Idade, crescimento e uso do habitat das espÃcies Stegastes rocasensis, no Atol das Rocas e Stegastes sanctipauli, no ArquipÃlago de SÃo Pedro e SÃo Paulo

AUTOR(ES)
DATA DE PUBLICAÇÃO

2004

RESUMO

Although the importance of coral reef environments, it is known by scientists all around the world that this ecossistem is actually under potencial impacts and declining. A vital part of coral reefs ecossistems is composed by coral reef fishes. It is estimated that 30-40% of marine fishes can be found in coral reefs. The Pomacentridae family has an important role since they represent a very abundant family, in number and species, besides having very specialized habits. In this work we studied two endemic species of Brazil: S. rocasensis, that has a larger distributional area, represented by Rocas Atol and Fernando de Noronha archipelago and Stegastes sanctipauli, that is registered only in SÃo Pedro e SÃo Paulo archipelago. Underwater visual census techniques were used to determine the distribution, density and size population structure of the two species, besides the relationship between these species and the substrate they occupy. Substrate covers was determined using the Reef Check methods. When the species density was confronted with substrate categories we could conclude that the specie size population is very close related with the structural complexity and its diversity. These two variables combined could be able to limit the size of population, for these two species that have habits close related with local substrate. The age and growth was determined from readings in whole and sectioned otoliths and the Von Bertalanffy growth curve adjusted to length-at-age data. For S. rocasensis the minimum age recorded was zero and the maximum was 13 years old. For S. Sanctipauli the minimum age recorded was zero and the maximum age recorded was 15 years old. Although these species do not occur in impacted environments with lack of predators, they have demonstrated a high longevity that could be positively influencing their stability and perpetuity, even being restricted to small areas populations. This way we could explain the capacity of endemic coral reef fishes on maintaining very abundant and dominant populations, even when they are found in very restricted areas such as oceanic islands, fragmented environments and small protected area

ASSUNTO(S)

pomacentridae-famÃlia ecossistemas oceanografia predadores-depleÃÃo

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