Thesis (Ph.D.)--Murdoch University, 2004. / Thesis submitted to the Division of Science and Engineering. Bibliography: leaves 199-219.

The world has never been more connected than it is today. While this is true for people, it is also true for Earth's flora and fauna. Unfortunately, this connectedness has contributed to unprecedented invasive species introductions around the world. Most introductions result in an introduced species dying out in the newly invaded territory and never becoming established. Other introduced species establish and persist for years, but never have a noticeable effect on local ecosystems. However, occasionally, an invasive species gets introduced to a new area and has negative impacts on native plant and animal life. The Indo-Pacific swimming crab, Charybdis hellerii, was introduced to the southern Indian River Lagoon (IRL) in the 1990s. Recently, it has been reported to be expanding its non-native range northward up the IRL and into more northerly east coast states. To better understand the ecological role C. hellerii fills in the lagoon and the threat it poses to the economically important and native Callinectes sapidus, this study utilized stable isotope analysis to assess dietary overlap and competition between these species. The results of this study indicate significant overlap in dietary resource usage suggesting C. hellerii is likely feeding on some of the same prey items and competing with native C. sapidus. Based on the increasing numbers of C. hellerii and their reported range expansion, they appear to be establishing populations in the U.S. and will continue to compete with C. sapidus. This could negatively impact C. sapidus populations in the IRL, which is bad for the crab, bad for the fishery, and bad for the lagoon. Further, competition in the IRL is concerning for the rest of the southeastern U.S. states that appear to be in the early stages of a C. hellerii invasion. The findings of this study illuminate the need for further research into the ecological niche C. hellerii is filling in the IRL and the interactions it is having with, as well as the effects it is having on, native species in the lagoon. This study and future research will allow fisheries managers to devise more effective strategies to limit the spread of C. hellerii and minimize the harm it can do in non-native environments.

O presente estudo teve como objetivo desenvolver uma nova proposta de uso de um biomonitor na identificação de fontes emissoras de metais no meio ambiente. Foi selecionada a espécie de siri Callinectes danae como biomonitor e o estuário de Santos como área de estudo. Numa primeira etapa e considerando que o siri é um organismo bentônico, foi realizada uma avaliação preliminar do teor de metais no sedimento do estuário. Em seguida, foi realizada uma avaliação preliminar do teor de metais nos diferentes tecidos de indivíduos coletados na região (brânquias, hepatopâncreas e músculos). Baseado nos experimentos anteriores, foi proposto um modelo de distribuição dos metais entre os tecidos e destes em relação aos sedimentos. A validação deste modelo de distribuição (assinatura química) foi realizada por meio de um conjunto de procedimentos que visaram testar: 1) a robustez em função do tempo; 2) a especificidade para a região de estudo; 3) a sensibilidade às alterações dos níveis de metais em cada tecido. A partir deste modelo, foram identificados indícios para atribuição de fontes emissoras de metais. Desta forma, concluiu-se que, para a região do estuário de Santos, o siri da espécie C. danae pode ser utilizado como um biomonitor. O modelo proposto foi eficaz, uma vez que foi capaz de responder de forma conclusiva-positiva a todos os testes realizados na sua validação, confirmando esta espécie como um biomonitor definitivo para região. A robustez do modelo irá aumentar com novas coletas e a realimentação do banco de dados. / This study aimed to develop a new methodology for the use of a biomonitor in the identification of metal discharges in environmental evaluations. Crabs of Callinectes danae species were used in an evaluation conducted in the Santos Estuarine System. In the first experiment and since C. danae is a benthic species, a preliminary assessment of the metal concentrations in sediment samples collected in the Santos Estuarine System was performed. Subsequently, a preliminary assessment of metal concentrations in the C. danae tissues was also peformed. The last experiment aimed to identify a chemical fingerprint for the Santos Estuarine System.The development of validation procedures for this model (chemical fingerprint) was conducted and aimed to test: 1) the stability of this model through time; 2) its local specificity for the Santos Estuarine System; 3) the sensibility of this model due to modifications in the metal concentrations in each tissue (gills, hepatopancreas and muscles). By the use of this model, it was possible to identify the sources of metal emissions. According to the results, C. danae can be used as a biomonitor for the Santos Estuarine System. The established model was able to responde in a positive-conclusive way to all the tests performed in its validation, confirming this species as a definitive biomonitor for this area. Thus, the stability of this model will increase with new sampling campaings and consequently introduction of new information in the database.

