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The current explanation for the absence, or low abundance, of filter-feeding invertebrates from some rocky shores is that because of local variation in nearshore oceanographic conditions, larvae do not arrive in sufficient numbers to establish populations. One putative consequence of this is that macroalgae are able to establish dominance in areas where filter-feeders (especially mussels) do not recruit well. While macroalgae have been transplanted to mussel-dominated shores with varying success, the survival, growth and reproduction of transplanted mussels has not been tested in areas dominated by macroalgae. To determine specifically what tips the balance between shores dominated by filter-feeding invertebrates and those dominated by macroalgae, I monitored the recruitment of intertidal mussels at four sites on the Kaikoura coast: two with mussels present and two algal-dominated. No significant differences in mussel recruitment rates were found between habitats and recruitment intensity at all sites was found to be very low. Recruitment limitation is not the reason for the absence of mussels from algal dominated shores but some form of limitation does occur to reduce the number of arriving mussels. Predation effects were examined by transplanting juvenile mussels into caged, uncaged and control treatments. No significant differences in predation rates between habitats were found and transplanted mussels in open cages at all sites were removed within 3 days. Mobile fish predators appeared to be the most likely cause of this intense predation. Growth of transplanted mussels into algal and mussel habitats was found to be significantly different. Mussels grew faster in mussel dominated habitats and after 6 months in algal dominated habitats, all mussels had died. The outcome of these experiments indicates that there is a close relationship between recruitment, survival and growth which tips the balance and allows the existence of mussel beds along the Kaikoura coastline.

Unionoid mussels are globally threatened and their conservation requires species-specific knowledge on their ecology and parasite-host interaction. Unio crassus is one of Europe’s most threatened unionoid species and has a temporary obligate parasitic life stage (glochidia) on fish. A lack of suitable hosts is probably a major limitation for mussel recruitment, but host species composition, suitability and availability in time and space have yet to be fully explored. This thesis examines different aspects of the host fish species, including their composition, suitability and ecological importance, in relation to U. crassus, using both field and laboratory studies. The effects of mussel and host density on mussel reproductive potential were considered, as were aspects of evolutionary adaptations between mussels and fish and how climate change may affect their interaction. The results show that U. crassus is a host generalist, parasitizing a variety of fish species. Host suitability and density, which varied among fish species and rivers, affected the level of glochidia encapsulation, hence mussel reproductive potential, more so than the density of mussels taking part in reproduction. Ecologically important hosts included both highly suitable primary hosts, and less suitable hosts that were highly abundant. Whether or not U. crassus has specific adaptations to its hosts to enhance juvenile transformation remains unclear. No distinct pattern of local adaptation was found, nor was there an effect of host fish presence on the timing of glochidia release by adult mussels. Instead, temperature played a major role, with results suggesting that changes in spring water temperature regimes can cause temporal and spatial mismatches in the mussel-host interaction. This thesis indicates that investigations of local mussel-host interactions help in identifying mechanisms important for unionoid conservation management and prioritization. / Många sötvattenmusslor har en komplex livscykel där larverna (glochidier) under sin utveckling till frilevande musslor parasiterar på gälarna hos lämpliga värdfiskar. Flera av våra musslor, såsom den tjockskaliga målarmusslan (Unio crassus), är globalt hotade och för att kunna bevara och förvalta dessa arter på bästa sätt behöver vi lära oss mer om deras ekologi och samspelet mellan musslan och dess värdfiskar. Avsaknaden av värdfiskar innebär förmodligen en stor begränsning för rekryteringen av juvenila musslor, men det finns trots detta en begränsad kunskap om hur artsammansättningen i fisksamhället och dess tillgänglighet påverkar musselpopulationer.  