Dissertationen: „Marine fishes – North Sea“

1

Leary, Arianne Ella. „Effects of the Deepwater Horizon Oil Spill on Deep Sea Fishes“. UNF Digital Commons, 2015. http://digitalcommons.unf.edu/etd/566.

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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.

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Baudron, Alan Ronan. „Length-based modelling of North Sea fish growth“. Thesis, University of Aberdeen, 2011. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=192287.

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This thesis focuses on the temporal variations in growth affecting commercial species of fish in the North Sea. The aims were firstly to review the modelling tools available to study fish growth in the North Sea, and secondly to investigate the implications of the observed increase in North Sea temperature on the growth of commercial fish species. The von Bertalanffy growth function (VBGF) is a reliable and flexible model to study fish growth and was employed throughout this thesis. The age-length keys (ALKs) used to model fish growth were length-stratified samples and were showed to result in biased VBGF parameter estimates. Thus, ALKs should be corrected by the length frequency observed in the population when possible. A warming trend has been observed in the North Sea over the last decades, with an overall increase of 1 °C in the northern North Sea. These warming temperatures were significantly linked with a decrease in asymptotic length (L∞) and an increase in the rate at which L∞ is reached (K) observed for North Sea haddock (Melanogrammus aeglefinus). Incorporating the temperature covariate into an extended VBGF to model haddock growth allowed quantifying a decrease in weight-at-age up to 40% at age 10 occurring at warmer temperatures, resulting in a 20% loss of individual yield. A meta-analysis was then conducted across North Sea commercial species and confirmed that most species experienced a synchronous decline in L∞, with the exception of cod (Gadus morhua) and sprat (Sprattus sprattus). This strongly suggests that the increase in temperature is the cause of the changes observed in VBGF parameters. Overall, the findings suggest that, in many commercial fish species of the North Sea, the increase in temperature induced a faster growth towards a smaller asymptotic length. This is likely to jeopardize fisheries yields and thus to affect the economic efficiency of North Sea fisheries. The results of this thesis advocate that the effect of temperature on growth is large enough to be incorporated into North Sea fish stock assessment models.

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3

O'Sullivan, Martha. „Population structure of demersal fish species in the north eastern Atlantic“. Thesis, Available from the University of Aberdeen Library and Historic Collections Digital Resources. Restricted: no access until Dec. 31, 2010. Online version available for University members only until June 2, 2011, 2009. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?application=DIGITOOL-3&owner=resourcediscovery&custom_att_2=simple_viewer&pid=26063.

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4

Buch, Tanja B. „Spatial structure of North Sea fishes : theory and application to abundance estimation“. Thesis, University of Aberdeen, 2018. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=237000.

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5

Kerby, Tina. „UK fisheries, climate change and North Sea fishes : a long-term perspective“. Thesis, University of East Anglia, 2013. https://ueaeprints.uea.ac.uk/47987/.

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North Sea demersal fishes and fisheries have changed over the past 100 years. To detect the main factors driving these changes, long-term data are needed. Using historical fisheries data that extend throughout the 20th century, this thesis aims to assess drivers influencing developments in fisheries as well as changes in the distribution and abundance of commercially important fishes in the North Sea. For English demersal fisheries, favourable political, technological and economical drivers were identified, inducing a vast rise in English fisheries in the first half of the 20th century; however, the same drivers, acting adversely, influenced the decline in recent decades and the emphasis of fisheries shifted from England to Scotland. Different trends in distribution were observed for North Sea whiting, turbot and brill between the 1920s and 2000s. Whiting distribution shifted westward between the late 1940s and1960s, whereas turbot nearly disappeared from the northern North Sea from the 1970s onwards. Brill distribution remained rather stable in the central and southern North Sea. The reasons for the longitudinal shift of whiting remained unclear as the relationships to two potential drivers, climate change and fishing pressure, were not strong. For turbot, the cause for the near disappearance from the northern North Sea is inconclusive. Commercial fisheries data were assessed reliable for distribution analysis when comparing commercial data of whiting, a commonly discarded species, and unbiased survey data. Whiting, compared to flatfish, is of secondary commercial importance. In areas where discrepancies occurred between commercial and survey data, higher discarding of whiting is suggested, as highly priced flatfish are caught there. This thesis demonstrates past conditions of demersal fish populations and fisheries in the North Sea and presents the effects of different drivers on them. The documented changes in fishes and fisheries contain valuable information for resetting baselines and developing appropriate management strategies.

