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The El Nino–Southern Oscillation (ENSO) strongly influences climate and hydrology on the planet and may drive the structure and functioning of estuarine communities. However, the effects of the ENSO on coastal areas are dependent on the spatial scale and the intrinsic characteristics of the estuary. Over six years (2013 to 2018), we investigated the variability in macrobenthic secondary production of Spartina alterniflora marshes and adjacent unvegetated areas in a subtropical coastal lagoon in Southern Brazil. We tested whether the ENSO events affect the benthic secondary production of these two habitats. Most environmental variables (air temperature, northward surface stress and northward wind component) did not differ significantly between ENSO phases, except for precipitation. Monthly precipitation totals during El Nino months were 70% higher than neutral and La Nina conditions. A total of 25,862 organisms (8,191 in salt marshes and 17,671 in unvegetated areas) belonging to 39 taxa (25 in marshes and 34 unvegetated areas) were collected throughout the study. The tanaid Monokalliapseudes schubarti, and Nereididae polychaeta Laeonereis acuta were largely the most abundant species in both vegetated and unvegetated areas, with higher biomass and productivity. The secondary production in unvegetated areas increased 216%, from a mean of 107.5 g C/m2/y to 336.4 g C/m2/y during El Nino. However, the salt marshes responded differently than the unvegetated areas, with secondary production more stable over the time, with highest value of 164.2 g C/m2/y-1. There is also a distinction in the effects on different species, L. acuta showed an increase only in biomass (from 0.024 to 0.042 g DW/0.03m2), whereas M. schubarti increased both in biomass (more than 4000%) and density (more than 5000%). In contrast, no significant differences in density, biomass and secondary production for both species were detected over time in the salt marshes. Our findings indicate that large scale climatic variations, such as ENSO, can strongly affect estuarine density, biomass and secondary production, but salt marshes buffer El Nino effects on benthic associations.

Summary Brazil has one of the largest varieties of aquatic ecosystems and rich freshwater biodiversity, but these components have constantly been damaged by the expansion of unsustainable activities. Free-living nematodes are an abundant and ubiquitous component of continental benthic communities, occurring in all freshwater habitats, including extreme environments. Despite this, hardly any studies have examined the generic composition of nematodes in different latitudes and the geographic overlap of assemblages. We provide data on nematode genera from six regions in Brazil, over a north-south gradient spanning about 4000 km, encompassing rivers, coastal lakes, and reservoirs with different levels of human impact. Interpolation/extrapolation curves were generated and the zeta diversity was used to assess the overlap of nematode assemblages. Freshwater nematode assemblages comprised 54 families and 132 genera. Mononchidae, Monhysteridae, Chromadoridae, Tobrilidae and Dorylaimidae were the most diverse families. Differences in diversity and high turnover of genera were found among regions, probably related to stochastic processes. Mononchus was the only widely distributed genus. Our results revealed a high biodiversity of free-living freshwater nematodes among the regions. The limited spatial coverage of the data reveals an enormous knowledge gap in a country with 12% of the world’s freshwater resources. The lack of spatial patterns, e.g., latitudinal variation, suggests that freshwater nematode assemblages are primarily structured by the intrinsic properties of habitats. This reinforces the uniqueness of freshwater ecosystems and suggests that the nematode assemblages may be sensitive to environmental disturbances, since the limited distributions of taxa may lead to lower resilience.

In Brazil, the mosquito Aedes (Stegomyia) aegypti is considered the main vector of the dengue, chikungunya, and Zika arbovirus transmission. Recent epidemiological studies in southern Brazil have shown an increase in the incidence of dengue, raising concerns over epidemiological control, monitoring, and surveys. Therefore, this study aimed at performing a historical spatiotemporal analysis of the Ae. aegypti house indices (HI) in southern Brazil over the last 19 years. As vector infestation was associated with climatic and environmental variables, HI data from the Brazilian Ministry of Health, climate data from the Giovanni web-based application, and environmental data from the Mapbiomas project were used in this study. Our results showed an expressive increase in the number of HI surveys in the municipalities confirming the vector presence, as compared to those in 2017. Environmental variables, such as urban infrastructure, precipitation, temperature, and humidity, were positively correlated with the Ae. aegypti HI. This was the first study to analyze Ae. aegypti HI surveys in municipalities of southern Brazil, and our findings could help in developing and planning disease control strategies to improve public health.

The El Nino–Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO) are large-scale climatic phenomena affecting atmospheric and oceanic teleconnections, and thus triggering weather events at different temporal and spatial scales, both in tropical and extratropical areas. During 11 years (2007–2017), the influence of ENSO events (El Nino, La Nina and neutral), ENSO types (canonical and Modoki) and PDO phases (cold and warm) on meteorological conditions and macrobenthic invertebrates were analyzed in two distinct (tide-dominated and river-dominated) subtropical estuaries of Southern Brazil. The estuarine macrobenthic communities differed markedly, with higher species richness in the tide-dominated estuary (146 taxa) than river-dominated (44). We showed that long-term variability of benthic macrofauna in both estuaries was strongly influenced by the PDO and ENSO events. However, the signs of PDO and ENSO effects differed between the estuaries. While the main modulating force of the decadal variability of the macrofauna of the tide-dominated estuary was the PDO (19%), the river-dominated estuary was primarily influenced by the ENSO (9%). Besides, PDO and ENSO teleconnections have combined effects, with higher macrofauna dissimilarities during constructive periods (PDO Positive/EL Nino vs. PDO Negative/La Nina). Our findings indicate that: (1) The effects of the ENSO on coastal areas are dependent of the spatial scale and the intrinsic characteristics of each estuary; (2) Studies relating ENSO and biodiversity should consider the ENSO type (Modoki and canonical) and interdecadal modes, such as PDO, because the location of the warm pools and the intensity of induced heating affect the atmospheric teleconnections.

Rhodoliths are free-living and morphologically diverse marine calcareous algae commonly distributed over the continental shelf seafloor. They increase the seabed structural complexity and are of potential value as feeding and reproductive grounds for a myriad of marine fauna. The higher structural seabed complexity within rhodolith beds may also increase benthic diversity by creating microhabitats, but this relationship has been rarely explored within rhodolith beds worldwide. Here we compared benthic macrofaunal (>500 µm) structure on rhodolith beds (nodule epifauna) and within unconsolidated sediments (sediment infauna) under high and low-density beds to test whether rhodolith bed density and nodule morphology influenced macrofaunal assemblages. We observed that macrofaunal density on nodules (2538 ± 288.7 ind·m−2) was 15-fold higher when compared to sediments under those beds (166 ± 38.8 ind·m−2). Rhodolith bed density was positively related to macrofaunal density, composition, and functional diversity on the rhodoliths. Low-density beds (61 ± 27.1 nodules·m−2) with discoid-shape nodules were dominated by peracarid crustaceans whereas high-density beds (204 ± 18.7 nodules·m−2) with spheroidal nodules were dominated by Annelid polychaetes. The sediment macrofauna was also positively influenced by the density of rhodolith nodules, which increased sediment carbonate and organic quality (protein and lipids) under high-density beds. Macrofaunal functional diversity was generally higher on rhodoliths, with low similarity (low nestedness) and high taxa turnover between macrofaunal assemblages of rhodoliths and sediments. These findings indicate that rhodolith beds provide an unique habitat for benthic macrofaunal communities, with exclusive functional and taxonomic richness that are likely not typical in the unconsolidated sediment below these beds in SE Brazil. This study highlights the importance of protecting rhodolith beds from multiple sources of anthropogenic disturbance and exploration on continental shelves.

