Dinâmica populacional, micro-hábitat, biologia reprodutiva e alimentar de Ophioderma appressum (Say, 1825) (Ophiodermatidae, Ophiuroidea, Echinodermata) em recifes costeiros da Paraíba, Brasil

Abstract

Ophioderma appressum is a common species on the Brazilian coast. However, studies about the ecological and biological aspects of the species are absent for this region, being documented only for the Caribbean. Considering that information about the biology and ecology of species is essential for their conservation, this study aimed to analyze the pattern of spatial distribution, abundance, size structure, characteristics of the micro-hábitat, diet and reproductive biology of O. appressum. The ecological study was carried out on two shallow reefs at Paraíba State (Barra de Mamanguape and Seixas reefs), using linear transects, totaling 1,600m² of area sampled per reef. To describe the diet and reproduction, sampling was conducted only in the Seixas reef, through intensive searches for 12 months, with a monthly average of 14 individuals sampled. Salinity and temperature were measured monthly aiming to evaluate their possible relationship with the reproductive period. An abundance of 27 specimens with a density of 0.016 ind.m² was recorded in the Seixas reef and an abundance of 14 individuals with a density of 0.008 ind.m² in Barra de Mamanguape. The population from the Seixas was a randomly distributed (ID = 1.86), while in Barra de Mamanguape they showed aggregate distribution (ID = 4.0), this may have occurred due to differences in the environmental characteristics of each reef, since the unequal distribution of micro-hábitats can influence the pattern of spatial distribution of species that live under rocks. The size structure differed between reefs. In Seixas reef adult individuals predominated, while the opposite was found in Barra de Mamanguape. The main component of the micro-hábitat recorded for the species in the Seixas reef was calcareous algae (66%), while in Barra de Mamanguape it was filamentous algae (57%). The main food items found were: unidentified material, foraminifera, crustacean fragments and sediment, indicating that the species has an omnivorous and opportunistic habit, since its diet showed temporal variation. As for the gonadal index, it showed peaks in December / 2018 and January / 2019, however, with the histological analysis it was possible to observe mature oocytes and testicles during all months of the year, indicating that the species has long annual reproduction, with increased activity gonadal in the summer months. However, temperature and salinity do not seem to affect the species' reproductive cycle for the period studied.