Fish and fisheries research to inform ScotMER evidence gaps and future strategic research in the UK: review

Evidence Gap FF.15: Chemical/toxicity effects

Review of current knowledge

Little attention has been given to aspects relating to the potential chemical emissions from corrosion protection systems associated with MRE offshore structures to date. As the industry expands, however, interest has grown to better understand this issue. Recent progress on this topic is summarised below:

• Preliminary studies undertaken around offshore wind farms in the Belgian part of the North Sea in which the concentration of Zn was measured, found no evidence of higher Zn levels in the wind farms than in reference areas. It was highlighted, however, that more extensive research was needed to validate the results (Degraer et al 2019).
• Recent investigations on galvanic anode materials used in corrosion protection systems (Reese et al 2020) have found that toxicologically relevant elements such as Zn, Cd and Pb are emitted during the lifetime of galvanic anodes and that depending on chemical behaviour in the solution phase, these will be transported via the water body or associated with suspended particulate matter and subsequently deposited on the sediment in the proximity of MRE sites.
• Research focused on the study of chemical emissions from offshore wind farms and their potential impact on the environment is currently on-going as part of project funded by the German Federal Maritime Hydrographic Agency (BSH). The project is focused on the following aspects: identification of potential organic and inorganic substances emitted from corrosion protection of offshore wind farms; development of analytical methods and sampling strategies to determine emissions; and evaluation of the relevance of the identified pollutants and their influence on the local and regional environment (HZG 2021).

There is no clear evidence of negative impacts as a result of corrosion protection systems on the marine environment, however, there is a need to improve our knowledge to understand its effects. Available data is scarce and makes assessing the impact of the emissions on the marine environment difficult. In addition, whilst chemical emissions from MRE infrastructure are probably low compared to other offshore activities, they may become more important as the industry continues to grow (Kirchgeorg et al 2018).

Next steps in research

Taking account of the findings of the literature review presented above in respect of "Evidence Gap FF.13 Chemical/toxicity effects", the following next steps in research have been identified to help address current knowledge gaps:

• Monitoring of corrosion protection systems and chemical emissions associated with operational wind farms in the UK; and

Research on potential environmental impacts, including bioaccumulation of heavy metals within the food chain.

Recommendations

Table 5 and Table 6 outline recommendations for future research for fish and fisheries related aspects, respectively. These include information on the evidence gaps for which the proposed research is of relevance, the feasibility and challenges associated with the undertaking of the research and an indication of potential collaborators.

In addition, priority rankings of "high" "medium" and "low", have been assigned to the various research recommendations. The criteria used for assigning priority are outlined below:

• High Priority: Research is critical to reduce consenting risks and uncertainty and would facilitate the undertaking of more robust impact assessments and address key stakeholder's concerns.
• Medium Priority: Existing evidence suggests limited potential for major impacts. The research undertaken to date, however, is limited or may not fully account for the current level of proposed MRE development and/or upcoming technologies/project designs. Additional, more focused research, would increase certainty in the accuracy of assessments undertaken and reduce stakeholder's concerns.
• Low Priority: Significant concerns have not been raised to date on the particular aspect that the research may address and/or the topic is not a key consenting risk. Limited research has been undertaken on the subject to date and further investigation would improve our ability to identify potential for negative interactions with fish and fisheries receptors.

With regard to evidence gaps relating to fish receptors, key recommendations relate to improving our understanding of the impact of operational wind farms on fish and shellfish through the implementation of strategic research in operational sites. In addition, the undertaking of further research to address knowledge gaps associated with underwater noise and its effect on fish and shellfish species, as well as the development of mapping tools on essential habitat (including spawning grounds) are also considered priority aspects to reduce consenting risks and uncertainty in relation to the assessment of impacts of MRE projects (Table 5).

In the case of commercial fisheries, key recommendations relate to improving access to fisheries data and the format in which data are made available, the development of detailed assessment guidelines and the undertaking of research to allow the assessment of the displacement effects at a strategic level. In addition, the undertaking of trials to demonstrate the viability of fishing within operational sites, as well as the development of technical guidance on wind farm design and its compatibility with fishing, are considered critical to reduce consenting risks and uncertainty in relation to commercial fisheries receptors (Table 6).

As shown in Table 5 and Table 6, most of the individual research recommendations made are expected to contribute to addressing aspects which are of relevance to more than one evidence gap. It is therefore recommended that when defining future detailed research proposals to address evidence gaps, their inter-dependences are given due consideration.