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Martínez, Iñigo. „Demersal fish assemblages around sea bed features : Buzzard oil & gas field platform in the North Sea and Jones Bank, Celtic Sea“. Thesis, University of Aberdeen, 2011. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=183828.

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The maximum number (Nmax) of fish was recorded using baited underwater camera (BUC) techniques to study spatio-temporal changes of the fish community in localize areas. In the central North Sea (~100m depth) abundance models revealed that for both, whiting and flatfish, the Nmax was influenced by light level at the time of deployment. Nmax of hagfish was strongly related to current speed in a non-linear way with a predicted upper threshold (~11 cm.s-1) above which Nmax declined. Current speed and inter-annual variation had an important effect on haddock Nmax. Large predators that prompt avoidance mechanisms (e.g. large conger eel, marine mammals and fishing vessels) and bottom current speed >25 cm.s-1 can modify demersal fish behaviour depending on size and species and therefore have important effects on BUC-derived data. The BUC was applied for the first time to the monitoring of the Buzzard platform, a new oil and gas development in the central North Sea that host 12 demersal and benthic fish species. The benthic taxa, flatfish and hagfish, showed higher numbers closer to the platform whilst the most mobile species showed constant numbers (haddock) or highest numbers outside of the 500m of Exclusion Area (whiting). No significant changes in fish diversity were found between the areas surveyed before the platform construction. After the construction, the species richness and diversity were higher outside the 500m Exclusion Area surrounding the platform. Offshore sand banks, like oil platforms, can modify the composition of the local fish abundance. BUC and commercial trawl observations on the Jones Bank (75-150m depth, Celtic Sea) recorded 23 species, the highest richness, on top of the bank and 18 species on the slope and off-bank areas. Conger eel and Nephrops were both absent from the top of the bank site whereas haddock was only observed in the bank area.

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7

Mair, Angus. „Investigation into a prominent 38 kHz scattering layer in the North Sea /“. St Andrews, 2008. http://hdl.handle.net/10023/490.

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8

Casazza, Tara L. „Community structure and diets of fishes associated with pelagic Sargassum and open-water habitats off North Carolina“. View electronic thesis, 2008. http://dl.uncw.edu/etd/2008-3/casazzat/taracasazza.pdf.

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9

Cheung, Wai Lung. „Vulnerability of marine fishes to fishing : from global overview to the northern South China Sea“. Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/31272.

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Fishing has become a major conservation threat to marine fishes. Effective conservation of threatened species requires timely conservation risk assessment and formulation of socio-economically viable policies. A fuzzy logic expert system is developed to predict the intrinsic vulnerability and depletion risk of marine fishes to fishing. Firstly, the expert system predicts intrinsic vulnerability (i.e., fishes' inherent ability to withstand fishing mortality) from simple parameters of life history and ecology. Secondly, the system predicts the relative depletion risk of marine fishes from their intrinsic vulnerability and exploitation status inferred from catch time-series. These methods reveal the increasing dominance in global catches by fishes with low intrinsic vulnerability, particularly those in coral reefs. The opposite trend is observed in seamounts where species are highly vulnerable to fishing and are increasingly being exploited and serially depleted in recent years. Moreover, risk of population depletion increased greatly from the 1970s to 2000s. Among all extant marine fishes, 10 to 20% are predicted to have high depletion risk. In the northern South China Sea (NSCS), relative abundance of 15 out of the 17 studied taxa declines by over 70% in 15 years. The rate of decline is con-elated with the intrinsic vulnerability of the taxa. Using the Ecopath with Ecosim modelling approach, the structures of the NSCS ecosystem in the 1970s and 2000s are reconstructed and compared. The models show that the NSCS ecosystem has chanced from being demersal-dominated to pelagic-dominated, with a large decline in overall biomass and decrease in ecosystem maturity. Primary production is largely utilized by the fisheries compared to some 30 years ago when primary production was mainly utilized by marine fauna. The model is able to emulate the changes of observed relative abundance of commercial taxa. Using Ecosim, trade-off between conservation status (indicated by a depletion index) and economic benefits is identified as convex-shaped. The 2000s ecosystem appears sub-optimal ecologically and economically, thus improvement in conservation and economic benefits can be achieved simultaneously. However, the resulting social problems due to loss of fishing-related jobs need to be addressed first. Thus, developing viable alternative livelihoods for fishers is a priority to meet conservation and economic objectives.
Science, Faculty of
Resources, Environment and Sustainability (IRES), Institute for
Graduate

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Allsop, Timothy. „Early compaction history of marine siliciclastic sediments“. Thesis, Durham University, 1994. http://etheses.dur.ac.uk/5675/.

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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.