Aedes albopictus is native to Asia and is ranked among the top 100 invasive species worldwide, with vector competence for dengue, Zika, and chikungunya viruses. Understanding Ae. albopictus dispersal is essential for effective monitoring and vector control strategies. In this study, we analysed and updated the distribution of Ae. albopictus in Brazil using data available from the Ministry of Health through the Rapid Index Survey for Aedes (LIRA) for the years 2015-2020. The results of this research were mapped to visually represent the current distribution of Ae. albopictus in Brazil. In 2015, the presence of the vector was confirmed in 271 of the 1,820 Brazilian municipalities sampled (14.9%), and in 2020 it was detected in 728 of the 2,937 municipalities sampled (24.8%). In 2020, all Brazilian states had recorded the presence of this critical vector with a broader geographic distribution in the Southeast and Midwest regions as compared to the North, Northeast, and South regions. It was possible to note some stabilization of dispersion of this species in the Brazilian territory. The record of Ae. albopictus distribution advanced in Brazilian states and municipalities from 2015 to 2020; it is suggested that surveys of this vector be conducted periodically in all Brazilian municipalities and authorities should developing control strategies for this species together with Ae. aegypti.

Rhodolith beds increase the seabed complexity and are hotspots of biodiversity. Despite the crucial ecosystem services provided by rhodoliths, they are threatened by global change and local anthropogenic impacts. In this study, conducted on one of the largest beds of calcareous algae in the world located on the continental shelf of eastern Brazil, we tested whether the higher complexity of the seabed within rhodolith beds could explain the spatial biodiversity patterns of free-living nematodes. Our results show that beds with the highest densities of rhodoliths are associated with higher sedimentary organic matter (OM) contents and by a different biochemical composition. The higher OM nutritional quantity and nutritional quality, as shown by higher biopolymeric C contents and higher values of the protein to carbohydrate ratio, respectively, were associated with higher abundance, biomass, and diversity of nematode genera, thus supporting our hypothesis. Though based on a correlative approach, the results of this study suggest that a decrease in density of rhodoliths caused by human impacts may affect benthic biodiversity and, consequently, the range of ecosystem services they provide.

This study presents the first stable isotopic and sclerochronological calibration of the bivalve Anomalocardia flexuosa (Linnaeus, 1767) in relation to environmental variables in a subtropical coastal area of southern Brazil. We investigate incremental shell growth patterns and δ18O and δ13C values of modern specimens collected alive from the Laguna Lagoonal System (LLS). Shells of Anomalocardia flexuosa are also one of the main biological components of pre-Columbian archaeological shell mounds and middens distributed along the Brazilian coastline. We therefore selected archaeological specimens from a local late Holocene shell mound (Cabecuda) to compare their stable carbon and oxygen isotope values with those of modern specimens. Shell growth increments, δ18O and δ13C values respond to a complex of environmental conditions, involving, for example, the effects of temperature and salinity. The isotopic information extracted from archaeological specimens from Cabecuda shell midden in the LLS indirectly indicates that environmental conditions during the late Holocene were different from present day. In particular, intra-shell δ18O and δ13C values of archaeological shells reveal a stronger marine influence at 3 ka cal BP, which is in contrast to the seasonal freshwater/seawater balance that currently prevails at the LLS.

Made available in DSpace on 2018-12-11T16:54:47Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-11-15 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Current climate change directly affects species distribution by altering their physical environment and indirectly by altering interspecific interactions. The geographical distribution of fiddler crabs, keystone species of intertidal estuarine sediments, is supposed to expand poleward as a response to climate change. We experimentally investigate whether the introduction of a new species of fiddler crabs, where another different species already occurs, may affect the structural and functional composition of meiobenthic communities in intertidal areas. In order to disentangle the effect of abundance from species identity, we set up two indoor experiments (substitutive and a partial additive design) manipulating the diversity and density of two keystone species, Leptuca uruguayensis and L. leptodactyla. The results showed that the increase of the diversity keystone species did not impact any measured descriptors of nematode assemblages. By contrast, high density of keystone species, independent of the species, strongly affected the meiofauna total density, and the density of numerically dominant nematode genera. The results did not reveal any functional change in the meiofauna. Our experiments, designed to mimic the indirect effects of range expansion showed that while increasing diversity of functionally redundant keystone species had no effect on preys, increasing density negatively affected the structure of intertidal habitats. Marine Science Laboratory University of Southern Santa Catarina UNISUL, Av Acácio Moreira 787, Dehon Laboratory of Ecology and Animal Behaviour São Paulo State University UNESP Biosciences Institute Coastal Campus Praça Infante Dom Henrique, s/n, Bitaru Laboratory of Ecology and Animal Behaviour São Paulo State University UNESP Biosciences Institute Coastal Campus Praça Infante Dom Henrique, s/n, Bitaru

As regiões costeiras têm exibido um rápido crescimento urbano sem, no entanto, estar associado a um adequado planejamento. Dentro das diversas fontes de alteração destas regiões estão as provenientes dos efluentes domésticos que são lançados através dos dutos de drenagem urbana. O sistema de drenagem urbana pode ser caracterizado como o conjunto de resíduos que percorrem as canaletas das vias públicas desembocando nos dutos também conhecidos como bocas de lobo. Além destas substâncias, a contaminação de áreas estuarinas pode ser ainda agravada pelas ligações residenciais clandestinas de esgoto junto a esta rede de drenagem. Este estudo objetivou investigar a resposta de associações bênticas, representadas pelo microfitobentos, macrofauna e meiofauna, frente ao coquetel de substâncias lançadas através da desembocadura de dutos de drenagem urbana. Para isso foram tomadas amostras imediatamente junto aos dutos de drenagem urbana e a aproximadamente 10 metros lateralmente em áreas com influência do lançamento de drenagem. Áreas controles igualmente estabelecidas e localizadas a aproximadamente 1000 metros distantes dos dutos. Parâmetros como salinidade, temperatura, pH, teor de matéria orgânica, granulometria, coliformes fecais e totais foram analisados juntamente com as associações bênticas. Os resultados deste estudo mostram que a estrutura das associações bênticas foram afetadas com a drenagem urbana. Locais com despejo direto de drenagem, apresentaram menor biomassa microfitobêntica. Do mesmo modo, a macrofauna foi menos diversa nesses locais. A meiofauna apresentou-se como um interessante indicador de perturbações ambientais, visto que sua diversidade e riqueza foram menores nos locais afetados pela drenagem urbana. O presente estudo alerta para as intensas descargas recebidas pelos ambientes aquáticos. Por tratar-se de uma poluição crônica, muitas vezes é considerada coadjuvante. Uma vez que os impactos causados referem-se não só as associações bênticas, como ao estuário inteiro é imprescindível que sejam realizados mais estudos envolvendo a resposta do estuário frente a essas perturbações.

