A Plataforma Oeste da Península Antártica (POPA) é uma região onde a produtividade primária na superfície do oceano apresenta padrões altamente sazonais e considerável variabilidade interanual. A dinâmica do gelo marinho é o principal fator condicionante da produtividade e, por consequência, dos fluxos de matéria orgânica da superfície para o leito marinho. A matéria orgânica particulada depositada, chamada de fitodetrito, forma densas camadas de alimento lábil disponível para os organismos bênticos. Essa relação estreita entre os processos da coluna de água e aqueles que ocorrem no bentos é chamada de acoplamento bento-pelágico. Com o objetivo de avaliar as respostas da macrofauna bêntica aos fluxos e deposição de alimento, foi realizada uma série temporal sazonal de amostragens (novembro/1999 a março/2001) na POPA em três estações de coleta perpendiculares à costa. Cerca de 25.000 indivíduos pertencentes a 22 táxons foram coletados em 15 amostras de box corer (0,25 m2 cada). Mesmo com alguma variação ao largo da plataforma (de 10.886 ind.m-2 (estação A) a 2.326 ind.m-2 (B)), atribuída a diferenças na topografia, a macrofauna apresentou pouca variabilidade em termos de composição e abundância ao longo do período estudado. Além disso, diferenças na composição e abundância entre estratos sedimentares também foram notáveis, sendo que 90% dos indivíduos foram encontrados entre 0 e 5 cm. Dentre as 185 espécies identificadas, Aurospio foodbancsia (Polychaeta, Spionidae), uma espécie típica de regiões de plataforma na Antártica, mas muito próxima da espécie de mar profundo A. dibranchiata, foi a espécie dominante em todos os períodos e estações (2.087 ind.m-2). Além de Polychaeta, outros grupos abundantes na POPA foram Bivalvia, Tanaidacea e Oligochaeta. Picos de abundância foram observados para algumas espécies, provavelmente associados a eventos sazonais de recrutamento, porém nem sempre associados à chegada do alimento ao fundo marinho da região. Os grupo funcionais de Polychaeta também não variaram ao longo do período estudado, o que indicou que animais depositívoros de superfície e subsuperfície se alimentam ao longo de todo o ano, aproveitando o alimento que permanece lábil e disponível, mesmo no inverno, quando o fluxo de matéria orgânica para o bentos é mínimo. Os resultados encontrados neste trabalho confirmam os resultados já encontrados dentro do projeto FOODBANCS, que a macrofauna da POPA age como um filtro, respondendo menos às flutuações sazonais. / The West Antarctic Peninsula shelf (WAP shelf) experiences a high seasonal and interannual variability in surface primary production. Sea ice dynamics is the principal factor controlling productivity and, therefore, the downward particulate organic matter (POM) fluxes. The deposited POM, also called phytodetritus, forms dense layers of available labile food for benthic organisms. This straight relationship between water column and benthic processes is called benthic-pelagic coupling. A seasonal time-series study was conducted between November 1999 through March 2001 in tree sites on WAP shelf, to determine this relationship, specially the benthic macrofauna (> 300 µm) response to the POM flux and its posterior deposition. From a total of 15 box-corer samples (0.25 m2 each), approximately 25,000 macrofaunal individuals were collected, belonging to 22 taxa. Even with some variation along the shelf, ranging from 10,886 ind.m-2 (site A) to 2,326 ind.m-2 (B), the abundance and composition of macrofauna showed only modest seasonal changes. Differences in these parameters were clear between the inner and outer shelves, probably owing to the topography, which was composed of a basin in the innermost region and a flat region, in the offshore area. Differences in abundance and composition between sediment layers were also notable, with 90% of all individuals belonging to the 0-5 cm layer. Among the 185 identified species, Aurospio foodbancsia (Polychaeta, Spionidae), a typical species of Antarctic shelf regions and closely related to the deep-sea species A. dibranchiata, was dominant in all seasons and sites (2,087 ind.m-2). Besides polychaetes, bivalves, tanaids and oligochaetes were also abundant in WAP shelf. Peaks in abundance were observed for some species and this is believed to be related to seasonal recruitment, however not always associated with the availability of food. Polychaete functional groups did not vary along seasons, indicating that surface and subsurface deposit feeders were subsisting on the labile POM along the year, even during the winter, when POM flux to the benthos is extremely low. The results are similar to those obtained in other FOODBANCS works, and indicate that the WAP shelf macrofauna act as a low-pass filter, muting the seasonal water column processes.

