• Latest Version, 2024 Assessment
• 2018 assessment

Biological effects (micronucleus) of contaminants in fish

Results indicate that flatfish in the UK marine waters generally have near-background exposure to chemicals that can damage genetic information, although several individual locations show increased exposure to such chemicals. These findings indicate that risks of fish suffering genetic damage from such chemicals are generally likely to be low. 

Background

A number of anthropogenic and natural contaminants are known to be mutagenic or carcinogenic, meaning they can cause genetic damage in significantly exposed organisms.  Nuclear abnormalities in fish can be assessed to inform on genetic instability, DNA damage induced by exposure to genotoxic substances and cytotoxic effects. Micronuclei in fish has been validated as a biomarker of genotoxicity in fish and provides valuable information on the exposure to substances that cause damage to the genetic information of cells (genotoxins). 

This indicator is used to supplement the target covering the biological effects of contaminants set out in the 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. Micronuclei in fish is included in the OSPAR Joint Assessment and Monitoring Programme (JAMP) as a voluntary indicator and 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 the presence of contaminants in the environment, such as polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and some heavy metals, that can damage genetic information.  In the UK Initial Assessment (UK Initial Assessment, HM Government, 2012), the main anthropogenic pressures responsible for the presence of contaminants in the sea were identified as being point sources (e.g. industrial and sewage discharges and emissions) and diffuse sources (e.g. agriculture, roads run-off, households, and atmospheric deposition).  No significant new pressures have since been identified.  

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 itself 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 organisms, loss of biodiversity, are hazardous to human health, impair water quality, and reduce our ability to use the sea”.  

A number of anthropogenic and natural contaminants are known to be mutagenic or carcinogenic, that is they can cause genetic damage in significantly exposed organisms.  These contaminants include some polycyclic aromatic hydrocarbons (PAHs), metals (including cadmium, copper, mercury and zinc), flame retardants such as polybrominated diphenyl ethers (PBDEs), alkylphenols, phthalates, certain pesticides, pharmaceuticals and radionuclides.  

The concentrations of several of these substances have long been monitored in flatfish as part of the UK marine monitoring programme, the additional use of biological effects monitoring allows an integrative measure of the impacts caused by the mixtures of contaminants found in the marine environment, including of substances that can cause genetic damage (genotoxins) that are not included in the chemical monitoring programme.  The UK has begun to monitor the genotoxic impacts of contaminants by determination of the incidence of micronuclei within red blood cells (erythrocytes) of flatfish collected as part of the routine annual monitoring surveys.   

Micronuclei are membrane-bound fragments of nuclear material, originating as acentric chromosome fragments or as whole chromosomes that did not migrate fully to the spindle poles during mitotic cell division (Fenech, 2000).  The micronuclei assay therefore detects the effects of substances that cause clastogenic (disruption or breakage in chromosomes) or aneugenic (abnormal number of chromosomes) events.  It was first developed as a screening test in the safety assessment of new pharmaceuticals (Heddle, 1972; Schmid, 1975; OECD, 1997).  Whilst micronuclei can be determined in many cell types, fish erythrocytes provide a convenient and sensitive tissue for the assay.  Exposure to genotoxic contaminants using the micronuclei assay has been reported for fish from marine and freshwaters around the world (D’Agostini and La Maestra, 2021), including the Firth of Forth (Bombail and others, 2001), North Sea (Baršienė and others, 2004, 2013; Rybakovas and others, 2009), Baltic Sea (Baršienė and others, 2004, 2012b; Rybakovas and others, 2009), and Aegean Sea (Çakal Arslan and others, 2015).  Furthermore, the frequency of micronucleated erythrocytes has been shown to be positively correlated to liver tumour formation in flatfish (Köhler and Ellesat, 2008), and micronuclei frequency in lymphocytes is predictive of increased risk of breast, pancreas and lung cancers in humans (Bonassi and others, 2010; Chang, and others, 2011; Cardinale and others, 2012).  Other nuclear abnormalities can be observed during the micronuclei assay, some of which are due to genotoxicity and are predictive of carcinogenicity whilst others indicate cytotoxicity (Rybakovas and others, 2009; Bonassi and others, 2010; Baršienė and others, 2013).  This indicator assessment sheet focuses on the frequency of micronucleated erythrocytes in flatfish as OSPAR has developed Background Assessment Criteria for this biomarker of genotoxic exposure. 