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Speckman, Suzann Gail. „Characterizing fish schools in relation to the marine environment and their use by seabirds in lower Cook Inlet, Alaska /“. Thesis, Connect to this title online; UW restricted, 2004. http://hdl.handle.net/1773/5301.

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12

Aboim, Maria Ana. „Population genetics and evolutionary history of some deep-sea demersal fishes from the Azores, North Atlantic“. Thesis, University of Southampton, 2005. https://eprints.soton.ac.uk/17742/.

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MtDNA sequences and microsatellite loci were used as independent molecular markers to reveal the genetic population structure in three deep-sea demersal fish species from the North Atlantic. In the Azores archipelago, the demersal fishery is the second most important after tuna and Helicolenus dactylopterus, Beryx splendens and Beryx decadactylus are among the most captured species. Partial sequences for the mitochondrial control region and cytochrome b gene were obtained for the three species using universal primers. The diversity encountered for these markers is consistent with diversity found on other marine fishes, except for B.decadactylus in which the d-loop and cyt b diversity was lower than expected. Haplotype data indicated a strong genetic differentiation between Helicolenus dactylopterus NW, Cape Verde and NE Atlantic populations suggesting long distance colonisation processes by jump dispersal events along major oceanic currents. Eight microsatellite loci were developed for H.dactylopterus in order to resolve population structure at a finer intraregional scale (within Portuguese waters). Significant deviations from allelic frequencies expected under Hardy-Weinberg equilibrium were detected at several loci. Analysis of FIS revealed significant differences from zero as a result of heterozygote deficiency. Estimates of FST, RST and AMOVA were also significant, suggesting that the population structure of this species within Portuguese waters was not homogeneous. Pairwise comparisons of FST, RST and genetic distances (DSW and (s)2) between populations revealed a significant separation of the Azores and Peniche (continental Portugal) populations as well as a moderate differentiation among subpopulations of the Azores archipelago. Beryx splendens and Beryx decadactylus are two congeneric species with many similarities in known biology. Analysis of haplotype data revealed striking differences in structure and history of the populations of these two species. MtDNA sequences confirmed that Beryx splendens is constituted by one panmitic population within the Northeast Atlantic as has been previously hypothesised by other authors. Surprisingly, indices of genetic diversity were lower in the closely-related B.decadactylus and there was a strong genetic differentiation between Cape Verde and the rest of the NE Atlantic populations when analysed for the same molecular markers. Differences found are discussed based on the limited knowledge of these species especially with respect to lifehistory. Population structure results are discussed in relation to historical and on-going hydrogeographic events. Evidence for the strong influence of several events previous to the last glacial maximum (LGM) on the population demographic history and evolution of deep-sea demersal fish species in the North Atlantic was found.

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13

Ingram, Caroline S. „Ostracod palaeoecology and biogeochemistry of marine and estuarine interglacial deposits in North West Europe“. Thesis, Bangor University, 1999. https://research.bangor.ac.uk/portal/en/theses/ostracod-palaeoecology-and-biogeochemistry-of-marine-and-estuarine-interglacial-deposits-in-north-west-europe(4cd7fd25-815b-4e1d-aebb-cada60a3d9b4).html.

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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.

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Gypens, Nathalie. „Modélisation des efflorescences algales et des cycles du C, N, P et Si dans l'écosystème eutrophisé de la mer du Nord“. Doctoral thesis, Universite Libre de Bruxelles, 2006. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210778.

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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

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Fraser, Helen M. „Do fish predators in the North Sea live beyond their means is prey production sufficient to meet consumption? /“. Thesis, Available from the University of Aberdeen Library and Historic Collections Digital Resources, 2008. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?application=DIGITOOL-3&owner=resourcediscovery&custom_att_2=simple_viewer&pid=24693.

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Schneider, von Deimling Jens [Verfasser]. „Hydroacoustic and geochemical traces of marine gas seepage in the North Sea / Jens Schneider von Deimling“. Kiel : Universitätsbibliothek Kiel, 2010. http://d-nb.info/1019951257/34.

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17

Brewster, Jasmine Dawn. „Characterizing the diet and habitat niches of coastal fish populations in the Beaufort Sea Tarium Niryutait Marine Protected Area“. Marine Ecological Progress Series, 2016. http://hdl.handle.net/1993/31961.