O presente estudo teve como objetivo desenvolver uma nova proposta de uso de um biomonitor na identificação de fontes emissoras de metais no meio ambiente. Foi selecionada a espécie de siri Callinectes danae como biomonitor e o estuário de Santos como área de estudo. Numa primeira etapa e considerando que o siri é um organismo bentônico, foi realizada uma avaliação preliminar do teor de metais no sedimento do estuário. Em seguida, foi realizada uma avaliação preliminar do teor de metais nos diferentes tecidos de indivíduos coletados na região (brânquias, hepatopâncreas e músculos). Baseado nos experimentos anteriores, foi proposto um modelo de distribuição dos metais entre os tecidos e destes em relação aos sedimentos. A validação deste modelo de distribuição (assinatura química) foi realizada por meio de um conjunto de procedimentos que visaram testar: 1) a robustez em função do tempo; 2) a especificidade para a região de estudo; 3) a sensibilidade às alterações dos níveis de metais em cada tecido. A partir deste modelo, foram identificados indícios para atribuição de fontes emissoras de metais. Desta forma, concluiu-se que, para a região do estuário de Santos, o siri da espécie C. danae pode ser utilizado como um biomonitor. O modelo proposto foi eficaz, uma vez que foi capaz de responder de forma conclusiva-positiva a todos os testes realizados na sua validação, confirmando esta espécie como um biomonitor definitivo para região. A robustez do modelo irá aumentar com novas coletas e a realimentação do banco de dados. / This study aimed to develop a new methodology for the use of a biomonitor in the identification of metal discharges in environmental evaluations. Crabs of Callinectes danae species were used in an evaluation conducted in the Santos Estuarine System. In the first experiment and since C. danae is a benthic species, a preliminary assessment of the metal concentrations in sediment samples collected in the Santos Estuarine System was performed. Subsequently, a preliminary assessment of metal concentrations in the C. danae tissues was also peformed. The last experiment aimed to identify a chemical fingerprint for the Santos Estuarine System.The development of validation procedures for this model (chemical fingerprint) was conducted and aimed to test: 1) the stability of this model through time; 2) its local specificity for the Santos Estuarine System; 3) the sensibility of this model due to modifications in the metal concentrations in each tissue (gills, hepatopancreas and muscles). By the use of this model, it was possible to identify the sources of metal emissions. According to the results, C. danae can be used as a biomonitor for the Santos Estuarine System. The established model was able to responde in a positive-conclusive way to all the tests performed in its validation, confirming this species as a definitive biomonitor for this area. Thus, the stability of this model will increase with new sampling campaings and consequently introduction of new information in the database.

Dans le contexte actuel de changements environnementaux globaux, la croissance populationnelle et les besoins grandissants en termes de services écosystémiques en zone côtière occupent une place de plus en plus importante dans les problématiques de conservation. Le développement des pêcheries et la surexploitation qui en découle souvent, sont ainsi à l’origine d’un grand nombre d’effets délétères sur le plan écologique mais peuvent également conduire à une perte de diversité génétique associée à une diminution des capacités d’adaptation pour les espèces exploitées. Le programme transdisciplinaire GIPREOL présente ainsi pour vocation première de mesurer les conséquences de cette littoralisation et de proposer un plan de gestion adapté, sur le territoire de Marennes-Oléron, en mettant à contribution un panel de disciplines variées. Cette étude se focalise sur l’étrille (Necora puber), un crustacé décapode, particulièrement abondant sur les côtes oléronnaises, qui est la cible de pressions de prélèvement, récréatives et commerciales, importantes. Afin d’évaluer les conséquences de ces deux types de pêches sur les populations d’étrilles à l’échelle européenne, une analyse du polymorphisme génétique d’un locus mitochondrial, le COI, et de 10 marqueurs microsatellites a été réalisée pour 29 sites présentant des niveaux d’exploitation différents. Une signature d’expansion démographique datant de la fin du dernier maximum glaciaire du Pléistocène a été mise en évidence, associée à une diversité génétique limitée en accord avec une diversification actuelle des populations. L’étude de la structure génétique observée entre nos sites d’étude a par ailleurs démontré une différenciation génétique contemporaine, détectée grâce au loci microsatellites, révélatrice d’une possible rupture progressive aux flux de gènes entre populations et soulevant ainsi un questionnement légitime quant à l’avenir des étrilles européennes. L’étude de la dispersion larvaire, par une approche de modélisation a, quant à elle, démontré un potentiel de dispersion important. / Nowadays, population expansion and human growing needs in term of services provided by ecosystems biodiversity has become one of the major issues of conservation biology. Fisheries development and the resulting over-exploitation of marine species are heavily impacting marine resources and can furthermore lead to a genetic diversity tumble undermining species adaptive abilities. The GIPREOL transdisciplinary program, conducted by the University of La Rochelle and IODDE partnership, intends on measuring the consequences of coastal development and providing an accordingly suitable and sustainable management plan for the Marennes-Oléron territory. Our study focuses on the velvet swimming crab (Necora puber), a decapod crustacean highly targeted by both professional and recreational fisheries. In order to assess the impacts of such exploitation on Necora puber populations along the eastern coasts of Europe, we analyse the genetic polymorphism of the COI mitochondrial gene and 10 microsatellites loci from 29 European sites with contrasted degrees of anthropogenic pressures. Our results depicted a clear signature of recent demographic expansion from the last glacial maximum of the Pleistocene era combined with an overall low polymorphism. As for the genetic structure within the zone, microsatellites markers revealed a recent differentiation of populations, raising issues concerning the velvet swimming crab European populations future. Lastly, the dispersal abilities of the species were investigated and showed a significant dispersal potential over large distances.

