Unit 3 - Environmental Monitoring
The sections below address the post-incident monitoring for environmental impact assessment (e.g. explain why is necessary an effective and pre-considered post-incident monitoring). The sampling strategies as well as the main scientific approaches employed in monitoring programmes in the case of an accidental HNS marine pollution event are described. Furthermore, a recommended baseline battery of biomarkers and bioassays for use in post-incident monitoring and the relevance of indicator /sentinel species are also provided. The last topic of this unit describes the major gaps and environmental monitoring priorities (e.g. standardized guidelines).
1. Post-incident monitoring for environmental impact assessment
A fully integrated and effective response to a chemical spill at sea must include a well planned and executed post-incident assessment of environmental contamination and damage.
Environmental post-incident monitoring is a set of integrated data-collecting activities to characterise and monitor the quality of a defined environment after an incident such as an HNS spill. Monitoring data may be used to compare spatial or temporal trends in relevant parameters as required for the preparation of an environmental impact assessment.
"Why is effective and pre-considered post-incident monitoring necessary?"
Six key reasons to respond to this question are proposed in the following paper:
Impact assessment is a process through which the consequences of an event (such as a marine HNS spill) or process are evaluated through the monitoring of key parameters and compared to a previous or “normal” status. Impact assessment aims to establish the magnitude, type, and significance of any monitored changes and for them to be “quantified” as far as possible.
Therefore, after chemical spill incidents ...
Post-spill monitoring and impact assessment studies may be required to investigate and understand the behaviour and fate of a chemical spill, its effects and any associated clean-up response which, in turn, helps to address any wider concerns (e.g. from the public).
The arrangement and co-ordination of post-incident monitoring and impact assessment need to consider sampling design, biological effects, chemical analysis and collection/interpretation of expert local knowledge, etc.
2. Sampling strategies
Sampling should include both impacted and reference (unimpacted) sites, ideally with similar characteristics. Sites that are not impacted at the time of sampling but are likely to be impacted later or during the incident (e.g. as indicated by predictive modelling of the trajectory of the spilled material) can provide excellent reference (pre-incident) information.
The range of samples to be collected can be very wide, including:
- Subtidal and intertidal sediments;
- Subtidal and intertidal biota;
- Coastal (supratidal) biota and sediments;
- Commercial fish and shellfish;
- Samples of the spilled chemical(s) from the sea surface or from beaches. Dissolved concentrations of contaminants are usually very low even during marine incidents.
Samples should be taken in a representative manner and in accordance with guidelines, protocols and operating procedures established during the planning and preparedness phase.
3. Main scientific approaches employed
In the case of an accidental HNS marine pollution event a monitoring programme is usually set up applying three types of scientific approaches:
- Monitoring of chemical contamination (i.e. measurement of the chemical concentration (through chemical analysis) in the various marine compartments (water, air, sediments, organisms tissues).
- Monitoring of biological responses at sub-individual and individual level (e.g. physiological and epidemiological markers; biomarkers of exposure/effect (e.g. enzyme levels); biological responses in ecotoxicological assays).
- Ecological monitoring at population and/or community level (population dynamic and/or community structure parameters e.g. abundance, mortality, etc.) (Ecological domains: Marine mammals; Birds; Fish/Shellfish; Plankton; Benthos).
For example, in case of a spill with evaporators or gases, it is essential to:
- Evaluate the presence and concentration of contaminants in air (monitoring the plume).
- Monitor oxygen levels, flammability and toxic levels.
An overview of main scientific monitoring approaches and methodologies can be found in the following articles:
3.1. Ecotoxicology in post-spill monitoring
Ecotoxicological methods can be used as powerful tools in post-incident monitoring and the assessment of actual or potential impacts.
It is highly recommended that a baseline standard approach is available, including standardised techniques, to facilitate the prompt deployment of testing following a spill incident. Tables 1 and 2 outline a recommended baseline approach.
Table 1 - Recommended baseline battery of bioassays for use in post-incident monitoring.
Bioassay: a toxicity study in which specific toxic effects from chemical exposure are measured in the laboratory using living organisms. Acute toxicity: can be defined as toxicity elicited immediately following a short time period of exposure to a single dose (usually) of a chemical. EC50: A statistically or graphically determined concentration of a chemical that reduces a sublethal response parameter of interest by 50%. LC50: The concentration of a test chemical that, when a population of test organisms is exposed to it, is estimated to be fatal to 50% of the organisms under the stated conditions of the test (acute toxicity test).
Table 2 - Recommended baseline battery of biomarkers for use in post-incident monitoring (short-term).
Note: The term biomarker has been generally used to refer to a xenobiotically induced variation in cellular, or biochemical components as well as processes, structures, or functions that are measurable in a biological system or samples, resulting in an observable change (not necessarily pathological) in a normal status. This definition includes biochemical, physiological, histological, morphological, and behavioural measures. In other words, a biomarker can be defined as a biochemical, genetic, or molecular indicator that can be used to screen disease or toxicity. Therefore, this parameter can be used as an indicator of exposure, effect, or susceptibility and may be a metabolite, enzyme, or cell surface marker, among others.
