The effects of sediment-associated triorganotin compounds on the gills of the European flounder, Platichthys flesus (L.).
The effects of exposure to sediment-associated tri-n-butyltin chloride (TBT) and triphenyltin chloride (TPhT) were examined in the euryhaline European flounder, Platichthys flesus (L.). The effects were quantified by measuring the changes in sodium efflux, Na(+)/K(+)-ATPase activity and the numbers, areas and distribution of chloride cells in the gills of freshwater-adapted fish, following a rapid transfer to seawater. After transfer, the Na(+)/K(+)-ATPase activity and the sodium efflux significantly increased in both the TPhT and control groups but not in the TBT group. However, Na(+)/K(+)-ATPase activity and the sodium efflux in the TPhT group had returned to pre-salinity transfer levels by day 15 after the initial exposure to TPhT. Morphological changes in the numbers and areas of chloride cells, known to be associated with seawater adaptation, took place in the control group, i.e. there was a significant reduction in the number of lamellar chloride cells accompanied by an increase in the number of interlamellar chloride cells. There was a reduction in the numbers of lamellar chloride cells in the TBT-exposed group following transfer to seawater but the mean number was significantly higher than the control group by the end of the experiment. In the TPhT-exposed group, the reduction was not significantly different to that seen in the control group. By the end of the experiment, both organotin-exposed groups had significantly lower mean numbers of interlamellar chloride cells than the control group. Before transfer to seawater, the mean areas of lamellar and interlamellar chloride cells of all three groups were not significantly different. On transfer, the mean areas of lamellar chloride cells in the control group became significantly smaller than the mean areas of the organotin groups. There was no significant difference in the mean areas of interlamellar chloride cells in the control and TBT groups between the start and finish of the experiment but there was a significant increase in the mean area of TPhT-treated animals at the end of the experiment when compared to the control group. The results presented in this study lead to the conclusion that tri-n-butyltin chloride and triphenyltin chloride in sediments are capable of significantly disrupting both the physiological as well as morphological components of ionic regulatory functions of an estuarine fish, at concentrations currently found in estuarine sediments.
Hartl
M G.J.
MG
Southampton Oceanography Centre, School of Ocean and Earth Science, University of Southampton, European Way, SO14 3ZH, Southampton, UK
Hutchinson
S
S
Hawkins
L E.
LE
Grand
D J.
DJ