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 Oslo and Paris (OSPAR) Convention (OSPAR Commission, 2014), together with the 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 (micronuclei in fish) is one of several used to inform progress against the target covering the biological effects of contaminants set out in the Marine Strategy Part One (HM Government, 2012).  The micronuclei test gives a sensitive and integrated measure of exposure to genotoxic substances and provides information to assess progress towards this target.  Within 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). 

Micronuclei in fish is an OSPAR candidate indicator, as not all countries use it in environmental monitoring.  OSPAR has developed species-specific background assessment criteria (BAC) to assess genotoxicity in fish blood cells using the micronuclei assay.  Below BAC, the effects are deemed to be at a background level and the organisms are not significantly exposed to genotoxic contaminants.  Currently, there is no upper-threshold for the micronuclei assay that indicates significant environmental harm (i.e. OSPAR have not defined an Environmental Assessment Criteria-EAC, for use with this exposure indicator).  The UK has also been active within OSPAR and ICES (the International Council for the Exploration of the Sea) to develop an integrated assessment framework for contaminants and their biological effects (Davies and Vethaak, 2012; OSPAR Commission, 2016; Vethaak and others, 2016), including an extensive practical workshop to test this at the Regional Seas scale (Hylland and others, 2016a,b; Robinson and others, 2016; Vethaak and others, 2016). 

Assessment method

The 2022 assessment of CSEMP contaminant and biological effects data includes an assessment of the status and trends of the prevalence of micronucleated cells in fish at monitoring stations around the UK.  Micronuclei in fish cells were monitored as part of the UK CSEMP, an integrated approach to contaminant and biological effects monitoring. Samples were taken in annual monitoring surveys based on the sampling frequencies specified in the OSPAR Joint Assessment and Monitoring Programme guideline (OSPAR Commission, 2014). The time between sampling visits varied from annually to once every six years.  The data were provided by CEFAS and Marine Scotland, since the data is undergoing submission to the Marine Environment Monitoring and Assessment National database. The frequency of micronucleated erythrocytes was determined in dab and flounder collected on annual CSEMP monitoring surveys (Figure 1).  

Figure 1: Micronuclei in fish red blood cell (image is ca. 40 µm by 40 µm; photo: J. Baršienė) 

In the majority of sites 1000 cells from 20 fish were scored, however, for some historical sites 4000 cells from 10 fish were scored. Following fish collection, a drop of blood from the caudal sinus was placed on an identification-coded microscope slide, air dried and fixed with methanol.  Subsequently, cells were stained and microscopically examined (without knowledge of sampling information) for the presence of micronuclei at 1000x magnification.  Micronuclei were identified as round or oval membrane-bound bodies within the cytoplasm, of similar colour to the nucleus, but of less than approximately 1/3 of the nuclear diameter and completely separated from it (Carrasco and others, 1990; Fenech and others, 2003; Baršienė and others 2006, 2012a and Stankevičiūtė and others, 2022).  Quality assurance between the UK analytical laboratories was ensured via staff training and BEQUALM (Biological Effects Quality Assurance in Monitoring) intercalibration exercises (last one carried on in 2019).   

Assessment thresholds for micronucleus in flatfish  

OSPAR Background Assessment Criteria (BAC) for micronuclei frequency have been developed for flounder (Platichthys flesus) and dab (Limanda limanda) based on the empirical 90th percentile of observations from five or more reference stations (Table 1).  BACs were developed to test whether observed results are near background levels.  For most contaminants and biological effects, upper-level Environmental Assessment Criteria (EAC) have been developed by OSPAR; exceeding these indicates environmental harm.  However, EACs have not been derived for micronuclei in fish as this is a marker of exposure to genotoxins and not of harmful effect at the population-level. In the absence of an OSPAR EAC, the assessment is of the degree of exposure to genotoxic substances. 

Table 1:  OSPAR Background Assessment Criteria (BAC) for the micronucleus assay in flatfish red blood cells. 