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To evaluate the niche of coastal fish populations in the Beaufort Sea, stable isotopes (SI) and fatty acids (FA) were used to characterize species-specific niches, niche overlaps and resource partitioning (nicheROVER) of the Shingle Point fish populations. Fishes were grouped into three isotopic groups: marine, coastal, and freshwater (Ward’s clustering analysis), and five dietary groupings (using FA), where benthic feeding strategies were prevalent (correspondence analysis). Niche metrics were used to evaluate if total mercury (THg) could contribute complementary trophic information (residual permutation procedure (RPP)). Three THg groups (high, intermediate, low) were identified (boxplot analysis). High THg was identified in high trophic and benthic feeders, high THg ranges were observed in species with large niche sizes, high trophic feeding, and freshwater influences (RPP). The bioavailability of freshwater introduced THg to marine biota was assessed, however further research needs to be performed. Combining dietary indicators SI, FA, and THg, allowed for the characterization of the diet and habitat use of coastal fish populations, better understanding of the niches of these species, and developed baseline information for future monitoring in an MPA, as climate change continues to effect the Beaufort coastal environment.
February 2017

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Ali, Heba. „THE EFFECT OF DEPTH ON DEVELOPMENT AND SEXUAL DIMORPHISM OF THE SONIC SYSTEM IN DEEP SEA NEOBYTHITINE FISHES: THE UPPER CONTINENTAL SLOPE“. VCU Scholars Compass, 2016. http://scholarscompass.vcu.edu/etd/4095.

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Abstract Background: Cusk-eels from the subfamily Neobythiitinae are one of the major groups of sound-producing fishes on the continental slope. Sounds have never been recorded from a member of this subfamily, and sonic anatomy is considered a proxy for sound production. As the first part of a study on the effects of depth on sonic anatomy, we examined three relatively shallow species from the upper continental slope. Methods: Three species (Hoplobrotula armata, Neobythites longipes and Neobythites unimaculatus) were examined for sonic anatomy (skeleton, swimbladder and sonic muscles), and sonic and epaxial muscle fibers were measured for diameter. Regressions of dimensions and weights of sonic muscles and swimbladders against fish total length and weight were compared to determine sexual dimorphism and relative development between species. Results: Four pairs of sonic muscles (two medial and two lateral) originate on the skull and insert on the medial swimbladder or on modified epineural ribs that attach to the lateral swimbladder. The medial and medial intermediate muscles are generally larger in males than females and are made of relatively small fibers (ca 10 um in diameter), and lateral muscles are generally larger in females and consist of larger fibers as in epaxial muscles. Medial muscles are considerably larger in Hoplobrotula armata than in the Neobythites species. Conclusion: Neobythitines from the upper slope have relatively well-developed sexually-dimorphic sonic systems, suggesting that males produce advertisement calls for courtship. There are major quantitative differences between species. We suggest that sound production involves tonic contraction of the large-fibered lateral muscle pair and oscillatory contractions of the smaller medial fibers setting the swimbladder into vibration. Hoplobrotula armata is probably capable of making more intense sounds than the Neobythies spp.

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Roncari, Chiara. „Evaluation of microplastic content in faecal sample from hospitalized loggerhead sea turtles (Caretta caretta) of the North Adriatic Sea“. Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/20386/.

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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.

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Tonino, Marco <1982&gt. „Transboundary governance of marine protected areas : a comparison of the North Adriatic and Wadden Sea case studies“. Doctoral thesis, Università Ca' Foscari Venezia, 2014. http://hdl.handle.net/10579/4672.

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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.

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Weissbach, Astrid, Urban Tillmann und Catherine Legrand. „Allelopathic potential of the dinoflagellate Alexandrium tamarense on marine microbial communities“. Linnéuniversitetet, Institutionen för naturvetenskap, NV, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-7332.

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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

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Colhoun, Elizabeth F. „Ecological Correlates of Community Structure in Seagrass-Associated Fishes in North Biscayne Bay and Port of Miami, Florida“. Thesis, NSUWorks, 2018. https://nsuworks.nova.edu/occ_stuetd/466.

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Seagrass habitats are critical habitat for many fish species and are currently threatened by anthropogenic and natural factors, such as coastal development, pollution, global climate change, and sea level rise. There are few studies that have tracked long- term changes in seagrass habitat and their associated fish communities. This project addressed this need using data collected by the United States Geological Survey (USGS) from two South Florida sites, North Biscayne Bay, FL (NBB) and Port of Miami, FL (POM). The USGS sampling was part of ongoing monitoring projects designed to assist future management decisions that would enhance the protection of these valuable habitats. Data were collected biannually at the conclusion of the dry (April) and wet (September) seasons from 30 cells at each site. In each cell, the data collected included: six replicates for seagrass species and cover, five sweep net collections for fish species and abundance, as well as abiotic variables (water temperature, salinity, turbidity, water depth, and sediment depth). A distinct loss in fish and seagrass species were observed, particularly between the years of 2011-2014. These years coincided with several events including: the Port Miami Deep Dredge (PMDD) project during the years 2013-2015; periods of drought; and major storm events. Changes in fish community structure over this time period were largely driven by loss of species and increased homogenization of fish communities at both locations. More specifically, the NBB community shifted to resemble that of POM by 2014. These changes mirrored the loss of seagrass cover at both locations. Further studies are required to assess the extent to which ongoing dredging activities and other factors might be affecting seagrass cover, which ultimately affect fish communities.

