STUDIES ON ZOOPLANKTON AND ICHTHYOPLANKTON COMMUNITIES OFF THE RIO DE JANEIRO COASTLINE

Abstract

Zooplankton and ichthyoplankton studies were carried out off Rio de Janeiro in June 1977 and May-June 1980. Their were collected 141 samples by R/V "Almirante Saldanha". Vertical hauls were taken from 5 m above the bottom to surface in the neritic region and from 200 m depth in oceanic stations. Through T/S diagrams water masses were identified and associations with zooplankton and ichthyoplankton density were made. The main pattern of spatial differentiation observed in density and among 700 plankton groups was related to neritic/oceanic gradients and intrusions of toe South Atlantic Central Water in the neritic region. The greatest abundance of zooplankton was observed in the inner shelf (< 100 m) ranging from 1,000-5,000 ind.m³. Copepods was the dominant group with 60 species identified. The highest values of specific diversity among the copepods (> 3.5 bits.ind^-1) were found in front of Ponta Negra, as much in Shelf water as in Tropical Water. The fish larvae present in Shelf water showed values up to 200 larvae.100m³. In the ichthyoplankton 32 families were identified. Larvae of Clupeidae, Engraulidae, Bothidae and Paralichthyidae were more dominant in stations located shoreward from the 100 m isobath, while Phycidae , Gonostomatidae and Myctophidae were most abundant offshore. Highest concentrations of herbivorous zooplankton were observed, suggesting favorahle conditions for the spawning of Engraulis anchoita in shelf waters.