Influence of abiotic factors on the soft-bottom macrofauna in the intertidal zone of Santa Cruz channel, Pernambuco State, Brazil

Abstract

The benthic macrofauna is made up of organisms associated with the substrate sediment and, in the intertidal zone, is dominated by crustaceans, mollusks and polychaetes, alternating their dominance according to abiotic conditions. The present study was carried out on May 4 and 5, 2001 (rainy season) in order to assess the intertidal zone soft-bottom macrofauna, mainly mollusks, polychaetes and crustaceans and correlate them with abiotic data on salinity and intertidal water temperature, sediment’s grain size and organic matter content. Sampling was performed on two fixed stations at Santa Cruz channel (Forte Orange and Itapissuma), Pernambuco State, Brazil. Collections were made from a 100 m2 area using a PVC cylindrical sampler with 0.0078m2. In each station 30 samples were collected, totalizing 0.234 m2. At Forte Orange station average salinity was 39.7‰ and the sandy sediment predominated with medium sand grains and medium organic matter content (1.62%). In this station juvenile stages of Anomalocardia brasiliana (Gmelin, 1791), Neritina virgínea (Linnaeus, 1758) and Odostomia laevigata (Orbigny, 1842) stood out. At Itapissuma station average salinity was 30.4‰, the predominant sediment was sand-muddy with a higher fraction of fine sand grains and medium organic matter content (4.48%); and among the fauna the polychaetes Haploscoloplos sp. and Glycinde sp. were predominant.