ISSN:1208-6053    

DOI:10.1139/ercontents00

出版商:NRC Research Press    

年代:2000

数据来源: NRC

摘要:

Although chemical measurement techniques and geochemical speciation modelling may detect and predict the different forms of copper in aquatic systems and hence provide some information about the likely toxicity of the water to aquatic organisms, they do not givedirectquantitative data on adverse biological effects. Bioassays or toxicity tests are generic tests that use living organisms as indicators of contaminant bioavailability in aquatic systems. The microbial community, including protozoa, algae, bacteria, and fungi, provides a useful tool for directly assessing the hazard of copper in natural ecosystems. Most of our information on copper toxicity in aquatic systems comes from single-species tests using cultured organisms. However, whole community bioassays with natural phytoplankton and bacterial populations are finding increasing use. Although laboratory toxicity tests using ionic copper spiked into pristine seawater or synthetic softwater provide information on copper toxicity under controlled conditions, their usefulness for estimating bioavailable copper is limited in natural waters, where copper toxicity is ameliorated by complexation and adsorption. Careful selection of appropriately sensitive test species, bioassay endpoints, and test protocols is necessary to ensure the environmental relevance of the bioassays used. An understanding of metal speciation, metal-cell binding, mechanisms of toxicity, and limitations of the bioassays is required to understand copper bioavailability in natural waters and sediments. In this review, the use of bioassays with bacteria and microalgae for assessing copper bioavailability in marine and fresh waters and sediments is discussed, with particular emphasis on the limitations of current techniques. There is an urgent need for more environmentally relevant tests with sufficient sensitivity to detect bioavailable copper at concentrations close to water and sediment quality guideline values.Key words: bioassay, copper, metal, bioavailability, toxicity, bacteria, algae.

ISSN:1208-6053    

DOI:10.1139/a00-010

出版商:NRC Research Press    

年代:2000

数据来源: NRC

摘要:

Is sea-level rise and (or) climate change responsible for current declines in important coastal bird populations in Great Britain, and how might these processes affect bird populations in future? We review the current status of coastal bird populations in Britain and identify two important species, Common Redshank (Tringa totanus) and Twite (Carduelis flavirostris), whose populations are currently declining. We then review the evidence relating to the causes of these declines. There is evidence that habitat loss, driven by sea-level rise and climate change (e.g., an increase in wind and wave energy reaching the coast due to an increase in the frequency of storms), could have contributed to the decline in Twite. Common Redshank numbers are declining because of changes in grazing management, not sea-level rise. Populations that are currently stable or increasing, such as wintering waders and wildfowl, might in future experience declines in abundance because there is a link between climate, food supply, and bird abundance. There are insufficient reliable data at present to allow us to predict future changes with any confidence. Sea-level rise and climate change are currently important issues facing coastal zone management in Great Britain, and these issues may become even more pressing in future. But, in addition to these environmental processes, coastal bird populations are affected by a range of other anthropogenic factors. Conservationists, therefore, need to identify important bird populations that are (or could be in future) detrimentally affected by any of these activities rather than focusing exclusively on single issues such as sea-level rise. Allowing the sea to breach existing sea defences, thereby creating new saltmarsh, provides a way forward but is not without its practical and political difficulties.Key words: coastal birds, sea-level rise, climate change, population decline, habitat loss, saltmarsh.

ISSN:1208-6053    

DOI:10.1139/a00-011

出版商:NRC Research Press    

年代:2000

数据来源: NRC