Made available in DSpace on 2015-03-12T11:48:01Z (GMT). No. of bitstreams: 1 MarinaGV_TESE.pdf: 3115364 bytes, checksum: 35f6859ed189e76dc56e8be8b28a3c16 (MD5) Previous issue date: 2013-12-16 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / This study aimed to characterize, for the first time, the benthic invertebrates that inhabit the region of soft bottoms adjacent to the APARC reefs in order to situate them as an important component of infralittoral coastal areas of Northeast Brazil. Soft bottoms areas of APARC corresponds to infralittoral zones vegetated by seagrass Halodule wrightii and unvegetated infralittoral zones, both subjected to substantial hydrodynamic stress. Through scuba diving, biological and sedimentary samples of both habitats were analyzed, with a cylindrical sampler. We identified 6160 individuals belonging to 16 groups and 224 species. The most abundant macrofaunal group was Polychaeta (43%), followed by Mollusca (25%) and Crustacea (14%), what was expected for these environments. In the first chapter, regarding vegetated areas, we tested three hypotheses: the existence of differences in the faunal structure associated with H. wrightii banks submitted to different hydrodynamic conditions; the occurrence of minor temporal variations on the associated macrofauna of banks protected from hydrodynamic stress; and if the diversity of macrofauna is affected by both benthophagous predators and H. wrightii biomass. It was observed that macrofauna associated at the Exposed bank showed differences in structure when comparing the Protected bank, the granulometry of the sediments, that co-varies with the hydrodynamism, was the cause of these variations. The results also pointed to a lower temporal variation in the macrofaunal structure on the Protected bank and a negative relation between macrofaunal and benthophagous fish abundance. At the Exposed bank, a greater faunal diversity was observed, probably due to the higher seagrass biomass. The second chapter compares the vegetated and non-vegetated areas in order to test the hypothesis that due to greater seasonal stability in tropical environments, seagrass structure would act to distinguish the vegetated and non-vegetated areas macrofauna, over time. It was also expected that depositivores were the most representative invertebrates on non-vegetated environments, on the assumption that the seagrass bank would work as a source of debris to adjacent areas, enriching them. Considering all sampling periods, the total macrofauna abundance and diversity were higher in vegetated areas, when compared to non-vegetated ones. Seasonally, the structural complexity provided by Halodule differentiated more clearly the fauna from vegetated and non-vegetated areas, but only at the climatic extremes, i.e. Dry season (extreme climatic stability, with low hydronamism variation) and Rainy season (great hydrodynamism variation and probably vegetated bank burial). Furthermore, the high organic matter levels measured in the sandy banks coincided with an outstanding trophic importance of deposit feeders, proving the debris-carrying hypothesis. The last chapter focused on the non-vegetated areas, where we tested that the hypothesis infaunal halo in tropical reefs depending on local granulometry. In this context, we also tested the hypothesis that benthophagous fish predation would have an effect on the low abundance of macrofaunal groups due to the high hydrographic stress, thus allowing other predatory groups to have greater importance in these environments. Proving the hypothesis, no spatial variation, both on abundance families neither on community structure, occur along distance of the edge reefs. However, we found that complex combinations of physical factors (grain size and organic matter levels originated from local hydronamic conditions) covary with the distance from the reefs and has stronger influence on macrofauna than considered biological factors, such as predation by benthophagous fishes. Based on the main results, this study shows that unconsolidated areas around APARC reefs are noteworthy from an ecological and conservational point of view, as evidenced by the biota-environment and organismal relations, never before described for these areas / Objetivou-se caracterizar, pela primeira vez, os invertebrados bent?nicos que habitam a regi?o de fundos moles adjacentes aos recifes da ?rea de Prote??o Ambiental dos Recifes de Corais (APARC), a fim de situ?-los como importante componente das zonas infralitorais costeiras do Nordeste do Brasil. As ?reas de fundos moles, ou n?o consolidadas, da APARC compreendem regi?es de infralitoral, vegetadas pela angiosperma marinha Halodule wrightii, e regi?es de infralitoral n?o vegetadas, ambas submetidas a um considerado estresse hidrodin?mico. Atrav?s de mergulho aut?nomo, foram analisadas amostras biol?gicas e sedimentares de ambos os habitats, com aux?lio de amostrador cil?ndrico de PVC. Foram identificados 6160 indiv?duos, distribu?dos em 16 grandes grupos e 224 esp?cies, sendo que o grupo macrofaunal mais abundante foi Polychaeta (43%), seguido de Mollusca (25%) e Crustacea (14%), resultado j? esperado para ambientes n?o consolidados infralitorais. No primeiro cap?tulo, relacionado ?s ?reas vegetadas, foram testadas tr?s hip?teses: a exist?ncia de diferen?as na estrutura??o da fauna associada a bancos de H. wrightii, submetidos a diferentes condi??es hidrodin?micas; a ocorr?ncia de menores varia??es temporais sobre a macrofauna associada aos ambientes mais protegidos do estresse hidrodin?mico; e se a diversidade da macrofauna ? afetada, tanto pelos predadores bent?fagos como pela biomassa da pr?pria H. wrightii. Foi verificado que a macrofauna associada do banco Exposto apresentou diferen?as na estrutura??o quando comparado ao banco Protegido, sendo a granulometria dos bancos, a qual varia conjuntamente com o hidrodinamismo, a respons?vel por estas varia??es. Os resultados tamb?m apontaram para uma menor varia??o temporal na estrutura da macrofauna no banco Protegido e uma rela??o negativa entre a abund?ncia