Min avhandling undersöker olika aspekter av interaktioner mellan U. crassus och dess värdfiskar, som hur värdfisksamhällen och fiskarters värdlämplighet påverkar musslans reproduktionspotential. Jag har även studerat hur tätheter av olika fiskarter och vuxna musslor påverkar rekryteringen, eventuella evolutionära anpassningar samt om en förhöjd temperatur skulle kunna påverka interaktionen mellan U. crassus och dess värdfiskar. Resultaten visar att U. crassus är en generalist som parasiterar på en mängd olika fiskarter. Jag fann dock en stor variation i dominerande fiskarter och lämpliga värdar mellan olika åar, vilket påverkade reproduktionspotentialen hos musslorna mer än vad tätheten vuxna musslor som deltog i reproduktionen gjorde. Som ekologiskt viktiga värdar fanns således både särskilt lämpliga, primära värdarter, men också mindre lämpliga arter som förekom i höga tätheter. Ingen tydlig lokal anpassning kunde observeras, och fiskens närvaro påverkade inte tidpunkten för när de vuxna musslorna släppte sina glochidielarver. Däremot fann jag att temperaturen spelade en viktig roll för musslans reproduktion, där ökad temperatur föreslås ha negativa effekter på interaktionen mellan musslan och dess värdfiskar. Avhandlingen visar på vikten av att studera interaktioner mellan den tjockskaliga målarmusslan och dess värdar på lokal skala för att bättre kunna identifiera och prioritera viktiga naturvårdsåtgärder. / UnioCrassusforLIFE (European LIFE+ project: LIFE10 NAT/SE/000046)

xx, 198 p. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / "Bathymodiolus" childressi is a mixotrophic mussel from Gulf of Mexico cold seeps. There is no genetic differentiation of mussels among the seeps, suggesting wide dispersal of their larvae. This dissertation describes larval biology, ecology, and recruitment dynamics for "B." childressi. Cleavage is spiral at a rate of one per 3-9 hours, with blastula larvae hatching by 40 hours at 7-8 à à °C. At 12-14 à à °C, D-shell veligers developed by day 8 without being fed. Egg size and shell morphology indicate planktotrophy, but feeding was not observed. Embryos developed normally from 7-15 à à °C and 35-45 ppt. Although survival of larvae declined with temperature, some survived at 25 à à °C. Larval survivorship was similar at 35 and 45 ppt. Oxygen consumption increased from blastulae to trochophores and was higher for "B." childressi than for shallow-water mussel trochophores. Estimated energy content of "B." childressi eggs was greater than the energy content of shallow-water mussel eggs. An energetic model predicts that the eggs provide sufficient energy for "B." childressi trochophores to migrate into the euphotic zone. In fact, "B." childressi veligers were found in plankton tows of surface waters. The influence of recruitment on fine-scale distributions of adults at the Brine Pool cold seep was examined through manipulative field experiments. The "Bathymodiolus" childressi population at this site has a distinct bimodal size structure that shifts across an environmental gradient. New recruits of "B." childressi are abundant in the inner zone, where methane and oxygen are high and sulfide is low, leading to the inference that larvae settle preferentially there. Experiments were placed in the inner and outer zones and 2-m away from the bed. The number of larvae collected in traps did not differ among the three zones, nor did settlement density. Juveniles survived and grew in all zones, but more caged than uncaged juveniles survived. Mortality of uncaged juveniles was similar in all zones, suggesting that predation does not cause the bimodal distribution. These results suggest that the bi-modal distribution cannot be attributed to settlement preferences or juvenile mortality, but instead to migration or early post-settlement mortality. This dissertation includes my co-authored materials. / Adviser: Craig M. Young

