The use of biomarkers to assess the impact of pollution in coastal environments of the Iberian Peninsula: a practical approach
Introduction
In recent years, levels of contaminants in the marine environment have increased as a consequence of anthropogenic activities. The diminishing of water and sediment quality can involve a decrease in natural resources. For this reason there is an increasing need to develop methods for the identification, estimation, comparative assessment and management of the risks posed by chemical pollutant discharges to the environment and natural resources. As recognised in the last years by international organisations and environmental agencies, risk assessment can not be solely based on chemical analysis of environmental samples because this approach does not provide any indication of deleterious effects of contaminants on the biota. Therefore, the measurement of the biological effects of pollutants has become of major importance for the assessment of the quality of the environment (Bayne, 1989, Gray, 1992).
Recently, the use of biological markers or biomarkers measured at the molecular or cellular level have been proposed as sensitive ‘early warning’ tools for biological effect measurement in environmental quality assessment (McCarthy and Shugart, 1990). The selected biomarkers should indicate that the organism has been exposed to pollutants (exposure biomarkers) and/or the magnitude of the organism’s response to the pollutant (effect biomarkers or biomarkers of stress). One of the most important features of molecular/cellular biomarkers is that they have the potential to anticipate changes at higher levels of biological organisation, i.e. population, community or ecosystem. Thus these ‘early warning’ biomarkers can be used in a predictive way, allowing the initiation of bioremediation strategies before irreversible environmental damage of ecological consequences occurs. Biomarkers are then defined as short-term indicators of long-term biological effects.
Recently the biomarker approach has been incorporated into several pollution monitoring programmes in Europe and the USA (e.g. the North Sea Task Force Monitoring Master Plan and the NOAA’s National Status and Trends Program). Likewise, different methods for biological effect measurement have been evaluated in a series of practical workshops organised by the International Council for the Exploration of the Sea (ICES) and the Intergovernmental Oceanographic Commission (IOC), such as those in the North Sea (Stebbing and Dethlefsen, 1992). The United Nations Environment Programme has funded a biomonitoring programme in the Mediterranean Sea including a variety of biomarkers (UNEP, 1997, and see below). Recently, biomarkers have also been included in the Joint Monitoring Programme of the OSPAR convention where Portugal and Spain are members.
In the Iberian Peninsula there has been no attempt to perform a periodical monitoring programme of pollution effects on the coastal environments. In Spain, only chemical monitoring has been performed on a regular basis using bivalve molluscs and other indicator species since 1986 (Porte and Albaigés, 1993, Solé et al., 1994). The Spanish Institute of Oceanography (IEO) is currently in charge of chemical monitoring along the Spanish coast. In Portugal only chemical monitoring has been performed, under the responsibility of the Portuguese Ministry for the Environment, in order to fulfil the obligations under the ICES and OSPAR Conventions. Apart from chemical monitoring, individual research groups have been involved in recent years in applying the biomarker approach to measure the effects of pollution in selected coastal areas of the Iberian Peninsula. In the following sections we describe some of the biomarkers used and overview the results obtained in different case studies along the coastal environments of the Iberian Peninsula. This information was presented and discussed thoroughly in the Workshop on Biomarkers held during the 2nd Iberian Congress on Environmental Contamination and Toxicology (University of the Basque Country, Leioa, June 1998). The aims of the workshop were to discuss the usefulness and problems associated with the biomarker approach and to prepare a report with suggestions of biomarkers and sentinel species adequate to detect the effects of pollution in littoral and coastal zones of the Iberian Peninsula. Potential areas for future research on the use of biomarkers in marine pollution monitoring were also identified.
Section snippets
Metallothionein induction
Metals are among the major contaminants reaching the marine environment. Their levels have been increasing over the last decades as a result of technological development. The exposure of marine organisms to certain metals can lead to alterations of several biochemical processes that have the potential to be used as biomarkers of exposure and therefore as ‘early warning’ signals of the presence of these particular contaminants. It is generally accepted that toxicity will manifest itself at the
Application of the biomarker approach in the Med Pol monitoring programme
Several of the biomarkers mentioned in the above section have been applied in a pollution monitoring programme of the Mediterranean Sea (Med Pol, UNEP, 1997). Recently a Med Pol II Programme was carried out with the aim of evaluating the toxic effects of the pollutants on the marine organisms along the Mediterranean coast.
The Med Pol II Mediterranean Biomonitoring Programme was planned following the establishment of some important general criteria to standardise field/laboratory activities in
Conclusions
From the practical cases discussed above it becomes clear that there is a need to plan and develop a multidisciplinary monitoring programme to assess environmental pollution in the Iberian Peninsula, particularly on the Atlantic coast. The Mediterranean coast has received more attention and has been included in the Med Pol monitoring programme, which attempts to assess environmental pollution in the Mediterranean Sea as a whole.
Besides the sampling stations where chemical monitoring is carried
Acknowledgements
This collaborative effort has been possible thanks to the funding of CICYT (Spanish Ministry of Education and Culture) through a Special Action (ref AMB98-1330-E). Work in the laboratory of MP Cajaraville has been funded by projects AMB96-0523 (CICYT), UPV 076.310-EC219/97 (University of the Basque Country) and PL97-3827 (EU FAIR Programme). The work in the laboratory of C. Porte and A. Viarengo was partially supported by the CE-BIOMAR project refs. EV5V-CT94-0550 and ENV4-CT96-0300.
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