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Carew, Andrea M. E. „Oil pollution and the Newfoundland and Labrador fishery : current and potential threats for the conservation of commercial fisheries resources in Placentia Bay /“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ62375.pdf.

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Marshall, A. M. „Understanding shifts in body size distributions : a comparative study of the impacts of fishing and climate on North Sea demersal fishes“. Thesis, University of Sheffield, 2017. http://etheses.whiterose.ac.uk/18955/.

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The North Sea is a huge economic resource for millions of people and is undergoing dramatic changes due to overfishing and climate change. The extent to which fishing and climate are causing changes in the North Sea demersal fish community status and ecosystem health is difficult to quantify. This thesis implements newly combined empirical methods and adaptive modelling techniques in an attempt address this area of uncertainty. The first study develops a statistical framework for understanding variations in size-based indicators (SBIs), metrics for describing ecosystem health, across space and time simultaneously, as well as finding the most likely driver of observed changes. SBIs declined in the central North Sea due to fishing, but increased in the Norwegian trench region due to changing sea bottom temperature. This highlights the need to consider environmental and fishing impacts on the change in body size distribution of fish communities. The remainder of the thesis improves an existing multispecies, size-structured model by incorporating empirical relationships between growth and temperature and oxygen. Including temperature or temperature and oxygen leads to a smaller body size distribution under warmer, deoxygenated waters. When oxygen alone is included no significant effects on either the individual size or the community size structure are found. The temperature-oxygen size-structured model is subsequently used alongside extracted environmental data from two global climate models (GCMs) to project a number of size-based indicators for 2100. The most striking result is the huge difference in size-based indicators depending on which GCM is used. Corrections to the GCMs must therefore be made before the use in ecological projections. The common result, however, is that temperature and oxygen will cause changes in the body size distribution. Although these effects are much smaller than fishing effects, they demonstrate that ignoring impacts of climate change could cause considerable overestimates in the biomass of North Sea demersal fish.

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Ilyina, Tatjana P. „The fate of persistent organic pollutants in the North Sea : multiple year model simulations of [gamma]-HCH, [alpha]-HCH and PCB 153 /“. Berlin [u.a.] : Springer, 2007. http://www.loc.gov/catdir/toc/fy0710/2006939205.html.

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Phoel, William C. „Community structure of demersal fishes on the inshore U.S. Atlantic continental shelf: Cape Ann, MA. to Cape Fear, N.C. (United States, cluster analysis, Massachusetts, North Carolina)“. W&M ScholarWorks, 1985. https://scholarworks.wm.edu/etd/1539616807.

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Numerical classification analyses (clustering) of spring, summer and fall National Marine Fisheries Service bottom trawl catches on the inshore continental shelf between Cape Ann, Ma. and Cape Fear, N.C., showed consistent species associations and faunal zones over a three year period. Analysis of a data set created by combining all nine survey cruises also produced consistent species associations, however sites clustered by seasons as well as by geographic area. The three faunal provinces of the U.S. east coast (Gulf of Maine, Middle Atlantic Bight and South Atlantic Bight) were represented in the study area, as were the seasonal faunal barriers at Nantucket Shoals and Cape Hatteras. Generally, the faunal zones correlated well with the thermal regimes of each province and respected the faunal barriers when strong thermal gradients were present. Only south of Cape Hatteras did depth appear to define a boundary between faunal zones. During the spring, when bottom water temperatures were lowest, four species associations and three faunal zones were identified. The species associations consisted of a cold water boreal group (affiliated only with the faunal zone between Cape Ann and Cape May, N.J.), a less cryophilic boreal group, a eurythermal warm temperate group and a warm temperate group which was restricted to waters south of Cape Hatteras. With vernal warming, a northerly and onshore migration of warm temperate species increased to five the number of species associations in summer. Beside the four groups found in spring, a more thermophilic association was identified. Separations between the northern three summer faunal zones occurred at Nantucket Shoals and northern New Jersey. The other two summer zones were restricted to south of Cape Hatteras and were separated longitudinally (inshore and offshore). In fall, when bottom temperatures were highest, a sixth species group of primarily southern species was identified. This group appeared restricted to the inshore faunal zone south of Cape Hatteras. The five faunal zones recognized in summer were also identified in fall.

