Thesis (M.Sc.)--Memorial University of Newfoundland, 2003. / Bibliography: leaves 113-127. Also available online.

Thesis (Ph. D.)--Rhodes University, 2005. / Title from PDF t.p. (viewed on July 21, 2006). Includes bibliographical references (p. 251-270).

The freshwater mussel family Unionoida lives a complex life with its host animals and the freshwater mussel family’s existence is threatened worldwide. One of these species, the pearl mussel (Margaritifera margaritifera), is a “responsibility species” for Scandinavia and a lot of work is ongoing to save the species. In Scandinavia there are still existing populations, but in many waters recruitment of juvenile mussels is completely lacking or insufficient. To support recruitment and also reintroduce the mussel into suitable watercourses, more knowledge about its complex life cycle and how it affects its host brown trout (Salmo trutta), is required. Attempts have been made to introduce gravid mussels or already infected trout in order to try to rejuvenate or to reintroduce mussels in some rivers. In this study, 293 trout individuals were captured from three watercourses in western Sweden with no or inadequate recruitment of juvenile pearl mussels. The brown trout were treated with mussel infection by being kept in containers with the presence of gravid mussels and compared to a control group where no mussels were present. Growth, condition factor and habitat selection were investigated and checked after treatment by scanning the trout with a mobile scanner and recaptured for control. The analyzes showed a significantly lower growth on those trout treated with mussel infection during the time they were stored in the containers. After a month in freedom in the streams, there was no differences in growth or condition factor. Habitat choice studies showed that trout with a higher degree of infection chose calmer water with a bottom layer of finer sediment. The study showed that this method could be a simple way of increasing the reproduction success of pearl mussel. The method requires relatively little work effort and small disturbance to host fish or the aquatic environment. / Familjen sötvattensmusslor har ett larvstadie som parasit och lever ett komplext liv tillsammans med sina värddjur och sötvattensmusslornas existens är hotade världen över. Flodpärlmusslan (Margaritifera margaritifera) är en hotad art vars populationer i Skandinavien, där den är en ansvarsart, har en utebliven eller otillräcklig föryngring. Mer kunskap behövs om dess livscykel och hur den påverkar sin värd, öringen (Salmo trutta), för att hitta bra metoder som kan stödja musslans rekrytering. Försök har gjorts med att plantera in gravida musslor eller redan infekterad öring för att på det viset försöka få till stånd en föryngring av musslor eller att återinföra öring i vissa vatten. I denna studie undersöktes om det fanns någon skillnad med avseende på tillväxt och konditionsfaktor mellan infekterad eller inte infekterad öring och om infektionsgraden påverkade deras val av habitat. Tvåhundranittiotre öringar elfiskades ur tre vattendrag i Västsverige med ingen eller otillräcklig föryngring av flodpärlmussla. Öringarna behandlades genom att infekteras i sumpar med närvaro av gravida musslor och jämfördes med en kontrollgrupp, utan musslor i sumparna. Tillväxt, konditionsfaktor och habitatval undersöktes och kontrollerades efter behandling genom att öringen scannades med mobil scanner och elfiskades åter 30 dagar efter att de släppts. Tillväxten på de öringar som behandlades med musselinfektion var signifikant lägre än de som inte behandlades med musselinfektion under den tid de förvarades i sumpar. Efter en månad i frihet fanns ingen skillnad i tillväxt mellan de infekterade och inte infekterade öringar. Ingen skillnad i konditionsfaktor kunde påvisas innan de placerades i buren, när de togs ur buren eller efter 30 dagar i frihet i bäckarna. Öring med högre infektionsgrad valde lugnare vatten med högre andel fint substrat. Resultatet visade att den infekterade öringen påverkades negativt med avseende på tillväxt när den utsattes för stress men också att den hade förmåga att återhämta sig snabbt. Habitatvalet gav också det indikationer på att den mer infekterade öringen drog sig till en mindre krävande miljö. Studien visade att metoden kan rekommenderas och kan vara en enkel metod att öka reproduktionsframgången för flodpärlmusslan som kräver liten arbetsinsats, är relativt kostnadseffektiv och ger en liten störning på värdfisken och vattendragets miljö.

