Distribution et effets du chlorure de tributylétain et de ses produits de dégradation sur la croissance de l'algue marine Pavlova lutheri en culture continue

摘要: Organotin compounds have been used as biocides, wood preservatives, plastic stabilizers and antifouling agents for many years (Maguire, 1991). The acute toxicity well the sublethal effects of tributyltin (TBT) derivatives tested numerous freshwater marine species (Alzieu, 1989; Kelly et al., 1990). biodegradation TBT in dibutyltin (DBT) monobutyltin (MBT) is established some phytoplankton (Lee 1989) but little known about physiological adaptation microalgae to a long term contamination by TBT. The objective this study was evaluate ability alga Pavlova lutheri, cultured “chemostat mode” under axenic conditions, accomodate increasing cocentrations TBTCl culture medium determine its capacity degrade DBT MBT. Chemostat P. lutheri were exposed contaminated nutrient supplies containing 18.5, 74, 185 nmol l−1 chloride (expressed TBT+) respectively. For comparison purposes, batch concentration 13 48 h-period. (BuSn) monitored GC/ITD three different fractions: dissolved medium, adsorbed on external cellular walls, fluid. Within 24 h-period, observed fluid indicating rapid uptake contaminant. confirmed found more effective continuous than similar conditions. MBT both fractions all cultures (Tables 2 3) seems particularly efficient form at low concentration. amount BuSn onto cell directly related supply intracellular decreased from 150 g−1 (dry weight) less 60 when increased 74 (Fig. 2). The density growth rate continous (Figs 3 4) not affected level 18.5 TBT. In receiving suffered toxic impact first few days experiment, loosing 40% density, However, recovered initial next 10 spite an uninterrupted contamination. Finally, severe shock leading major dysfunction only days. productivity 5) treatments are also illustrated significant decrease chlorophyll α [Fig. 6(A)] individual cells 6(B)] which indication preservation life functions experiments. These results evidence chemostat mode, resist accommodate input high degrading into much DBT. As comparable aspects open natural environment (Rhee, 1980; Wangersky Maass. behavior might be extended coastal where present. If such assumption correct least regarding general processes bioaccumulation degradation, clearly indicates that play important role food filter feeders other herbivorous due bioaccumulate large quantities [Fig 2(A) 2(B)] without being irreversibly affected. Fortunately, simulated our strongly accelerate degradation MBT, two tin species. Results previous studies micro-algae, conducted cultures, should interpreted with caution since possibly algae survive grow media grossly underestimated.