Effects of tributyltin (TBT) on fertility of the invasive apple-snail Pomacea canaliculata.

CLÉMENT, MARÍA E.; GIRAUD BILLOUD, M; CASTRO-VAZQUEZ, A

Mendoza

Congreso; XXVIII Reunión Anual de la Sociedad de Biología de Cuyo; 2010

Sociedad de Biología de Cuyo

In previous experiments designed with another purpose we observed that TBT may affect spawning in this species, so we wanted to confirm and to further explore this effect. A group of 6 adult male/female couples was exposed to 60 ng TBT/L during 30 days, while a similar, non exposed group was used as control. Both body mass changes and the frequency of copulations and spawning (episodes/month; e/m) were recorded. At the end of the experiment the gonad (in both sexes) and the seminal receptacle (in females) were prepared for routine histology. As expected, TBT caused a significant increase on VDSI (a common index of ‘imposex’; Kruskal-Wallis test, P<0.05) and no deleterious effects of TBT on body mass were observed. A significant decrease in the frequency of both copulation (controls 7.2 ±1.2 e/m vs. TBT 2.8±1.0 e/m; Student’s t test, P<0.05) and spawning (controls 5.2±0.4 vs. TBT 2.7±0.6; Student’s t test, P<0.05) was observed. No differences in either the spawn mass or in the percent of fertile eggs were observed at first spawning (which occurred within 7 days of treatment) but both parameters were drastically reduced in subsequent spawns. No apparent histological changes were observed in TBT-treated gonads, but sperm stored in the seminal receptacle appeared drastically decreased in 4 out of 6 TBT-treated females. It is tentatively concluded that TBT may affect fertilization by affecting the stored sperm in female P. canaliculata