Estuaries are threatened coastal ecosystems that support relevant ecological functions worldwide. The predicted global climate changes demand actions to understand, anticipate and avoid further damage to estuarine habitats. In this study we reviewed data on polychaete assemblages, as a surrogate for overall benthic communities, from 51 estuaries along five Marine Ecoregions of Brazil (Amazonia, NE Brazil, E Brazil, SE Brazil and Rio Grande). We critically evaluated the adaptive capacity and ultimately the resilience to decadal changes in temperature and rainfall of the polychaete assemblages. As a support for theoretical predictions on changes linked to global warming we compared the variability of benthic assemblages across the ecoregions with a 40-year time series of temperature and rainfall data. We found a significant upward trend in temperature during the last four decades at all marine ecoregions of Brazil, while rainfall increase was restricted to the SE Brazil ecoregion. Benthic assemblages and climate trends varied significantly among and within ecoregions. The high variability in climate patterns in estuaries within the same ecoregion may lead to correspondingly high levels of noise on the expected responses of benthic fauna. Nonetheless, we expect changes in community structure and productivity of benthic species at marine ecoregions under increasing influence of higher temperatures, extreme events and pollution.

Sedimentary sterols and linear alkylbenzenes associated with allochthonous organic matter (AOM) inputs were studied in surface sediments along the Tubarão riverbed, South Brazil. These markers were analysed in terms of concentrations, diagnostic ratios and by using multivariate analyses to identify the main organic matter sources. It was necessary to integrate all these factors to distinguish the sources and determine sewage contamination. Phytosterols predominated over faecal sterols, but the contributions of livestock waste along the river (determined in 50% of the sites) were confirmed by the fingerprint analysis. Raw sewage contamination was verified at one site, according to the increased levels of sewage molecular markers and confirmed by the multivariate analyses and diagnostic ratios calibrated to this region. A possible synergistic effect between inorganic nanoparticles from coal mine waste and organic contaminants related to AOM input was suggested and should not be ignored since both activities severely contribute to the environmental changes in much of this fluvial-estuarine gradient from the South Atlantic.

A urbanizacao de areas costeiras nao tem sido acompanhada de tratamento adequado de esgoto, e a sobrecarga de materia orgânica compromete importantes valores economicos, ecologicos e sociais suportados por esses ecossistemas. Os emissarios oceânicos podem ser uma alternativa eficaz para o destino final das aguas residuarias nas regioes costeiras, desde que devidamente instalados e monitorados. Neste estudo nos investigamos os efeitos de um pequeno emissario em uma costa arenosa e de alta energia, utilizando como indicadores esteroides sedimentares, composicao bioquimica e qualidade nutricional da materia orgânica e biodiversidade da meiofauna. Os resultados mostraram que perturbacoes fisicas predominaram nas areas proximas ao emissario, afetando as densidades da fauna e a concentracao de fitopigmentos. As maiores concentracoes de esterois sedimentares, detectados a 1000 m a NE do emissario, indicaram a influencia da hidrodinâmica local no processo de transporte e dispersao do esgoto. Nesta area, a contaminacao do esgoto alterou o estado trofico bentico e levou a uma forte diminuicao na diversidade trofica e aumento de formas oportunistas. No geral, os resultados mostraram um impacto espacial relativamente baixo e espacialmente limitado do emissario. O uso combinado de esterois fecais, estado trofico bentico e biodiversidade da meiofauna foram muito eficazes na deteccao da contaminacao de esgoto por um pequeno emissario de aguas residuarias em uma costa arenosa e de alta energia.

Environmental filtering is a major mechanism structuring ecological communities. However, it is still not clear how different abiotic drivers composing the environmental filter interact with each other to determine local species assemblage and create spatial patterns in species distribution. Here, we evaluated the effects of two strong and uncorrelated environmental variables (salinity and sediment properties) on the β-diversity of an estuarine macrobenthic community while accounting for spatial effects. Our results show that the benthic community composition has a strong spatial structure along the estuary, which can be greatly explained by salinity and sediment variation. Salinity is most associated with species replacement (turnover), whereas sediment is more important for species loss (nestedness). However, the effects of sediment variation on nestedness are mainly detected at a smaller spatial scale (estuarine sectors), whereas the effects of salinity on species turnover are stronger as spatial scale increases (entire estuary). Our findings suggest that environmental filters can drive both turnover and nestedness components of β-diversity, but that their relative importance depends on the spatial scale of investigation. Although abiotic drivers associated with detrimental effects (sediment) usually result in nestedness, larger spatial scales encompass abiotic drivers associated with different suitable conditions (salinity), increasing the relative importance of the replacement component of species β-diversity.

This chapter examines the estuaries within the Southern Brazilian Marine Ecoregion (SBE), a coastline of some 850 km in the tropical-temperate transition zone of the extreme southern portion of Brazil. A particular attention is given to the ecology of benthic communities, considering their structure, functioning, impacts, and conservation issues. In a microtidal and wave dominated environment, there are tens of small coastal plain estuaries and lagoons along the SBE. Although there is much overlapping of characteristics between small estuaries and lagoons, differences in the freshwater influence, spatial organization, and variability of gradients constitute important drivers since they directly affect species composition, abundance, and dominance of ecological guilds. This is particularly true for estuaries with intermittently open inlets, which are dominant in SBE. El Nino Southern Oscillation (ENSO) has a strong influence on the regional climate, affecting interannual estuarine hydrodynamics, benthic fauna distribution and recruitment. The environmental quality status of 27 SBE estuarine systems according to the AZTI Marine Biotic Index (AMBI index) was largely classified as moderately disturbed (80%), whereas 20% of the sites were of slightly or undisturbed classifications. Different categories of marine protected areas (MPAs) are implemented in the estuaries in the SBE. Although MPAs, the Brazilian Coastal Management Plan as well as other policies could foster the sustainable use of coastal resources and ecosystem services, difficulties in coastal planning and in policy implementation still allow unsustainable practices, impacts, and habitat loss over all SBE estuaries.

