Variação temporal da fauna de Ophiuroidea (Echinodermata) associada aos fitais do recife de coral da ponta Verde, Maceió, Alagoas, Brasil

Abstract

Temporal variation fauna of Ophiuroidea (Echinodermata) associated to phytal on the Ponta Verde coral reef, Maceió, Alagoas, Brazil: The class Ophiuroidea (Echinodermata) comprises marine animals found with different types of substrate, such as rocks, gravel, sand, mud, in association on other organisms including algae, sponges and corals. The subject of this study is to evaluate the temporal variability, including the qualitative and quantitative composition of Ophiuroidea fauna associated to three different macroalgae, Amphiroa fragilissima (Linnaeus) Lamouroux, Dictyota cervicornis (Kuetzing) and Caulerpa racemosa (Forsskal) J. Agardh, on the Ponta Verde coral reef, Maceió, State of Alagoas. The samples were collected at low tide during 10 years, between 1998 and 2007, on dry and rainy season. Three samples of 25cm² of each alga were collected, put one individually packed in plastics bags with sea water and 10% Magnesium Chloride as anesthetic. In the laboratory samples were fixed in 10% formalin, later then separated the groups and the ophiuroids were stored in 70% ethanol for the qualitative and quantitative studies. Nine species of Ophiuroidea were identified and recorded 10.664 individuals associated to three phytal communities. Amphipholis squamata (Delle Chiaje, 1828) was the dominant species of Ophiuroidea in the phytal, followed by Ophiactis savignyi (Müller & Troschel, 1842) were dominant or frequent in the three phytal analyzed, and the other species were occasional or rare. The highest richness and abundance were found in A. fragilissima phytal, followed by D. cervicornis and C. racemosa. On cluster analysis and NMDS were detected the formation of two groups separately showed that during summer (dry) and winter (rainy), but other groups mingled both periods, and O. savignyi and A. squamata were the main species responsible for the formation of such groups. The largest number of specimens of some species of Ophiuroidea during winter was due to asexual reproduction by fission. This reproductive strategy may have been brought about by the lack of maturation of gonads due to low food availability during winter.