertidal period when the seagrass is accessible while roosting is mostly confined to around high and low tides. The second part of the project explored the influence black swans have on the tidal seagrass landscape through their foraging habits. This showed that while swan foraging occurs across the tide flats it is concentrated on denser patches, on both small (meters) and large (hectares) scales. Experimental grubbings showed that the grubbing activity of swans is capable of forming and expanding bare sand patches within seagrass beds and that these bare patches can persist for at least two months. The third part of the project focused on the direct impacts of swan foraging on the seagrass and associated benthic invertebrates. Exclusion plots showed that at some sites swan foraging can significantly reduce Zostera biomass and invertebrate biodiversity. The final aspect examined was the role of swan in biomass and nutrient cycling. A faecal deposition survey showed swans consume 23.40 g DW ha-1 day-1 of Zostera. The average intake rate was 27.25 g DW ha-1 day-1. Nutrient analysis of seagrass 4 showed that shoot material has significantly higher N, P, Ca and fibre than rhizome and that rhizome has significantly more soluble carbohydrates than shoots. On the basis of the swans’ direct and/or indirect influences on Zostera muelleri beds and the associated invertebrate fauna, swans could arguably be considered to be a major ecosystem engineer in the intertidal sandflats of Golden Bay.

Sedimentological and palynological datasets have been integrated to improve the understanding of syn-rift, deep-marine hanging wall strata. Upper Jurassic fault scarps were examined from Inner Moray Firth (IMF) outcrops and subsurface data from the Central Graben. Reduced sand supply recorded in IMF sediments, comprising siltstones, sandstones and breccias with Devonian clasts, was investigated by logging of 970 m of outcrop, provenance and palynological analysis, identifying three factors: exhumation of resistant footwall strata; climate change and sea-level rise. Sedimentation rates and lithofacies distribution identified an initial turbidite prone syn-rift phase; MTC dominated rift climax and late stage rifting when sedimentation declined. Thirty-two palynological samples determined palaeoclimate and palaeoenvironment variations; documenting change from humid-temperate to semi-arid. The nature of debris flows implies trigger by earthquakes and their frequency describes three phases of tectonism; turbidites are not distal MTC expressions but correlate with sea-level falls. Temporal and spatial relationships of MTCs and sandstones adjacent to the Josephine Ridge were investigated. One hundred and twenty one palynological samples were used to indicate subaerial exposure of the Judy Horst; Jade remained submerged, with implications for Central Graben palaeogeography. Seismic studies suggest footwall collapse of the horsts provided MTCs. Wireline signatures from sixteen wells and 116.7 m of core demonstrate a Triassic provenance for the MTCs. Distally the massive Freshney Sandstone is interpreted as gravity flow deposits; petrographic and HM studies indicate it was not sourced from the Josephine Ridge. Biostratigraphy shows sandstones were deposited during initial rifting; pre-dating MTCs, which are not predicted to have damaged the reservoir interval due to their non-erosive nature. This study has disentangled the effects of relative sea-level change and growth faulting in rift basins. Rift stages have been identified independently from multiple datasets. The effect of climate change on rift basin stratigraphy has been highlighted and changing footwall lithology has been shown to have a major impact on the development of siliciclastic sediments.

The use of iceberg-keel ploughmarks as proxy indicators of past and present iceberg morphology, keel depth and drift direction has seldom been approached in the southern hemisphere. Using high-resolution multi-beam swath bathymetry of the mid-shelf Pine Island Trough and outermost Weddell Sea shelf regions of Antarctica, detailed analysis of >13,000 iceberg-keel ploughmarks was undertaken. By considering the draft of icebergs calved from Antarctica today, calculated from detailed satellite altimetric datasets by this work, almost all observed ploughmarks were interpreted to be relict features. In Pine Island Trough, ploughmark planform parameters and cross-sections imply calving of a large number of non-tabular icebergs with v-shaped keels from the palaeo-Pine Island-Thwaites ice stream. Geological evidence of ploughmark form and modern water depth distribution indicates calving-margin thicknesses (949 m) and subaerial ice cliff elevations (102 m) equivalent to the theoretical threshold predicted to trigger ice-cliff structural collapse and calving by marine ice-cliff instability (MICI) processes. Thus, ploughmarks provide the first observational evidence of rapid retreat of the palaeo-Pine Island-Thwaites ice stream, driven by MICI processes commencing ~12.3 cal ka BP. On the Weddell Sea shelf, ploughmark morphologies imply considerable variation in palaeo-iceberg shape and size, most likely reflecting calving from multiple source margins. In turn, an absence of grounded ice on the Weddell Sea shelf and a palaeo-oceanographic regime comparable to today are implied at the time of formation. Analysis of a 3D seismic cube of the Sea Lion Field area of the North Falkland Basin reveals iceberg-keel ploughmarks incised into the modern- and palaeo-seafloor, formed by icebergs of varying shape and size that most-likely calved from the Antarctic Ice Sheet during three past glacial periods (estimated ages ~18 - 26.5 ka BP, ~246 ka BP, ~9.8 Ma BP). Despite illustrating the possibility of iceberg drift into the North Falkland Basin today, the relict ploughmark age implies little risk to any seafloor structures in the area, which might be required for hydrocarbon production. By these analyses, the significance of iceberg-keel ploughmarks as indicators of palaeo-glaciology and palaeo-oceanography at the time of formation is emphasised.

