EROD - Marine online assessment tool

The assessment shows that overall flatfish in UK marine waters do not have elevated 7-ethoxyresorufin O-deethlyation (EROD) enzyme activity which indicates that they are not significantly exposed to organic contaminants including some polycyclic aromatic hydrocarbons, polychlorinated biphenyls, furans and dioxins.

Background

Detoxification enzymes are proteins that the body produces to speed up the breakdown of harmful substances. In fish, CYP1A is a detoxification enzyme which is produced when the fish is exposed to some organic contaminants including certain polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), furans and dioxins. Fish can be exposed to these contaminants through contaminated water, sediment and diet.

The measurement of EROD (7-ethoxyresorufin O-deethylase) activity in fish indicates if CYP1A is present and therefore if the fish may have been exposed to contaminants. EROD represents the cumulative effect of all CYP1A enzyme inducing chemicals that the fish may have been exposed to. Other factors which affect EROD activity include sex, reproductive status, season and environmental temperature.

The EROD indicator is used to supplement the target for biological effects of contaminants set out in UK Marine Strategy Part One (HM Government, 2012) which requires that concentrations of substances identified within relevant legislation and international obligations are below levels at which adverse effects are likely to occur. EROD is included in the in the OSPAR Joint Assessment and Monitoring Programme (JAMP) as a voluntary indicator. EROD is recommended by the International Council for the Exploration of the Sea (ICES) as an assessment tool to include in an integrated monitoring and assessment programme on hazardous substances and their biological effects.

The key pressures associated with this indicator are riverine and direct inputs of legacy contaminants arising from point and diffuse sources, atmospheric and acute events that have entered marine sediments, which can then accumulate in fish and increase the activity of detoxification enzymes (HM Government, 2012).

Further information

As stated in the Marine Strategy Part One (HM Government, 2012): “Contaminants can enter the marine environment from natural sources and as a result of anthropogenic activities, either as direct inputs or via rivers, estuaries and the atmosphere. Pollution is considered to be the introduction of substances which have, or are likely to have, deleterious effects on the marine environment and its uses. This includes effects that result in harm to the health of aquatic organisms, loss of biodiversity, chemicals hazardous to human health, impair water quality, or reduce our ability to use the sea.“

7-ethoxy-resorufin-O-deethylase (EROD) is an enzyme found in fish liver, which is important in the metabolism of persistent organic contaminants. The expression and activity of EROD increases in fish exposed to these contaminants through the food they eat, contact with contaminated sediments or their presence in water column.

The measurement of EROD activity in the liver of fish is useful for biomonitoring purposes because its expression and activity can increase following the exposure of fish to contaminants that bind to the aryl hydrocarbon receptor and stimulate the induction of CYP1A enzyme activity. These substances include some polycyclic aromatic hydrocarbons, planar polychlorinated biphenyls, dibenzo-p-furans and dibenzo-p-dioxins, many of which are readily metabolised and excreted by fish, meaning that exposure cannot be reliably determined by analytical chemical methods. The induction of CYP1A can lead to the production of genotoxic metabolites (particularly those formed after the biotransformation of polycyclic aromatic hydrocarbons) and consequently it can be used as an indicator of adverse effects in exposed animals. In support of this, there is a considerable amount of field evidence correlating CYP1A induction with DNA damage, chemical carcinogenesis and other pathological conditions in marine organisms (ICES, 2011). The concentrations of hazardous substances have long been monitored in flatfish as part of the UK marine monitoring programme, EROD was added to the monitoring programme in 2000. The additional use of biological effects monitoring allows the exposure of organisms to compounds that are metabolised and excreted to be observed and provides an integrative measure of exposure to mixtures of contaminants with the same mode of action (that is aryl hydrocarbon-receptor binding).

Within the United Kingdom, the Clean Seas Environment Monitoring Programme (CSEMP) is one means by which our national and international commitments to monitor marine biota in near-shore and offshore marine waters are met (Nicolaus and others, 2016). The main drivers for the current programme are the Co-ordinated Environmental Monitoring Programme (CEMP) and Joint Assessment and Monitoring Programme (JAMP) of the OSPAR Convention (OSPAR Commission, 2014), together with UK Marine Strategy. Within the CSEMP, the UK monitors contaminants and their biological effects in flatfish (mainly dab but also flounder and plaice) from around British seas. This indicator (EROD activity in fish liver) is one of several used to assess progress against the target covering the biological effects of contaminants set out in the UK Marine Strategy Part One (HM Government, 2012).