macrofaunal e peixes bent?fagos. J? no banco Exposto, foi encontrada uma maior diversidade faunal, provavelmente em fun??o da maior biomassa de gram?nea. O segundo cap?tulo aborda uma compara??o entre ?reas vegetadas e n?o vegetadas, pretendendo testar a hip?tese de que, em fun??o de uma maior estabilidade sazonal nos ambientes tropicais, a estrutura da faner?gama atuaria na distin??o da macrofauna associada entre ?reas vegetadas e n?o vegetadas, ao longo do tempo. Tamb?m se esperava que os deposit?voros fossem os invertebrados mais representativos nos ambientes n?o vegetados, partindo da premissa de que o banco de faner?gama funcionaria como fonte de detritos para ?reas adjacentes, enriquecendo-as. Todavia, sazonalmente, a complexidade estrutural proporcionada por Halodule discriminou, com mais evid?ncia, a fauna de ?reas vegetadas de n?o vegetadas somente nas extremidades clim?ticas, isto ?, no per?odo Seco (extrema estabilidade clim?tica, com pouca varia??o no hidrodinamismo) e no per?odo Chuvoso (grande varia??o do hidrodinamismo e prov?vel soterramento do banco vegetado). Al?m disso, os elevados teores de mat?ria org?nica medidos nos bancos arenosos coincidiram com uma destacada import?ncia tr?fica dos deposit?voros, comprovando a hip?tese de carreamento de detritos. O ?ltimo cap?tulo focou nas ?reas n?o vegetadas, em que se testou a hip?tese de que a varia??o da estrutura da macrofauna perto e longe ocorre em decorr?ncia da granulometria. Neste contexto tamb?m foram testadas a hip?tese de que a preda??o por peixes bent?fagos teria um baixo efeito na abund?ncia dos grupos da macrofauna em fun??o do alto estresse hidrogr?fico, abrindo, assim, espa?o para outros grupos de predadores bent?fagos terem uma maior import?ncia nestes ambientes. Comprovando as hip?teses levantadas, n?o foi verif icada varia??o espacial significativa entre as dist?ncias da borda dos recifes, tanto na abund?ncia das principais fam?lias identificadas como na estrutura geral das comunidades bent?nicas. Entretanto, verificou-se que uma complexa combina??o de fatores f?sicos (tamanho do gr?o e teor de mat?ria org?nica derivadas das condi??es hidrodin?micas locais) variam conjuntamente com a dist?ncia e influencia mais a macrofauna do que os fatores biol?gicos considerados, como a preda??o por peixes bent?fagos. Com base nos principais resultados encontrados, este trabalho mostrou que as ?reas de fundos n?o consolidados do entorno dos recifes da APARC merecem destaque do ponto de vista ecol?gico e de conserva??o, pois evidenciou-se importantes rela??es da biota com o ambiente e da biota com outros organismos n?o descritas antes para estas ?reas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / As extensas pradarias submersas formadas pelas gramas marinhas são importantes habitats da costa, onde ocorrem interações ecológicas entre diversas espécies da vegetação subaquática, invertebrados bentônicos e peixes. As gramas marinhas e algas de deriva são conhecidas como macrófitas marinhas e, por ocuparem o mesmo tipo de substrato, são normalmente encontradas juntas, proporcionando oxigênio, alimento, proteção, abrigo além de sítios de reprodução e pastagem para os animais associados a essas pradarias. Amostras de algas de deriva e de H. wrightii foram coletadas, ao longo de transectos fixos de 50 m paralelos à Ilha do Japonês, a fim de analisar a existência de relações positivas entre as espécies de macrófitas marinhas e sua macrofauna associada, comparar as duas comunidades e avaliar a estruturação da comunidade macrofaunal bêntica do local. Os transectos foram alocados de acordo com a posição do banco de grama marinha. Observou-se que a densidade de eixos e a biomassa de H. wrightii não explicam a variação da biomassa, riqueza de espécies e diversidade (Índice de Simpson) das algas de deriva. A grande movimentação das algas de deriva ao longo do banco de grama marinha faz com que elas se homogeneízem e ocupem diferentes lugares ao acaso na pradaria, muitos desses locais com baixa biomassa de H. wrightii devido à grande variabilidade na distribuição dessa espécie no local de estudo. Os descritores ecológicos da grama marinha também não tiveram relações positivas com sua macrofauna bêntica associada. A comunidade macrofaunal associada às gramas marinhas foi mais densa, rica e diversa do que a comunidade macrofaunal associada às algas de deriva. Os moluscos Anomalocardia flexuosa, Cerithium atratum, Ostrea sp, Tellina lineata e Divalinga quadrissulcata dominaram o ambiente de gramas marinhas. A maior complexidade estrutural das algas de deriva forneceu um habitat protegido mais atrativo para os crustáceos como, Pagurus criniticornis, Cymadusa filosa e Batea catharinensis. A malacofauna associada às algas não foi abundante, mas um novo registro foi a ocorrência do bivalve invasor Lithopaga aristatus, perfurando uma concha de Ostrea sp. As relações entre os descritores da biomassa algal foram comprovadas para a maioria dos descritores de sua fauna associada. As relações das macrófitas marinhas com a macrofauna total associada seguiram o mesmo padrão das relações das algas de deriva. As análises de agrupamento e ordenação mostraram que as comunidades macrofaunais bênticas do local são estruturadas de acordo com os táxons dos organismos associados mais dominantes influenciados pelo tipo de vegetação basibionte (algas de deriva ou grama marinha). Destaca-se com o presente estudo a importância de medidas de maior proteção no local para a preservação e manutenção do ecossistema da Ilha do Japonês, RJ, Brasil / Extensive submerged meadows formed by seagrasses are an important habitat of the coast, where ecological interactions among different species of the submerged vegetation, benthic invertebrates and fish occur. The seagrasses and drift algae are known as marine macrophytes and, since they often can be found occupying the same substrate, they make a viable coexistence, providing oxygen, food, protection, shelter, besides breeding and grazing sites for the animals associated with these meadows. Samples of drift algae and H. wrightii were