The effect of temperature and salinity on the elimination of enrofloxacin in the Manila clam Ruditapes philippinarum.

ABSTRACT

The effect of temperature and salinity on the elimination of enrofloxacin (EF) in Manila clams Ruditapes philippinarum was investigated. The clams, cultured under different temperatures and salinities (16 degrees C and 30 per thousand, 22 degrees C and 30 per thousand, or 22 degrees C and 20 per thousand), were exposed to EF at 5 microg/mL of water in a medicated bath. After a 24-h exposure, the concentration of EF in various tissues was measured by high-performance liquid chromatography and the elimination rate of EF in those tissues was investigated by regression analysis. After the treatment, the initial concentrations of EF among tissues were (in decreasing order) plasma > gill > visceral mass > foot > adductor muscle. In all tissues the elimination half-life (t1/2) of EF in the clams cultured at 22 degrees C and 20 per thousand and 16 degrees C and 30 per thousand were markedly longer than in those cultured at 22 degrees C and 30 per thousand, and the t1/2 at 16 degrees C and 30 per thousand was slightly longer than that at 22 degrees C and 20 per thousand. Slight differences were also observed in t1/2 values among various tissues. These data indicate that both temperature and salinity had significant effects on the elimination of EF in the Manila clams and that lower temperature or salinity could result in slower elimination.