Behavioural pattern in changes to diets and food availability during broodstock conditioning of captive clam Ruditapes decussates

Abstract

In terms of the nutritional needs, the choice of the appropriate phytoplankton strain is the main criterion during bivalves breeding improvement in captivity. Seven nutritional diets based on tree microalgae species (Chaetoceros calcitrans, Tetraselmis suecica and Pavlova lutheri), and seven feeding rations (0%, 1%, 2%, 3%, 4%, 5% and 6%) were used to assess the nutritional pattern of Ruditapes decussatus during conditioning practices. All regimes have shown the highest ingestion rate at low food availability (1% to 3%) with a leaning to diets based on C. Calcitrans followed by T. suecica and P. lutheri respectively.A significant influence of diets quality on absorption efficiency of phytoplankton was observed for both monospecific and bispecific diets (F = 21.78, p =3.2 10-7 *** and F = 250.09, p= 2.2 10-16 ***respectively). Whereas, low influence of food availability on absorption efficiency among all used rations has been revealed by clams reared under mono, bi and trispecific diets respectively (F = 11,19, p= 1.9 10-7 ***; F = 16,63, p= 1.03 10-9 *** and F = 2.78, p=0.0534ns). Consequently, this study could be handled as a standard protocol for conditioning process in furtherance of yield maximizing and cost minimizing during spat production of bivalves in hatcheries.