EFFECT OF Bacillus thuringiensis ON RESPIRATION RATES OF MARINE INTERTIDAL MYTILASTER INTERTIDAL, MYTILASTER MINIMUS (MOLLUSCA, BIVALVIA)

Increasing body of research deals with the impact of agricultural products marine environment. Indeed it is expected to detect insecticides, including the ones for biocontrol, in nearshore marine waters and thus predicting where, when and with what magnitude these impacts are most likely to occur is imperative if we are effectively interested in understanding the role of biological products as Bacillus thuringiensis (Bt) on marine biodiversity. Bivalves are important elements of marine biodiversity and very often they play a role of ecosystem engineers in that many other species structurally depend on their presence. Oxygen consumption through respiration in these organisms varies with natural physical and chemical factors like temperature and food availability. However, it has been demonstrated that also several contaminants may affect respiration rates in intertidal bivalves like the small Mediterranean Mytilid, Mytilaster minimus. Since the respiration is an important component of energy budget, deviation of its magnitude from common natural patterns may alter the amount of energy available for growth and reproduction. Such a fact, by cascade, may induce alteration of biodiversity. Experiments have been carried out with adult mussels of about 1.4 ± 0.3 cm collected in March 2010 from the coasts around Palermo (Northern Sicily). We measured standardised respiration rates (µmoli h-1 g-1) at ambient temperature (20.0 ± 1.0°C) in mesocosmal tanks both in presence of Bt and without. The significance of the results and the importance of the methods to detect chronic exposure is discussed.