The determination of EROD activity gives a sensitive and integrated measure of exposure to hazardous substances that bind to the aryl hydrocarbon receptor of fish and provides information to assess progress towards this target. Within the CSEMP, monitoring and assessments are done at the scale of the 8 UK biogeographical marine regions that were defined in the Charting Progress 2 report on the status of the seas (UKMMAS, 2010).

Assessment method

EROD is an OSPAR candidate Indicator, as not all countries use them in environmental monitoring. OSPAR has developed species-specific Background Assessment Criteria (BAC) to assess EROD activity in fish liver. Below BAC, the effects are deemed to be at a background level and the organisms are not significantly exposed to contaminants. OSPAR have not defined Environmental Assessment Criteria (EAC) (OSPAR Commission, 2009) for use with this exposure indicator, which means that there is no upper threshold for EROD activity that indicates significant environmental harm. The UK has also been active within OSPAR and ICES to develop an integrated assessment framework for contaminants and their biological effects (Davies and Vethaak, 2012; OSPAR Commission, 2016; Vethaak and others, 2017), including an extensive practical workshop to test this at the Regional Seas scale (Hylland and others, 2017a, Hylland and others, 2017b; Robinson and others, 2017; Vethaak and others, 2017).

Results

Findings in the 2018 UKMS Assessment

The 2018 UKMS assessment for EROD activity concluded that there was limited exposure to contaminants and that the UK met the target described in the UK Marine Strategy Part One (HM Government, 2012) for this biological effects indicator (Nicolaus and others, 2018). For the Greater North Sea and Celtic Seas, 67% and 68%, respectively, of the assessments were significantly below the Background Assessment Criteria.

2024 UKMS Assessment Results

EROD activity in fish was assessed at 33 locations in UK marine waters, excluding estuarine sites (Figure 1). The time between sampling visits varied from annually to once every six years. The data used in the assessment was collected between 2000 and 2021.

Figure 1: Monitoring sites used to assess EROD activity in fish in each Marine Strategy region (dark lines) and biogeographic subregion (light lines). The filled circles indicate sites where there are sufficient data to assess both status and trends; the open circles indicate sites where only status can be assessed. There are additional sites that are not shown because they were not sampled often enough.

Status Assessment

For regional assessment, only biogeographic regions with a minimum of three suitable stations with a reasonable geographic spread were included. There was insufficient data for regional analysis of the Minches & Western Scotland region (Table 1).

Levels of EROD activity were compared to OSPAR Background Assessment Criteria (BAC), Table 2. These assessment criteria were developed to determine if observed levels are at background or elevated above background. EROD activities above background levels indicate exposure to increased concentrations of organic contaminants. There is no upper threshold for EROD activity.

Table 1: Number of time series and stations within each sub-region used in the assessment of status and trends.

UK Marine Strategy sub-region	Biogeographic region	Status assessment	Trend assessment
Greater North Sea	Northern North Sea	12 (9 stations)	9 (6 stations)
Greater North Sea	Southern North Sea	12 (6 stations)	12 (6 stations)
Greater North Sea	East Channel	6 (3 stations)	6 (3 stations)
Celtic Seas	Minches & W Scotland	1 (1 station)	1 (1 station)
Celtic Seas	Irish Sea	19 (11 stations)	17 (3 stations)
Celtic Seas	West Channel & Celtic Sea	6 (3 stations)	6 (3 stations)

Table 2: OSPAR Background Assessment Criteria for the EROD activity in flatfish liver. Background Assessment Criteria are expressed as pmol min-1 mg S9 protein-1 (pico-mol per minute per milligram of S9 protein).

Regional assessment found that EROD activity was below the BAC in five biogeographic regions assessed (Figure 2) which indicates that, overall, there is limited exposure to contaminants. However, when assessed individually, a number of individual assessments are still above BAC – 50% (n=30) of assessments in the Greater North Sea and 12% (n=26) of assessments in the Celtic Seas exceed the BAC implying there is still some exposure to contaminants at individual sites (Figure 3).

Figure showing the mean EROD activity relative to the Background Assessment Criterion in five biogeographic regions. The regions are the Northern North Sea, the Southern North Sea, the Eastern Channel, the Irish Sea, and the Western Channel and Celtic Sea. The mean EROD activity is significantly below the Background Assessment Criterion in all five regions.