We report a 40 year record of eutrophication and hypoxia on an estuarine ecosystem and its recovery from hypereutrophication. After decades of high inorganic nutrient concentrations and recurring anoxia and hypoxia, we observe a paradoxical increase in chlorophyll-a concentrations with decreasing nutrient inputs. We hypothesise that algal growth was inhibited due to hypereutrophication, either by elevated ammonium concentrations, severe hypoxia or the production of harmful substances in such a reduced environment. We study the dynamics of a simple but realistic mathematical model, incorporating the assumption of algal growth inhibition. It shows a high algal biomass, net oxygen production equilibrium with low ammonia inputs, and a low algal biomass, net oxygen consumption equilibrium with high ammonia inputs. At intermediate ammonia inputs it displays two alternative stable states. Although not intentional, the numerical output of this model corresponds to observations, giving extra support for assumption of algal growth inhibition. Due to potential algal growth inhibition, the recovery of hypereutrophied systems towards a classical eutrophied state, will need reduction of waste loads below certain thresholds and will be accompanied by large fluctuations in oxygen concentrations. We conclude that also flow-through systems, heavily influenced by external forcings which partly mask internal system dynamics, can display multiple stable states.

The Belgian Coastal Zone (BCZ) in the Southern Bight of the North Sea is a highly dynamic and optically complex area. This is due to high non-algal particles (NAP) and coloured dissolved organic matter (CDOM) content which in spring adds together with undesirable blooms of the haptophyte Phaeocystis globosa. There is a need for improving the algorithms for chlorophyll a (chl a) retrieval in these highly turbid waters and for developing algorithms for species detection in order to attempt to create an early warning bloom system. This information will contribute to the knowledge of the extent and magnitude of the P. globosa bloom in Belgian waters. In this study, pure cultures of the main taxa present in the BCZ, diatoms and P. globosa, were combined with field measurements of light absorption of total particles, phytoplankton and dissolved material, pigment determination and phytoplankton counts to address the main objectives. Sampling was performed during 8 cruises covering winter, spring, summer and late summer, and along nearshore-offshore gradients from 2003 to 2006.

The area is characterised by a high spatio-temporal variability of IOPs due to the high dynamics of the area in terms of currents, salinity gradients and biological production. During spring the presence of P. globosa modulates the IOPs across all the area, the particle absorption is significantly higher than summer and there is no significant coast-offshore variability for phytoplankton and CDOM.

The design of chl a retrieval algorithms assumes negligible absorption of NAP and CDOM in the near infrared (NIR) and the use of a fixed value of specific phytoplankton absorption. It is shown that neglecting the NAP and CDOM absorption in the NIR will have a significant overestimation impact in retrieval of chl a. On the other hand, the specific phytoplankton absorption was found to be highly variable (0.015 „b 0.011 m2 mg chl a-1). Both results will affect directly the retrieved chl a. The spatial variability of CDOM was significant varying between 0.20-1.31 m-1 in the marine area and between 1.81-4.29 m-1 in the Scheldt estuary. CDOM was found to be related to salinity with conservative mixing within the Scheldt estuary and during some seasons in the BCZ, however deviations from conservative mixing suggest other inputs to the CDOM pool. Analyses of the spectral slope of the CDOM absorption curve revealed two main CDOM pools in the area, an allochthonous one delivered by the Scheldt estuary and an autochthonous one associated with the phytoplankton spring bloom decomposition. Algorithms for CDOM retrieval will be affected if the variability in the relation between CDOM and salinity is not taken into account.

The optical characterisation of diatoms and P. globosa from the BCZ in pure cultures revealed that the main differences in the phytoplankton absorption spectra were found at 467 and 500 nm corresponding to the absorption of the pigments chlorophyll c3 (chl c3) characteristic of P. globosa and fucoxanthin, respectively. Accordingly, both the absorption at 467 nm and the ratio 500/467 nm were successfully used to discriminate the two taxa in cultures and field samples. This latter indicator was not preserved in the reflectance signal due to degradation of the signal when passing from absorption to reflectance, and thus could not be used for algorithm development. The spectral feature at 467 nm was later used as the basis for the development of a flag-type algorithm to detect chl c3 using either absorption or water-leaving reflectance data. Also, the correlation between the algorithm¡¦s retrieved chl c3 and P. globosa cell number allowed the quantification of the bloom. The main findings of this thesis highlight the importance of the IOPs characterisation for the improvement and development of ocean colour retrieval algorithms in these highly complex waters.

