A novel Amazonian reef biome was discovered, encompassing large rhodolith and sponge beds under low light, low oxygen, and high POC.

A B S T R A C TThis paper provides a description of the wave climate off the Brazilian coast based on an eleven-year time series (Jan/1997-Dec/2007) obtained from the NWW3 operational model hindcast reanalysis. Information about wave climate in Brazilian waters is very scarce and mainly based on occasional short-term observations, the present analysis being the first covering such temporal and spatial scales. To define the wave climate, six sectors were defined and analyzed along the Brazilian shelf-break: South (W1), Southeast (W2), Central (W3), East (W4), Northeast (W5) and North (W6). W1, W2 and W3 wave regimes are determined by the South Atlantic High (SAH) and the passage of synoptic cold fronts; W4, W5 and W6 are controlled by the Intertropical Convergence Zone (ITCZ) and its meridional oscillation. The most energetic waves are from the S, generated by the strong winds associated to the passage of cold fronts, which mainly affect the southern region. Wave power presents a decrease in energy levels from south to north, with its annual variation showing that the winter months are the most energetic in W1 to W4, while in W5 and W6 the most energetic conditions occur during the austral summer. The information presented here provides boundary conditions for studies related to coastal processes, fundamental for a better understanding of the Brazilian coastal zone. R E S U M OO presente trabalho apresenta o clima de ondas da região ao largo da costa brasileira com base em uma série temporal de onze anos (Jan/1997-Dez/2007) obtida através de dados de reanálise do modelo operacional NWW3. Informações sobre o regime de ondas no Brasil são escassas e baseadas em observações ocasionais de curto período, sendo a presente análise inédita na escala espaço-temporal apresentada. Para a definição do clima de ondas foram definidos e analisados seis setores ao longo da quebra da plataforma continental brasileira: Sul (W1), Sudeste (W2), Central (W3), Leste (W4), Nordeste (W5) e Norte (W6). W1, W2 e W3 possuem os regimes de ondas controlados pela Alta Subtropical do Atlântico Sul (ASAS) e pela passagem de frentes frias sinóticas; W4, W5 e W6 são controlados pela Zona de Convergência Intertropical (ZCIT) e sua oscilação meridional. As ondas mais energéticas são de S, geradas por ventos intensos associados à passagem de frentes frias, afetando principalmente a região sul e sudeste do país. A energia das ondas apresenta um decréscimo de sul para norte, com a sua variação anual mostrando que o período de inverno as ondas são mais energéticas nos setores W1 a W4, enquanto que nos setores W5 e W6 as condições mais energéticas ocorrem nos meses de verão do hemisfério sul. As informações aqui apresentadas fornecem condições de contorno para diferentes estudos relacionados a processos costeiros, fundamentais para a melhor compreensão da zona costeira do Brasil.

Here we provide a broad overview of the Great Amazon Reef System (GARS) based on the first-ever video surveys of the region. This footage supports four major hypotheses: (1) the GARS area may be six times larger than previously suggested (up to 56,000 km 2 ); (2) the GARS may extend deeper than previously suggested (up to 220 m); (3) the GARS is composed of a greater complexity and diversity of habitats than previously recognized (e.g., reef platforms, reef walls, rhodolith beds, and sponge bottoms); and (4) the GARS represents a useful system to test whether a deep corridor connects the Caribbean Sea to the Southwest Atlantic Ocean. We also call attention to the urgent need to adopt precautionary conservation measures to protect the region in the face of increasing threats from extractive oil and gas practices. With less than 5% of the potential area of the GARS surveyed so far, more research will be required to inform a systematic conservation planning approach and determine how best to establish a network of marine protected areas. Such planning will be required to reconcile extractive activities with effective biodiversity conservation in the GARS.

The present work characterizes the time-space scales of variability and forcing dependencies of a unique 26 year record of daily to hourly shoreline data from a steep beach at Duck, North Carolina. Shoreline positions over a 1500 m alongshore span were estimated using a new algorithm called ASLIM based on fitting the band of high light intensity in time exposure images to a local Gaussian fit, with a subsequent Kalman filter to reduce noise and uncertainty. Our findings revealed that the shoreline change at long times scales dominates seasonal variability, despite that wave forcing had only 2% variance at interannual frequencies. The shoreline response presented 66% of the variance at interannual scales. These results were not expected since from wave forcing it would have been expected that the shoreline response should similarly lack interannual variability, but we found it to be dominated by this scale. The alongshoremean shoreline time series revealed no significant annual cycle. However, there are annual oscillations in the shoreline response that are coherent with wave forcing and deserves further explanations. The pier was found to have a significant influence on shoreline behavior since restricts the seasonal longshore transport between the sides, resulting in a seasonally reversing sediment accumulation. Thus, there is a significant annual peak in shoreline variability that is coherent with the annual forcing but becomes insignificant in the longshore-average.

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(Praça do Oceanográfio, 191, SP, Brasil) 4 Centro de Pesquisas Aquáticas do Instituto de Pesquisas Científicas e Tecnológicas do Estado do Amapá (Rodovia Juscelino Kubitschek, km 10, 68903-000 Macapá, AP, Brasil)Corresponding author: nilsasp@ufpa.br A B S T R A C TThe hydrodynamics, morphology and sedimentology of the Taperaçu estuary were investigated. This is one of several estuaries located within the largest mangrove fringe in the world, bordering the Amazon region, subject to a macrotidal regime and regionally atypical negligible fresh water supply. The results reveal widespread sand banks that occupy the central portion of the estuarine crosssection. Well-sorted very fine sandy sediments of marine origin prevail. Shorter flood phases, with substantially higher current velocities, were observed in the upper sector of Taperaçu, as expected for a shallow, friction-dominated estuary. However, ebb domination can be expected for estuaries with large associated mangrove areas and substantial estuarine infilling, both of which situations occur on the Taperaçu. The tidal asymmetry favoring flood currents could be the result of the absence of an effective fluvial discharge. Furthermore, it was observed that the Taperaçu is connected by tidal creeks to the neighboring Caeté estuary, allowing a stronger flux during the flood and intensifying the higher flood currents. As a whole, the results have shown a complex interaction of morphological aspects (friction, fluvial drainage, connections with neighbor estuaries, infilling and large storage area) in determining hydrodynamic patterns, thus improving the understanding of Amazon estuaries. R E S U M OA hidrodinâmica, morfologia e sedimentologia do estuário do Taperaçu foram investigadas. Este é um entre vários estuários do litoral amazônico que integram a maior extensão contínua de manguezais do mundo, apresentando uma descarga de água doce muito reduzida, atípica para a região. Os resultados revelam grandes bancos arenosos que ocupam em grande parte a porção central do estuário. Areias muito finas e bem selecionadas de origem marinha prevalecem. Fases de enchente mais curtas, com velocidades de corrente substancialmente mais altas, são observadas na porção superior do estuário, como esperado para um estuário raso e dominado por fricção. Por outro lado, uma vazante mais intensa poderia ocorrer como resultado de grandes áreas de manguezais associadas e intenso preenchimento estuarino, sendo que ambas as condições são observadas no Taperaçu. Neste caso, a prevalência da enchente parece estar associada à ausência de uma descarga fluvial efetiva. Além disso, alguns canais de maré conectam o Taperaçu com seu vizinho estuário do Caeté, o que contribuiria para o domínio de enchente. Como um todo, os resultados demonstram uma complexa interação de aspectos de configuração (fricção, drenagem fluvial, conexões com estuários vizinhos, preenchimento e grandes áreas intermareais) na determinação dos padrões hidrodinâmicos, contribuindo para o entendimento dos estuários da região ...

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