Figure 2: The mean EROD activity (coloured circle) in each biogeographic region relative to the Background Assessment Criterion (BAC). A value of 1 occurs when the mean activity equals the BAC. The horizontal line indicates the upper one-sided 95% confidence limit on the mean. The mean activity is significantly below the BAC (p < 0.05) if its upper confidence limit is less than 1. The light blue circle indicates that the mean activity is significantly below the BAC (p < 0.05).

Figure 3: The mean EROD activity (coloured circles) at each monitoring site relative to the Background Assessment Criterion (BAC). A value of 1 occurs when the mean activity equals the BAC. The mean activity is significantly below the BAC (p < 0.05) if its upper one-sided 95% confidence limit (not shown) is less than 1. Mean activity is estimated separately for females and males, so there are usually two circles (one for each sex) for each site. Light blue: the mean activity is significantly below the BAC (p < 0.05). Amber: the mean activity is not significantly below the BAC (p > 0.05).

Overall, there is high confidence in this assessment, but no confidence in whether the exposure is harmful at stations where the BAC was breached due to the lack of an upper threshold.

Trend Assessment

Trends in EROD activity were also assessed in biogeographic regions where there were at least five years of data from representative sites (Figure 4). Regional trend assessment was made in five biogeographic regions. There was insufficient data for trend analysis in the Minches & Western Scotland region.

Figure 4: The percentage annual change (circle, triangle) in the mean EROD activity in each biogeographic region. The horizontal line is the associated 95% confidence interval. There is a significant change in mean activity (p < 0.05) if the confidence interval does not cut the vertical line at 0. Circle: no significant change in mean activity (p > 0.05). Downward triangle: significant decrease in mean activity (p < 0.05).

Decreasing trends were observed in the Northern North Sea, Irish Sea and West Channel & Celtic Sea regions (Table 2). In the Southern North Sea and East Channel, the level of EROD activity was stable. On an individual level, of the 51 time series trend assessments (Figure 5) in the Celtic Seas and Greater North Sea, 20 assessments (4 in the Greater North Sea and 16 in the Celtic Seas) showed significant downward trends. The rest were stable.

Figure showing the percentage annual change in mean EROD activity at each monitoring site in six biogeographic regions. The regions are the Northern North Sea, the Southern North Sea, the Eastern Channel, the Minches and Western Scotland, the Irish Sea, and the Western Channel and Celtic Sea. The mean EROD activity is significantly decreasing at 20 sites and is stable at the remaining 36 sites.

Figure 5: The percentage annual change (circle, triangle) in mean EROD activity at each monitoring site. The horizontal line is the associated 95% confidence interval. There is a significant change in mean activity (p < 0.05) if the confidence interval (not displayed) does not cut the vertical line at 0. Circle: no significant change in mean activity (p > 0.05). Downward triangle: significant decrease in mean activity (p < 0.05).

Further information

The 7-ethoxy-resorufin-O-deethylase (EROD) enzyme activity was measured in livers of male and female dab, male plaice and male flounder from 33 stations in UK marine waters (Figure 6) which included six biogeographic regions - Northern North Sea, Southern North Sea, East Channel, Minches & Western Scotland, Irish Sea and West Channel & Celtics Sea. Altogether 56 status assessments (Figure 3) and 51 trend assessments (Figure 5) were carried out.

The two biogeographic regions in the Celtic Seas UKMS subregion, that were assessed regionally, were below Background Assessment Criteria (BAC) (Figure 2). At an individual level, 88% (23 out of 26) of assessments in the Celtic Seas were below BAC, and 3 out of 26 assessments exceeded the BAC in this subregion (Table 3). These three assessments were each from a different biogeographic region: one in the West Channel & Celtic Sea; one in the Irish Sea; and one in Minches and Western Scotland. This was the only station included in Minches and Western Scotland for this assessment. In the UKMS 2018 assessment 68% of the assessments from the Celtic Sea were significantly below BAC so there has been an improvement in this region since the last assessment (Figure 7).

Figure 6: Status and trends of EROD activity in female and male fish at each monitoring site. Light blue: the mean activity is significantly below the Background Assessment Criterion (BAC) (p < 0.05). Amber: the mean activity is not significantly below the BAC (p > 0.05). Circle: no significant change in mean activity (p > 0.05) or no trend assessment possible. Downward triangle: significant decrease in mean activity (p < 0.05).