Doctorat en Sciences
info:eu-repo/semantics/nonPublished

The Deepwater Horizon Oil Spill (DWH) released about 4.4 million barrels of crude oil into the Gulf of Mexico (GOM), making it one of the largest oil spills in U.S. history. Additionally, the depth of the spill (i.e., 1500 meters) created a unique research opportunity because most oil spills occur at the surface and affect coastal rather than deepwater habitats. Polycyclic aromatic hydrocarbons (PAHs) are the most toxic components of oil, and are often the focus of oil exposure studies. PAHs are quickly metabolized by vertebrates; therefore, indicators of biological responses to PAH exposure (PAH “biomarkers”) such as the levels of PAH detoxification enzymes and the resulting metabolites are commonly used to examine oil exposure. This study measured multiple PAH biomarkers including hepatic activity of the PAH detoxification enzymes cytochrome P4501a1 (CYP1A) and glutathione-S-transferase (GST), as well as biliary PAH metabolites in deep sea sharks and bony fishes from areas affected by the Deepwater Horizon Oil Spill. Samples were collected from 2011-2013 from seven species of sharks, with special focus on the four most abundant deep sea species: Centrophorus niakang, Centrophorus cf granulosus, Squalus cubensis and Squalus cf mitsikurii. Overall enzyme activity was low in these sharks, yet it was higher in oiled sites compared to reference locations. Additionally some species showed declining CYP1A activity since the time of the oil spill, suggesting exposure to CYP-inducing compounds during the beginning of the survey period. Last, PAHs of a petrogenic nature were more abundant in oiled sites compared to reference locations. Overall, this project provides the much need biomarker data for sharks as well as insight on exposure and metabolism of PAHs in deep sea sharks after the DWH.

The New Zealand (NZ) sea lion Phocarctos hookeri is the only pinniped endemic to NZ with a population of approximately 12,000 individuals. Its breeding range is currently restricted to NZ sub-Antarctic islands, and it has failed to recolonise its pristine distribution around the NZ main islands despite its protection since 1881. The current hypothesis is that the population growth of this pinniped is limited by the distribution of suitable prey on the Auckland Islands (50°30'S, 166°E) shelf, and by the direct and indirect pressure exerted by the arrow squid Nototodarus sloani fishery. However, this hypothesis has not been fully tested to date as there has been limited information on the diet of the NZ sea lion and their potential prey. The objective of this thesis is to analyse the diet of NZ sea lions over several years with particular emphasis on the most reproductively important segment of the population: lactating females. This thesis provides the first quantification by percentage mass of the diet of NZ sea lion using a combination of stomach content analysis, qualitative fatty acid (FA) analysis, and quantitative FA signature analysis (QFASA). Stomach contents and blubber FAs were analysed from 121 individuals incidentally caught (by-caught) in the southern arrow squid fishery from the years 1997 to 2006. The blubber FAs of 78 freeranging lactating females captured at Enderby Island, Auckland Islands, were also examined during January and February of 2000 to 2005. Data obtained from both stomach analysis and QFASA indicate that arrow squid, rattails Macrouridae, hoki Macruronus novaezelandiae and red cod Pseudophycis bachus are key prey species for NZ sea lions in the Auckland Islands region. Because these prey species live mostly at depths greater than 200 m, lactating females must undertake long foraging trips and dive regularly to greater depths than other sea lion species. Data from QFASA indicates that this foraging pattern is conducted over an extended period through the summer and autumn. The daily food requirement of a lactating female was estimated by a simple energetic model to be greater than 20% of its body mass. During years of low arrow squid recruitment such as 1999 and 2001, the amounts of squid required by the NZ sea lion population may have been similar to the amount harvested by the fishery, suggesting that resource competition is likely to occur between the arrow squid fishery and NZ sea lions in years of low squid abundance. Half of the fishing activity of the southern squid fishery occurs in the north of the Auckland Islands shelf where NZ sea lions forage, leading to incidental captures every year. This research emphasises that management of the NZ sea lion must not only consider the direct interactions with the arrow squid fishery, but also the likelihood of food resource competition between the fishery and NZ sea lions.

Les cétacés grands plongeurs, cachalots Physeteridae et Kogiidae, et baleines à bec Zipiidae, sont des espèces marines rares. Leur faible densité, aire de distribution étendue et faible disponibilité en surface génèrent de faibles taux d’observations. Cette particularité constitue un défi pour la modélisation d’habitat de ces espèces, préalable à leur conservation. Les modèles doivent gérer l’abondance de zéros qui limitent leur capacité à inférer des résultats écologiquement cohérents. Cette thèse vise donc à trouver une méthodologie adaptée aux jeux de données abondants en zéros, à déterminer comment les variables environnementales influencent la distribution des grands plongeurs et à prédire les zones potentielles qu’ils utilisent. Tester la capacité de prédiction de différents modèles d'habitat confrontés à un nombre décroissant d’observations a permis de souligner la pertinence d’un modèle, même si un minimum de 50 observations est nécessaire pour fournir des prédictions fiables. Des données issues de différentes campagnes visuelles ont été assemblées afin de produire les premières cartes de densités de grands plongeurs à l’échelle de l’océan Atlantique Nord et la mer Méditerranée. Les densités les plus élevées sont prédites dans les eaux entre 1500 et 4000 m de profondeur et près des fronts thermiques, particulièrement le long des pentes continentales et à l'ouest de l'océan Atlantique Nord. Par ailleurs, l’analyse de la transférabilité des modèles a montré une variation des habitats préférentiels en fonction des écosystèmes. Finalement, cette thèse permet de discuter les défis de la modélisation statistique appliquée aux espèces rares et les applications de gestion associées
Deep-diving cetaceans, sperm- and beaked whales Physeteridae, Kogiidae and Ziphiidae, are rare marine species. Due to their low densities, wide distribution ranges and limited presence at the water surface, visual surveys usually result in low sighting rates. This paucity of data challenges the modelling of their habitat, prerequisite for their conservation. Models have to cope with a great number of zeros that weakens the ability to make sound ecological inferences. Consequently, this thesis aimed at finding a methodology suitable for datasets with a large number of zeros, determining how environmental variables influence deep-diver distributions and predicting areas preferentially used by these species. By testing the predictive performance of various habitat models fitted to decreasing numbers of sightings, I selected the most suitable model and determined that at least 50 sightings were needed to provide reliable predictions. However, individual surveys can rarely provide sufficient deep-diver sightings thus I merged many visual survey datasets to produce the first basin-wide deep-diver density maps in the North Atlantic Ocean and the Mediterranean Sea. Highest densities were predicted in waters from 1500-4000 m deep and close to thermal fronts ; hotspots were predicted along the continental slopes, particularly in the western North Atlantic Ocean. In addition, a model transferability analysis highlighted that habitat drivers selected by the models varied between contrasted large ecosystems. Finally, I discussed challenges related to statistical modelling applied to rare species and the management applications of this thesis

