Resistance of brown mussel Perna perna to high temperatures and its relationship with bacteriological contamination

Abstract

Brown mussel  Perna perna is a common species in Brazilian seacoast, very abundant between Rio de Janeiro and  Santa Catarina states. Temperature is one of the most important environmental factors, bounding the species distribution.  It has a direct in fl uence on basic physiological processes. This study aimed at determining the mussel resilience to high  temperatures. The animals were collected from two rocky coasts, the  fi rst is located at Urubuqueçaba Island, (Santos  – SP), a sheltered site subjected to bacteriological contamination. The other station is Guaraú Beach, (Peruíbe – SP), an  open sea site free of contamination. The experiments were conducted in January and July 2001. The temperatures tested  were 29.5, 31.0, 32.5 and 34.0ºC, each one with four replications. The time elapsed to occur 50% of mortality (TM 50)  and the number of dead animals in each parcel after a de fi ned exposition time were recorded. The results showed that  mussels from Urubuqueçaba were less resilient to high temperatures than those from Guaraú. This may point out that  mussels’ resilience is affected by the high bacteriological contamination even considering different sheltering conditions  at both studied sites.