Observações sôbre a fauna bêntica do complexo estuarino-lagunar de Cananéia (SP)

Abstract

The Cananeia region in the south of Sao Paulo State, is a estuarine-lagunar complex, tn this region we realesed 60 benthic stations with a Foerst Petersen grab of 1/10 sq.m. We had studied the density and alcoholic weight of the benthic groups and species. The polychaets was the dominant group in number of species and of individuals. The commonest species was Loandalia americana, Laonice japonica, Clymene sp., Clymenella sp.. The highest density of polychaets was obtained in station 51, 10 meters deepthty, temperature of 18.60oC, salinity of 25.90%0, water transparency (Secchy disc) of 2 meters, bottom of muddy, sand and pebles. In this station we found 72 individuals/sq. m. and a alcoholic weight of 5.9100 grm. The lamelibrancs was not dominant in neither one station. Tellina alternata and Macoma sp. occurred only in Trapande bay and Cubatao sea. Littoridina australis var. nana occurs in high density in the north region of Cananeia island. In this region it is the dominant benthic species. Kalliapseudes schubartii occurs only in the Cubatao sea. Renilla reniformis and Virgularia sp. occurs specially in the Trapande bay. It was possible to recognize five faunistics zones in the soft bottoms of the complex. Zone of Renilla reniformis and Virgularla sp.. The sediment of this zone have a low organic fraction and the zone is on direct influence of the ocean waters. Zone of Macoma sp. and Tellina alternata in the Cananeia sea. Zone of the tanaidaceous Kalliapseudes schubartii and Phoronis sp. principally in the Cubatao sea. In this sea there are the highest organic fraction of the sediment. Zone of Littoridina australis var. nana in the northern region of the Cananeia island. In this zone, we found a low transparency of the water, salinity of 4.91 to 12.36‰ and a high organic fraction in the sediment. Zone of hard bottoms with hydroids and ophiuroids. The Trapande bay, presents the richest muddy infralittoral benthic fauna of the complex. In this bay is found the highest oxygen content and water highest salinity of the complex. Near of the mouth of the rivers and of the marigots and in many places of the complex, we found a floculated softy sediment in the bottom. In these places we d'ont found animals or they are very much rare (stations 11, 14, 17, 20, 48, 54 and 56). In two stations near of the Cananeia bar, in result of strong currents we d'ont found animals (St. 2, 5). Inside of the estuarine-lagunar complex of Cananeia (SP) characterized by the presence of muddy and sand-muddy bottoms with a very much poor epifauna we found in the Casqueiro island a infralittoral stone bottom, with a rich epifauna, specially of the hydroids Eudendrium carneum Clarke, the Ophiothrix angulata Say, amphipods, etc. This occurs because this area is situated in a region of function of the waters of the Trapande bay and that of the Ararapira river, what permits the existence of a stone bottom not covered by the muddy. This situation permits the occurrence of that epifauna.