Species	Latin name	BAC  (MN/1000 cells)
Flounder	Platichthys flesus	0.3
Dab	Limanda limanda	0.5

Monitoring data are assessed for status and trends following standard OSPAR approaches. Assessments are made for many time series, each of micronucleated cell prevalence in a single species at a single monitoring station.  

An individual time series of micronuclei prevalence was assessed for status if: 

• there is at least one year with data in the period 2016 to 2021 

• there are at least three years of data over the whole time series 

An individual time series of micronuclei was also assessed for trends if: 

• there are at least five years of data over the whole time series. 

The counts of micronucleated cells were modelled assuming they had a negative binomial distribution with a log link and an offset to account for the total number of cells screened. The type of model fitted depended on the number of years of data: 

• 3-4 years; mean model - a common level over time 

• 5-6 years: linear model - a log linear trend over time 

For a regional status assessment, the status of each time series was summarised by the difference between the estimated log mean prevalence in the final monitoring year and the log assessment criterion. This ensures that status is always measured on the same scale, even though the assessment criterion might vary between species. Regional status is then estimated by fitting the following linear mixed model by restricted maximum likelihood: 

• response: status (log mean prevalence - log assessment criterion) 

• fixed model: region 

• random model: status estimation variation + residual variation 

The fixed model means that status is estimated for each region. The random model has two terms: 

• status estimation variation is the variance of the status estimates from the individual time series analysis, assumed known and fixed 

• residual variation is the variation that cannot be explained by any of the fixed effects or the other random effects 

There were no restrictions on the time series used in the status meta-analysis based on the classification of the monitoring station; time series from baseline, representative and impacted stations are all included. The meta-analysis was restricted to regions with at least three status stations with good geographic spread.  

There were only four stations where trends could be estimated, so no regional trend assessment was possible.

Areas that have been assessed 

Location of monitoring stations where there were suitable data are shown in Figure 2. Individual time series assessments were conducted in 5 of the 8 UK biogeographic marine regions set out in Charting Progress 2 (UKMMAS, 2010). However, only 4 of these regions had sufficient stations to conduct a regional status assessment, and no region had sufficient stations to conduct a regional trend assessment.  UKMS subregions Greater North Sea and Celtic seas were also considered. 

Figure 2: Monitoring sites used to assess micronuclei in flatfish 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. 

Differences in methodology used for the UKMS 2018 compared with the UKMS 2024 

There was not sufficient data for status and trend assessments when preparing the UKMS 2018, and the analysis was based on the proportion of sampled fish with micronucleated cells frequency above the BAC and categorised on a scale adopted from Baršienė and others (2012b). Here, the regional assessment is the main focus of the results which is in keeping with the other UKMS and OSPAR Quality Status Report contaminant assessments. 

Information on how the individual time series was assessed for status and trends is described in the OSPAR Hazardous Substances Assessment Tool (https://dome.ices.dk/ohat/?assessmentperiod=2023). 

Results

Findings in the 2018 UKMS Assessment 

In the 2018 UKMS assessment the level of micronucleus in flatfish red blood cells indicted a negligible or low risk of exposure to substances that can cause genetic damage, for both the Celtic Seas and the Greater North Sea sub regions. Being a recent indicator, there was however insufficient data to carry out status and trend assessments.  There was therefore a low level of confidence in the assessment as more detailed statistical modelling was deemed required. 

2024 UKMS Assessment Results 

Micronuclei in fish were assessed at 25 locations in UK marine waters (Figure 2). These stations were sampled for dab; three stations sampled for flounder were excluded due to the full data set being insufficient to be included or the sampling stations being in estuarine waters. The time between sampling visits varied from annually to once every six years. The data used in the assessment was collected between 2012 and 2021.  

Status Assessment  

For regional status assessment, only biogeographic regions with a minimum of three suitable stations with a reasonable geographic spread were included. There was insufficient data for regional status analysis of the Eastern Channel. 

The regional status assessment showed that micronuclei frequency was below the Background Assessment Criteria (BAC) in 4 biogeographic regions (Figure 3) which indicates that overall, there is limited exposure to substances that cause genetic damage.