collected, along fixed 50 meter transects parallel to the Ilha do Japonês, so as to analyze the relationships between the species of marine macrophytes and the associated macrofauna, compare both communities and assess the structure of the local benthic macrofaunal community. Transects were allocated according to the position of the seagrass bed. It was found that shoot density and biomass of seagrasses did not explain the variation in drift algae biomass, species richness and diversity (Simpson index). The constant movement of the drift algae along the seagrass bed makes the algae homogenize and occupy different places by chance on the meadow, many of these places with low biomass of H. wrigthii, due to the high variability on the distribution of this species in the study area. The descriptors of the seagrassdid not have positive relations with its associated fauna either. Macrobenthos associated with the seagrasses was denser, richer and more diverse than the macrobenthic community associated with the drift algae. The mollusks Anomalocardia flexuosa, Cerithium atratum, Ostrea sp., Tellina lineata and Divalinga quadrissulcata dominated the environment of seagrass. The greater structural complexity of drift algae provided a protected habitat more attractive for the detritivores Pagurus criniticornic, Cymadusa filosa and Batea catharinensis. Malacofauna associated with algae was not abundant, but an important record was a new occurrence of the invasive bivalve Myoforceps aristatus, drilling a shell of Ostrea sp. The relationships among the descriptors of the algae biomass were confirmed to most of the descriptors of its associated fauna. Linear relations between marine macrophytes and its total macrobenthic community followed the same pattern as drift algae linear relationships. Cluster and MDS analysis showed that the local macrobenthic communities are structured according to the taxa of the most dominant associated organisms influenced by the type of the basibiont vegetation (drift algae or seagrasses). The present study considers the importance of more protective measures at the place for the preservation and maintenance of Ilha do Japonês ecosystem, RJ, Brasil

Dissertação(mestrado) - Universidade Federal do Rio Grande, Programa de Pós–Graduação em Oceanografia Biológica, Instituto de Oceanografia, 2006. / Submitted by Cristiane Gomides (cristiane_gomides@hotmail.com) on 2013-12-16T02:44:18Z No. of bitstreams: 1 PedrodeSa.pdf: 1303104 bytes, checksum: 596561a98d86d6219a45778a049ce092 (MD5) / Approved for entry into archive by Sabrina Andrade (sabrinabeatriz@ibest.com.br) on 2013-12-18T18:16:36Z (GMT) No. of bitstreams: 1 PedrodeSa.pdf: 1303104 bytes, checksum: 596561a98d86d6219a45778a049ce092 (MD5) / Made available in DSpace on 2013-12-18T18:16:36Z (GMT). No. of bitstreams: 1 PedrodeSa.pdf: 1303104 bytes, checksum: 596561a98d86d6219a45778a049ce092 (MD5) Previous issue date: 2006 / Este trabalho objetiva avaliar a estrutura e dinâmica da associação de macroinvertebrados bentônicos da zona entremarés de dois locais com distintas características ambientais da praia do Cassino, RS, Brasil. O local 1 possui características de praia dissipativa extrema, sedimentos finos e baixa hidrodinâmica, enquanto que o local 2 características dissipativas/intermediárias, sedimento mais grosseiros e maior hidrodinâmica. Eventos esporádicos de deposição de lama são observados no local 1. Foi realizado um acompanhamento durante 14 meses (abril/04 até maio/05) com amostragens mensais. Os 2 primeiros meses foram considerados como piloto, sendo seus dados abordados no capítulo III. Em cada local, foram demarcadas três transversais (separadas por 50m) perpendicular a linha d’água, nas quais amostras foram coletadas em triplicata em 4 níveis (separados por 10 m). As transversais se estenderam desde 10m acima do varrido superior, até cerca de 1m de profundidade. No capítulo I, foi considerada a variabilidade temporal da associação. Esta apresentou uma marcada dinâmica, sendo as principais variações ligadas às dinâmicas populacionais e perturbações físicas. Durante o inverno foram observadas baixas densidades, as quais foram relacionadas à ausência de recrutamentos, deposição de lama em abril e embancamentos de baixas intensidades. Na primavera ocorreu explosão populacional de Scolelepis gaucha, migração de adultos de Mesodesma mactroides do infralitoral para a zona entremarés e um evento de embancamento. Durante o verão foram observados recrutamentos de M. mactroides, Donax hanleyanus e Emerita brasiliensis. O outono foi caracterizado por baixas densidades, exceto pelo recrutamento de D. hanleyanus. O capítulo II abordou a distribuição perpendicular à linha d’água e paralela à linha d’água da fauna em diferentes escalas. O local 2 apresentou maior diversidade do que o local 1. A diversidade foi maior provavelmente devido a presença dos anfípodes Phoxocephalopsis sp. e Plastyschnopidae, os quais estiveram praticamente ausentes no local 1. Verificou-se que praias dissipativas/intermediárias podem suportar maior diversidade da macrofauna bentônica do que as dissipativas extremas, possivelmente, pela capacidade da associação macrozoobentônica de se beneficiar da maior hidrodinâmica na zona de varrido. As diversidades menores no local 1, podem ainda, ser atribuídas as perturbações causadas pelas deposições esporádicas de lama. Através de análises multivariadas foram identificadas 3 zonas: o mesolitoral médio, o superior do varrido e o inferior do varrido juntamente com a arrebentação interna. As espécies características de cada zona variaram com a estação do ano. Foram observadas densidades decrescentes do mesolitoral em direção ao infralitoral. Não foram evidentes padrões de distribuição paralela à linha d’água na escala de dezenas de metros, devido a grande homogeneidade sedimentar registrada nesta escala. No capítulo III foram analisados com maiores detalhes dois eventos: mortalidade pós deposição de lama em abril/04 e embancamento em outubro/05. A recomposição da fauna mostrou-se bastante rápida, em ambos eventos, registrou-se a mesma