Distribuição vertical do filo Chaetognatha em um ponto fixo na baía de Guanabara (RJ-Brasil)

Abstract

The Guanabara Bay had been submited to a strong anthropic influence and the study of pelagic organisms is fundamental to evaluate and accompany this process . The chaetognaths lives in all oceans of the world . Their vertical distribution is result of ontogenetic migrations and environmental variations . The purpose of this study is evaluate the vertical distribution of the Phylum Chaetognatha species at one fixed point of Guanabara Bay . Surface and bottom samples were done during five tidal cycles at the central channel of water circulation of the bay, to establish the distribution patterns of the chaetognaths at winter of 1995 and summer of 1996. Sagitta friderici, Sagitta enflata and Krohnitta pacifica, were found in the samples. S. friderici, the most abundant, is one species who had a fixed population at Guanabara Bay. This species do nictemeral migration, following the more superficial strates during the night. S. enflata, the second most abundant, is very associated to the subsuperficial enter of the coastal adjacent water. S. friderici and S. enflata are ontogenetically distributed at the water column. The young individuals still associated with the superficial water. Sazonality and tidal cycles had not significative difference to the chaetognath's distribution at the water column, at this point of the Guanabara Bay.