Structure and dynamics of the macrobenthic communities of Ubatuba Bay, southeastern Brazilian Coast

Abstract

Species composition, distribution, density, biomass, diversity and trophic relationships of the macrobenthic communities in Ubatuba Bay, southeastern Brazilian coast, were investigated seasonally from August 1995 to June 1996. Sampling was carried out at 9 stations of between 4 and 13 m depth and taken in duplicate with a 0.1m² van Veen grab. Two hundred and five macrofaunal species were identified, presenting low dominance and frequency. Polychaetes and nematodes dominated, representing 89% of the whole fauna. Spatial variations in the structure of the communities were correlated to sediment type whereas seasonal variations were correlated to the increase in wave size and current disturbance over the substrate during the rainy period. Carnivore and surface deposit-feeder polychaetes were dominant, totalling 81% of the species. Mean grain size, fine sand, very fine sand, silt and clay contents were among the main factors related to the patterns of macrofaunal distribution, density and diversity and to the dominance of trophic groups. Multivariate analysis showed that the area may be divided into two groups of stations each of them characterized, respectively, by the presence of Magelona papillicornis and Mediomastus capensis.<br>A composição, distribuição, densidade, biomassa, diversidade e relações tróficas das comunidades macrobênticas da Enseada de Ubatuba, costa sudeste brasileira, foram estudadas sazonalmente, de agosto de 1995 a junho de 1996. As amostragens foram realizadas em 9 estações de coleta, situadas entre 4 e 13 m de profundidade, e obtidas em duplicata com pegador de fundo van Veen de 0,1 m² de área amostral. Duzentas e cinco espécies macrobênticas foram obtidas, a maioria apresentando baixa dominância e freqüência. Poliquetas e nemátodes dominaram, representando 89% da fauna total. As variações espaciais na estrutura das comunidades foram correlacionadas ao tipo de sedimento, ao passo que as variações temporais o foram com o aumento da perturbação causada pelas ondas e correntes sobre o substrato durante o período de chuvas. Poliquetas carnívoros e detritívoros foram dominantes, totalizando 81% das espécies. O diâmetro médio das partículas, conteúdo de areia fina, areia muito fina, silte e argila estiveram entre os principais fatores relacionados aos padrões de distribuição da fauna, densidade, diversidade e com a dominância dos grupos tróficos. Análises multivariadas mostraram que a área de estudo pode ser dividida em dois grupos de estações, caracterizados, respectivamente, pela presença de Magelona papillicornis e Mediomastus capensis

Looking at the soft-bottom around a coastal coral reef: the impact of terrigenous input on Polychaeta (Annelida) community

“…Clay adsorbs to TOM, favoring its deposition (SNELGROVE; BUTMAN, 1994) and so, higher values of TOM were found at stations with a higher proportion of fine grains. Even the lesser values of TOM (about 5%) were high when compared to those found in other coastal areas (HSIEH, 1995;PIRES-VANIN, 2004), showing that there is no scarcity of food resources for polychaetes.…”

Spatio-temporal and functional structure of the amphipod communities off Santos, Southwestern Atlantic

“…A general relationship between primary production, water depth and abundance of benthos has been recognized for the southern Brazilian shelf (SANTOS; PIRES-VANIN, 2004;PIRES-VANIN, 2006). The pulsed seasonal input of new production promoted by the SACW may be responsible for the enhancement of biomass and density found in the Mixed Zone, especially in summer, when compared to the coastal areas.…”

“…There have been reports of the ecological influence of water mass dynamics on the benthic fauna of the southeastern Brazilian shelf (PIRES-VANIN, 1992;PIRES-VANIN, 2004;PIRES-VANIN, 2005), but the available data do not take the role of the estuarine system on the shelf into consideration. The main objective of the present study was, therefore, to examine the changes in diversity, density and life style of the amphipod community of the shelf adjacent to Santos Bay in the attempt to understand the environmental gradient addressed by the coastward SACW intrusion combined with the influence of the oceanward estuarine waters on superficial sediment communities.…”

Influência espacial, luminosa e lunar sobre a população de Lucifer faxoni (Borradaile 1915) no sistema estuarino do Canal de Santa Cruz, Pernambuco, Brasil.

“…Consequentemente, a instabilidade desta região afeta diretamente e/ou indiretamente a densidade dos organismos adultos, assim como suas formas larvais que vivem, muitas vezes, nos mesmos ecossistemas (SANTOS; PIRES-VANIN, 2004). …”