composição após 3 meses, entretanto as populações foram caracterizadas por organismos juvenis e recém assentados. Sendo que a manutenção de estoques adultos foi afetada. A deposição de lama ocasionou a mortalidade de toda a associação. O evento de embancamento afetou, principalmente, os juvenis+adultos do bivalvo M. mactroides. É provável que esses eventos sejam o principal fator estruturador de longo prazo das associações destes locais. / The present study aims to analyze the structure and dynamics of the intertidal macrobenthic assemblages in two sites with distinct environmental characteristics of Cassino beach, RS, Brazil. Site 1 can be characterized as an extreme dissipative beach, with fine sediments and low hydrodynamics and site 2 is a dissipative/intermediate beach, with coarser sands and high hydrodynamics. Sporadic muddy deposition events occur in site 1. Sampling was conduct monthly from april/2004 to may/2005. Data from the fist two months was considered as a pilot study and was included just in chapter III. In each site, three transect lines, spaced 50 m apart, were defined perpendicular to the shore line, samples were collect in triplicate in 4 levels (10 m apart). Each transect was extend from 10 above de swash limit to 1m deep in the inner surf zone. Chapter I aimed to describe the temporal variability of the intertidal assemblages. A striking dynamics was recognized through samplings times. The mains temporal changes were influenced by the population dynamics of numerically dominants species and physical disturbances. In winter was found a low density and diversity of the assemblages, with were related to absence of recruitments, an event of muddy deposition and stranding events of low effects. In spring was observed a population explosion of the polychaeta Scolelepis gaucha, migration of Mesodesma mactroides adults from the subtidal to the intertidal and a strand event. During summer was observed recruitments of tidal migrant species as M. mactoides, Donax hanleyanus and Emerita brasiliensis. Fall was characterized by low densities, except for an expressive recruitment of D. hanleyanus. Chapter 2 aimed to describe the spatial distribution across shore and along shore in distinct scales. Site 2 showed a higher diversity than site 1. The higher diversity were probably due the presence of amphipods Phoxocephalopsis sp. and Plastyschnopidae in site 2, which were absent in site 1. The results showed that dissipative/intermediate can support higher diversities than extreme dissipative conditions, probably because the assemblage can be beneficiated by the higher hydrodynamics of swash. The low diversities found in site 1, may be also related to sporadic muddy deposition events. The multivariate analyses showed three macrofaunal zones: mesolitoral; the higher swash; the lower swash together with the inner surf zone. The characteristics species of each zone varied according to the season. A decrease of density was verified from mesolitoral zone to the lower levels. No patterns were identified in a smaller scale (50m) of the along shore distribution, probably due the high homogeneity of the morpho-dynamics and sediments in this scale. In Chapter III, the period that occurred two mortality events were analyzed with more detail: muddy deposition in april/2004 and stranding in october/2004. The recuperation of the macrofauna assemblages was extremely fast, in three months they showed the same composition, although the populations were characterized by high densities of recruitments and juvenis. The adult stokes may be heavily impacted by this events. The muddy deposition caused a mortality of all population of the intertidal assemblages. The bivalve M. mactroides juvenis+adults was the organism most affected by the strand event. It’s likely that these events are the main long term factors structuring this assemblage.

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Sandy beaches are often highly allochthonous, depending on external subsidies of carbon and nutrients. Despite this, sandy beach macrofaunal assemblages have received little attention regarding their response to enhanced primary productivity generated from coastal upwelling. This thesis investigates the influence of upwelling on macrofaunal assemblages over a variety of spatial and temporal scales. Spatially, four regions were examined across two biogeographic provinces to remove temperature as a confounding factor, and limit biogeography-specific effects. A nested hierarchical design enabled both large and small scales to be examined and generalities about upwelling effects across multiple areas to be considered. Sampling was conducted in two seasons, and over two years, to test the persistence of any effects. Biogeography and region had the strongest influences on macrofaunal biodiversity. Upwelling influenced macrofaunal assemblages in every region when analyses were conducted at the species level. However, the particular effect, positive or negative, differed among regions depending on local factors, and between the response variables, abundance and biomass. Coarser scales of taxonomy, feeding guild and developmental mode were investigated; however, the influence of upwelling generally became weaker and more varied, and occasionally disappeared. Seasonality was greater on the South Coast but was still important in some analyses on the West Coast. At the small-scale, variation within-beaches was lower than between beaches, assemblage structure remained stable over time, and consistent zonation was not present. The influence of temperature on filtration rate and oxygen consumption of Donax serra was investigated to test a driving mechanism for assemblage responses to upwelling. Feeding ability was significantly reduced at colder temperatures indicating an important factor which may be involved in determining assemblage structure. These results suggest that alterations to upwelling regimes predicted under climate change scenarios will impact sandy beach macrofauna, however the specific outcome will depend on multiple contextual factors.