Biomarkers do not directly provide information concerning impacts on the higher levels of biological organization (e.g. population, community, and ecosystem) considered in ecotoxicology. Nevertheless, biomarkers often provide important tools for discerning contaminant exposures and potential impacts of ecological relevance, as well as sensitive early warning signals or incipient ecological damage. Hence, biomarkers play an important role in monitoring studies in the evaluation of the effectiveness of remedial action of xenobiotic effects, to assess the quality of the environment and how it changes over time.
Possible biomarkers suitable for ecotoxicological assessment and monitoring in both estuarine and marine systems can be found in the following article:
The term biomarker has been generally used to refer to a xenobiotically induced variation in cellular, or biochemical components as well as processes, structures, or functions that are measurable in a biological system or samples, resulting in an observable change (not necessarily pathological) in a normal status. This definition includes biochemical, physiological, histological, morphological, and behavioural measures. In other words, a biomarker can be defined as a biochemical, genetic, or molecular indicator that can be used to screen disease or toxicity. Therefore, this parameter can be used as an indicator of exposure, effect, or susceptibility and may be a metabolite, enzyme, or cell surface marker, among others.
Xenobiotic: (1) A general term used to describe any chemical interacting with an organism that does not occur in the normal metabolic pathways of that organism. The use of this term in lieu of “foreign compound” among others, has gained wide acceptance. (2) A substance not normally present in the environment, such as a pesticide or pollutant
Indicator / Sentinel species An indicator species is any biological species whose presence, absence or abundance reflects a specific environmental condition, such as pollution, species competition or climate change. Species that react positively to environmental contamination or whose behaviour suffers a modification compared to a normal status can also be considered indicator species. Hence, indicator species can be among the most sensitive species in an ecosystem and sometimes act as an early warning in biomonitoring studies (e.g. sentinel species).
Where a particular habitat is at threat or is already impacted, it is recommended the use of sentinel species (coastal organisms such as shanny fishes (Lipophrys pholis), mussels (Mytilus galloprovincialis, etc.)) that are representative of that particular environment (e.g. species that play an important role in the maintenance of the ecosystem sustainability) in impact assessment and recovery. As part of environmental monitoring programmes, marine researchers carry out analyses in sentinel species from different locations and in different seasons. These species may give the first signal of environmental contamination and are essential to monitor the efficiency of cleaning and environmental restoration activities.
Note: The ultimate selection of target species and assays (bioassays/biomarkers) will require a case-by-case approach, depending on the ecosystem affected (e.g. offshore, coastal or estuarine) and the financial constraints of the monitoring program.
4. Major gaps and environmental monitoring priorities
The major gaps and environmental monitoring priorities that have been mentioned in the literature are as follows:
Lack of research coordination - Priority to multidisciplinary studies rather than to particular scientific interests. Lack of reference/baseline data - Priority to set up reference databases by performing long-term monitoring programmes. Lack of knowledge on the biology of the selected species - Priority to use well validated and ecological relevant indicator species. Lack of information related with the hazards and consequences of HNS spills - Priority to gather information on the ecological hazards of HNS and to set up monitoring studies following major HNS spills.
Note: Toxicity bioassays with different species (e.g. sea urchin (Paracentrotus lividus), amphipod (Gammarus locusta), turbot (Scophthalmus maximus)) have been performed in the last years by CIIMAR in order to increase the information related with the hazards and consequences of HNS spills.
Lack of knowledge on long-term effects of the spills - Priority to set long-term monitoring programmes and funding allocation. Standardisation of procedures and guidelines for conducting monitoring programmes following a spill.
These major gaps and environmental monitoring priorities are explained in more detail in Neuparth et al. (2012).
Relevance of Guidelines and protocols
Every accidental spill is unique and therefore any monitoring programme will need to have some elements adapted to the local circumstances in order to consider all lines of evidence and specificities of the incident. Nonetheless, although monitoring programmes should be flexible, the establishment of guidelines and standard procedures (protocols) for conducting monitoring programmes would be of great benefit, as mentioned before.
Guidelines would provide benefits in developing a framework for best approach for a range of essential post-incident monitoring activities including:
Monitoring programme development; Survey design; Collection, transport and storage of samples (water, sediments and biota), for which biological and chemical analysis techniques are available and their purposes, ecological and ecotoxicological assessment techniques, statistical treatment of data and presentation of the outputs are in the most appropriate ways for the intended audience.
Therefore, the implementation of guidelines and protocols are essential to strengthen monitoring programmes in terms of speed, identification of the expertise needed (e.g. modellers, ecotoxicologists, marine ecologists), cost effectiveness, use of the best practices and improve integration and coordination.
Some guidelines and protocols on environmental monitoring (e.g. Post-incident monitoring guidelines developed under the PREMIUM project) can be found in the Hazardous and Noxious Substances Online Platform (explained in unit 4.2). To access these documents click HERE.
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