The Size Driven Variations in Physiological Responses of the Bearded Horse Mussel Modiolus barbatus and the Noah’s Ark Shell Arca noae

Özet

Bearded horse mussel and Noah’s ark shell are sometimes observed to live together in groups. Oxygen consumption,ammonia excretion and clearance rate were investigated on these species under laboratory conditions considering differentsize of individuals divided into three size groups (less than 25 mm; 25 to 50 mm and larger than 50 mm). Body size of bothspecies significantly influenced oxygen consumption, ammonia excretion and clearance rate of the Noah’s ark shell. In bothspecies, respiration and clearance rate decreased with body size while excretion rate increased with body size. For Noah’s arkshell groups of 25 to 50 mm and smaller than 25 mm, the atomic ratio between oxygen consumption and ammonium excretioni.e. O:N ratio was detected to be greater than 30. The same applies to a group of the bearded horse mussels smaller than 25mm. Animals of both species larger than 50 mm have O:N ratio smaller than 30 indicating use of proteins as metabolicsubstrate, compared to use of lipids and carbohydrates in younger animals.