L’objectif général était d’évaluer la réponse du macrobenthos à la dynamique d’un herbier marin à Zostera noltii (colonisation, maturation, destruction, restauration), dans le Bassin d’Arcachon, une lagune du sud-ouest de la France. Quand l’herbier commence à se développer, la structure de la macrofaune diverge immédiatement entre habitats d’herbier et de sables nus, sans cependant que les indice biotiques testés (BENTIX, BOPA, AMBI) varient. De même, la population du bivalve dominant, la coque (Cerastoderma edule), souffre du développement de l’herbier. Sa communauté parasitaire (trématodes) est modifiée, sans que cela n’influe sur la dynamique des coques. A l’échelle du Bassin, le développement de l’herbier (considéré comme un signe de “bonne santé”) a été comparé à la santé de deux bivalves endogés dominants, la palourde japonaise (Ruditapes philippinarum) et la coque (C. edule), évaluée en termes de prévalence de maladie. Aucune corrélation n’existe entre le taux de recouvrement d’herbier et la prévalence de trois maladies (trématodiase, perkinsose, maladie du muscle marron). Entre 2002 et 2010, la surface d’herbier a diminué de 1/3. En termes de structure de communautés et d’espèces dominantes, peu de différences sont notées au sein de chaque année (entre les 12 stations) et entre années, indépendamment du déclin de l’herbier. Parmi les indicateurs biotiques, l’indice multivarié MISS est en adéquation avec la relative similarité de la structure de la macrofaune benthique entre les groupes discriminés par l’analyse MDS. En 2005, des activités de dragage dans le Bassin d’Arcachon ont abouti à l’enfouissement de 0,32 km2 d’herbier à Z. noltii. La structure du macrobenthos a été immédiatement modifiée sans retour à l’état initial sur les zones couvertes de sable. En revanche, le macrobenthos (endofaune) s’est rapidement rétabli dans les zones couvertes de vase alors que l’herbier n’a commencé à se développer qu’au bout de 5 ans après les travaux. Le dernier chapitre de cette thèse donne un bref aperçu des connaissances actuelles sur les herbiers vietnamiens et des possibles travaux scientifiques à mener. / The overall objective was to assess macrobenthos response to marine Zostera noltii seagrass dynamics (colonization, maturation, destruction, restoration), in Arcachon Bay, a French Southwestern lagoon.When seagrass starts to develop, the structure of macrofauna community immediately diverges between sand and seagrass habitats, without however modifying tested biotic indices (BENTIX, BOPA, AMBI). As well, population of the dominant bivalve, the cockle (Cerastoderma edule), suffers from seagrass development. Their parasite (trematode) community are impacted, but not sufficiently to explain cockle deficit in seagrass.At the scale of the Bay, seagrass development (considered as a sign of “good health”) is compared to the fitness of the two dominant infaunal bivalves, the Manila clam (Ruditapes philippinarum) and the cockle (Cerastoderma edule), measured in terms of disease prevalence. There was no correlation among seagrass cover rate and the prevalence of three diseases: trematodiosis, perkinsosis and Brown Muscle Disease.Between 2002 and 2010, seagrass cover decreased by 1/3. When looking at community structure and dominant species, there were moderate differences within (among 12 stations) and among years, independently of seagrass decline. Among biotic indicators, multivariate index MISS was in adequation with the relative similarity of macrofauna structure among groups discriminated by MISS analysis.In 2005, dredging activities in Arcachon Bay led in burying 0.32 km2 of Z. noltii. Macrobenthos structure was immediately modified and did not recover in places buried by sand. Conversely, macrobenthos (infauna) recovered rapidly in areas cover by mud, while seagrass began to develop again five years after work. The last chapter of the thesis provides a brief insight of the seagrass in Vietnam, the actual knowledge and what could be investigated.

