Effects of water-borne cadmium on plasma cortisol and glucose in the cichlid fish Oreochromis mossambicus

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Effect of ambient and dietary cadmium on pavement cells, chloride cells, and Na+/K+-ATPase activity in the gills of the freshwater teleost Oreochromis mossambicus at normal and high calcium levels in the ambient water

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Calcium homeostasis in low and high calcium water acclimatized Oreochromis mossambicus exposed to ambient and dietary cadmium

Contains fulltext : 35050.pdf (publisher's version ) (Open Access)The effects of cadmium administered via ambient water (10 mg/l) or food (10 mgCd/fish/day) on plasma calcium, corpuscles of Stannius and bony tissues of Oreochromis mossambicus acclimated to low calcium (0.2 mM) and high calcium (0.8 mM) water were studied for 2, 4, 14 and 35 days. In low calcium water acclimated fish, ambient cadmium induced significant hypocalcemia, while the structure and morphometry of type-1 and type-2 cells of corpuscles of Stannius were not affected on day 2 and 4. Subsequently on day 14 and 35, recovery of plasma calcium to normal levels was observed followed by a decrease in corpuscles of Stannius index (CSI), cell size, volume of granular endoplasmic reticulum (p<0.05) of type-1 cells in both, fish exposed to ambient or dietary cadmium. The type-2 cells were not affected. In high calcium water acclimated fish both, ambient and dietary cadmium caused a significant reduction of plasma calcium levels on day 2 and 4. In these fish, there was a significant transient increase in the size of corpuscles of Stannius on day 4, followed by recovery on day 14 and 35. Ultrastructural observations of corpuscles of Stannius revealed that cadmium did not cause any cellular damage on type-1 and type-2 cells during 35 days exposure. In low or high calcium water acclimatized tilapia exposed to ambient or dietary cadmium had no effect on the calcium and phosphate composition of the scales, operculum and vertebrae. Thus, it is unlikely that recovery of hypocalcemia was due to the dissolution of calcium from bony tissues. This study also revealed that cadmium does not mediate stimulation of the corpuscles of Stannius gland, and that high Ca2+ water had a protective effect against ambient and dietary cadmium

Effect of waterborne and dietary cadmium on plasma ions of the teleost Oreochromis mossambicus in relation to water calcium levels

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Mineral composition and cadmium accumulation in Oreochromis mossambicus exposed to waterborne cadmium

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Heavy metal contamination in the Western Indian Ocean (a review)

Western Indian Ocean Coast has many potential marine ecosystems such as mangrove, seagrass meadows, macroalgae, and coral reefs. It is largely unspoiled environment however, tourism and population growth in coastal urban centres, industrialization, are presenting a risk of pollutants input to the marine environment of the Western Indian Ocean. Mining, shipping and agricultural activities also input contaminants into the marine environment via runoff, vessel operations and accidental spillage. Heavy metals are among the pollutants that are expected to increase in the marine environment of the Western Indian Ocean. The increase in heavy metal pollution can pose a serious health problem to marine organism and human through food chain. This paper reviews studies on heavy metal contamination in the Western Indian Ocean. It covers heavy metal studies in the sediments, biota, particulates and seawater collected in different sites. In comparison to other regions, only few studies have been conducted in the Western Indian Ocean and are localized in some certain areas. Most of these studies were conducted in Kenyan and Tanzanian coasts while few of them were conducted in Mauritius, Somalia and Reunion. No standard or common method has been reported for the analysis or monitoring of heavy metals in the Western Indian Ocean

Status of pollution in mangrove ecosystems along the coast of Tanzania

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Changes in morphology and growth of the mudskipper (Periophthalmus argentilineatus) associated with coastal pollution

Contains fulltext : 36046.pdf (publisher's version ) (Closed access)In this paper a comparison is made between the growth and morphology of barred mudskippers (Periophthalmus argentilineatus) from six mangrove forests along the coast of Tanzania. The fish populations from unpolluted sites consisted of different size classes, whereas only small sized fish were present in the polluted Mtoni mangroves. Age estimation based on the examination of otoliths revealed that the mudskippers followed similar growth patterns in all sites with limited pollution. However, the age estimates from the polluted Mtoni site revealed an abnormal growth pattern. The occurrence of unilateral anophthalmia in the Mtoni mudskippers suggested that these fish were affected by pollutants during early development. The study showed that the presence of urban and industrial wastes from Dar es Salaam city, as indicated by isotopic enrichment, correlated with abnormal growth and developmental effects in mudskippers. We hypothesize that pollution might also affect fish species that use the mangroves as a temporary habitat

Heavy metal levels in the sediments of four Dar es Salaam mangroves: accumulation in, and effect on the morphology of the periwinkle, <i>Littoraria scabra</i> (Mollusca: Gastropoda)

Heavy metals were determined in the soft tissue and shells of the littorinid, Littoraria scabra, and in the sediments of four mangrove areas along the Dar es Salaam coastline where L. scabra was collected. Several metals accumulate, preferentially in the animals' soft body parts, but do not seem to affect the shell morphology of this species. Sediment-metal levels, measured in the direct vicinity of Dar es Salaam have increased dramatically over the last decade. Nonetheless, these levels are still lower compared to metal-sediment levels reported in polluted European and American estuaries. Soft-tissue metal levels detected in L. scabra are, nevertheless, with the exception of Cr and Zn, comparable to metal levels reported in other gastropod species