The work is focused on the status and role of zebra mussels (Dreissena polymorpha) in the water reservoir Želivka. Literature review summarizes the basic characteristics of living zebra mussels and its impact on the aquatic ecosystem. Current knowledge about this invasive bivalves show that its presence in the water reservoir has certain advantages, but also disadvantages. The main advantage is that zebra as filtrator, increases the transparency of the water and provides food for the animals living in the aquatic environment, or in its vicinity. Disadvantages are then mainly from the economic point of view, the zebra clogs pipes and thus prevents water flow and attached to marker buoys, fishing nets and attaches to the hulls of ships that can be attacked from the inside. In field part population of zebra mussels was sampled in different parts of the reservoir and identified following parameters (temperature and oxygen stratification, coverage to substrate coverage depending on the depth and the substrate, the length of shells according to the horizontal and vertical gradient filtering capacity and the volume rate). The results showed that the incidence and size of shells affects both horizontal and vertical gradient. Zebra mussels occur most depth 1-9 m on rocky, or stony substrate. The greatest incidence was found at Budeč and at Hráz, where the water is less eutrophic than the Zahrádka. Based on these parameters, and literature data was calculated hypothetical filter capacity and discussed its possible impact on the ecosystem components of the reservoir.

The effect of climate on the fluvial system has long been investigated due the significant impact it can have on a river’s hydrological regime and fluvial processes. In recent years this interest has increased as global changes in climate are expected to bring more frequent high magnitude flood events globally and to North West Europe in particular. Despite the knowledge that the frequency and magnitude of floods is to increase, less is known about the geomorphological implications of this for river channels and where channel instability is likely to occur at both the river network and national scale. This is certainly the case in Scotland where increased flooding is expected and large floods have been abundant over the last two decades. To manage Scottish river catchments effectively in the future, in terms of hazard mitigation and nature conservation, river managers need to be able to predict not only how climate will impact flood magnitude and frequency in Scotland but the effect these changes will have on the internal dynamics of river channels in terms of erosion, sediment transport and deposition, and morphological dynamics. Such knowledge will ensure adequate measures are implemented to reduce fluvial risks to humans and to maintain and preserve valuable river habitats and linked species. In this thesis, several novel methods incorporating field, laboratory and GIS-based analysis, have been investigated as a means of predicting how climate change will affect channel stability in Scottish rivers and the implications of this for river management and river ecology. This includes (i) analysing the potential change in the frequency of geomorphologically-active flood flows with climate change; (ii) the use of stream power thresholds to predict changes in channel stability on a national scale with climate change; and (iii) using a Digital River Network developed using geospatial data to predict changes in the rate of bedload transfer and channel stability with climate change. Studies were undertaken on 13 different rivers across Scotland from north to south and east to west. vii As a case study of ecological implications, the thesis also examines how changes in habitat and stability of freshwater pearl mussels (Margaritifera margaritifera) may be altered by increased flooding. Predictions of the frequency of geomorphic activity, channel stability, rate of bedload transfer, and the stability of freshwater pearl mussel habitat with climate change are discussed along with the methods used to obtain these outcomes. The results all suggest an increase in the frequency and rate at which bedload is transferred through the river system and an increased frequency of flood flows resulting in greater channel instability. Morphological responses vary spatially with some river reaches experiencing greater increased erosion and transport potential than others. Climate change effects on the freshwater pearl mussel are: increased occasions of disturbance and transport downstream and the importance of specific populations in more stable environments for ensuring population recovery post flooding is highlighted. It is hoped that the methodologies developed for predicting changes in channel stability with climate change will provide useful screening tools to regulatory agencies which can be developed further to assist management decisions in the future which aim to reduce fluvial hazards and maintain good quality river environments for the species that inhabit it. The approaches used in this study allow for the identification of areas at high risk of morphological and ecological change, and the pro-active planning and management of sediment-related river management issues and nature conservation.

