DIFFERENTIAL RECRUITMENT OF MYTILID SPAT ON ARTIFICIAL COLLECTORS IN CHUBUT, ARGENTINA

Abstract

In the present study we compare the recruitment of Mytilus platensis d'Orb. and Aulacomya aterater Molina in four types of artificial substrata. The collector types used, of 1 m length, were: (1) nets of 11.02 mm of mesh size, cut into strips of 0.30 m in width; (2) nets of semi-rigid polyethylene with 8.46 mm mesh size, 0.12 m in width; (3) ropes of braided net strips, 0.30 m wideeachand 11.02 mm of mesh size; (4) ropes of braided net strips, 0.10 m wideeachand 40 mm mesh size. The collectors were immersed for 3 months between October 1984 and January 1985. A long-line was used to hang the collectors, at three different depths: 3,5 and 7 m, in San Román (San José Gulf, Chubut, Argentina). In all collector types the recruitment of A. ater ater was 6.4 times higher than that of M. platensis. In both species statistical analysis showed that settlement on the artificial collectors was not affected by depth. The number of recruited individuáis was significantly higher (p<0.001) in the open meshes than in the braided ones. There were no differences within open or braid nets.