Submarine canyons are major topographic structures forming deep incisions in shelfs and continental margins around the globe. Due to their topographic characteristics, canyons influence both local hydrodynamic conditions and the transfers of organic material and sediment from shelfs to deep seafloor. This leads to changes in sediment characteristics and organic enrichment that play a key role in deep-sea the functioning, and particularly affect benthic communities. Metazoan meiobenthos are the most abundant deep-sea infauna, with nematodes being dominant. Due to their small size, meiofauna is intimately related with the sediment so that the physical properties are highly influencing the assemblages harbored by a given ecosystem. Therefore, habitat heterogeneity, a particularly relevant canyons feature plays a key role in shaping meiofaunal distribution and biodiversity. Blanes canyon (NW Mediterranean) has been intensively explored during the last years, mostly in relation with the fishery activities in the area. However, as in many other canyons, the meiobenthic component had been almost neglected. Within this context and in the frame of the Spanish research project Dos Mares, the present thesis, focus on the metazoan meiofauna in the Blanes Canyon system. Samples were obtained by the multicore deployments from 500 to 2,000 m depth during four oceanographic campaigns (spring and autumn in 2012-2013). The main objective was to increase the knowledge and further understanding of the patterns and trends of meiofaunal density, diversity and community composition, as well as on its main environmental drivers, with a particular emphasis on the dominant nematode assemblages. Our results indicate that Blanes Canyon exhibits: marked sediment variability, high food availability (i.e., Organic Carbon, Chlorophyll a, Chloroplastic Pigments Equivalents) compared to the adjacent slope, together with higher density, and diversity, and more marked differences in community composition and distribution, both at higher (i.e., meiofauna) and lower (i.e., nematodes and kinorhynchs) taxon level. The observed temporal variability is only partly explained by the seasonal patterns of food input, derived from phytoplanctonic production, where major oceanographic processes such as recurrent dense shelf water cascading events; seem to play a key role. Moreover, the topographically heterogeneous environment associated to the canyon bathymetric gradient, combined with the existence of recurrent, non-seasonal food pulses, are better explaining the observed meiofaunal trends, particularly those concerning nematodes. However, among all gradients analysed, the greatest effect on nematode communities occurred at small-scale (cm), both in the canyon and on the slope, with the highest abundance at the surface sediment layer leading to a marked diversity decrease along the vertical sediment profile. This Thesis includes the first known study on Mediterranean deep-sea kinorhynchs, which contributes to increase the current knowledge on its diversity and distribution, as seven over the nine species found in the canyon system turned to be undescribed. Our results allowed us to avoid suggesting generalizations in the description of meiofauna patterns in the canyon, highlighting those different taxa may show different bathymetric-related responses, this being particularly relevant in the case of the rare taxa (e.g., the kinorhynchs). They also support the consideration of submarine canyons as hotspots of faunal density, biomass and diversity, confirming its key role in shaping the patterns and trends shown by benthic fauna. Finally, the overall results of this Thesis strongly suggest that the Blanes Canyon system is not functioning as a purely natural environment. The high sedimentation rates in the canyon axis suggest that the indirect but regular effects of bottom trawling are driving the structure, and possibly the functioning, of the associated meiobenthos, all along the axis down to at least, 1,750 m depth.
Los cañones submarinos son una de las principales estructuras geomorfológicas del margen continental y un recurso de heterogeneidad del fondo marino. Su abrupta topografía influye en el régimen hidrodinámico local, interrumpiendo y amplificando las corrientes e incrementando los flujos de partículas. Juegan un papel importante en el transporte entre plataforma y océano profundo atrapando, acumulando y canalizando sedimentos y materia orgánica con importantes consecuencias para la diversidad, funcionamiento y dinámica del bentos. La meiofauna es un componente importante del bentos. Dado su pequeño tamaño, está íntimamente relacionada con el sedimento y sus posibles alteraciones (p. ej., alteración de las tasas de sedimentación, resuspensión). Esta Tesis se centra en el Cañón de Blanes (NO Mediterráneo), lugar de importante actividad pesquera. Partiendo de muestras recogidas en primavera y otoño de 2012 y 2013, el principal objetivo ha sido incrementar el conocimiento y las pautas y tendencias de las comunidades de meiofauna (densidad, biomasa, diversidad y estructura) del Cañón de Blanes, así como de su talud adyacente con especial énfasis en los nematodos. Las elevados tasas de sedimentación detectados en el cañón (hasta los 1,750 m), sugieren un efecto indirecto de la pesca de arrastre, que estaría afectando a la meiofauna, sugiriendo la parcial antropogenización de los ambientes profundos del cañón. La variabilidad temporal observada obedece a: entradas estacionales de materia orgánica (derivadas de la producción primaria), procesos de formación de aguas profunda y heterogeneidad topográfica, combinados con entradas recurrentes no estacionales de materia orgánica. Sin embargo, la variabilidad a pequeña escala (cm) causa un mayor efecto en la estructura y diversidad de la comunidad de nematodos, principalmente debido a la disminución en diversidad a lo largo del perfil vertical del sedimento. El Cañón de Blanes muestra mayor variabilidad en el sedimento y disponibilidad de materia orgánica que el talud adyacente, así como una mayor variabilidad en la composición y estructura de las comunidades meiofaunales. Nuestros resultados apoyan la relevancia del papel de los cañones submarinos en la distribución de la fauna bentónica, así como su consideración como hot spots de densidad, biomasa y diversidad.