This thesis examines the contribution of a non-indigenous red alga, Mazzaella japonica, to wrack subsidies in Baynes Sound, British Columbia, and the effects of its removal by a commercial beach-cast harvest. Field and laboratory work was conducted to determine: 1) How large wrack inputs are in terms of biomass and spatial extent within the harvest region, and what proportion of this is comprised of M. japonica; 2) how wrack characteristics influence associated macrofauna communities; 3) if there is any detectable effect of beach-cast harvesting on either the wrack characteristics or macrofauna communities; and 4) if M. japonica provides a food source for native invertebrate consumers within the subtidal and supralittoral zones. Field surveys conducted from November 2014 through March 2015 found that wrack biomass within the harvest region could reach as much as 853 kg (±173 SD) per meter of shoreline, and cover up to 35 m2 (± 3 SD) of beach surface within this area. The macrophyte composition of the wrack was dominated by M. japonica, which accounted for 90% of the identifiable macrophyte biomass on average. Wrack in the later stages of decomposition hosted the most speciose and diverse assemblages of macrofauna, though community composition also differed among collection sites and with depth of the wrack. Though we were limited in our ability to disentangle the effects of beach-cast harvesting due to a concentration of effort at one site, we failed to detect any large influence on wrack biomass or macrofauna communities. Harvesting does, however, appear to be associated with a greater area of wrack cover and decreased mean depth. Stable isotope mixing models estimated that M. japonica contributed no more than 22% and 17% on average to the diets of supralittoral and subtidal consumers respectively, despite its overwhelming dominance in both environments. These results suggest that the non-indigenous red alga may experience a reprieve from herbivory within the subtidal environment. A lack of consumption within the supralittoral zone could influence nutrient cycling on recipient beaches and increase propagule pressure in the surrounding regions. Results from these studies are intended to help inform the management of M. japonica and its commercial harvesting. Combined, they indicate that this non-indigenous seaweed does not provide a substantial subsidy in the form of food provision for resident invertebrates. Furthermore, the commercial removal of M. japonica is small compared to the total biomass available, and had no detectable effect on the wrack-associated macrofauna communities examined. / Graduate / 2017-08-19 / jjulin.holden@gmail.com

A qualidade do solo está relacionada ao seu funcionamento e é mensurada por indicadores físicos e químicos, como também por organismos, os quais desempenham as mais variadas funções ecossistêmicas. A diversidade da pedofauna nos ecossistemas pode ser afetada por vários fatores, justamente por esses invertebrados serem sensíveis às mudanças ambientais. A pesquisa avaliou a qualidade de solos de fragmentos florestais urbanos na cidade de São Paulo, especificamente nos parques Cientec, Cantareira e Jaraguá, utilizando espécies de minhocas como bioindicadoras. Foi realizada nas áreas de estudo uma coleta concentrada no inverno (09/2014; 10/2014) em ambientes seco e úmido, com o objetivo de verificar a diversidade, ocorrência, biomassa (g.m²) e densidade (Ind.m²) dos indivíduos coletados e sua relação com as variações ambientais, especialmente com a temperatura do solo, profundidade do solo, presença e ausência de drenagem na parcela e atributos químicos como, pH, C.O, K, P, Ca, Mg e Al. Delimitou-se aleatoriamente, em ambiente seco e úmido, uma área fixa de 1,7 hectare por parcela amostral, onde foram amostrados nove TSBF por ambiente, com espaçamento de 30 m entre cada ponto e 20 m de bordadura, totalizando 54 pontos amostrais. Os exemplares de pedofauna subsuperficial foram capturados pela técnica TSBF (Tropical Soil Biology and Fertility), que consiste em monólitos de 30x30 de largura e 30 cm de profundidade. Após a triagem do solo os exemplares foram colocados em soluções de álcool 92%, e posteriormente, mensurados estatisticamente pelos índices de diversidade, equabilidade, e biomassa; por fim, foram identificados ao nível de espécie, as minhocas, e ao nível de família e gênero, as classes arachnida, coleoptera, quilopoda e diplopoda. Nos mesmos pontos do TSBF foram coletadas amostras de solo para a análise dos atributos químicos, assim como foram utilizados dados climáticos para avaliação de atributos físicos, que serviram como variáveis ambientais explicativas. Dos atributos climáticos, nos meses analisados a precipitação mensal não atingiu 70 mm e, em geral, ficou abaixo da média climatológica, caracterizando um período extremamente seco. Encontrou-se uma correlação positiva entre temperatura do solo, diversidade ecológica funcional, distribuição vertical no solo, hábito alimentar e dinâmica de biopedoturbação das minhocas. A umidade do solo influenciou diretamente ocorrência de Ind.m², além de favorecer espécies e gêneros específicos. Na análise de parâmetros químicos, a diminuição da acidez do solo, o aumento do teor de C.O e elevada disponibilidade de macronutrientes influenciaram no aumento de Ind.m² e o que justifica os 159 Ind.m² em ambiente seco e 148 Ind. m² em ambiente úmido para o Parque Jaraguá, representando 46% do total de exemplares coletados. O parque Cientec e Cantareira apresentaram solos muito ácidos e menores índices de C.O e macronutrientes se comparados com o parque Jaraguá, totalizando 24% e 30% dos exemplares coletados. Os índices bioestatísticos apontaram que as minhocas foram predominantes, tanto em densidade (minhocas.m²) quanto em biomassa (g.m²) dentre toda a macrofauna edáfica coletada e confirmaram que as variáveis químicas e climáticas do solo tem maior relevância para explicar a diversidade, ocorrência, biomassa e densidade de minhocas e consequentemente, as funções ecossistêmicas desempenhadas pelas mesmas. / Soil quality is related to its functioning and is measured by physical and chemical indicators, but also by organisms inserted therein, which play the most diverse ecosystem functions. The diversity of soil macrofauna in ecosystems can be affected by many factors, due these organisms being sensitive to environmental changes. The research evaluated the quality of urban forest fragments soils in São Paulo, specifically in Cientec, Cantareira and Jaraguá parks, using earthworms as bioindicators. It was performed at study sites a concentrated collection in winter (09/2014, 10/2014), in dry and wet environments, in order to assess the diversity, occurrence, biomass and density of individuals collected in accordance with variations in environment ,especially with soil temperature, soil depth, presence and absence of the drainage portion and chemical attributes such as , pH, O.C, K, Ca, Mg and Al. Delimited randomly, in a dry and humid environment a fixed area of 1.7 hectare per plot sample, where was sampled nine TSBF per environment, with spacing of 30 m between each point and 20 m margin, totaling 54 sampling points. Exemplary subsurface pedofauna were captured by adapted TSBF technique (Tropical Soil Biology and Fertility) consisting of monoliths 30x30 wide and 30 cm deep. After the soil screening the specimens were fixed in 92% alcohol solution and subsequently measured statistically by the diversity index, equability, and biomass; finally, were identified to species level, earthworms, and the family level and genus, the arachnida, coleoptera, quilopoda and diplopoda classes. In the same points of TSBF soil samples were collected for analysis of chemical attributes, as well as climate data were used for evaluation of physical attributes, which served as explanatory environmental variables. About the climatic attributes in the analyzed months, the monthly rainfall did not reach 70 mm and, in general, was below the climatological average, featuring an extremely dry period. It was found a positive correlation between soil temperature, functional ecological diversity, vertical distribution in the soil, feeding habits and dynamics of bioturbation of earthworms. Soil moisture directly influenced the frequency Ind.m², besides favoring specific genus and species. In the analysis of chemical parameters, the reduction of soil acidity, increased O.C. content and the high nutrient availability influenced the increase of Ind.m² which explains the 159 ind.m² in dry conditions and 148 ind. m² in a humid environment for the Jaraguá park, representing 46% of all copies of the collection TSBF. The Cientec and Cantareira park had more acidic and lower rates of soil organic carbon and macronutrients if compared to the Jaraguá park, totaling 24% and 30% of the collected specimens. The biostatisticians indexes pointed out that the worms were prevalent in both density (earthworms.m²) and biomass (g.m²), among all the soil macrofauna collected in contrasting environments and sites and confirmed that chemical soil and climatic variables have greater relevance to explain the diversity, occurrence, biomass and density of earthworms and consequently the ecosystem functions performed by them.

