Loss of Perna perna mussel seeds (L., 1758), cultivated in North Bay - Santa Catarina Island/SC - Brazil

This study had the objective of quantifying seed loss in the culture of young mussels as well as discussing the main causes of this loss, especially that derived from predators and parasites. The experiment was carried out in Ponta do Sambaqui beach, between December of 2004 and August of 2005. Fifty four mussel ropes were prepared, containing 600 seeds/m each. Half the ropes were disposed in a long line and protected with fishing net. This protection was removed from three of them every month. The other 27 ropes remained in a net-tank. Every month three ropes from each treatment were collected and the mussels counted. Thirty animals from each treatment were fixed and classical histology procedures were carried out, with stain HE. The salinity and the water temperature of the sea were measured weekly and diary, respectively. The seeds from the ropes of the long line suffered intense predation in the summer. In the following months there was no significant difference in the loss of animals between both treatments. The young Perna perna mussels are more vulnerable to predators than adult individuals. Besides predation, questions related with handling techniques and the excess of seeds in each rope can be causes for loss of animals. The prevalence of the trematod Bucephalus sp. was low (5.11%), there was no directly relation with the observed losses.