A variety of anthropomorphic and environmental stresses are threatening the existence of all seven species of sea turtles. There is growing evidence that alterations in surface waters and sediment temperatures are negatively impacting reproductive success of loggerhead sea turtles (Caretta caretta). Fluctuations in water temperature associated with localized climate oscillations heavily alter the food web dynamics of the ocean. Feeding conditions are expected to be a critical factor in determining body mass and productivity for breeding seasons. An increase in regional temperatures could lead to prolonged reduction in food sources, as well as reduced nesting and recruitment. Loggerhead sea turtle nesting data from 1995-2011 werre compared with the average yearly North Atlantic Oscillation (NAO) and Atlantic Multidecadal Oscillation (AMO) which are important climatic events impacting the SST in the Atlantic Ocean. Because El Niño Southern Oscillation (ENSO) is a global event, it was proposed that turtles in the Atlantic may follow a similar trend. ENSO was quantified using Oceanic Nino Index (ONI). Analysis of loggerhead sea turtle nest frequencies from the years 1995-2011 in comparison to seasonal climate changes showed a significant inverse relationship between the detrended loggerhead nests and average yearly NAO when lagged two years, suggesting loggerheads may spend years prior breeding obtaining optimum body mass to increase successful reproduction. The detrended nesting data showed a tendency toward higher occurrence of nests during La Niña years while nest frequencies decreased during El Niño year; when the yearly detrended loggerhead nesting data was compared with the average yearly ONI; showing a significant inverse relationship without a lag. This may also suggest a relationship between changes of productivity of the ocean influenced by smaller scale climate changes and loggerhead nest frequencies.

The conservation of marine mammals relies on the knowledge of species ecology in order to assess the impacts of anthropogenic activites and make appropriate species management decisions. Blubber biopsies are a relatively non-invasive sampling protocol to provide ecological information; two particular uses are for dietary analysis via fatty acid signature analysis (FASA) and investigating the uptake of organochlorine (OC) and polychlorinated biphenyl (PCB) environmental contaminants. Blubber composition and structure may vary according to body site and depth due to its dynamic functioning. This may result in the vertical stratification and heterogenous distribution of blubber FAs, OCs and PCBs between body sites, giving variable interpretations of diet and contaminant levels depending on biopsy sample site and depth. The aim of this thesis is to determine the FA distribution of blubber from two body sample sites (dorsal pelvic and ventral thoracic) currently used for FASA of the New Zealand sea lion, Phocarctos hookeri (NZSL) and to determine the level of OCs and PCBs in the blubber of healthy NZSLs for comparison to diseased NZSLs recorded in the 1997/98 epidemic. Blubber samples were collected from 29 by-caught NZSLs incidentally captured by the squid fishery around the Auckland Islands (50º42’S, 166º5’E) during the years 2005 to 2007 (not all NZSLs were able to be analysed for each chapter). Full blubber cores from both sample sites were collected from 18 NZSLs. Both sites showed a relative homogeneity of FA profiles, indicating the similar deposition and mobilisation of FAs at the two sample sites. To determine if FA stratification occurred, full blubber cores from both sample sites of 20 NZSLs were divided into inner and outer halves. Both sites displayed the same pattern of vertical stratification or biochemical layering of FAs between the two divisions, indicating that stratification of FAs occurs in the blubber of the NZSL. A range of OCs and PCBs were then determined in full thoracic blubber cores of seven NZSLs. The levels were higher than those previously recorded in NZSLs affected by disease during a 1997/98 epidemic. The SPCB in NZSLs was 0.034-0.192 mg/kg lipids, below the suggested threshold of 17 mg/kg for adverse health affects in marine mammals. From the results of this study I can support current blubber biopsy sampling techniques for FASA in NZSL. Obtaining full blubber cores from either the thoracic or pelvic sample site will give a comparable interpretation of diet. The low levels of blubber OCs and PCBs suggest a minor role of contaminants acting as a possible causative agent toward disease outbreaks in the NZSL. This research provides important information for developing correct and consistent blubber sampling techniques for NZSL and other pinniped species. This will ensure more accurate interpretations of ecological information obtained from blubber biopsies and therefore improved species management and conservation decisions that may be based on such research.