Resource subsidies are flows of biologically fixed energy and nutrients from one ecosystem to another. Oceanic sandy beaches are typical examples of systems constantly subjected to subsidies. A distinctive feature of some exposed sandy beaches is the brown discoloration of surf zone waters due to rich accumulations of diatoms housed on the sediments seaward of the breaker zone. Large amounts of the rich diatom accumulations may end up on the sediments of surf and the intertidal zones of sandy beaches. In this study, we described the seasonal frequency and compared the strength the subsidies among different beaches by measuring sediment chlorophyll a and total organic content. We hypothesized that large amount of fresh diatom subsidies to beaches sediment will fuel meiofauna from the surf zone to the upper intertidal and change the structure of these communities. Our results supported that pulsed subsidies by the deposition of A. glacialis represented an important resource for the meiofauna. The meiofauna responded quickly to the increase in concentrations of labile organic matter in the sediments along different tidal levels of the beach. This subsidized input, however, is not an isolated process but linked with the passage of cold fronts and significant physical changes in the surf zone. Subsides did not fuel surf and intertidal meiofauna similarly. At the surf zone, subsidies were mainly used by those forms that cope with increasingly turbulent flows that paralleled the accumulation events. Yet in the intertidal zone, the densities and richness of the most abundant meiofauna organisms, the nematodes, thrived together with other meiofaunal organisms. Due to their frequency over the time and differences on space, A. glacialis patch deposits most certainly are not the main food item for high-energy sandy beach consumers, but accumulations do represent a window of opportunity for meiofauna during the year, particularly in periods of food shortage during winter.

In the present study, we test whether large-scale patterns of estuarine nematodes are predicted by the “everything is everywhere” (EiE) hypothesis or by the moderate endemicity hypothesis (MEH). Specifically, we tested whether nematode genus richness and composition differ among geographical regions, latitudes, and between habitats (estuaries with and without mangroves). The meta-analysis included published data from 43 estuaries around the world. Only the most abundant genera (>1 % of relative abundance) were considered in the analysis. Each estuary was treated as an analytical unit. Results indicated that genus richness did not differ among geographical regions and between habitats, whereas latitude explained 36 % of the variability in genus richness. Genus richness assumed a bimodal pattern with higher values around the equator and in temperate regions. Canonical analysis revealed distinct nematode genus compositions in three main geographical regions and in both habitat types. These results suggest that nematodes are dispersion-limited and influenced by environmental conditions. The main conclusion is that large-scale patterns of estuarine nematodes are better predicted by the MEH, in line with studies of macroorganisms. Moreover, nematode genus turnover decreased with increasing latitude, a pattern already reported for harpacticoid copepods, land birds, vascular plants, mammals, and butterflies.

The pink prawn Farfantepenaeus paulensis is one of the most valuable fishery resources in the southwest Atlantic. It is exploited along the inner shelf and inside estuarine nursery grounds. Inside the nursery grounds, mainly artisanal fisheries are responsible for the capture of pink prawn juveniles. In this study, we experimentally assessed the impact of a light mini trawl, a gear extensively used for the capture of estuarine prawn along the southeast and south coast of Brazil. We simulated a single impact (represented by three consecutive trawling runs) on vegetated and non-vegetated bottom. Then we monitored changes in sediment properties and the response of the benthic fauna at the trawling and control sites at a logarithmic temporal scale in order to determine the initial impact and the recovery rates. Meiofauna and macrofauna, both numerically dominated by the ostracod Cyprideis multidentata, were significantly more diverse and abundant inside the submerged algal beds than in non-vegetated areas. In the vegetated areas, the only change caused by the mini trawl was a significant decrease in the percentages of fine sediments (silt+clay). By contrast, in the non-vegetated areas, the mini trawl caused a significant decrease of the total meiofauna, mainly due to lower nematode and C. multidentata abundances. Our results show that the mini trawl does not produce a loss of benthic diversity and causes minimal damage to the estuarine benthos. The absence of a general faunal response, as well as the absence of significant changes in sediment properties of the non-vegetated areas suggests that meiofauna may be resuspended rather than killed during trawling. The present study highlights the need for basic studies on gear impact and environmental health of nursery grounds. Otherwise, management of small-scale fisheries will continue to be based on evidence from large-scale fisheries.

Sandy beaches are central economic assets, attracting more recreational users than other coastal ecosystems. However, urbanization and landscape modification can compromise both the functional integrity and the attractiveness of beach ecosystems. Our study aimed at investigating the relationship between sandy beach artificialization and the landscape perception by the users, and between sandy beach visual attractiveness and biodiversity. We conducted visual and biodiversity assessments of urbanized and semiurbanized sandy beaches in Brazil and Uruguay. We specifically examined meiofauna as an indicator of biodiversity. We hypothesized that urbanization of sandy beaches results in a higher number of landscape detractors that negatively affect user evaluation, and that lower-rated beach units support lower levels of biodiversity. We found that urbanized beach units were rated lower than semiurbanized units, indicating that visual quality was sensitive to human interventions. Our expectations regarding the relationship between landscape perception and biodiversity were only partially met; only few structural and functional descriptors of meiofauna assemblages differed among classes of visual quality. However, lower-rated beach units exhibited signs of lower environmental quality, indicated by higher oligochaete densities and significant differences in meiofauna structure. We conclude that managing sandy beaches needs to advance beyond assessment of aesthetic parameters to also include the structure and function of beach ecosystems. Use of such supporting tools for managing sandy beaches is particularly important in view of sea level rise and increasing coastal development.

Estuaries are unique coastal ecosystems that sustain and provide essential ecological services for mankind. Estuarine ecosystems include a variety of habitats with their own sediment-fauna dynamics, all of them globally undergoing alteration or threatened by human activities. Mangrove forests, saltmarshes, tidal flats and other confined estuarine systems are under increasing stress due to human activities leading to habitat and species loss. Combined changes in estuarine hydromorphology and in climate pose severe threats to estuarine ecosystems on a global scale. The ReBentos network is the first integrated attempt in Brazil to monitor estuarine changes in the long term to detect and assess the effects of global warming. This paper is an initial effort of ReBentos to review current knowledge on benthic estuarine ecology in Brazil. We herein present and synthesize all published work on Brazilian estuaries that has focused on the description of benthic communities and related ecological processes. We then use current data on Brazilian estuaries and present recommendations for future studies to address climate change effects, suggesting trends for possible future research and stressing the need for long-term datasets and international partnerships. Resumo Estuários são ecossistemas costeiros que sustentam uma ampla variedade de serviços ambientais para a humanidade. Estuários abrigam muitos ambientes bentônicos com características específicas e seriamente ameaçados globalmente. Manguezais, marismas e planícies de maré são amplamente impactados por poluentes domésticos e industriais, por atividades comerciais que levam à perda de habitat e pela sobrepesca. Os diversos impactos locais, associados a mudanças regionais e globais na hidromorfologia estuarina e potenciais efeitos de mudanças climáticas, colocam sérias ameaças a ecossistemas estuarinos. A rede Bentos foi criada para estudar o efeito de mudanças no clima em ecossistemas bentônicos costeiros brasileiros. Este trabalho faz parte dos esforços iniciais do Grupo de Trabalho Estuários em rever o conhecimento sobre comunidades bentônicas estuarinas no Brasil. Aqui apresentamos uma breve revisão crítica sobre os trabalhos realizados objetivando o estudo, em nível de comunidades, do bentos estuarino e processos ecológicos associados. A partir do cenário atual, realizamos recomendações de estudo para responder questões científicas sobre efeitos de mudanças climáticas em comunidades bentônicas estuarinas, e enfatizamos a necessidade de bases de dados contínuas e de longa duração e o estabelecimento de parcerias internacionais com foco específico nos estuários brasileiros.