Table 3: Number and proportion of individual assessments with each status by biogeographic region and UK Marine Strategy sub-region. “<BAC”: the mean concentration is significantly (p < 0.05) below the Background Assessment Criteria. “>BAC”: the mean concentration is not significantly (p < 0.05) below the Background Assessment Criteria.

UK Marine Strategy sub-region	Biogeographic region	Status assessments	Number of EROD assessments	Proportion of EROD assessments (%)
Greater North Sea	Northern North Sea	< BAC	10	83
Greater North Sea	Northern North Sea	> BAC	2	17
Greater North Sea	Southern North Sea	< BAC	3	25
Greater North Sea	Southern North Sea	> BAC	9	75
Greater North Sea	East Channel	< BAC	2	33
Greater North Sea	East Channel	> BAC	4	67
Celtic Seas	Minches & W Scotland	< BAC	0	0
Celtic Seas	Minches & W Scotland	> BAC	1	100
Celtic Seas	Irish Sea	< BAC	18	95
Celtic Seas	Irish Sea	> BAC	1	5
Celtic Seas	West Channel & Celtic Sea	< BAC	5	83
Celtic Seas	West Channel & Celtic Sea	> BAC	1	17

The Greater North Sea UKMS sub region is of more concern. The three biogeographic regions in this subregion that were assessed regionally were also below BAC (Figure 2). However, at an individual level 50% (15 out of 30) of assessments in the Greater North Seas were below BAC (Table 3). This is a decrease from the previous assessment where 67% of the assessments in this sub region were below BAC (Figure 7). In this assessment, in the Northern North Sea 2 out of 12 assessments were above BAC; in the Southern North Sea 9 out of 12 assessments were above BAC; and in the East Channel 4 out of 6 assessments were above BAC. This implies that flatfish in the Southern North Sea and East Channel have had more exposure to contaminants than other regions.

In the Greater North Sea UKMS sub region all three biogeographic regions were also below BAC however only 50% (15 out of 30) of individual assessments in the Greater North Seas were below BAC (Table 3 and Table 4). This is a decrease from the previous assessment where 67% of the assessments in this sub region were below BAC (Figure 7). In the Northern North Sea 2 out of 12 assessments were above BAC; in the Southern North Sea 9 out of 12 assessments were above BAC; and in the East Channel 4 out of 6 assessments were above BAC. The assessment method is cautious, it is based on the upper 95% confidence interval exceeding the BAC. The mean value is below BAC for the majority (12 out of 15) of the assessments which are gauged as above BAC (Figure 3). In both the Southern North Sea and the East Channel there are more assessments above BAC than below BAC individually, but the region is considered below BAC because the confidence increases, and the 95% confidence interval decreases, when we combine the data. In the absence of an Environmental Assessment Criteria (EAC), these results must be interpreted with caution. This implies that flatfish in the Southern North Sea and East Channel have had more exposure to contaminants than other regions.

Figure showing the Percentage of individual assessments that were below or above the Background Assessment Criteria for each Marine Strategy Region in the previous assessment (MSFD 2018, Nicholaus and others (2018)) and this assessment (UKMS 2024).

Figure 7: Percentage of individual assessments that passed (blue; the mean concentration is significantly (p < 0.05) below the Background Assessment Criteria) and failed (orange: the mean concentration is not significantly (p < 0.05) below the Background Assessment Criteria) for each Marine Strategy Region in the previous assessment (MSFD 2018, Nicholaus and others (2018)) and this assessment (UKMS 2024).

Table 4: Number and proportion of individual assessments with each trend by biogeographic region and UK Marine Strategy sub-region.