Le traceur transitoire que constitue le tritium est devenu l'un des outils les plus prometteurs dens l'etude de la circulation oceanique generale et de la capacite de l'ocean a absorber le gaz carbonique anthropogene. L'utilisation simultanee du tritium et de son descendant par voie radioactive l'helium-3 ajoute une information supplementaire: la paire de traceurs tritium et helium-3 constitue une horloge dans l'etude des masses d'eau. En plus de son origine "tritiumgenique", l'helium-3 est emis au niveau des dorsales oceaniques et il constitue un traceur de choix dans l'etude de la circulation oceanique profonde. Toutes les mesures d'helium-3 et de tritium ont ete faites par spectrometrie de masse. Protocole analytique, limite de detection et reproductibilite de la methode sont reportes dans ce travail. Sont abordes au niveau de l'interpretation des resultats: -1) les donnees d'helium-3 a la campagne merou a (ete 1982) ont permis de localiser une source active et de mettre en evidence un courant de retour intermediaire (centre vers 1000 m de profondeur), prolongement du courant profond upwelle dans la partie meridionale du bassin. -2) l'utilisation des donnees de tritium concernant la mission phycemed 1 (avril 1981) a permis de decrire la grande variabilite spatio-temporelle des processus de convection ayant lieu dans le bassin nord; le temps de renouvellement des eaux profonbdes du golfe du lion est evalue a 11 +ou- 2 ans. Les circulations profondes et de subsurface au niveau des detroits de sardaigne et de gibraltar sont precisees. -3) l'etude simultanee, suivant des niveaux isopycnaux, des donnees tritium et helium-3 de la mission topogulf (ete 1983) a permis de localiser les zones ou les processus de convection sont actifs. Une approche theorique relative a l'utilisation simultanee du tritium et de l'helium-3 est abordee. Elle utilise un modele de melange distinguant, pour une masse d'eau consideree, le temps de transit du temps de ventilation. La validite de "age tritium-helium" est testee par comparaison avec les temps de transit et de ventilation determines par le modele

Une etude de la circulation de maree dans le golfe normand-breton est menee conjointement par un modele numerique bidimensionnel horizontal de maille fine (1 mille nautique) et par des mesures, des courants lagrangiens et euleriens, de longues durees. La confrontation de ces deux methodes d'approche de la circulation a permis de valider les resultats du modele numerique. Ensuite ce dernier a ete utilise pour reproduire la circulation residuelle (circulation a long terme) dans tout le domaine d'etude. Les mecanismes de production de vorticite residuelle ont ete egalement apprehendes

L'objectif de cette these est d'ameliorer notre connaissance des marees dans l'ocean atlantique. Ce travail a ete mene en particulier dans le cadre de la mission satellitale topex/poseidon, l'exploitation des donnees altimetriques necessitant des corrections tres precises de marees. Cette etude repose sur l'utilisation d'un modele hydrodynamique original, formule par le provost en 74. Ce modele est base sur les equations des ondes longues integrees sur la verticale et quasi lineaire. Une methode spectrale permet la decomposition en temps des equations et conduit a resoudre un probleme specifique pour chaque onde du spectre, avec pour inconnue la denivellation de la surface libre. Nous avons applique ce modele sur les deux bassins nord et sud de l'ocean atlantique, a partir de maillages elements finis de tres haute resolution spatiale adaptes a la topographie. Nous avons obtenu des solutions en amplitude et en phase pour les ondes m2, k1 et n2. Ces resultats ont ete valides par une comparaison aux donnees in situ disponibles. Les rms calcules sur l'ensemble des observations pelagiques et de plateaux sont, sur le bassin nord, inferieures a 3 cm. Par contre, sur le bassin sud, la precision est moindre: elle est comprise entre 1 et 7 cm. L'interpretation que nous avons proposee de cette difference entre les precisions des resultats dans les oceans atlantique nord et sud est d'une part l'abondance des donnees d'observations disponibles et utilisees pour l'optimisation des solutions dans l'atlantique nord et par contre notre ignorance de la topographie de la mer de weddell dont nous avons discute l'importance. Une premiere quantification des termes entrant dans le calcul des bilans d'energie a ete realisee a partir de nos solutions