Figure 3: The mean prevalence of micronucleated cells (coloured circles) in each biogeographic region relative to the Background Assessment Criterion (BAC). A value of 1 occurs when the mean prevalence equals the BAC. The horizontal line indicates the upper one-sided 95% confidence limit on the mean. The mean prevalence 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 prevalence is significantly below the BAC (p < 0.05). 

At the individual time series level, and as shown in Figure 4, the estimated mean prevalence off all but one station is below the BAC; however, the precautionary approach applied produced wide confidence intervals for some of the individual time series, rendering them being classed as above BAC. The mean prevalence of micronuclei per individual station indicated that 71% (10 out of 14) of assessments in the Greater North Sea and 36% (4 out of 11) of assessments in the Celtic Seas exceed the BAC. The regional assessment carried on integrated all these individual time series, for each region, showing that there is sufficient evidence overall that the mean micronuclei prevalence across each region is below background level.  

Figure 4 The mean prevalence of micronucleated cells (coloured circles) at each monitoring site relative to the Background Assessment Criterion (BAC). A value of 1 occurs when the mean prevalence equals the BAC. The mean prevalence is significantly below the BAC (p < 0.05) if its upper one-sided 95% confidence limit (not shown) is less than 1. Light blue: the mean prevalence is significantly below the BAC (p < 0.05). Amber: the mean prevalence is not significantly below the BAC (p > 0.05). 

Trend assessment 

Four stations within the Celtic Seas sub region were considered to have the minimum required to provide some evidence base at the regional level. At three of these stations there was a significant downward trend in micronuclei prevalence (Table 2). There were however insufficient trend stations to conduct a meta-analysis, as no region had at least three trend stations with good geographic spread. 

Table 2: Number and proportion of individual assessments with each trend, per biogeographic region and UK Marine Strategy sub-region. “Upward trend” indicates the mean prevalence is significantly increasing (p < 0.05), “no trend” indicates there is no significant change in mean prevalence (p > 0.05) or there are too few years to test for trends, and “downward trend” indicates the mean prevalence is significantly decreasing (p < 0.05). 

UK Marine Strategy sub-region	Biogeographic region	Trend assessment	Number of micronuclei assessments	Proportion (%) of micronuclei assessments
Celtic Seas	Irish Sea	upward trend	0	0
		no trend	1	50
		downward trend	1	50
	West Channel & Celtic Sea	upward trend	0	0
		no trend	0	0
		downward trend	2	100

There was insufficient data for trend analysis of the Northern North Sea and the Southern North Sea. 

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

Further information

The frequency of micronuclei was assessed in red blood cells of individual dab (Limanda limanda) from 25 stations in UK marine waters which included five biogeographic regions - Northern North Sea, Southern North Sea, East Channel, Irish Sea and West Channel & Celtics Sea. Altogether 25 individual status assessments and 4 individual trend assessments were carried out; but there was insufficient data to carry out regional trend assessments. 

Within the Greater North Sea UKMS sub region, the two biogeographic regions that were assessed regionally, Northern North Sea and Southern North Sea, were below BAC, although their micronuclei mean prevalence was greater than the Irish Sea and West Channel & Celtics Sea (Figure 5).  

Figure 5: Status and trends of the prevalence of micronucleated cells in flatfish at each monitoring site. Light blue: the mean prevalence is significantly below the Background Assessment Criterion (BAC) (p < 0.05). Amber: the mean prevalence is not significantly below the BAC (p > 0.05). Circle: no significant change in mean prevalence (p > 0.05) or no trend assessment possible. Downward triangle: significant decrease in mean prevalence (p < 0.05). 

Analysis at an individual level, which also accounts for the stations in Eastern Channel (where regional assessment was not possible), indicated that 29% (4 out of 14) of assessments in the Greater North Seas were below BAC (Table 2). In the 2018 assessment approximately 86% of sites in the Greater North Sea were classed as having negligible or low exposure to genotoxic substances, based on the proportion of fish exceeding the Background Assessment Criteria for the frequency of micronuclei in circulating erythrocytes of flatfish. Comparisons with the current assessment should be dealt with caution as the methods employed were different, with the current metric being more precautionary. In this assessment, in the Northern North Sea 3 out of 5 assessments were above BAC; in the Southern North Sea 5 out of 7 assessments were above BAC; and in the East Channel 2 out of 2 assessments were above BAC. This indicates that flatfish in these three biogeographic regions have had more exposure to genotoxic environmental contaminants than other regions.  