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Os hidrocarbonetos policíclicos aromáticos (HPA) constituem um grupo de poluentes ambientais persistentes são moléculas com dois ou mais anéis aromáticos condensados, pouco solúveis em água e estão presentes no ambiente como resultante de processos naturais e também de atividades antrópicas; desta forma, os HPA podem ser encontrados em diversas matrizes ambientais. No presente trabalho foram utilizados mexilhões da região de Búzios, no Estado do Rio de Janeiro. Esse organismo foi selecionado devido à facilidade de acumulação de HPA nos tecidos, decorrente das propriedades hidrofóbicas dos HPA. O presente projeto teve como objetivo estudar um novo material de limpeza capaz de minimizar os compostos interferentes da matriz. Os cartuchos de SPE Florisil 5 g, são convencionalmente usados na limpeza de amostras de organismos, porém para diminuir os custos foram testados outros materiais adsorventes que pudessem ser eficientes na remoção dos interferentes presentes nos tecidos de mexilhão. Sendo assim, na etapa de limpeza conhecida como clean-up, foi estudada a recuperação do pireno após a extração por micro-ondas através de duas abordagens diferentes; a) utilização de cartuchos de SPE comerciais de 5 g de Florisil; b) cartuchos preenchidos com argila comercial K-10 bentonite, simulando os cartuchos comerciais. A recuperação e eficiência dos procedimentos de limpeza foram testadas e comparadas. A clean-up com argila K-10 apresentou uma recuperação de até 77% de pireno, sendo eficiente na remoção de compostos de colesteróis; confirmando a eficiência do material escolhido para a limpeza da amostra. A técnica de Cromatografia Gasosa e detecção por Espectrometria de Massas (GC-MS) foi aplicada para identificação e quantificação do contaminante pireno no extrato finaa / Polycyclic aromatic hydrocarbons (PAH) are a group of persistent environmental pollutants are molecules containing two or more condensed aromatic rings, little soluble in water and are present in the environment as a result of natural processes and human activities; in this way, the HPA can be found in various environmental matrices. In this work we used mussels in Búzios, Rio de Janeiro State. That body was selected due to the ease of accumulation of HPA in the tissues, due to the hydrophobic properties of HPA. This project aimed to study a new cleaning material able to minimize interfering compounds of the array. The 5 g Florisil SPE cartridges, are conventionally used in the cleaning of samples of organisms, however for lower costs have been tested other adsorbent materials which could be effective in the removal of the present in the tissues of mussels interfering. Therefore, in step of cleaning known as clean-up, recovery of pyrene was studied after extraction by microwave through two different approaches; a) use of commercial SPE cartridges 5 g of Florisil; b) cartridges filled with K-10 clay bentonite commercial, simulating the commercial cartridges. Recovery and efficiency of cleaning procedures were tested and compared. The clean-up with K-10 clay presented a recovery of up to 77% of pyrene, being effective in removing compounds of cholesterols; confirming the efficiency of the chosen material for cleaning of the sample. The technique of gas chromatography and detection by mass spectrometry (GC-MS) was applied for identification and quantification of contaminant pyrene in the final extract