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Gebühr, Christina [Verfasser]. „Investigations on the ecology of the marine centric diatom Paralia sulcata at Helgoland Roads, North Sea, Germany / Christina Gebühr“. Bremen : IRC-Library, Information Resource Center der Jacobs University Bremen, 2012. http://d-nb.info/1037011295/34.

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Guerin, Andrew James. „Marine communities of North Sea offshore platforms, and the use of stable isotopes to explore artificial reef food webs“. Thesis, University of Southampton, 2009. https://eprints.soton.ac.uk/168947/.

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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.

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Holgate, Nicholas. „Geological characterisation of shallow marine-to-deltaic sandstone reservoir targets, Krossfjord and Fensfjord formations, Troll Field, Norwegian North Sea“. Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/32135.

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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.

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Norris, Joel R. „Interannual variability in cloudiness, sea surface temperature, and atmospheric circulation over the midlatitude North Pacific during summer“. Thesis, Connect to this title online; UW restricted, 1997. http://hdl.handle.net/1773/10050.

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Danis, Bruno. „Bioaccumulation and effects of polychlorinated biphenyls (PCBs) in the sea star Asterias rubens L“. Doctoral thesis, Universite Libre de Bruxelles, 2004. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/211171.

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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

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Chiti, Bernardo. „Holocene fluvial and marine influences and settlement interactions in the lower Ribble Valley, Lancashire, U.K“. Thesis, University of Stirling, 2004. http://hdl.handle.net/1893/1805.

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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.

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Keeble, Kathryn. „Common drivers and indicators of large-scale changes in the community structure and function of three UK marine ecosystems : the Irish Sea, North Sea and Western English Channel“. Thesis, University of Newcastle Upon Tyne, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.577148.

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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.

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Fortuna, Caterina Maria. „Ecology and conservation of bottlenose dolphins (Tursiops truncatus) in the north-eastern Adriatic Sea“. Thesis, St Andrews, 2007. http://hdl.handle.net/10023/157.

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Nooner, Scott L. „Gravity changes associated with underground injections of CO₂ at the Sleipner storage reservoir in the North Sea, and other marine geodetic studies /“. Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2005. http://wwwlib.umi.com/cr/ucsd/fullcit?p3171110.

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Bos, Ryan P. „The Association between Stomach Fullness and Vertical Migration Behavior in Deep-Pelagic Crustaceans and Fishes in the Gulf of Mexico, with Notes on Microplastic Ingestion“. Thesis, NSUWorks, 2019. https://nsuworks.nova.edu/occ_stuetd/502.

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This thesis presents: 1) the first statistically rigorous support for the longstanding hypothesis that state of satiation modifies diel vertical migration patterns of deep-sea micronektonic crustaceans and fishes; and, 2) the first assessment of microplastic ingestion by deep-pelagic micronekton in the Gulf of Mexico and Straits of Florida. Deep-sea pelagic crustaceans and fishes significantly contribute to abundance and biomass of pelagic ecosystems, are frequently consumed by commercially valuable fishery species, and serve to transport both nutrients and pollutants between shallow and deep waters. The results presented herein will be valuable for assessing risk associated with potential biomagnification of plastic through consumption or indirect consumption of deep-sea biota. Moreover, these data demonstrate that the extent of feeding at depth by non-migratory taxa as well as non-migrating individuals of migratory taxa is substantial. Feeding at depth is usually excluded from biogeochemical models, and these data demonstrate that this is an important factor that must be included to obtain more precise estimates of active nutrient flux by micronekton.

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Barbas, Ruthie E. „Tests of Reproductive Isolation Between the Fishes Fundulus heteroclitus and F. grandis“. UNF Digital Commons, 2016. http://digitalcommons.unf.edu/etd/624.