The Celtic Seas UKMS sub region is of least concern. The two biogeographic regions in this subregion that were assessed regionally, Irish Sea and West Channel & Celtic Sea were below Background Assessment Criteria (BAC) (Table 2). At an individual level, 64% (7 out of 11) of assessments in the Celtic Seas were below BAC (Table 3). Although there was limited or no data for significant parts of the Celtic Seas sub region, in the 2018 assessment all sites were classed as having Negligible or Low exposure to genotoxic substances. In the present assessment, 3 out of 8 assessments were above BAC for the Irish sea, and 1 out of 3 assessments were above BAC for the West Channel & Celtic Sea. The results suggest that there may be issues with exposure at localised sites, where concentrations of genotoxic environmental contaminants may be higher. 

Table 3: Number and proportion of individual assessments with each status, per biogeographic region and UK Marine Strategy sub-region. “<BAC “indicates the mean concentration is significantly (p < 0.05) below the Background Assessment Criteria. “>BAC “indicates 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 micronuclei assessments	Proportion (%) of micronuclei assessments
Greater North Sea	Northern North Sea	< BAC	2	40
		> BAC	3	60
	Southern North Sea	< BAC	2	29
		> BAC	5	71
	East Channel	< BAC	0	0
		> BAC	2	100
Celtic Seas	Irish Sea	< BAC	5	62
		> BAC	3	38
	West Channel & Celtic Sea	< BAC	2	67
		> BAC	1	33

As shown in Table 2, the available data only allowed to carry out individual trend assessments for some stations in the Irish Sea and West Channel & Celtic Sea; with 1 showing no trend and 1 showing a significant downward trend, and 2 showing a significant downward trend, respectively.  

 

Conclusions

Overall, flatfish in the Celtic Seas sub region were assessed as having a low level of exposure to substances that can cause genetic damage; flatfish in the Greater North Seas were also assessed as having a low degree of exposure overall, although there are a number of locations were the micronuclei frequency exceeded the Background Assessment Criteria.  There was also insufficient data to conduct regional trend assessments and therefore monitoring should continue to allow assessing individual stations progress, as well as, deriving trend assessments for all regions.  

An upper threshold or Environmental Assessment Criteria is not available for micronuclei frequency in flatfish; there is an expected time-lag between the formation of micronuclei and potential tumour formation and higher-level effects (e.g. mortality) therefore assessing progress towards population level effects has not been possible. Therefore, as all regional assessments were below the Background Assessment Criteria it can be considered that with the data available, the micronuclei indicator is meeting the UKMS target.

There is a low level of confidence in the status assessment for both UKMS sub regions as more detailed statistical modelling is required of the data, and additional sampling stations are needed particularly in the Eastern Channel region, in order to further investigate the possible higher level of risk in this area. 

Further information

Although the regional assessments were below the Background Assessment Criteria, there are a number of individual stations that still exceed this criterion for micronuclei frequency. The Northern North Sea and the Southern North Sea biogeographic regions are most at risk with 71% (5 out of 7) and 60% (3 out of 5), respectively, of assessments failing the Background Assessment Criteria threshold. For the Eastern Channel region, 100% (2 out of 2) of the assessments were above this criterion. There are however only two sampling stations in this region. These results suggests that some flatfish are exposed to certain genotoxic environmental contaminants at concentrations higher than background, and increased frequency of micronuclei is present.

Overall, fish from both the Celtic Seas and the Greater North Sea sub regions were assessed as having a low risk from exposure to genotoxic substances, with some individual locations of higher risk. 

Knowledge gaps

Monitoring should continue to allow obtaining enough data so that robust regional trend assessments can be carried on, making micronuclei frequency more consistent with other UK indicator assessments. Additional sampling should be established, particularly in the Eastern Channel, Minches and Western Scotland and the Scottish Continental Shelf.  

Additional sampling stations would be available if plaice and cod data could be included and if assessment criteria are established for these species. Furthermore, there is currently no data of micronuclei frequency in flatfish from Northern Ireland, additional sampling could also bridge this knowledge gap. 

