Biomonitoring of pollution impacts in the marine environment
Biomonitoring of marine pollution
Biomonitoring uses organisms and their biological responses to detect pollutant exposure and harmful biological effects, including effects of substances or mixtures that may escape chemical monitoring.
The Coastal Wiki articles on this subject provide complementary perspectives:
- Biomonitoring of pollution impacts in the marine environment – general framework and monitoring principles;
- Biomarkers for assessing marine pollution effects – principal biomarkers and their interpretation;
- Endocrine disruption by marine pollutants – a specific mechanism of pollutant impact;
- Health biomarkers in marine mammals – application of physiological and immune biomarkers to marine mammals.
Effects of diverse toxic substances on different marine animals are described in articles in the category ecotoxicology.
Contents
Biomonitoring
Marine pollution is traditionally monitored by measuring concentrations of known contaminants in water, sediment or organisms. Chemical analysis provides essential information on contaminant occurrence and exposure, but cannot by itself show whether the mixture of contaminants present in the environment causes biological effects. Biological monitoring complements chemical monitoring by measuring contaminant accumulation in organisms and biological responses at different levels of biological organization. Responses at the molecular, biochemical, cellular, physiological or behavioral level can be evaluated through biomarkers. Common biomarkers are described in the article Biomarkers for assessing marine pollution effects.
Organisms used for biomonitoring are often called bioindicators or sentinel species. Their contaminant burden or biological responses are used as indicators of environmental exposure or pollution effects. Suitable bioindicators are generally widespread, sufficiently abundant, readily sampled and show a sufficiently well-characterized response to the pollutants or effects being monitored. A biomarker is a measurable biological characteristic or response of the bioindicator organism.
Mussels and other bivalves are particularly useful because they are sessile or weakly mobile, filter large volumes of water and accumulate many contaminants. Fish provide complementary information because they integrate exposure over larger areas and occupy higher trophic levels. Other organisms, including gastropods and marine mammals, are useful for particular pollutants or effects. See the article Bioindicator for further details.
Biological responses to pollutants are often detected before adverse effects become apparent at population or community level. Such responses can therefore provide early warning of environmental deterioration. However, biomarkers are also influenced by natural environmental conditions and the physiological state of organisms. Biomonitoring is therefore most informative when biological responses, contaminant concentrations and relevant environmental variables are evaluated together.
Complex mixtures
Biological-effect monitoring can reveal biologically active pollution even when the responsible substances are not included in routine chemical analysis. This is particularly relevant for complex mixtures and for the very large number of chemicals for which routine environmental monitoring is impractical. Detection of an unexplained biological effect can then guide more targeted chemical investigation.[1]
Laboratory or in vitro bioassays on environmental samples are increasingly used to assess the combined biological activity of contaminant mixtures and can help identify which samples require further chemical investigation.
Response of marine organisms to toxic contaminants
Exposure to toxic contaminants can affect marine organisms at different levels of biological organization. Early responses often occur at the molecular and cellular level, for example through changes in enzyme activity, oxidative stress, DNA damage or disruption of cellular processes. With increasing exposure, these effects can propagate to tissues and physiological functions and eventually impair behavior, growth, development, reproduction or survival.
If such adverse effects are sufficiently strong or persistent, they can reduce population abundance and alter community composition and ecosystem functioning. Biomarkers are therefore useful for detecting pollutant effects at an early stage, before consequences at population or community level become apparent. Biomarkers at the molecular, biochemical, cellular, physiological or behavioral level are described in Biomarkers for assessing marine pollution effects.
The relation between responses at different levels is not always straightforward. Some early responses represent protective or compensatory mechanisms and do not necessarily result in adverse effects at higher levels. Conversely, effects on growth, reproduction or survival are ecologically more significant but are generally less easily attributed to a particular pollutant.
Interpretation of biomarker responses therefore requires information on contaminant exposure and on other factors that influence the physiology and sensitivity of the bioindicator organism. Temperature, salinity, food availability, reproductive condition, age, disease and other environmental stressors can modify biomarker responses. Reliable assessment is strongest when biological responses, contaminant concentrations and relevant environmental conditions are evaluated together.[1][2] Biological-effect monitoring increasingly also uses laboratory or in-vitro bioassays on environmental samples to detect the combined biological activity of contaminant mixtures.
Passive sampling for estimating contaminant exposure
Biomarker responses integrate exposure over time, whereas concentrations measured in occasional water samples can vary strongly with discharges, currents and other environmental conditions. Passive samplers provide complementary information by accumulating selected contaminants during deployment over periods ranging from days to weeks or longer.
Depending on sampler design, calibration and deployment time, passive sampling can provide an estimate of the average concentration of selected dissolved contaminants over the sampling period. For many hydrophobic organic pollutants, passive samplers measure the freely dissolved fraction, which is often more closely related to bioavailability than the total concentration in water. Several passive sampling devices have been developed to collect contaminants such as persistent organic pollutants and heavy metals from seawater, using sorbent materials with an affinity for the targeted contaminants.[3]
Passive samplers do not reproduce all routes of contaminant uptake by organisms, especially dietary uptake and trophic transfer. They should therefore be regarded as complementary tools for characterizing contaminant exposure rather than as direct substitutes for measurements in organisms.
Related articles
- Bioindicator
- Biomarkers for assessing marine pollution effects
- Endocrine disruption by marine pollutants
- Health biomarkers in marine mammals
- Coastal pollution and impacts
- Biomarker
- Endocrine disrupting compounds
- Endocrine system
References
- ↑ 1.0 1.1 Burgeot, T., Mauffret, A., J., Anderson, Brooks, S., Assuncao, M., Bellas Bereijo, J., Bignell, J., Campillo, J.A., Coorman, K., Förlin, L., Giltrap, M., Guls, H.D., Hylland, K., Halldorsson, H.P., Martinez-Gomez, C., McHugh, B., Parmentier, K., Scharsack, H., Sturve, J. and Tairova, Z. 2022. Integrated biological effects and chemical contaminants approach: a case study. In: OSPAR, 2023: The 2023 Quality Status Report for the North-East Atlantic. OSPAR Commission, London.
- ↑ Chahouri, A., Yacoubi, B., Moukrim, A. and Banaoui, A. 2023. Bivalve molluscs as bioindicators of multiple stressors in the marine environment: Recent advances. Continental Shelf Research 264, 105056
- ↑ Vrana, B., Allan, I.J., Greenwood, R., Mills, G.A., Dominiak, E., Svensson, K., Knutsson, J. and Morrison, G. 2005. Passive sampling techniques for monitoring pollutants in water. TrAC Trends in Analytical Chemistry 24: 845–868.