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The closely related killifishes Fundulus heteroclitus and F. grandis hybridize in a small region where their ranges overlap in coastal northeastern Florida. Hybrids of these species are rare in frequency within the contact zone, suggesting the presence of relatively strong reproductive isolation between these species. The objective of this study was to elucidate barriers to reproduction between F. heteroclitus and F. grandis in the lab, as well as to quantify the relative strengths and contributions of various isolating barriers. Pre-zygotic (mating and fertilization) and post-zygotic (hatching) barriers were investigated by performing a variety of choice and no-choice laboratory mating experiments. The results revealed that under no-choice conditions, barriers to mating had the biggest influence on hybrid production in F. grandis, whereas hatching barriers contributed to the majority of reproductive isolation in F. heteroclitus. However, under choice conditions pre-zygotic barriers had the greatest influence on both species’ ability to produce hybrids. The total relative reproductive isolation that was observed in females of each species was stronger in F. heteroclitus than in F. grandis overall, and was nearly complete in F. heteroclitus females under choice conditions while moderate in F. grandis females. These results reveal an asymmetry in the potential gene flow between these two species, with F. grandis being more likely to hybridize than F. heteroclitus in the absence of environmental influences.

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Simmons, Kayelyn Regina. „Evidence of the Enemy Release Hypothesis: Parasites of the Lionfish Complex (Pterios volitans and P. miles) in the Western North Atlantic, Gulf of Mexico, and Caribbean Sea“. NSUWorks, 2014. http://nsuworks.nova.edu/occ_stuetd/2.

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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.

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Wilson, Sarah Jane. „High resolution comparative palynostratigraphy and palaeoecology of oligocene sequences in the terrestrial basins of the Western British Isles and the marine North Sea basin“. Thesis, University of Sheffield, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.527316.

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Ray, Kacy Lyn. „Factors affecting Wilson's Plover (Charadrius wilsonia) demography and habitat use at Onslow Beach, Marine Corps Base Camp Lejeune, North Carolina“. Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/30996.

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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

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Colmenero, Ginés Ana Isabel. „Towards biological and ecological knowledge of Lophius spp. in the NW Mediterranean Sea for a sustainable fishery“. Doctoral thesis, Universitat de Barcelona, 2017. http://hdl.handle.net/10803/462032.

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In the northwestern Mediterranean Sea, anglerfishes Lophius budegassa Spinola, 1807 and Lophius piscatorius Linnaeus, 1758 are among the most valuable demersal species and support an important fishery. Both anglerfishes are mainly caught in mixed bottom trawl fisheries operating in the continental shelf and upper slope. Their landings, which are primarily composed of L. budegassa (86%) and a small percentage of L. piscatorius (14%), have increased lately with the development of directed fisheries reaching 9,486 t with a value of 65 million of Euros over the period 2000-2016. Up to date, European Commission has been conducted stock assessment for L. budegassa inhabiting Mediterranean waters but no effort has been made to assess L. piscatorius. Due to the commercial importance of both Lophius species, the aim of this Thesis is to improve the knowledge of the population parameters of L. budegassa and L. piscatorius of the northwestern Mediterranean Sea in order to determine the state of exploitation of both species and establish an effectively management. To achieve this aim, a set of specific objectives are addressed: to determine the behavioural activity and sensory mechanisms for reducing the levels of their ecological competition; to describe the reproductive parameters for a better understanding of the life cycle of both Lophius spp.; to examine morphological characteristics of ova in the two species of Lophius for aid in identification of eggs from ichthyoplankton samples; to provide new data on population dynamics as well as on population structure and biometric relationships for modelling the stock of both Lophius spp.; to explore the sustainability indicators for monitoring the state of Lophius population relative to exploitation; and to analyse the prevalence of the microsporidian parasite Spraguea lophii for hypothesize about the health status of the population of Lophius spp. and the possible side effects of severe infections on their morphology. The results demonstrate that although L. budegassa and L. piscatorius occupy the same habitat in the northwestern Mediterranean Sea, differences noted in their life history traits support the hypothesis that both species of Lophius have different ecological strategies in order to lessen competition between them. According to the differences found in the life history traits for both species, it is highly recommended to carry out a differentiated management for each Lophius species in the northwestern Mediterranean Sea. In conclusion, this Thesis improves the current understanding of the biology and ecology of L. budegassa and L. piscatorius; and it is the first study to provide information on the reproductive strategy of L. piscatorius in the northwestern Mediterranean Sea; contributing to increase the scientific knowledge of both Lophius spp. which will be useful to improve future stock assessments and ensure proper management actions.
En el noroeste del mar Mediterráneo, las especies de rape Lophius budegassa Spinola, 1807 y Lophius piscatorius Linnaeus, 1758 se encuentran entre las especies demersales más valiosas sobre las cuales se efectúa una actividad pesquera importante. Ambas especies son capturadas generalmente en pesquerías mixtas de arrastre de fondo que operan en la plataforma continental y en el talud superior. Las descargas se componen principalmente de L. budegassa (86%) y un pequeño porcentaje de L. piscatorius (14%), y han aumentado en los últimos años debido al desarrollo de una pesca más dirigida, alcanzando 9,486 t y un valor de 65 millones de euros durante el período 2000-2016. Hasta la fecha, la Comisión Europea ha realizado evaluaciones de las poblaciones de L. budegassa que habitan las aguas del Mediterráneo, pero no se ha hecho ningún esfuerzo respecto a L. piscatorius. Atendiendo a la importancia comercial de estas especies, el objetivo de esta Tesis ha sido mejorar el conocimiento de los parámetros de la población de L. budegassa y L. piscatorius del noroeste del Mar Mediterráneo para determinar su estado de explotación y establecer una gestión efectiva. Para alcanzar dicho objetivo, se plantearon un conjunto de objetivos específicos: determinar su comportamiento y los mecanismos sensoriales para reducir los niveles de competencia ecológica; describir los parámetros reproductores para mejorar la comprensión del ciclo de vida; examinar las características morfológicas de los óvulos para identificar los huevos a partir de muestras de ictioplancton; proporcionar nuevos datos sobre la dinámica de la población, así como sobre la su estructura y las relaciones biométricas para modelar los stocks; explorar los indicadores de sostenibilidad para monitorear el estado de la población en relación con la explotación; y analizar la prevalencia del parásito microspordio Spraguea lophii para formular hipótesis sobre el estado de salud de la población de Lophius y los posibles efectos secundarios de infecciones graves en su morfología. Los resultados han demostrado que L. budegassa y L. piscatorius ocupan el mismo hábitat en el noroeste del Mediterráneo, si bien las diferencias observadas en sus parámetros del ciclo de vida apoyan la hipótesis de que ambas especies tienen diferentes estrategias ecológicas para disminuir la competencia entre ellas. De acuerdo con las diferencias encontradas, se recomienda realizar una gestión diferenciada para cada especie de Lophius en el noroeste del Mar Mediterráneo.

