Fish assemblages and environmental variables on an artificial reef north of Rio de Janeiro, Brazil

A 32-module artificial reef (concrete and tyre) was built on the coast north of Rio de Janeiro in 1996. Temporal distribution patterns in the fish assemblage were determined and correlations between environmental variables and species distribution investigated, based on monthly sampling during 2 years (including monitoring of salinity, pH, dissolved oxygen, water clarity, temperature, rainfall, and Paraiba do Sul river flow). Trammel nets were used to record species richness and weight and number of individuals on the reef site. The assemblage varied seasonally, with highest abundances during the summer months, especially of Choroscombrus chrysurus, Rhizoprionodon lalandii, and Mustelus higmani, while catches were generally low during the winter and fall months. Canonical Correspondence Analysis indicated that rainfall, river outflow, water clarity, and salinity were the environmental factors most strongly correlated with temporal variation in the fish assemblage. The reef area is considered a high-energy open system with continental influence. The instability of hydrological features in combination with endogenous biological features of the reef (e.g. higher food availability and more shelter) might control the seasonal distribution of the local ichthyofauna. (C) 2002 International Council for the Exploration of the Sea. Published by Elsevier Science Ltd. All rights reserved.