Made available in DSpace on 2014-06-11T19:30:11Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-04-24Bitstream added on 2014-06-13T20:20:29Z : No. of bitstreams: 1 camargo_fv_me_botib.pdf: 2205953 bytes, checksum: e1b8e3fbcc0f56e4f6a5f6427c780dcc (MD5) / O objetivo deste estudo é descrever a composição e a estrutura da comunidade de decápodos braquiúros associada ao cultivo de mexilhão Perna perna em Ubatuba, litoral norte paulista (23”27’07 S – 45”02’49 W). Foram realizadas coletas mensais durante o período de março de 2002 a abril de 2003, em sistema “long-line” de cultivo. As amostras das redes de P. perna foram triadas e mensuradas quanto ao volume. Os braquiúros amostrados foram identificados quanto a espécie e sexo, mensurados quanto a largura de carapaça (LC) e analisados quanto a diversidade, equidade e equitabilidade. Foi obtido um total de 849 indivíduos distribuídos em 14 gêneros e 16 espécies, sendo que Panopeus austrobesus e Pachygrapsus transversus apresentaram a maior abundância com 711 e 68 indivíduos respectivamente, correspondendo juntos a 83% do total amostrados, além disso, foram registradas para essas duas espécies os maiores valores de diversidade, constância e abundância. A presença de P. austrobesus e P. tranversus durante todo estudo sugere que essas espécies apresentem maior eficiência competitiva em relação a colonização primária das redes, além disso essas espécies foram consideradas responsáveis pela dinâmica e regulação da comunidade de braquiúros nas redes. A baixa riqueza encontrada nas redes de cultivo quando comparada a ambientes heterogêneos é esperada, devido ao estágio inicial de desenvolvimento da comunidade de caranguejos em relação a um substrato homogêneo e recém-formado e as perturbações por ele sofridas. / The main goal of this study is describe the composition and structure of the community of the Decapod Brachyuran associated to the commercial raft of the mussel Perna perna in the southeastern Brazilian coast (23º27”07’S–45º02”49’W). Monthly collections of mussels’ net culture were carried out from March, 2002 to April, 2003. The crabs were sexed and identified as juvenile and adult, based on the abdomen morphology, and measured as the largest carapace width (CW). The samples were analyzed for some ecologic index as richness, diversity, constancy, evenness and equitability. A total of 849 individuals was obtained, distributed into 14 genera and 16 species. Panopeus austrobesus and Pachygrapsus transversus were the most abundant species, with 711 and 68 specimens respectively, together corresponding to 68% of the total crab’s samples. For these two species were also recorded the largest values for diversity and constancy. The presence of these two species over all sampled period pointing out its high competitive efficiency during the initial phase of the mussel colonization, thereby responsible for the community regulation during this colonization phase. The low values of richness recorded on the mussel rafts are expected for the homogeneous environments, as those created among the mussel shells. So, the crab community established on the mussel raft, in the southeastern Brazilian coast, is dominated for two pioneers’ species that are the main pieces for its regulation.

A maricultura, ou mais especificamente a mitilicultura, tema deste trabalho, é uma das áreas da aquicultura que mais tem crescido nos últimos tempos. Muito embora possa ser praticada como atividade empresarial, vem se constituindo mais e mais como alternativa viável de geração de renda para pescadores artesanais profissionais e produtores individuais autônomos, devido ao baixo custo de implantação e manutenção, graças à extensa faixa litorânea e a condições climáticas ideais para o desenvolvimento desse tipo de atividade. Esta pesquisa objetivou proporcionar uma visão do estado atual da mitilicultura, notadamente na cidade de Ubatuba, Estado de São Paulo, Brasil, e investigar ações que possam promover o processo de forma financeiramente viável, de modo a tornar-se esta uma atividade geradora de trabalho e renda para as comunidades locais e colaborar com a diminuição da extração dos estoques pesqueiros. Especificamente, a pesquisa objetiva identificar as áreas produtivas, de acordo com a legislação vigente no Estado de São Paulo, caracterizar a mitilicultura implantada no município de Ubatuba e o perfil dos produtores, analisar economicamente o cultivo de mexilhões no município de Ubatuba. Foi realizado um estudo de caso sobre criação do mexilhão Perna perna, no qual se colheram dados por meio de entrevistas semi-estruturadas, sendo utilizada a abordagem qualitativa. A análise qualitativa dos dados utilizou a técnica da Análise de Conteúdo. A presente pesquisa mostra que a mitilicultura, como atividade geradora de trabalho e renda para as comunidades locais, pode ser estimulada no município de Ubatuba. Isto colaboraria para a diminuição da extração dos estoques pesqueiros, e o consequente impacto sobre o meio ambiente, aliado à geração de emprego e renda para as populações menos privilegiadas. / The mariculture, or more specifically the mitiliculture, theme of this investigastion, is one of the fastest growing areas of aquaculture in recent times, and although it can be practiced as a business activity, it is becoming more and more as a viable alternative for generating income for fishermen and professional autonomous individual producers due to the low cost of deployment and maintenance, thanks to the extensive coastline and ideal climate conditions for the development of this type of activity. This study aims to provide an overview of the current state of the mitiliculture, especially in the city of Ubatuba, State of Sao Paulo, Brazil, and to investigate actions that may promote the process in an financially available in order to become an activity that creates jobs and income for local communities and collaborate with the decrease in extraction of fish stocks. Specifically, the study attempts to identify productive areas, according to the law in the state of Sao Paulo, to describe mitiliculture deployed in Ubatuba and profiles of producers, and an economic analysis cultivation of mussels in Ubatuba. A case study was conducted on creation of the mussel Perna perna, in which data was collected through semi-structured interviews, and used the qualitative approach. The qualitative data analysis used the technique of content analysis. This research showed that the mitiliculture, as an activity which generates work and income for local communities, can be stimulated in Ubatuba. This would work to reduce the extraction of fish stocks, and the consequent impact on the environment, coupled with the generation of employment and income for the under-served.