The mouth dynamics of temporarily open/closed estuaries (TOCEs) play a key role in their overall functioning. In this study, the effect of the inlet state (closed vs. artificially breached) on spatial variability of macrobenthic invertebrates (composition, abundance, and biomass) was assessed in a temporarily open/closed lagoon of South Brazil (28°35′S/48°52′W). Samplings were carried out in two periods during closed (July and November) and open phases (July and November). Additionally, in order to evaluate possible transitory effects of breaching, data obtained during closed and open phases were compared with those samples taken 60 days after the end of mechanical opening of the mouth (January). The artificial breaching markedly changed the dynamic of the benthic environment. After the inlet dredging and bulldozing, total organic content and microphytobenthic biomass were significantly reduced. The disturbance also resulted in a population crash of the macrobenthic invertebrates, with a reduction of 50% in biomass and 90% in density. Following the shock produced by the artificial breaching, most of the macroinvertebrates descriptors recovered, as shown by the univariate and multivariate analysis. However, a benthic community with a significantly different structure emerged. During the study, the macroinvertebrates from inner portions of the lagoon were less variable than those in the middle or near the lagoon inlet. The results of this study showed that the macrobenthic associations of Camacho lagoon were primarily structured by salinity and microphytobenthic biomass, which in turn, were regulated by the state of the inlet.

The exploratory phase is the first step in drilling operations for oil and gas extraction in oceanic waters. If hydrocarbons are present, additional wells are then drilled to assess the dimension and outline of the petroleum accumulation. Thus, the exploratory program for the ocean areas may foresee the drilling of an expressive number of exploratory wells. When a well is drilled, drilling fluids or mud are launched at high pressure to transport waste cuttings to the surface, maintain well stability, and to cool, lubricate, and support part of the weight of the drill bit and drill pipe (Darley and Gray 1988). Two basic types of drilling fluid are generally used, water-based fluids (WBFs) and non-aqueous fluids (NAFs). According to Darley and Gray (1988), NAFs include all fluids that are non-aqueous and non-water-dispersible, and may

The great variety of geological and hydrological conditions in the deep sea generates many different habitats. Some are only recently explored, although their true extent and geographical coverage are still not fully established. Both continental margins and mid-oceanic seafloors are much more complex ecologically, geologically, chemically and hydrodynamically than originally thought. As a result, fundamental patterns of species distribution first observed and explained in the context of relatively monotonous slopes and abyssal plains must now be re-evaluated in the light of this newly recognized habitat heterogeneity. Based on a global database of nematode genus composition, collected as part of the Census of Marine Life, we show that macrohabitat heterogeneity contributes significantly to total deep-sea nematode diversity on a global scale. Different deep-sea settings harbour specific nematode assemblages. Some of them, like coral rubble zones or nodule areas, are very diverse habitats. Factors such as increased substrate complexity in the case of nodules and corals seem to facilitate the co-existence of a large number of genera with different modes of life, ranging from sediment dwelling to epifaunal. Furthermore, strong biochemical gradients in the case of vents or seeps are responsible for the success of particular genera, which are not prominent in more typical soft sediments. Many nematode deep-sea genera are cosmopolitan, inhabiting a variety of deep-sea habitats and oceans, whereas only 21% of all deep-sea genera recorded are restricted to a single habitat. In addition to habitat heterogeneity, regional differences are important in structuring nematode assemblages. For instance, seeps from different regions yield different genera that thrive on the sulphidic sediments. This study also shows that many areas and habitats remain highly under-sampled, affecting our ability to understand fully the contribution of habitat heterogeneity versus regional differences to global nematode diversity.

This study was elaborated to identify and describe the main links of the sea shrimp productive chain in the municipal district of Laguna, historically known as the main sea shrimp (Litopenaeus vannamei) production area in the State of Santa Catarina, Brazil. The study, held from April to July 2005, previously identified the local productive process through observation, interviews and bibliographical research. Afterwards, specific questionnaires were elaborated for each of the several segments connected to the local activity. A total of 90 interviews were conducted, intending to map out the procedures and functionality of the productive chain, from the necessary inputs for production to the moment of shrimp acquisition by final consumers. Results indicated that the entire productive chain requires actions that range from improvement of sanitary and genetic conditions of larvae to product commercialization. Reduction of bureaucracy in public organs, better investment credit conditions, improvement in productive practices, training of technical and productive labor, and reduction of production costs will not occur until industrialization politics and commercialization of local production are standardized.O presente estudo foi elaborado para identificar e descrever os principais elos da cadeia produtiva no município de Laguna, região que historicamente constitui-se em principal área de produção de camarão marinho (Litopenaeus vannamei) em Santa Catarina, Brasil. O estudo foi desenvolvido de abril a julho de 2005, a partir de uma prévia identificação do processo produtivo local, através de observação, entrevistas e busca bibliográfica. Foram elaborados questionários específicos para os vários segmentos atrelados à atividade local. Foi realizado um total de 90 entrevistas, pretendendo-se fazer um acompanhamento do desempenho e funcionalidade da cadeia produtiva desde os insumos necessários à produção até o momento da aquisição do camarão pelo consumidor final. Os resultados indicam que todos os elos descritos necessitam ações que visem desde o melhoramento sanitário e genético das pós-larvas até a comercialização do produto. Desburocratização dos órgãos públicos, maior acesso ao crédito para investimentos, melhorias nas práticas produtivas, capacitação da mão-de-obra técnica e produtiva e redução de custos produtivos não ocorrerão até haver uma normalização das políticas industriais e de comercialização da produção local.