Made available in DSpace on 2016-04-28T20:17:29Z (GMT). No. of bitstreams: 1 2008 - Marcelo Santos de Oliva.pdf: 3554572 bytes, checksum: 0fae31785d5eaf0f107b4791b1e03628 (MD5) Previous issue date: 2008-11-13 / Mussels are bivalve mollusks that developed a filtrating system enabling them to uptake nutrients from water. This is a not selective mechanism, so mussels microbiological analysis shows up the aquatic environment quality. Therefore, the present work aimed to isolate and identify bacterial microbiota from bivalve mollusks incrustated into the rocky coast of Arquip?lago de Santana, Maca?, RJ. The antimicrobial resistance pattern of prevalent microorganisms isolated was also analyzed. The surrounding water microbiological quality was also evaluated in order to detect contamination source from fishing and subaquatic activities in the studied region. From the bacteriological analysis it was obtained a total of 51 isolates of Vibrio spp., being V. damsela (n=15) the prevalent specie, followed by V. harveyi (n=13) and V. alginolyticus (n=07). It was also obtained a total of 20 isolates of Enterobacteriaceae species, being Escherichia coli (n=06) the prevalent one, followed by Proteus vulgaris (n=04). Vibrio spp. isolates presented 100% of sensitivity to tested antimicrobials, except for ampicillin with no detected sensitivity corroborating to literature. For enterobacteria, it was detected a high percentile of sensitivity to all testes antimicrobials. In the six samples of ocean water analyzed it was not possible to detect total or fecal coliforms. The low percentile of isolated microorganisms from mussels at Arquip?lago de Santana can be justified for its location at the open sea, far away from the coast and influenced by sea currents, in a environment not yet altered by human action. / Os mexilh?es s?o moluscos bivalves filtradores que se alimentam de microrganismos captados pela corrente de ?gua e n?o apresentam capacidade seletiva de filtra??o do seu alimento, consequentemente, a an?lise dos mexilh?es reflete a qualidade microbiol?gica do habitat aqu?tico. Desse modo, o presente trabalho objetivou executar o isolamento e identifica??o da microbiota bacteriana a partir de moluscos bivalves incrustados em cost?es rochosos no Arquip?lago de Santana, Maca?- RJ, bem como analisar o perfil de resist?ncia dos microrganismos prevalentes. Tamb?m se buscou avaliar a qualidade da ?gua de modo a detectar poss?veis contamina??es decorrentes das atividades pesqueiras e subaqu?ticas nesta regi?o. A partir das an?lises bacteriol?gicas foi obtido um total de 51 col?nias de Vibrio spp. com preval?ncia da esp?cie V. damsela (n=15), seguida de V. harveyi (n=13) e V. alginolyticus (n=07) e um total de 20 col?nias de enterobact?rias com preval?ncia de Escherichia coli (n=06) seguida de Proteus vulgaris (n=04). Os isolados de Vibrio spp. apresentaram 100% de sensibilidade aos antimicrobianos testados, com exce??o da ampicilina, para a qual n?o foi detectada qualquer sensibilidade a semelhan?a de outros relatos na literatura. Nos isolados de enterobact?rias avaliados, foram detectados elevados percentuais de sensibilidade aos antimicrobianos testados. No total de seis amostras de ?gua do mar analisadas, n?o foi detectada a presen?a de coliformes totais e termotolerantes. O baixo percentual de microrganismos isolados de mexilh?es no Arquip?lago de Santana pode ser justificado por ser um local de mar aberto, afastado da costa e sobre a influ?ncia de correntes mar?timas, e ainda pouco impactado pela a??o humana.

As bactérias patogênicas em moluscos bivalves podem ser agentes causadores de doenças como a gastroenterite e responsáveis por vários surtos de origem alimentar, representado um risco para os consumidores. Os vírus entéricos são a causa mais comum de surtos de gastroenterites não bacteriana em humanos no mundo e podem ser encontrados nas águas utilizadas no cultivo de moluscos bivalves. Este estudo teve como objetivo avaliar a contaminação de mexilhões (Mytella falcata) e ostras (Crassostrea brasiliana) provenientes do Complexo Estuarino Lagunar de Cananéia-Iguape, Estado de São Paulo, por bactérias (coliformes totais, coliformes termotolerantes, patotipos de Escherichia coli), por astrovírus e norovírus humanos. Um total de 150 amostras de moluscos bivalves (75 ostras e 75 mexilhões) foram coletadas de junho de 2016 a fevereiro de 2017. A estimativa de coliformes totais nos tecidos das ostras variou de 14,1 a 154,5 número mais provável (NMP)/g e de coliformes termotolerantes de 3,0 a 48,6 NMP/g, enquanto que para as amostras de mexilhões, os coliformes totais variaram de 97,4 a 1300 NMP/g e coliformes termotolerantes de 3,6 a 927 NMP/g. E. coli foi detectada em 