<p>A low content of organic matter, which is largely refractory in nature, is characteristic of most sediments, meaning that aquatic deposit-feeders live on a very poor food source. The food is derived mainly from sedimenting phytodetritus, and in temperate waters like the Baltic Sea, from seasonal phytoplankton blooms. Deposit-feeders are either bulk-feeders, or selective feeders, which preferentially ingest the more organic-rich particles in the sediment, including phytodetritus, microbes and meiofauna.</p><p>The soft-bottom benthos of the Baltic Sea has low species biodiversity and is dominated by a few macrobenthic species, among which the most numerous are the two deposit-feeding amphipods <i>Monoporeia affinis</i> and<i> Pontoporeia femorata</i>, and the bivalve <i>Macoma balthica</i>. This thesis is based on laboratory experiments on the feeding of these three species, and on the priapulid <i>Halicryptus spinulosus.</i> </p><p>Feeding by benthic animals is often difficult to observe, but can be effectively studied by the use of tracers. Here we used the radioactive isotope ¹⁴C to label food items and to trace the organic matter uptake in the animals, while the stable isotopes ¹³C and¹⁵N were used to follow feeding on aged organic matter in the sediment. </p><p>The abundance of<i> M. balthica</i> and the amphipods tends to be negatively correlated, i.e., fewer bivalves are found at sites with dense populations of amphipods, with the known explanation that newly settled <i>M. balthica</i> spat are killed by the amphipods. Whether the postlarvae are just accidentally killed, or also ingested after being killed was tested by labelling the postlarvae with ¹⁴C and Rhodamine B. Both tracer techniques gave similar evidence for predation on and ingestion of postlarval bivalves. We calculated that this predation was likely to supply less than one percent of the daily carbon requirement for <i>M. affinis</i>, but might nevertheless be an important factor limiting recruitment of <i>M. balthica. </i></p><p>The two amphipods <i>M. affinis</i> and <i>P. femorata </i>are partly vertically segregated in the sediment, but whether they also feed at different depths was unknown. By adding fresh 14C-labelled algae either on the sediment surface or mixed into the sediment, we were able to distinguish surface from subsurface feeding. We found <i>M. affinis</i> and <i>P. femorata</i> to be surface and subsurface deposit-feeders, respectively. </p><p>Whether the amphipods also feed on old organic matter, was studied by adding fresh ¹⁴C-labelled algae on the sediment surface, and using aged, one-year-old ¹³C- and ¹⁵N-labelled sediment as deep sediment. Ingestion of old organic matter, traced by the stable isotopes, differed between the two species, with a higher uptake for <i>P. femorata</i>, suggesting that <i>P. femorata</i> utilises the older, deeper-buried organic matter to a greater extent.</p><p>Feeding studies with juveniles of both <i>M. affinis</i> and <i>P. femorata</i> had not been done previously. In an experiment with the same procedure and treatments as for the adults, juveniles of both amphipod species were found to have similar feeding strategies. They fed on both fresh and old sediment, with no partitioning of food resources, making them likely to be competitors for the same food resource. </p><p>Oxygen deficiency has become more wide-spread in the Baltic Sea proper in the last half-century, and upwards of 70 000km² are now devoid of macrofauna, even though part of that area does not have oxygen concentrations low enough to directly kill the macrofauna. We made week-long experiments on the rate of feeding on ¹⁴C-labelled diatoms spread on the sediment surface in different oxygen concentrations for both the amphipod species, <i>M. balthica</i> and <i>H. spinulosus. </i>The amphipods were the most sensitive to oxygen deficiency and showed reduced feeding and lower survival at low oxygen concentrations.<i> M. balthica</i> showed reduced feeding at the lowest oxygen concentration, but no mortality increase. The survival of <i>H. spinulosus</i> was unaffected, but it did not feed, showing that it is not a surface deposit-feeder. We conclude that low oxygen concentrations that are not directly lethal, but reduce food intake, may lead to starvation and death in the longer term.</p>