The impact of mussel farms on the benthic environment was investigated using free-living nematode assemblages as indicators of environmental condition of the Enseada do Brito, a shallow embayment in South Brazil. The studied area is located at the State of Santa Catarina, responsible for 90% of the production of mussel farmed in the country. Samplings were carried out quarterly, from July 2004 to May 2005, below mussel ropes and at control sites located 300 m apart from the longlines. The results suggested that the mussel culture changed ecological functioning of the benthic environment at studied coastal embayment. The intense organic loads due to the biodeposition of the mussel farms, which had been in production for more than 10 years, have turned fine and well-sorted sand bottoms into a muddy deposit with significantly higher total organic content than the control. The number of nematode genera, diversity, dominance and trophic diversity were significantly lower under the mussel farms than at the control sites. The mussel farms biodeposition had also affected the temporal variability of nematode assemblages, which was detected only for samples at the control sites. The low depth and environmental energy, together with the age of the farms, were probably responsible for the observed changes in the nematode assemblages.

The response of the meiofauna communities to the discharge of synthetic-based mud (SBM) cuttings from an exploratory drill was analyzed in a deep-sea site (mean depth of 890 m) in the Campos Basin, southeast Brazil. A total of 159 samples were taken on three sampling cruises: one pre- and two post-drilling (1 month and 1 year after drilling). One month after drilling, significant decreases in the meiofauna density and number of taxa were observed, as well as in nematode density and richness (number of families and genera); conversely, relative abundances of non-selective deposit-feeding nematodes, particularly the genus Sabatieria, increased significantly. Univariate and multivariate analyses indicate that the impacts on meiofauna were not restricted to a potential area of impact predicted by a model of cuttings dispersal; meiofauna changes just after the drilling agreed with the model in showing northward dispersal but over a larger area. The meiofauna, however, showed a weak correlation with the analyzed chemical parameters, such as hydrocarbon and metal concentrations. The results suggest that the effects of SBM drill cutting discharge on the meiofauna were probably related to physical changes in the substrate. Twelve months after drilling, most of the values of the meiofauna descriptors had returned to pre-impact period values. Nonetheless, the multivariate structure of meiofauna community was still significantly different, and the number of meiofauna taxa, densities of copepods, and epigrowth-feeder nematodes increased significantly. The increase of superficial forms of meiofauna in the deep sea may last until complete disaggregation of the cuttings.

The influence of a passive shrimp fishing gear on benthic communities was studied at Laguna Estuarine System (South Brazil), a shallow choked coastal lagoon. The gear is composed by a group of fyke nets (25 mm mesh size) set in contact to the bottom, fixed with stakes forming a cage-like structure (around 30 m2). Samplings were conducted in the two main fishery areas of the estuarine system, Mirim (sand bottoms) and Imarui (muddy bottoms) lagoon, in May 2005. In each area, 10 fyke net enclosures and 10 nearby sites without nets (control) were sampled. Microphytobenthos biomass (chlorophyll a and phaeopigments), number of taxa/species, density, Hill’s number N 1 and N 2, and estimated number of species (ES100) were used as community attributes. For the nematodes, values of the maturity index and abundance of Wieser’s feeding type were used as well. The effects of the small-scale passive shrimp fishing gear on the coastal lagoon bottoms were dependent on the benthic component analyzed and the type of sediment. Whereas macrofauna was not affected by the net enclosures, meiofauna and nematodes, particularly from the mud sites were. At the sand site, the fyke net enclosures caused a decrease in the microphytobenthos biomass and changed the relative abundances of non-selective deposit feeding and epigrowth-feeding nematodes. The results indicated that small-scale static nets, such as the studied fyke enclosures, produced low intensity levels of disturbance. However, the enclosed area by nets at Laguna had already reached around 25,000 m2. Given the large proportion of the coastal population involved and the area closed by nets, management policies should consider site-specific differences within the same estuarine system.

There is little meiofauna data from the southwest Atlantic, and especially lacking are studies examining deep-sea communities. In this study, the structure of meiofauna communities, particularly nematodes, was analyzed from data derived from 101 samples (48 samples on the continental-slope and 53 samples at a deep-sea site) collected at Campos Basin, SE Brazil. Differences in the meiofauna densities and in the number of taxa between continental slope and deep-sea sites depended on the taxonomic level examined. While total meiofauna abundance did not differ significantly between sites, nematode densities were significantly higher in the deep sea (mean of 157 inds.10 cm−2) than on the slope (mean of 129 inds.10 cm−2). The number of meiofauna taxa was significantly higher at the continental slope site. Yet for the most abundant meiofaunal group, the nematodes, whilst the number of families did not differ between continental slope and deep sites, the number of genera was significantly higher in the deep sea. The remarkable resemblance between the dominant nematodes (Halalaimus, Acantholaimus, Daptonema, Theristus and Sabatieria) from SE Brazil and other deep sea studies confirmed earlier suggestions of a typical deep-sea nematode community with a broad geographical distribution. Multivariate analysis derived from meiofauna and nematode data showed that the structure of the fauna differed significantly between sites. Correlations detected between meiofauna and some sediment properties, such as grain size and sediment heterogeneity, although significant, were very low.

The effects of cold fronts in a shallow sublittoral system at the Island of Santa Catarina, S Brazil, were investigated in June 2002. Atmospheric, pelagic and benthic data were taken daily covering the days before, during and after the passage of two cold fronts, summing 8 days of sampling. The results clearly showed that the passage of cold fronts, a short-term event, promote changes in the whole shallow sublittoral system, from the pelagic to the benthic one. At the pelagic system, both the cold fronts changed seston, nutrients and chlorophyll a concentrations. The increase in chlorophyll a just after the cold fronts probably resulted from phytoplankton retention and accumulation next to the coast, the microphytobenthos resuspension and the increase in nutrients availability. At the benthic system, sediment features and all of the three benthic components studied- microphytobenthos, meiofauna and macrofauna were also affected by the passage of the cold fronts. The sediments from the studied site suffered a clear homogenizing process. While medium grain size decreased, fine sand percentages gradually increased after the cold front passage. In contrast, sediment organic content was significantly higher just after the first cold front. The effects of the passage of cold fronts in the benthos were dependent on the biological component, the vertical distribution and on the cold front magnitude. The sediment chlorophyll a concentration was lower exactly one day after both cold fronts passage while phaeopigments were significantly higher. The results of the study showed that both macrofauna and meiofauna, particularly nematodes, of the upper layer of the sediment exhibited a decrease in density and number of taxa during the passage of the first frontal system. The nematodes, more than suffering erosion and transport, showed a vertical migration process to the deeper layers of the sediment during the passage of the cold fronts.