24 amostras (16%), em concentrações variando entre <3 e >927 NMP/g. Quatro amostras (17%) foram identificadas com Escherichia coli enteropatogênica (EPEC), apresentando o gene eae por PCR (Reação em Cadeia da Polimerase) e RFLP (Polimorfismo no Comprimento de Fragmentos de Restrição), e os amplicons positivos foram sequenciados. As porcentagens de similaridade relativas ao gene phoA de E. coli, para as cinco amostragens realizadas no estudo, apresentaram valores iguais ou superiores a 88,6%. As sequências de EPEC agruparam-se em diferentes clados com outras sequências do Brasil, Suíça e Uruguai, exibindo similaridade de 57,7 e 97,1% quando comparadas umas as outras. Quando comparadas a outras sequências de referência depositadas no GenBank, a similaridade variou entre 56,2 e 95,4%. Estes resultados são os primeiros a indicar a presença de EPEC em moluscos bivalves no Brasil. Astrovírus não foram identificados nas amostras de moluscos analisadas neste estudo. Norovírus (NoV) foi identificado em 21 (14%) das amostras, sendo 38% de mexilhões e 62% de ostras. As amostras de NoV genogrupo II (GII) foram agrupadas num clado único, juntamente com outras sequências de NoV GII, sendo mais próximas filogeneticamente de sequências originárias do Brasil, Japão e México, com similaridade de 93,8 a 96,6% do que com as outras sequências homólogas. A triagem de moluscos bivalves para coliformes, E. coli e presença de vírus entéricos significativos para a saúde pode ajudar na prevenção de surtos entre os consumidores e contribuir para a melhoria do ambiente estuarino. / The pathogenic bacteria in bivalve molluscs are causative agents of diseases such as gastroenteritis and responsible for several food-borne outbreaks, representing a risk to consumers. Enteric viruses are the most common cause of outbreaks of non-bacterial gastroenteritis in humans in the world and can be found in waters used in the cultivation of bivalve molluscs. The objective of this study was to evaluate the contamination of mussels (Mytella falcate) and oysters (Crassostrea brasiliana) from the estuarine complex Lagunar of Cananéia-Iguape, State of São Paulo, by bacteria (total coliforms, thermotolerant coliforms, Escherichia coli) and by human astroviruses and noroviruses. A total of 150 samples of bivalve molluscs (75 oysters and 75 mussels) were collected from June 2016 to February 2017. The total coliform estimate in oyster tissues varied from 14.1 to 154.5 most probable number (MPN)/g and thermotolerant coliforms from 3.0 to 48.6 MPN/g, whereas for mussel samples, total coliforms ranged from 97.4 to 1300 MPN/g and thermotolerant coliforms from 3.6 to 927 MPN/g. E. coli was detected in 24 samples (16%) at concentrations ranging from <3 to >927 NMP/g. Four (17%) were identified with enteropathogenic Escherichia coli (EPEC), presenting the gene eae by PCR (Polymerase Chain Reaction) and RFLP (Restriction fragment length polymorphism), and the positive amplicons were sequenced. The percentages of similarity relative to the phoA gene of E. coli, for the five samplings carried out in the study, presented values equal or superior to 88.6%. The EPEC sequences were grouped in different clades with other sequences from Brazil, Switzerland and Uruguay, exhibiting similarity of 57.7 and 97.1% when compared to each other. When compared to other reference sequences deposited in GenBank, the similarity ranged from 56.2 to 95.4%. These results are the first to indicate the presence of EPEC in bivalve molluscs in Brazil. Astroviruses were not identified in the mollusk samples analyzed in this study. Norovirus (NoV) was identified in 21 (14%) of the samples, representing 38% of mussels and 62% of oysters. NoV genogroup II (GII) samples were clustered in a single clade, along with other NoV GII sequences, keeping phylogenetically closest to sequences originating in Brazil, Japan and Mexico, with similarity of 93.8 to 96.6% than with the other homologous sequences. The screening of bivalve molluscs for coliforms, E. coli and the presence of enteric viruses significant to health can help preventing outbreaks among consumers and contribute to the improvement of the estuarine environment.