An investigation into the chemistry of four species of marine invertebrates which were found to produce cytotoxic crude extracts (ED50 against the L1210 murine leukemia cell line 5 30 pg/mL) led to the isolation of nine new and eleven previously known secondary metabolites. The structures of the novel compounds were elucidated by a combination of spectroscopic analysis and chemical interconversion. The metabolites were tested against the in vitro L1210 murine leukemia, the drug-sensitive MCF-7, or the drug-resistant MCF-7 Adr breast cancer cell lines. Investigation of the cytotoxic extracts of the marine sponge Aplysilla glacialis led to the identification of the novel 9, 11-secosteroids glaciasterol A (100) and glaciasterol B (101). These compounds are the first examples of secosteroids isolated from a sponge of the genus Aplysilla. Glaciasterol A (100) proved active in vitro against theMCF-7 human breast cancer cell line at an ED50 of 19 pg/mL. The ED50 for Glaciasterol A (100) against the drug-resistant MCF-7 Adr breast cancer cell line was 18 tig/mL. The structures of the glaciasterols were determined by aseries of chemical interconversions in addition to extensive analysis of spectroscopic data. Glaciasterol B diacetate (107) was one of the derivatives synthesized and it proved to be the most active in the cytotoxicity assays.Glaciasterol B diacetate was active against both the MCF-7 and the drug-resistant MCF-7 Adr cell lines with ED50values of 1.8 pg/mL. A study of the metabolites of a gray-white sponge collected off the coast of Vancouver Island yielded the new cytotoxic secosteroid blancasterol (102). Blancasterol (102) was found to be active against the MCF-7 and drug-resistant MCF-7 Adr breast cancer cell lines with ED50 values of 3 g.ig/mL and 10.6 pg/mL, respectively. The new sesquiterpenes 0-methyl 9-oxofurodysinin lactone (72), 2-oxomicrocionin-2 lactone (73), 0-methyl2-oxomicrocionin-2 lactone (74) as well as seven previously reported sesquiterpenes (35, 36, 56, 57, 41, 43, and 44)were also isolated from the sponge extract. An understanding of the secondary metabolism of the invertebrate was useful in identifying the sponge as a Pleraplysilla species, the first found off the west coast of North America. Langarin (142) proved to be the cytotoxic component of the extract of an undescribed species of Aplidium, a compound tunicate found in the waters off the Queen Charlotte Islands. Langarin (142) was active in vitro againstL1210 murine leukemia cells with an ED50 of 0.44g/mL. Examination of extracts of the colonial tunicate Aplidium californicum resulted in the isolation of two new prenylated hydroquinone derivatives (160 and 161) as well as the known compounds 149, 150, 152, and 158. Compound 152 was tested in vitro against the L1210 murine leukemia cell line and found to be cytotoxic with anED50 value of 3.9 pg/mL.

Tese de Doutoramento, Ciências do Mar, especialidade de Recursos Marinhos, 27 de Novembro de 2015, Universidade dos Açores.
A região dos Açores apresenta uma grande diversidade de comunidades faunísticas em ecossistemas marinhos de profundidade, com numa grande variedade de "hotspots" no fundo do mar, tais como montes submarinos, encostas das ilhas e fontes hidrotermais. No entanto, apesar desta enorme biodiversidade, os seus invertebrados marinhos de profundidade nunca foram bio prospectados enquanto produtos naturais marinhos funcionais. Esta tese teve como objectivo fazê-lo. Foram extraídos lípidos de dezanove espécies animais, num total de trinta e seis extractos brutos, subsequentemente testados in vitro como antibacterianos, antimaláricos e anticancerígenos. Da diversidade de animais de profundidade que incluiu corais, esponjas, ouriços e invertebrados das fontes hidrotermais, os resultados revelaram que os extractos apresentam actividade para todos os ensaios biológicos testados, com as esponjas a apresentarem-se como os animais mais úteis como fonte de compostos naturais marinhos anticancerígenos e os corais de água fria, como antimaláricos. Foi usada uma estratégia de fracionamento guiado pela bioactividade, nos extractos dos animais mais activos: as mega-esponjas Petrosia sp. E Leiodermatium sp.. Os esteróis (Petrosterol, Sitosterol e 23, 24-Dihydrocalysterol) foram identificados nas fracções de Petrosia sp. Mais anticancerígenas mas devido a perca de actividade durante a separação dos compostos, não foi possível confirmá-los como principais anticancerígenos presentes. O estudo com a esponja Leiodermatium sp. resultou no isolamento de uma mistura complexa de compostos, demonstrando um potente efeito anticancerígeno (IC75=0,08 μg/ml). Os compostos foram identificados como pertencentes a uma mesma família de macrólidos e foram denominados "azorelides". Foi possível isolar os compostos azorelide A e azorelide B mas a esteroquímica absoluta de ambas as moléculas não foi determinada devido às suas escassas quantidades (1,1 mg de azorelide A/kg e 0,47 mg de azorelide B/kg de esponja Leiodermatium seca).
ABSTRACT: Azores region presents a great diversity of deep-sea ecosystems with faunal communities in a variety of benthic hotspots, as seamounts, islands slopes and hydrothermal vents. Despite its high biodiversity, these deep-sea invertebrates were never bio prospected in regard to their natural products. This thesis aims to do so. Lipids were extracted from nineteen animal species and a total of thirty-six crude extracts were tested in vitro as potential antibacterial, antimalarial and anticancer activities. From a deep-sea diversity of corals, sponges, seaurchins and hydrothermal vents invertebrates, results showed that extracts were active for all tested bioassays, with sponges presenting the best outcomes as anticancer and corals as antimalarial natural product sources. A bioactivity-guided fractionation strategy was used in the most active animal extracts: the mega sponges Petrosia sp. and Leiodermatium. Sterols (Petrosterol, Sitosterol and 23, 24- Dihydrocalysterol) were identified in the most active anticancer fraction from Petrosia sp. but, due to activity lost during compounds isolation, it was not possible to confirm these as the main anticancer compounds present. Study with Leiodermatium sponge extracts lead to isolation of a complex mixture of compounds, showing potent anticancer activities (IC75=0.08 μg/ml). Compounds were identified as belonging to the same macrolide family and were named "azorelides". It was possible to isolate azorelide A and azorelide B, but their absolute stereochemistry was not achieved due to amount scarcity (1.1 mg of azorelide A/kg and 0.47 mg of azorelide B/kg of dry Leiodermatium sponge).
Several projects financed part of laboratory consumables and chemicals products used during this research, namely PTDC/QUI-QUI/119116/2010-"Ocean Treasures", PTDC/MAR/111749/2009-DeepFun; PEst-C/EQB/LA0006/2013, Pest-OE/BIA/UI0457/2011-CREM, FP7/2007-2013 n° PCOFUND-GA-2009-246542 and LA 9-2013-2014-PEST OE/EEI/LA0009/2013, financed by FCT, Ministério da Educação e Ciência, Portugal and FEDER.

