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Endocrine mediated "imposex" phenomenon was investigated and recorded in the muricoid gastropod species Thais carinifera during the two decades from 1993 to 2012 at three (3) sites out of six (6) localities investigated along the Sindh and Balochistan coast, Pakistan. The VDS stages 1 to 4 were apparent in Thais carinifera. The intensity of imposex has remained comparatively low in the populations of harbours in close proximity to port Mohammad Bin-Qasim, namely; Old Korangi Fish Harbour (OKFH) and New Korangi Fish Harbour (NKFH) where shipping activities are sporadic as compared to those in Manora Channel and the adjoining Karachi Port area where intensive shipping activity is rather frequent. Target species found to be good bioindicators have shown a marked decrease over the prolonged study period. Investigations show that this decrease is solely due to globally imposed effective bans on tributyltin (TBT) based antifouling paints over the past decade. AbstrActDescriptors: Imposex, Gastropod, Biomonitoring, Endocrine Disruption, Karachi Coast. O fenômeno hormonal "imposex" foi investigado e relatado para o gastrópode muricídeo Thais carinifera durante duas décadas, de 1993 a 2012, em três das seis localidades investigadas ao longo da costa de Sindh and Balochistão, Paquistão. Os estágios VDS 1 a 4 foram aparentes na espécie. A intensidade do imposex permaneceu comparativamente baixa nas populações dos portos próximos do porto de Mohammad Bin-Qasim, especificamente em Old Korangi Fish Harbour (OKFH) e New Korangi Fish Harbour (NKFH), onde as atividades portuárias são esporádicas quando comparadas às de Manora Channel e à área adjacente do Porto de Karachi, onde a atividade portuária é mais intensa. A espécie alvo mostrou-se um bom bioindicador por ter apresentado decréscimo acentuado ao longo do extenso período de estudo. As investigações mostraram que esse decréscimo é apenas devido ao efetivo banimento globalmente imposto da tributiltina (TBT) como base de tintas anti-incrustantes ocorrido na década passada. resumoDescritores: Imposex, Gastrópodes, Biomonitoramento, Perturbações Endócrinas, Costa de Karachi.

The larviparous oyster Ostrea nomades from two different localities was examined histologically and found to be mostly hermaphroditic. However, pure males, pure females and indifferent oysters were also found. The hermaphrodites of O. nomades were classified into three categories: ambisexual, predominantly female and predominantly male. Gonadal development appears to take place throughout the year with increasing activity and ripening in the winter months, leading to immediate spawning and later resorption. The number of brooding larvae of O. nomades was low at both collection sites.

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Annual reproductive cycle and spawning ecology of Kelee shad, Hilsa kelee were studied. The sex ratios did not exhibit as 1 : 1; whereas 69.19% were females. On the basis of histological examination, the maturity of female gonads of H. kelee was categorized in eight developmental stages: immature, developing, fully developed, hydrated, running ripe, partially spent, spent and post spawning. Whereas males of this spe cies were categorized in five developmental stages: immature, developing, ripe, partially spent and spent. This fish is repeatedly spawner and spawns twice per year: in April to June and August to October. The values of exponent b in the length weight regressions (W = al b ) slightly varied in males b = 3.133, R 2 = 0.96 and P < 0.01 and females b = 3.143, R 2 = 0.95 and P < 0.001. The linear regressions of length weight relationships were significant for both males and females.