Parmi les nombreuses activités exercées sur les systèmes socio-écologiques littoraux, la pêche récréative a connu un essor important devenant ainsi un enjeu de développement durable. En France, les défauts de gouvernance de l'État dans la gestion du DPM invitent à s'interroger sur la pertinence et la faisabilité d'une co-gestion de ces pratiques de loisir. Ce paradigme, se voulant une alternative à une gestion top-down, prône la participation accrue des populations locales dans la gestion de l'environnement pour améliorer ses résultats. L'île d'Oléron ne déroge pas à ces constats qui sont renforcés par les modifications sociétales spécifiques aux territoires insulaires. Dans le cadre de recherches dont l'objet d'étude est une problématique sociétale, il est approprié de faire appel à une approche interdisciplinaire pour améliorer la pertinence des réponses apportées. Concernant la pêche à pied récréative à l'étrille, les résultats obtenus en biologie et en écologie mettent en évidence des caractéristiques qui semblent indiquer un faible impact potentiel à court comme à long termes de ces perturbations ponctuelles sur les populations locales. D'un point de vue sociétal, la pertinence d'une co-gestion de la pêche récréative est clairement établie par les nombreux conflits d'usages impliquant les pêcheurs récréatifs, le manque de moyens pour gérer la pratique et acquérir des données scientifiques, le manque de concertation, etc. La dynamique de développement du territoire oléronais et les initiatives locales à l'instar des conflits d'usages soutiennent l'idée de l'existence d'une « fenêtre politique » pouvant permettre la mise en place d'une co-gestion de la pratique dans les prochaines années, sous réserve d'une communication suffisante et d'une réelle volonté des acteurs concernés par la gestion de la pratique. / Among several other activities practice on coastal socio-ecological system, recreational fishing ones have significantly increased over the past few years, becoming an issue for sustainable development. In France, the weakness of states governance concerning DPM management, questions the relevancy and feasibility of a co-management policy for these leisure activities. This paradigm, constituting a good substitute for top-down management, recommends an increased participation of local populations for managing environments and improving their outcomes. Oléron Island is thus affected by these observations, which are intensified by societal changes distinguishing island territories. In the current research context, aiming at solving societal problematic, it is relevant to consider an interdisciplinary approach to provide relevant answers. Concerning recreational shellfish gathering targeting the velvet swimming crab, results in biology and ecology highlight some characteristics which should indicate a weak short and long terms potential impact of the disturbances affecting local populations. As regards to societal aspects, the relevancy of co-management is clearly demonstrated by several land-use conflicts, a lack of means to manage the practice and scientific data, the lack of consultation, etc. The territorial dynamic and local initiatives, as well as land-use conflicts, underline the existence of a “political window” which should allow the implementation of a co-management process for recreational fishing in the following years, subject to further efficient communication and a real desire from stakeholders concerned by the management of this practice.