Sea turtles have experienced dramatic population declines during the last century as a consequence of direct harvest, by-catch in fisheries, and habitat loss. Despite almost 50 years of partial international protection, several populations of sea turtles are still at imminent risk of extinction. Our knowledge of their complex life histories is still far from complete; these knowledge gaps hinder our ability to provide scientific advice regarding their conservation and management. It is the very complexity of their life histories, which allows them to exploit widely separated habitats during development, often over the course of decades, which makes them inherently difficult to study. I used satellite telemetry (n=60) to investigate the movements and habitat use patterns of juvenile loggerhead (Caretta caretta), green (Chelonia mydas), and Kemp's ridley (Lepidochelys kempii) sea turtles on their summer feeding grounds in North Carolina estuaries. These turtles migrate into and out of the estuarine waters each spring and autumn, encountering a gauntlet of fishing gear on each journey. The by-catch of sea turtles is an important conservation issue in North Carolina, and throughout the world's oceans. I evaluated conservation measures established to reduce the by-catch of sea turtles in Pamlico Sound's autumnal large-mesh gill net fishery for southern flounder (Paralichthys lethostigma), using a spatially explicit predator/prey model. My findings indicated that species-specific habitat preferences contributed to a turtles' risk of encountering fishing gear and that areas of high by-catch are predictable from patterns of overlap between sea turtle habitat use and flounder fishing effort. I then examined how the behavior of green turtles affected their vulnerability to incidental capture in estuarine commercial fisheries. Individual green turtles interact with multiple gears per season as a result of strong site fidelity to habitats also preferred by fishers. Telemetry also allowed me to examine individual variation in movements, habitat use, and site fidelity patterns of juvenile loggerhead turtles, both within the estuary and as the turtles migrated out into the North Atlantic. I used these observations to test the hypothesis of a discrete ontogenetic shift in habitat and diet in juvenile loggerheads. Approximately one-third of large juvenile loggerheads tagged in North Carolina estuaries return to oceanic habitat, sometimes for several years, where they are vulnerable to by-catch in pelagic fisheries. This led me to conclude that the long held notion of a discrete ontogenetic habitat shift between the oceanic and neritic habitat was incorrect for juvenile loggerheads (and possibly also for green turtles). Finally, I explored variation in migratory destinations in these animals through multivariate analyses of carbon and nitrogen stable isotope ratios in blood plasma and red blood cells, and through analysis of sex, genetic, haplotype, body size, and remigration records, and described the trophic niche of these turtles with Bayesian isotope mixing models. Variation in migratory destination (oceanic or neritic habitat) was best described by stable isotope ratios of nitrogen and remigration tendency. Turtles that returned to the open ocean had significantly lower nitrogen ratios than those animals that remained in the neritic zone and their diets retained a substantial contribution of epipelagic prey items. The diet composition of neritic turtles, on the other hand, consisted primarily of estuarine benthic invertebrates during the summertime and autumn foraging season but shifted toward pelagic jellyfish, fish, and Sargassum during the overwintering period. Oceanic turtles likely came from open ocean regions prior to entering the summer foraging grounds while neritic turtles likely overwintered at the edge of the Gulf Stream. The agreement between the dietary compositions and migration patterns between the two groups of turtles suggest that these feeding and habitat use strategies were persistent characteristics in the turtles I sampled. My work has improved our understanding of sea turtle habitats in North Carolina estuaries and identified their migratory destinations and overwintering habitats. I hope that this work lays the groundwork for future studies that will explore how variation in habitat use and feeding strategies are manifested in life history traits that affect fitness directly, such as survivorship, growth rates, stage durations, and fecundity.

Dissertation