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There are important gaps to understand the composition of the fauna associated with macroalgae, such as, how distinct algal morphology and environmental features, like turbulence or circulation patterns, may affect the distribution of them. In this study, macroalgae and associated fauna samples were undertaken between 4 and 12-m depth at three sites within the Admiralty Bay, King George Island, during the austral summer of 2000/2001. Previous physical oceanography data from the bay showed that each of these sites featured different circulation regimes. Differences and similarities in composition and density of the fauna associated with five species of macroalgae with different morphologies were analyzed: foliose (Monostroma hariotii and Palmaria decipiens); mixed (Myriogramme mangini); and branched (Desmarestia menziesii and Phaeurus antarcticus). Results showed differences in density, dominance of taxa, and richness among taxonomic groups of the associated fauna were related to algal morphology and circulation patterns. The dominance of epifaunal groups among macroalgae (e.g., D. menziesii, M. hariotii, and M. mangini) showed an adaptive response to different water flow settings within the bay, particularly in the community under the most intense flow. Further studies on associated fauna, should consider other environmental physical features and take our study like baseline to understand how major processes (e.g., climate change, seawater properties and circulation) may affect the communities, especially in more vulnerable shallow water zones.

Macrobenthos distribution along the salinity gradient and the pattern of species temporal changes were investigated in the Itanhaem River Estuary. Environmental variables such as grain size, sediment organic content, water salinity, water temperature and dissolved oxygen were examined as factors likely to influence the distribution of species. A total of 2130 individuals, distributed in 16 taxa (species/genera) were collected from the 12 samples obtained. The most abundant species were Cyprideis salebrosa, Heteromastus similis, Scololepsis squamata, Nephtys squamosa, Diplodonta sp. and Tellina sp. The canonical ordinations analysis indicated the presence of three benthic associations: a marine Diplodonta sp. - Tellina sp. community; a brackish water C. salebrosa - N. squamosa community and a wide spread S. squamata - H. similis community. The distribution of the estuarine macrozoobenthic species seems to be mainly controlled by salinity and the observed gradient in species compositon and dominance in the marine and brackish part of the Itanhaem River Estuary is similar to the one occurring in other mixohaline habitats of the Brazilian South eastern Coast. Composicion estacional y distribucion espacial de asociaciones macrobentonicas en un gradiente estuarino de Itanhaem, Sao Paulo, Brasil La distribucion de los macrobentos a lo largo del gradiente de la salinidad y el patron de los cambios temporales de las especies fueron investigados en el estuario del Rio Itanhaem. Las variables ambientales tales como tamano de grano, contenido organico del sedimento, salinidad del agua, temperatura del agua y el oxigeno disuelto fueron examinados como factores que determinan la distribucion de las especies. Se recolectaron un total de 2130 individuos, de 16 taxa (especies/generos) de las 12 muestras obtenidas. Las especies mas abundantes fueron Cyprideis salebrosa, Heteromatus similis, Scololepsis squamata, Nephtys squamosa, Diplodonta sp. y Tellina sp. El analisis canonico de correspondencia indico la presencia de tres asociaciones bentonicas: una comunidad marina, Diplodonta sp. - Tellina sp.; una comunidad de agua salobre, C. salebrosa - N. squamosa y una comunidad de extension amplia, S. squamata - H. similis . La distribucion de la especies macrozoobentonica de estuario parece ser controlada principalmente por la salinidad y el gradiente observados en composicion. La dominancia de especies en las partes marina y salobre del estuario del Rio de Itanhaem es similar a la de otros habitats mixohalinos de la costa del sudeste brasileno.

The monthly fluctuations of amphipods associated to the algae Bryocladia trysigera was described from March 1997 to February 1998 at the rocky shore known as Poço de Anchieta in the Peruíbe Beach, Itanhaém, Southeastern Brazil. A total of 75,344 individuals were sampled, belonging to 10 species and 9 families. Three species dominated the phytal in number: Hyale nigra, Caprella danileviskii and Caprella penantis. Despite the alternation in dominance of the 3 most abundant species, the amphipod species composition remained generally unchanged, so that the majority of the species were observed in all sampling months. The temporally changing pattern of the community structure, with a decline in amphipod abundance in winter followed by an increase in spring, was probably due to a higher predation pressure in winter period. Flutuações mensais de Amphipoda associados à alga Bryocladia trysigera são descritas. As coletas foram realizadas no período de março de 1997 a fevereiro de 1998 no costão rochoso do Poço de Anchieta na Praia de Peruíbe, Itanhaém (SP). Foram coletados 75.344 indivíduos, identificados em 9 famílias e 10 espécies. Três espécies dominaram numericamente: Hyale nigra, Caprella danileviskii e Caprella penantis. Embora tivesse sido registrada alternância na dominância dessas espécies, foi observada pequena variação na composição específica nos meses amostrados. A variação temporal na estrutura da comunidade, com o declínio da abundância de Amphipoda no inverno, seguido de aumento na primavera, pode ser causada pela maior pressão de predação no inverno.