Taxonomia, distribuição e variações intraespecíficas de Ophiuroidea (Echinodermata) em ecossistemas recifais do Atlântico Sudoeste Tropical, Brasil

Abstract

The class Ophiuroidea, popularly known as brittle star, composes the most recent group, diverse and abundant group of the Echinodermata phylum. This class has about 2100 described species, of which about 153 occur in Brazil. This study aimed to know the Ophiuroidea associated with different types of substrates from reef formations in shallow waters off the coast of Paraíba. To better organize the contents covered, this dissertation is subdivided into three chapters: 1– Ophiuroidea (Echinodermata) of the reef ecosystems of Paraíba, Southwestern Tropical Atlantic, Brazil; 2– Spatial-temporal distribution patterns of Ophiuroidea (Echinodermata): influence of the micro-habitat; 3– Intraspecific variations in species of Ophiuroidea (Echinodermata) from the Paraíba coast, Northeast, Brazil. Sampling was carried out between 2019 and 2021, with collections between the dry and rainy season, covering seven collection points along the coast of the state of Paraíba: Barra de Mamanguape beach, Formosa beach (sand and reef), Bessa beach, a Cabo Branco beach, Carapibus beach and Tambaba beach. A total of 428 specimens were collected and identified into 13 species, 2 orders, 5 families and 7 genera. The systematic study of Ophiuroidea was performed from the analysis of the external morphology, in which the variation in size of the specimens was evaluated using morphometry. The largest intraspecific variations observed were between young and adult individuals, the morphometry showed that the biggest variations in size occur in the length of the arms and in the diameter of the disc. The normality and homoscedasticity of the data was tested using the Shapiro and Levene test. To assess whether there is statistical difference between diversity and location, the test of Kruskal-Wallis and Dunn test were used to for multiple comparisons and controlling the experimental error rate. A PERMANOVA was carried out to statistically compare the effect of environmental variables in dry and rainy periods, and to relate the environmental matrix to biotics, an RDA was made. To assess the diversity, the diversity indices were observed. The species Amphipholis squamatas howed wide spatial and temporal distribution and greater abundance (63.82%). The Carapibus beach community stood out in terms of species richness and abundance, followed by Barra de Mamanguape beach and Formosa beach (Reef), because they configure places where there is a greater diversity of micro-habitats available. The description of the growth series allowed the identification of typical characteristics of certain stages. This faunal survey with the identification of species of the Ophiuroidea class for the Paraíba coast is fundamental for understanding the structure, dynamics, and diversity of the communities of each sampled location to help the management and conservation of the species, as well as expanding the understanding about the Phylum Echinodermata.