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 measurin g the changes in sodium efflux, Na+/K+-ATPase activity and the numbers, are as and distribution of chloride cells in the gills of freshwater-adapted fi sh, following a rapid transfer to seawater. After transfer, the Na+/K+-ATPa se activity and the sodium efflux significantly increased in both the TPhT and control groups belt not in the TBT group. However, Na+/ K+-ATPase activ ity and the sodium efflux in the TPhT group had returned to pre-salinity tr ansfer levels by day 15 after the initial exposure to TPhT. Morphological c hanges in the numbers and areas of chloride cells, known to be associated w ith 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 r eduction in the numbers of lamellar chloride cells in the TBT-exposed group following transfer to seawater but the mean number was significantly highe r 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 co ntrol group. By the end of the experiment, both organotin-exposed groups ha d 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 di fferent. On transfer, the mean areas of lamellar chloride cells in the cont rol group became significantly smaller than the mean areas of the organotin groups. There was no significant difference in the mean areas of interlame llar chloride cells in the control and TBT groups between the start and fin ish 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 t hat tri-n-butyltin chloride and triphenyltin chloride in sediments are capa ble of significantly disrupting both the physiological as well as morpholog ical components of ionic regulatory functions of an estuarine fish, at conc entrations currently found in estuarine sediments. (C) 2001 Elsevier Scienc e B.V. All rights reserved.