UK Marine Strategy sub-region	Biogeographic region	Trend assessment	Number of EROD assessments	Proportion of EROD assessments (%)
Greater North Sea Greater North Sea Greater North Sea	Northern North Sea Northern North Sea Northern North Sea	upward trend no trend downward trend	0 5 4	0 56 44
Greater North Sea Greater North Sea Greater North Sea	Southern North Sea Southern North Sea Southern North Sea	upward trend no trend downward trend	0 12 0	0 100 0
Greater North Sea Greater North Sea Greater North Sea	East Channel East Channel East Channel	upward trend no trend downward trend	0 6 0	0 100 0
Celtic Seas Celtic Seas Celtic Seas	Minches & W Scotland Minches & W Scotland Minches & W Scotland	upward trend no trend downward trend	0 1 0	0 100 0
Celtic Seas Celtic Seas Celtic Seas	Irish Sea Irish Sea Irish Sea	upward trend no trend downward trend	0 4 13	0 24 76
Celtic Seas Celtic Seas Celtic Seas	West Channel & Celtic Sea West Channel & Celtic Sea West Channel & Celtic Sea	upward trend no trend downward trend	0 3 3	0 50 50

This status assessment is supported by the trend assessment (Table 4). No assessments indicate an upward trend. All stations either showed no trend or no significant decreases in EROD activity. Three of the five assessed biogeographic regions show a significant downward trend (Northern North Sea, Irish Sea and West Channel & Celtic Seas), while the other two biogeographic regions are stable (East Channel, and Southern North Sea) (Figure 4). 15 individual trend assessments showed significant downward trends (5 in the Greater North Sea and 10 in the Celtic Seas) (Figure 5). The other 46 assessments stayed stable (27 in the Greater North Sea and 19 in the Celtic Seas). The two regions with a stable trend, East Channel, and Southern North Sea, are also the two regions where there is a higher proportion of assessments above BAC.

The trend assessment made in 2018 also showed similar results for the UK overall with either downward trends observed or stable levels of EROD activity. There was no change in trend assessment for Northern North Sea, East Channel and Irish Sea. The Southern North Sea was decreasing and is now stable. There is now sufficient data for a trend assessment in the West Channel & Celtic Sea region which was not the case in 2017 and unfortunately the opposite is true for the Minches & Western Scotland region where there is now insufficient data for a trend assessment.

Conclusions

Overall, the regional assessments conclude that contaminants in the UK marine environment do not significantly induce EROD enzyme activity in flatfish. This indicates that mostly flatfish are not exposed to harmful contaminant concentrations in UK coastal and offshore areas. This supports the other UKMS 2024 contaminant assessments in polycyclic aromatic hydrocarbons and polychlorinated biphenyls.

An upper threshold or EAC is not appropriate for EROD so assessing progress towards the target in that way has not been possible. However, as all regional assessments were below the Background Assessment Criteria this can be considered as meeting the UK Marine Strategy target.

Further information

Although the regional assessments were all below the Background Assessment Criteria (BAC), there are a number of individual assessments with elevated levels of EROD above the BAC. This suggests that some flatfish are exposed to certain organic contaminants at concentrations higher than background, and increased enzyme activity results from their metabolization. In the absence of an Environmental Assessment Criteria (EAC) these should be interpreted with caution. The majority of these assessments are only just above BAC so unlikely to be at a level that causes significant harm.

Knowledge gaps

There were insufficient data for regional assessment of Minches and Western Scotland, increasing sampling in the region would enable this. Also, there are currently no data of EROD enzyme activity from Northern Ireland. Additional sampling would be advantageous to breach this knowledge gap.

During severe exposure to contaminants EROD activity is inhibited. However, levels of exposure are not expected to be high enough to trigger this response, and it would, therefore, be useful to develop Environmental Assessment Criteria to indicate an unacceptable level of response.

References

Davies IM, Vethaak AD (2012) ‘Integrated marine environmental monitoring of chemicals and their effects’ ICES Cooperative Research Report Number 315, 277 pages (viewed on 16 November 2018)

European Commission (2000) ‘Directive 2000/60/EC of the European Parliament and of the Council establishing a framework for the Community action in the field of water policy’ Official Journal of the European Union L 327, 22122000, pages 1–73 (viewed on 16 November 2018)

European Commission (2008) ‘Directive 2008/56/EC of the European Parliament and of the Council of 17 June 2008 establishing a framework for community action in the field of marine environmental policy (Marine Strategy Framework Directive)’ Official Journal of the European Union L 164, 2562008, pages 19-40 (viewed on 16 November 2018)

HM Government (2012) ‘Marine Strategy Part One: UK Initial Assessment and Good Environmental Status’ (viewed on 5 July 2018)

HM Government (2015) ‘Marine Strategy Part Three: UK Programme of Measures’ December 2015 (viewed on 5 July 2018)

