Material and Methods
From September 2006 to July 2008, 120 juvenile giant clams (Tridacna maxima, T. squamosa and T.
derasa; Fig. 1) were reared in a closed recirculation
system in ZMT Bremen (500 l volume, 32 PSU salinity, 27 °C temperature, 12 hours light vs. 12 hours dark regime, use of protein skimmer, calcium reactor, nitrate reactor, biofilter, UV units for water treatment). Maintenance conditions and species identification were performed after Lucas (1994) and Knop (1994).