The composition and abundance of the meiofauna and macrofauna were studied in a survey carried out within 6 locations in a mangrove at the Island of Santa Catarina, South Brazil. Nine meiofaunal taxa were registered with densities ranging between 77 and 1589 inds.10 cm−2. The nematodes, composed by 94 putative species (86 genera), largely dominated the meiofauna. The most abundant genera were Haliplectus (Haliplectidae), Anoplostoma (Anoplostomatidae) and Terschillingia (Linhomoidae). Contrary to the meiofauna, the macrofauna showed a low number of taxa (only 17 recorded) and abundance (up 7250 inds.m−2). The macrofauna was mainly composed by deposit feeders, and numerically dominated by oligochaetes and capitellid polychaetes. For both components, differences in the composition and abundance along the sampling sites were significant but not primarily related to the typical variations along estuaries, such as salinity. The results of the stepwise multiple regression analyses showed that the detritus biomass (ash-free dry weight) was the most important predictor of faunal densities and diversity. The clear relationship between detritus and fauna, together with the contrasting community structure of the two component of the benthos suggest that the meiofauna showed a high efficiency in exploiting the micro-habitat created by the presence of the detritus. Yet the macrofauna, potentially the main consumer of the debris, is negatively affected by their low palatability and poor nutritive value.

The composition of meiobenthic and macrobenthic communities between different intertidal reef-flat pools on Rocas Atoll (South Atlantic) was compared, and related to properties of the carbonate sediments and patterns of reef growth. Both univariate and multivariate statistical analyses showed that the reef height and size influenced the properties of the reef-derived sediments and were correlated with the composition and abundance of the benthic fauna in the intertidal pools. The temperature and the salinity between Rocas tidal flat reef pools did not vary significantly, despite the differences in size, exposure degree and elevation, suggesting that percolation through the porous lime body of the reef and/or the connection between the tidal pools and seawater by blowholes have a significant effect on the tidal pools. The major asymmetry in the reef topography of Rocas Atoll was observed between the leeward and windward reefs, which paralleled the largest changes in sediment properties and faunal structure inside intertidal reef pools. Sediments from the tidal pools located in the windward side of the atoll were significantly finer, the organic content higher and the benthic fauna more abundant and diverse. The results of this study suggest that significant changes in the sediment properties and benthic community structure between the intertidal reef-flat pools of Rocas Atoll may be primarily conditioned by different patterns in reef growth.

Rocas, the only atoll in the South Atlantic, is located 266 km off the northeast Brazilian coast. Spatial patterns in community structure of meiofauna, particularly nematodes, and macrofauna were examined along a transect through the sediment path from windward to leeward of the Rocas Atoll sand flat. Differences in benthic community structure between four zones of the sand flat were found to be significant and related to the major local processes of carbonate-grain transport and sedimentation. Both meiobenthic and macrobenthic assemblages were significantly more diverse and abundant within the sediment inflow zone (the initial part of the detrital path of Rocas sand flat) than in the other zones, where a clear impoverishment of benthic invertebrates occurred. This first study of the benthos of an intertidal sand flat over a reef island in the Atlantic showed that the meiofauna is numerically dominated by the nematodes Metoncholainus sp. 1 (Oncholaimidae) and Epsilonema sp. 1 (Epsilonematidade), whilst the macrofauna is largely dominated by oligochaetes and large Oncholaimidae nematodes. Analysis of the species composition, trophic structure and abundance of both the meiobenthos and the macrobenthos revealed an impoverished community subjected to an intense water-movement disturbance.

Rocas is the only atoll of the South Atlantic and it is built almost exclusively by coralline red algae, vermetid gastropods and encrusting foraminiferans. Patterns in the community structure of meiofauna and macrofauna, particularly nematodes and polychaetes, at Rocas Atoll, north-east Brazil, are determined and compared for different habitats: sublittoral, tidal flat, reef pools and lagoon. Nematodes and copepods were the most abundant meiofaunal taxa. In all studied habitats at Rocas Atoll, oligochaetes, nematodes and polychaetes numerically dominate the macrofauna. Univariate and multivariate analyses reveal clear differences in community structure between the habitats of the atoll, especially between the sublittoral and the inner habitats. The number of species, total density, diversity (H') and trophic structure vary significantly between the habitats, but the differences are dependent on which faunistic category (meiobenthic or macrobenthic) is analysed. Nematodes belonging to the Epsilonematidae and Draconematidae, together with a diverse community of meiobenthic polychaetes, characterize the sublittoral habitat of Rocas Atoll. Both meiofauna and macrofauna are depressed in the tidal flat, and the local sediment instability particularly affects the polychaete abundance. Reef pools and lagoons support a very dense aggregation of invertebrates, particularly the macrofauna, when compared with other carbonate reef sediments. However, differences in the structure of meiofauna and macrofauna communities between reef pools and lagoons are not significant. Changes in meiobenthic and macrobenthic community structure are related to the gradation in the physical environment of the atoll.

Topographically controlled fronts are small-scale phenomena caused by the interaction between currents and complex reef topography, resulting in zones of convergence and eddies where debris and organisms are accumulated. Rocas is the only atoll in the South Atlantic (3°51’S, 33°49' W) and it is constructed predominantly by coralline red algae, vermetid gastropods and encrusting foraminiferans. The structure of meiobenthic and macrobenthic communities, particularly nematodes and polychaetes, over the sublittoral carbonate deposits was examined during May 1996. Univariate and multivariate analyses showed a gradual change in the meiobenthic and macrobenthic community structure from the windward to the leeward side of Rocas Atoll, which was significantly correlated with the measured environmental variables. The characteristics of the carbonate deposits, ranging from coarse sands to medium well-sorted sand, and their enrichment process towards the leeward, as shown by the organic content, suggest a strong linkage with the hydrodynamic regime. Even though both components of the benthos are influenced by this hydrodynamic heterogeneity, the meiobenthic and macrobenthic fauna over the sublittoral area of Rocas Atoll are affected in different ways. Changes in the hydrodynamic regime promote a significant increase in diversity and density of the meiofauna, particularly nematodes, but the macrobenthos showed a more complex response, with a decreasing number of taxa and a variable abundance towards the leeward side. The results of this study suggest that the significant changes in the sediment characteristics and benthic community structure along the atoll may be a result of topographically controlled fronts.

The influence of Spartina alterniflora marshes and detritus availability on the spatial structure and time variability of macrobenthic associations was investigated in Paranagua Bay, a subtropical estuary in southern Brazil. Four sampling sites were established along the salinity and exposure gradient of Paranagua Bay in the winter and summer of 1992. At each site, 5 samples (0.02 m2corer) were taken in the salt marshes and adjacent unvegetated tidal flats. Sediment composition, salt marsh structure (stem height and density, live and dead above- and below-ground biomass of S. alterniflora) and vegetal detritus biomass were determined to assess whether they can affect the dynamics of macrobenthic invertebrates. The development of salt marshes and the amount of detritus, the latter mainly originated from adjacent mangroves, were determined by the energy and salinity gradients along the bay. Plant above- and below-ground components, together with detritus biomass, exert a strong influence on the composition and distribution of macrofauna in Paranagua Bay. Salt marshes support higher densities and species number of macrobenthic invertebrates. Multivariate analyses showed that oscillations of different fractions of Spartina alterniflora, as well as detritus availability, affect the different components of macrobenthic associations in a variable degree. Spatial and temporal shifts of infaunal organisms appear to be more evident than those of mobile epibenthic forms.

