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Distribución de equinodermos en el golfo San José y sur del golfo San Matías (Chubut, Argentina)

2000; University of Valparaíso; Volume: 35; Issue: 2 Linguagem: Inglês

10.4067/s0718-19572000000100002

0718-1957

Héctor E. Zaixso, Zulma I. Lizarralde,

Marine Biology and Ecology Research

The distribution of the most frequent species of subtidal echinoderms of the San José Gulf and south of the San Matías Gulf (Chubut Province, Argentina: 42° 20' S and 64° 20' W) is studied.The selected species were the echinoids Trypilaster philippii, Pseudechinus magellanicus and Arbacia dufresnei; the ophiuroids Ophioplocus januarii, Ophiactis asperula, Amphiura crassipes and Amphiura magellanica and the holothurians Chiridota marenzelleri and Pentamera chiloensis.The densities (individuals m -2 ) of the species were drawn on the Gulf chart using the point kriging method.The environmental parameters recorded in each sampling station were: depth, substrata granulometry, presence of hard substrata, velocity of the surface currents, bottom temperatures in August and December and presence of seaweeds.The data were analyzed by canonical correspondence analysis (CCA) with a forward selection of environmental variables and the complementary use of HOF (Huisman, Olff and Fresco) hierarchical models in the analysis of abundance response curves in ecological gradients.Several groups of species were defined using these methods: 1-A group formed by the echinoids Arbacia dufresnei and Pseudechinus magellanicus and the ophiuroids Ophioplocus januarii, Amphiura magellanica and Ophiactis asperula, which presented a negative monotonic relationship to the increasing quantity of the very fine sand fraction, some of them are positively associated to strong surface currents (P.magellanicus, A. magellanica and O. asperula), other to shallow waters (A.dufresnei and O. januarii).Ophiactis asperula and Pseudechinus magellanicus are the most abundant echinoderms in these gulfs.The holothurian Pentamera chiloensis, which is near to this first group in the CCA, is not related to any of the analyzed environmental factors.2-The other species (Trypilaster philippii, Amphiura crassipes and Chiridota marenzelleri), have all of them preference for substrates of very fine granulometry but differ in other habitat characteristics.The possible feeding habits of these species are discussed.