Hylland K, Burgeot T, Martínez-Gómez C, Lang T, Robinson CD, Svavarsson, J, Thain JE, Vethaak AD, Gubbins, MJ (2017a) ‘How can we quantify impacts of contaminants in marine ecosystems? The ICON project’ Marine Environmental Research 124:2-10 (viewed on 10 December 2018)

Hylland K, Robinson CD, Burgeot T, Martínez-Gómez C, Lang T, Svavarsson J, Thain, JE, Vethaak AD, Gubbins MJ (2017b) ‘Integrated chemical and biological assessment of contaminant impacts in selected European coastal and offshore marine areas’ Marine Environmental Research, 124:130-138 (viewed on 10 December 2018)

ICES (2011) ‘Report of the Joint ICES/OSPAR Study Group on Integrated Monitoring of Contaminants and Biological Effects (SGIMC)’ ICES CM 2011/ACOM:30 REF ACOM, OSPAR (viewed on 10 December 2018)

Nicolaus EEM, Wright SR, Bolam TPC, Barber JL, Bignell JP, Lyons B (2016) ‘Spatial and temporal analysis of the risks posed by polychlorinated biphenyl and metal contaminants in dab (Limanda limanda) collected from waters around England and Wales’ Marine Pollution Bulletin, 112(1-2):399-405 (viewed on 10 December 2018)

Nicolaus EEM, Robinson CD, Fryer R (2018) ‘Status assessment for biological effects (EROD enzyme activity) in fish’. UK Marine Online Assessment Tool, available at: https://moat.cefas.co.uk/pressures-from-human-activities/contaminants/erod/ (viewed 23 February 2023)

OSPAR Commission (2009) ‘Background Document on Assessment Criteria used for assessing CEMP Monitoring Data for the Concentrations of Hazardous Substances in Marine Sediments and Biota in the Context of QSR 2010’ OSPAR Publication 461/2009 ISBN 978-1-907390-08-1 (viewed on 03 December 2018)

OSPAR Commission (2014), ‘OSPAR Joint Assessment and Monitoring Programme (JAMP) 2014 – 2021’ Ospar Agreement 2014-02 (viewed on 27 November 2018)

OSPAR Commission (2016) ‘Trial application of the OSPAR JAMP Integrated Guidelines for the Integrated Monitoring and Assessment of Contaminants’ OSPAR Commission, London, UK (viewed on 10 December 2018)

Robinson, CD, Webster, L, Martínez-Gómez, C, Burgeot, T, Gubbins, MJ, Thain, JE, McIntosh, AD, Vethaak, AD, and Hylland, K (2017) ‘Assessment of contaminant concentrations in sediments, fish and mussels sampled from the North Atlantic and European regional seas within the ICON project’ Marine Environmental Research, 124:21-31 (viewed on 10 December 2018)

Stagg R, McIntosh AD, and Gubbins MJ (2016) ‘Determination of CYP1A dependent mono-oxygenase activity in dab by fluorimetric measurement of EROD activity in S9 or microsomal liver fractions’ ICES Techniques in Marine Sciences number 57 21pp (viewed on 10 December 2018)

UKMMAS (2010) ‘Charting Progress 2: An assessment of the state of the UK seas’ Published by Defra on behalf of the UK Marine Monitoring and Assessment Strategy community (viewed on 4 January 2018)

Vethaak AD, Davies IM, Thain JE, Gubbins MJ, Martínez-Gómez C, Robinson CD, Moffat CF, Burgeot, T, Maes T, Wosniok W, Giltrap M, Lang T, Hylland K (2017) ‘Integrated indicator framework and methodology for monitoring and assessment of hazardous substances and their effects in the marine environment’ Marine Environmental Research, 124:11-20 (viewed on 10 December 2018)

Authors

Hannah Anderson ¹

¹Marine Directorate of the Scottish Government)

Assessment metadata

Assessment Type	UK Marine Strategy Framework Directive Indicator Assessment
	D8
	D8.2 Effects of Contaminants
	Marine Strategy Part One
Point of contact email	marinestrategy@defra.gov.uk
Metadata date	Sunday, June 1, 2025
Title	Biological effects (EROD enzyme activity) in fish
Resource abstract
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Conditions applying to access and use	© Crown copyright, licenced under the Open Government Licence (OGL).
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Dataset DOI	The Scottish Government, Marine Directorate. 2025. https://doi.org/10.7489/12541-1

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