Superficial sediment characteristics of salt marshes and adjacent unvegetated sites were compared in Paranagua Bay, SE Brazil, in order to assess the influence of Spartina alterniflora . Twenty stations were sampled along a salinity and environmental gradient, from the inner to the outer bay, to provide a first characterization of sediment distribution along the tidal flats. Paranagua Bay was then divided into three different sectors according to the hydrodynamic regime and sediment characteristics. The mesohaline sector is characterized by typically fluid sediments, with the predominance of medium silt, and high organic and water contents. Deposits of the middle polyhaline sector are poorly sorted, very fine sands, with variable organic matter content. Sediments in the higher-energy euhaline sector are well-sorted fine sands, with low organic content. Four sampling sites were chosen in different sectors to assess whether S. alterniflora marshes can introduce differences in sediment texture along spatial and seasonal gradients. Differences in sediment parameters between marshes and unvegetated tidal flats are not evident in the inner sector, but are increasingly significant towards the high-energy euhaline sector. With the exception of water and organic content, the latter usually higher in summer, seasonal differences in sediment parameters are not significant. The results suggest that differences between the sediments of salt marshes and adjacent unvegetated tidal flats are positively correlated with the environmental energy gradient along Paranagua Bay. Sand unavailability and high sedimentation rates lead to a marked sedimentological homogeneity between vegetated and unvegetated flats in the upper reaches of the bay. On the other hand, S. alterniflora is a major source of sediment heterogeneity between vegetated and unvegetated sites in the high-energy euhaline sector, characterized by more mature sediments.

Intertidal zonation and seasonal variability of benthic macrofaunawere analysed along a Spartina alterniflora (Loisel) marshand nearby unvegetated flat in a subtropical bay. Fivereplicate samples were taken along six tidal levels from the uppermarsh, limited by mangroves, to the lower unvegetated flat.Sediment composition, live and dead above- and below-ground biomassof S. alterniflora and detritus biomass from the vegetatedand unvegetated areas were determined to evaluate whethervariations on plant structure and detritus along the 25 m transectaffect the dynamics of benthic invertebrates. Composition andabundance of invertebrates varied with the elevation and plantcover clearly plays a key role on the distribution patterns of themacrofauna. Below-ground and dead above-ground biomass presentedthe highest correlation with the densities of the invertebrates.Vertical distribution of benthic fauna, however, appears not to beaffected by bellow-ground fraction. Higher detritus biomass in theupper unvegetated flat coincided with higher densities ofdetritivorous or omnivorous species in this level. An eruptivealgal growth during summer affected positively most of the dominantspecies.

This study summarizes taxonomic information on polychaetes from Santa Catarina State, southern Brazil, between25º57'S and 29º23'S, and provides species distribution records together with information on habitats, based on historicaldata and novel records from primary surveys. Rarefaction curves showed that most species were found in the shallowsublittoral (to 60 m) rather than in deep sublittoral (>60 m) or estuarine habitats. Altogether, 228 valid species belongingto 141 genera and 44 families were recorded. This inventory adds 141 new records to previous regional reports. We founda shift in occurrence of species when comparing data from the study area with data from both southward (29–33º S) andnorthward (23–26º S) sites. Few species were shared between consecutive sites: this could be a response to the regionalbehaviour of the atmosphere and water masses, with a progressive increase in the influence of subantarctic waters and a decrease in the influence of subtropical waters.

An experimental analysis of benthic response to sediment disturbance by the blue crab Callinectes danae was carried out in an unvegetated flat adjacent to a salt marsh of the tidal Perequ& Creek (Paranagua Bay, SE Brazil). In order to mimic the natural pits dug by C. danae, we made randomly arranged holes, which were subsequently sampled together with undisturbed control sites on 6 different sampling dates, up to 18 d after disturbance. Analyses of variance were performed to determine if significant differences in macrobenthic population densities and abiotic parameters existed at different sampling times, and between control and disturbed areas. Apart from water content, physical variables did not differ significantly between disturbed and control areas, suggesting that adaptive strategies of the organisms themselves were the maln structuring factor of the recolonization process. We provide evidence that active immigration, together with passlve deposition, is a major colonization vector for the fauna of local low-energy tidal flats. Recolonization rates of the local fauna paralleled the mobility degrees of individual species or taxa. The numerically dominant surface crawler Heleobia australis and the burrower Lumbrineris tetraura, which are the more mobile species of local macrofauna, also exhibited the more rapid recolonization. There was no evidence that the catchment action of pits actually concentrated food resources, since sediment organic content was essentially similar between disturbed and control sites. Evidence for passive deposition was shown for the sedentariate species Laeonereis acuta, Capitella capitata and an unidentified nematode, whose recolonization rates were moderate and followed the sediment infill of pits. The only species to exhibit evidence of exploiting conditions created by pit simulation was the suspension-feeding bivalve Anomalocardia brasiliana that exhibited fast recolonization rates and higher abundance at disturbed sites. The infaunal predator Sigambra grubji was the only species present at significantly lower densities in pits throughout the experiment, probably due to the removal of its putative food source. Disturbances made by blue crabs, though short-lived, are abundant and frequent enough actually to maintain high densities of species that are otherwise scarce in similar tidal habitats. Such biogenic disturbances can be considered as a mechanism that allows for the persistence and numerical dominance of opportunistic species in tidal flats of local tidal creeks.

The present study investigates the effects of drill cutting discharges on the structure of meiofauna communities in an area of the shelf break at Campos Basin, Southeast Brazil. Drilling activities were operated, in a first phase, with water-based fluid and, in a second phase, with synthetic fluid paraffin-based (NAF-III). A total of 135 samples taken at a pre-drilling situation (MS1) and two post-drilling moments (MS2 and MS3—3 and 22 months post-drilling, respectively) were analyzed. Effects on meiofauna were dependent on two main factors: 1—the impact received during drilling operation, if water-based or synthetic/water-based drilling fluid and 2—the background state, if it already presented signs of previous drilling activities or not. Based on univariate and multivariate analysis, there were evidences that the most affected area after drilling was those under the influence of synthetic-based fluid and that already had signs of previous drillings activities. The region impacted only by water-based fluid was less affected and the only one that completely recovered after 22 months. Nematodes and copepods had different responses to the impact. While copepods flourish in the impacted area and recovered 22 months after drilling, nematodes were adversely affected shortly after drilling and the community structure only recovered where hydrocarbons had been depleted.