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An ecotoxicological study were conducted to evaluate the concentrations of PAHs and n-alkanes, in gut, liver and kidney tissues of two individuals of Enhydrina schistose (Daudin, 1803), using gas chromatography/mass spectrometry. The concentrations of PAHs (0.10 µg/g) and n-alkanes (8.12 µg/g) were elevated in the gut, and liver (PAHs 0.05 µg/g tissue, n-alkanes 29.16 µg/g tissue). In kidney of both specimen-A and B the PAHs (0.01 and 0.1 µg/g) and n-alkanes (0.22 and 2.06 µg/g) concentration was detected. This was an initial survey (n = 2) and the main goal was to know accumulation and distribution of PAHs and n-alkanes in the sea snakes. This study indicates high accumulation of petroleum hydrocarbon in gut, liver and kidney of sea snake. Since, this species also act as pray for sea eagles and some predatory fishes such as tiger shark, there is high possibilities of PAHs being circulated in marine food chain. [ABSTRACT FROM AUTHOR]

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The reproductive cycle of Polymesoda erosa was studied over a 12-month period from July 2004 to July 2005 at Chorao Island, Goa. Macroscopic observation revealed that P. erosa is dioecious and gametogenic development was synchronous between the sexes. Sexes can be determined at a total length of <34 mm, based on the colour of the gonads. The gonadosomatic index (GSI) indicated that gametogenesis began in November and by March-April most clams were ripe. Spawning began in August and by October nearly all clams were completely spent. Maturation and high GSI were observed to begin during the warm summer months with low GSI values in August (20.0) and September (22.0). Correlation between GSI and chlorophyll a content in the adjacent estuarine water suggests that gametogenesis in mud clam is directly related to the phytoplankton production. The condition index (CI), which is generally used to characterize the physiological activity of organisms, varied from 1.9 in September to 4.7 in March, with low values during the spawning period. The clams attained their best condition in quality of flesh weight during March-May. The data presented here should provide valuable information on the timing of spawning events for P. erosa, necessary for developing sustainable management strategies and broodstock selection, which is crucial in aquaculture development. [ABSTRACT FROM AUTHOR]

Estuaries provide enumerable ecosystem services to mankind in terms of provisional, regulating, supporting, recreational and information services. However, the persistent human-environment interactions for these services altered the ecological integrity of estuaries. Although the small estuaries receive little attraction in scientific studies due to their low surface area and regional importance, these ecosystems are more vulnerable to anthropogenic pressures and require urgent attention from the scientific fraternity. The Terekhol Estuary (TRE) is a small tropical estuary situated along Goa, west coast of India, gaining recognition in recent years due to the pollution risk from tourism activities. Moreover, the estuary also behaves as an extension of the marine realm during the dry season. The food web structure and network flow indices of the TRE was assessed to reveal its present ecological status. The Ecopath modelling approach was employed to delineate the ecosystem structure and trophic functioning of the estuary distributed in 22 ecological compartments from 2018 to 2019. The trophic level of the food web ranged from detritus (TL-1) to sharks (TL- 4.53). The ecosystem structure demonstrated a grazing chain (herbivory) based organization over the detritus-based pathway. The proportion of exports to the total flows was 35% for the TRE. The model has a high total system throughput (12,043.6 t km−2 year−1), low system omnivory index (0.17) and connectance index (0.21), and a moderate relative ascendency (45.1%). Finn's cycling index (2.17%) indicated very low recycling in the system. All these indicators along with the eco-exergy index (8567.22 g detritus equivalent m−2), specific eco-exergy (38.25) and robustness index (0.11) classified the estuary as be immature, less stable and less organized and is in the initial stages of its development. The ecological indicators analyzed here point towards a medium to a high level of impact in the TRE due to anthropogenic activities. We also highlight the management measures to be implemented in order to restore the ecological quality of the TRE. [Display omitted] • The food web model of a small tropical estuary, Terekhol along the west coast of India was constructed. • A grazing chain based on herbivory followed by detritivory was identified in the estuary. • The estuary is identified as an immature, low recycling and developing ecosystem. • The health and stability indices indicated a less stable and less organized stature of the ecosystem. [ABSTRACT FROM AUTHOR]