Development of Environmental Assessment Criteria is difficult for exposure indicators such as micronuclei frequency.  Whilst this frequency can be predictive of tumour formation in individuals, the significance of this at the population-level is unclear.  The development of alternative approaches to assessing exposure biomarkers is required. 

Further information

Different numbers of cells were scored by Cefas (1000 cells/fish) and MSS (4000 cells/fish).  A review of the incidence and power to detect MN above the BAC (dab=0.5 MN/1000 cells) is currently underway to agree the number of cells to be scored. This outcome is expected to inform the recently published ICES TIMES protocol on nuclear abnormalities in mussel haemocytes and fish erythrocytes (Stankevičiūtė and others, 2022).  

Monitoring should be continued to allow for a trend assessment. To be sure that the current situation is not worsening (e.g. from emissions of emerging contaminants such as pharmaceuticals or nanoparticles) this should include stations that are currently classed as being of low risk from genotoxins, as well as including stations classified as being of higher risk and where status might be expected to be improving.   

Relatively few of the flatfish monitoring stations are from near-shore areas, an assessment of genotoxic exposure would be more complete if it included data from coastal fish or mussel sites. 

Micronuclei frequency has been correlated with higher incidences of tumours in fish (Köhler and Ellesat, 2008) and, mechanistically, DNA damage can lead to cancer formation meaning micronuclei frequency in lymphocytes is predictive of human cancer risk (Bonassi et al., 2010; Cardinale et al., 2012).  However, due to the expected time-lag between the formation of micronuclei and tumour formation, and higher level effects such as mortality, the development of Environmental Assessment Criteria based upon population-level responses (such as the median concentration to cause mortality used to develop Environmental Assessment Criteria and Environmental Quality Standards) requires very lengthy exposure experiments and alternative approaches to assessing environmental risk of genotoxins are required.   

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Vethaak A.D., Davies, I.M., Thain J.E., Gubbins, M.J., Martínez-Gómez, C., Robinson, C.D., Moffat, C.F., Burgeot, T., Maes, T., Wosniok, W., Giltrap, M., Lang, T., and Hylland, K. (2016).  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 http://dx.doi.org/10.1016/j.marenvres.2015.09.010 

Authors

Marta Assunção¹ 

¹Centre for the Environment, Fisheries and Aquaculture Science 

Assessment Metadata

Please contact marinestrategy@defra.gov.uk for metadata information

Assessment metadata

Assessment Type	UK Marine Strategy Framework Directive Indicator Assessment
	D8 Contaminants
	D8.2.  Effects of Contaminants
Point of contact email	marinestrategy@defra.gov.uk
Metadata date	Sunday, June 1, 2025
Title
Resource abstract
Linkage
Conditions applying to access and use	© Crown copyright, licenced under the Open Government Licence (OGL).
Assessment Lineage
Indicator assessment results
Dataset metadata
Links to datasets identifiers
Dataset DOI	The Scottish Government, Marine Directorate. 2025. https://doi.org/10.7489/12541-1

The Metadata are “data about the content, quality, condition, and other characteristics of data” (FGDC Content Standard for Digital Geospatial Metadata Workbook, Ver 2.0, May 1, 2000).

Metadata definitions

Assessment Lineage - description of data sets and method used to obtain the results of the assessment

Dataset – The datasets included in the assessment should be accessible, and reflect the exact copies or versions of the data used in the assessment. This means that if extracts from existing data were modified, filtered, or otherwise altered, then the modified data should be separately accessible, and described by metadata (acknowledging the originators of the raw data).

Dataset metadata – information on the data sources and characteristics of data sets used in the assessment (MEDIN and INSPIRE compliance).

Digital Object Identifier (DOI) – a persistent identifier to provide a link to a dataset (or other resource) on digital networks. Please note that persistent identifiers can be created/minted, even if a dataset is not directly available online.

Indicator assessment metadata – data and information about the content, quality, condition, and other characteristics of an indicator assessment.

MEDIN discovery metadata - a list of standardized information that accompanies a marine dataset and allows other people to find out what the dataset contains, where it was collected and how they can get hold of it.