Estrutura da assembleia e influência da estação chuvosa sobre a ictiofauna de poças de maré da praia da Pedra Rachada, Paracuru - CE

Abstract

The extensive coastal zone of Ceará is characterized by the predominance of sandy beaches, being interrupted by rocky outcrops. In these environments, as the tide retreats, depressions can be formed in the bottom, where the water is temporarily dammed and forms tidal pools. Many species of fish seek in this ecosystem the guarantee of areas propitious for reproduction, nursery, feeding and refuge against predators. In order to characterize the assemblage structure of fish in tidal pools of Pedra Rachada beach, identifying possible changes due to the rainy season, monthly and daytime visual censuses were conducted between September 2014 and August 2015 in three tidal pools. For the best isolation among the pools, only tides below 0.3 were chosen. After the field procedures, abundance and frequency of the species were checked each month. A total of 2886 individuals were registered, belonging to 30 species and 21 families. Haemulidae was the most representative family and the species Haemulon parra, Haemulon plumieri, Sparisoma axillare, Acanthurus chirurgus and Abudefduf saxatilis were the most abundant, in descending order, and were present in all censuses. About 60% of the species surveyed were classified as scarce and rare. There was a predominance of individuals belonging to the length class between 0 and 5 cm. Predators of invertebrates were dominant, followed by carnivores, in relation to the number of species, and herbivores, in relation to the abundance. Transient and opportunistic species outranked in relation to permanent residents, although they had adaptations to the intertidal environment. The influence of rain on herbivorous fish was proven. However, there was no change in richness and density patterns according to the season (dry and rainy), suggesting that rainfall is not an important variable at Pedra Rachada beach during the sampling period. The presence of individuals generally smaller than 5 cm indicates that the pools studied play a key role in the life cycle of important reef fish species in northeastern Brazil.