Metallothionein as an indicator of water quality: assessment of the bioavailability of cadmium, copper, mercury and zinc in aquatic animals at the cellular level

The study of metallothioneins (MTs) has greatly improved our understanding of body burdens, metal storage and detoxification in aquatic organisms subjected to contamination by the toxic heavy metals, Cd, Cu, Hg and Zn. These studies have shown that in certain organisms MT status can be used to assess impact of these metals at the cellular level and, whilst validation is currently limited to a few examples, this stress response may be linked to higher levels of organisation, thus indicating its potential for environmental quality assessment. Molluscs, such as Mytilus spp., and several commonly occurring teleost species, are the most promising of the indicator species tested. Natural variability of MT levels caused by the organism's size, condition, age, position in the sexual cycle, temperature and various stressors, can lead to difficulties in interpretation of field data as a definitive response-indicator of metal contamination unless a critical appraisal of these variables is available. From laboratory and field studies these data are almost complete for teleost fish. Whilst for molluscs much of this information is lacking, when suitable controls are utilised and MT measurements are combined with observations of metal partitioning, current studies indicate that they are nevertheless a powerful tool in the interpretation of impact, and may prove useful in water quality assessment.

Equatorial upwelling at Galapagos: the cadmium record in corals since 1600 [abstract and figures]

EXTRACT (SEE PDF FOR FULL ABSTRACT): Chemical isolation of lattice-bound trace elements in marine carbonates has opened new windows to paleoceanographic study. In a modern context at the Galapagos Islands, oceanic upwelling variability is mirrored by changes in the Cd content of reef-building corals. This association derives from cadmium's nutrient-like distribution in the water column and its ability to substitute for calcium in the aragonite lattice of corals. Given corals of sufficient age, it is thus possible to reconstruct near-term ENSO-related changes in surface waters of the eastern Equatorial Pacific on annual and sub-annual timescales.

Biochemical variation during ovarian vitellogenic growth in a hill stream teleost Garra mullya (Sykes) due to cadmium toxicity

Some biochemical variations during ovarian vitellogenic growth in hill-stream teleost Garra mullya due to sublethal concentration of cadmium has been discussed. Total protein, cholesterol and glycogen in ovary and liver along with gonadosomatic index (GSI) and hepatosomatic index (HSI) in Cd-treated fish exhibited significant decrease while liver glycogen remained unaltered.