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McArthur, Adam D. „Temporal and spatial relationships of syn-rift, deep-marine hangingwall stratigraphy : examples from the Upper Jurassic of the Inner Moray Firth and the Central North Sea“. Thesis, University of Aberdeen, 2012. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=191932.

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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.

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Wise, Matthew Geoffrey. „Iceberg-keel ploughmarks on the seafloor of Antarctic continental shelves and the North Falkland Basin : implications for palaeo-glaciology“. Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/276147.

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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.

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Cox, Tom, Tom Maris, Karline Soetart, Daniel Conley, Damme Stefan van, Patrick Meire, Jack J. Middelburg, Matthijs Vos und Eric Struyf. „A macro-tidal freshwater ecosystem recovering from hypereutrophication : the Schelde lease study“. Universität Potsdam, 2009. http://opus.kobv.de/ubp/volltexte/2010/4518/.

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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.

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Astoreca, Rosa. „Study and application of the Inherent Optical Properties of coastal waters from the Phaeocystis-dominated Sounthern Bight of the North Sea“. Doctoral thesis, Universite Libre de Bruxelles, 2007. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210646.

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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

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Meynier, Laureline. „Feeding ecology of the New Zealand sea lion (Phocarctos hookeri) : a thesis presented in partial fulfilment of the requirements for the degree of Doctor Philosophy in Zoology at Massey University, Palmerston North, New Zealand“. Massey University, 2009. http://hdl.handle.net/10179/901.

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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.

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Moulins, Aurélie. „To the integrated approach and to the management of pelagic biodiversity inside a marine protected area : case of the cetacean populations in the Pelagos sanctuary (north-western Mediterranean sea)“. Lyon 1, 2008. http://www.theses.fr/2008LYO10027.

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Virgili, Auriane. „Modelling distributions of rare marine species : the deep-diving cetaceans“. Thesis, La Rochelle, 2018. http://www.theses.fr/2018LAROS003/document.

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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

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Alappat, Linto [Verfasser]. „Application of OSL dating on coastal sediments : case studies from shallow marine sediments of Southern North Sea, Germany, and coastal sub-surface and surface sediments from south India / Linto Alappat“. Berlin : Freie Universität Berlin, 2011. http://d-nb.info/1025938771/34.

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Hammill, Allison L. „Effects of Localized NAO, ONI (ENSO) and AMO Events on Reproductive Patterns in Loggerhead (Caretta caretta) Sea Turtles in Broward County, FL, USA“. NSUWorks, 2013. http://nsuworks.nova.edu/occ_stuetd/135.

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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.

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Dissertationen zum Thema „Marine fishes – North Sea“

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