Growth evaluation of brown mussel Perna perna and invasive bivalve Isognomon bicolor of a natural bed in Palmas Island, Santos Bay, São Paulo State, Brazil

Abstract

Brown mussel Perna perna and invasive bivalve Isognomon bicolor cohabit the natural beds of Santos Bay, São Paulo State, Brazil. The growth parameters L∞ and k were estimated for these species by means of von Bertalanffy equation. Data were collected from November 2005 to October 2006 in a natural bed from Palmas Island, Santos Bay, São Paulo State, Brazil. The results showed that P. perna could reach the asymptotic length (L∞) and growth coefficient (k) of 146.40 mm and 0.72 year^-1, respectively for animals living at intertidal zone, and of 137.20 mm and 0.96 year^-1 for those from subtidal zone. Regarding I. bicolor, its L∞ and k were 59.30 mm and 1.80 year^-1 for subtidal and 52.00 mm and 1.68 year^-1 for intertidal, respectively. Natural beds occupation densities varied from 1,625 to 3,875 individual m^-2 for P. perna and from 2,750 to 8,375 individual m^-2 for I. bicolor, concluding that both species have different growth rate on natural habitat.