The Upper Mississippi River (UMR) basin contributes over 50,000 metric tons of nitrogen (N) to the Gulf of Mexico each year, resulting in a “dead zone” inhospitable to aquatic life. Land-applied N (fertilizer) in the corn-belt is attributed with a majority of the N-load reaching the Gulf and is difficult to treat as run-off is considered a non-point source of pollution (i.e. not from a pipe). One solution to this “grand challenge” of intercepting N pollution is utilizing filter-feeding organisms native to the UMR. Freshwater mussel (order Unionidae) assemblages collectively filter over 14 billion gallons of water, remove tons of biomass from overlying water, and sequester tons of N each day. Our previous research showed mussel excretions increased the sediment porewater concentrations of ammonium by 160%, and indirectly increased nitrate and nitrite by 40%, presumably from microbial degradation of ammonium. In response, the goal of this research was to characterize how mussels influenced microbial communities (microbiome) to determine the fate of N in UMR sediment. First, we used qPCR and non-targeted amplicon sequencing within sediment layers to identify the N-cycling microbiome and characterized microbial community changes attributable to freshwater mussels. qPCR identified that anaerobic ammonium oxidizing (anammox) bacteria were increased by a factor of 2.2 at 3 cm below the water-sediment interface when mussels were present. Amplicon sequencing of sediment at depths relevant to mussel burrowing (3 and 5 cm) showed that mussel presence reduced microbial species richness and diversity and indicated that sediment below mussels harbored distinct microbial communities. Furthermore, mussels increased the abundance of ammonia oxidizing bacteria (family Nitrosomonadaceae), nitrite oxidizing bacteria (genus Nitrospira), but decreased the abundance of ammonia oxidizing archaea (genus Candidatus Nitrososphaera), and microorganisms which couple denitrification with methane oxidation. These findings suggested that mussels may enhance microbial niches at the interface of oxic and anoxic conditions, presumably through excretion of N and burrowing activity. In response, we performed metagenomic shotgun sequencing to identify which genes of the microbiome were most impacted by mussels. We hypothesized that genes responsible for ammonia and nitrite oxidation would be greater in the sediment with mussel assemblages. We found the largest abundance of N-cycling genes were responsible for nitrate reduction and nitrite oxidation, which is corroborated by the high concentration of nitrates in UMR water. Linear discriminant analysis statistical analyses showed nitrification genes were most impacted by mussels, and this presented an opposing effect on genes responsible for producing nitrous oxide, a potent greenhouse gas. Further investigation showed an increased abundance of a novel organism capable of completely oxidizing ammonia to nitrate (Candidatus Nitrospira inopinata) and coexisted with metabolically flexible Nitrospira (sp. moscoviensis), likely enhancing both carbon and N-cycling. We demonstrated that native mussels harbor a unique niche for N-cycling microorganisms with large metabolic potentials to degrade mussel excretion products. Our findings suggest the ecosystem services of mussels extend beyond water filtration, and includes enhanced biogeochemical cycling of carbon, N, and reduces the potential for a potent microbially-produced greenhouse gas. Ultimately, this research could be used to advocate for mussel habitat restoration in the UMR to lessen the impacts of non-point pollution.

Freshwater mussels are a viable option to detect real-time changes in water quality within aquatic ecosystems. Known as ecosystem engineers, freshwater mussels are constantly filtering particles and recycling nutrients in the benthic community. Therefore, identifying their physiological responses to alterations in water quality will enable mussels to not only serve as biomonitors but help model their impact on nitrogen cycle. This research focuses on identifying how mussel gape and heart rate respond to the addition of phytoplankton following a period of limited food availability. Immediately following phytoplankton addition, mussels show a decreased gape position linked with changes heart rate. As the gape returns to an open position, overlying ammonia concentrations increase showing an end of the metabolism process. As a result, pairing physiological changes with increased concentrations of phytoplankton, freshwater mussels' impact on ammonium concentrations can be accurately predicted. By inputting experimental excretion rates combined with variations in gape position, dynamic models will be simulate ammonium concentrations in the overlying water.

Labeled by the National Academy of Engineering (NAE) as one of fourteen Grand Challenges for Engineering, the management of the nitrogen cycle has become an increasingly difficult obstacle for sustainable development. In an effort to help overcome this challenge, the goal of our study is to expand on the limited scientific understanding of how the nitrogen cycle within aquatic environments may be affected by increasing human- and climate-induced changes. To this end, we are using freshwater mussels as a sentinel species to better understand the impacts of ecosystem perturbation on nitrogen processing in large river systems. This was completed by examining the physical, biological, and chemical characteristics of a mussel habitat in the Mississippi River, evaluating the impact of the 2008 floods on the habitat and the ecosystem's nutrient processing, establishing a well-equipped mussel laboratory habitat to investigate mussel behavioral responses, and analyzing highly time resolved data to examine the mussels' contribution to daily nitrate fluxes.