Intertidal mussels regularly experience emersion-induced anoxia, in contrast to normoxic conditions experienced during submersion. We therefore hypothesized that acclimation to a tidal rhythm, as opposed to a rhythm of constant submersion, preconditions the proteome of the California mussel, Mytilus californianus, to respond differently to emersion-induced anoxia. Following acclimation, mussels either continued to receive the acclimation conditions (control) or were exposed to 100% nitrogengas (anoxia) during aerial emersion. We collected gill tissue for subsequent analysis of protein abundance with 2D gel electrophoresis and protein identification with tandem mass spectrometry. Relative to subtidally-acclimated mussels, tidally-acclimated mussels showed a greater propensity to respond to distrupted protein homeostasis during emersion through higher levels of several small heat shock protein isoforms, while they showed lower levels of several chaperones involved in redox-sensitive protein maturation in the endoplasmic reticulum during acute anoxia. Several metabolic proteins showed elevated levels in tidally-acclimated mussels, suggesting a compensatory response to reduced feeding times. However, changes in the abundance of several tricarboxylic acid cycle enzymes (e.g. aconitase, succinate dehydrogenase) suggest that tidally-acclimated mussels are also primed to sense reactive oxygen species (ROS) and limit their production, respectively. These findings are further supported by higher abundances of several aldehyde dehydrogenases and thioredoxin peroxidase, which function as scavengers of aldehydes and ROS, common products of lipid peroxidation. Finally, tidally-acclimated mussels are also more responsive to changes in cytoskeletal and vesicular trafficking dynamics in response to acute anoxia. Together, our analysis showed that proteostasis, energy metabolism, oxidative stress and cytoskeletal and trafficking processes are all involved in priming tidally-acclimated mussels to respond more dynamically to acute emersion-induced anoxia in Mytilus gill.

As our knowledge of bivalves has increased, so has information about their parasites. Most studies of bivalve parasites have been devoted to groups infesting commercially important mollusks, notably trematodes and copepods. Another group of bivalve symbionts which has been known since the early nineteenth century is the brachyuran genus Pinnotheres Latreille, 1802 (commonly known as pea crabs). The generic name was given because of the belief that the crabs were predators upon the scallops in which they were most frequently found (Pearce, 1966). However, Stebbing (1893) suggested that instead of acting as predators, the crabs were in fact serving as guards for their hosts.

Zooarchaeological mussel shell assemblages can be affected by an array of biases, one of which is cultural bias. Cultural biases may be exhibited in the transport of mussels from nonlocal mussel beds, and/or in preferential taste. There are a few methods used to help determine if cultural biases are at play (e.g., nestedness and detrended correspondence analysis). This thesis aims to test a new method, the life history approach, to determine if it is a viable method for assessing cultural bias in prehistoric mussel assemblages from the Tombigbee River drainage. Shell assemblages from the drainage previously have been demonstrated to not be culturally biased; therefore, these assemblages will act as a control against which to test the life history approach as a method for cultural bias assessment.