Offshore man-made structures like wind farms could be detrimental to marine biodiversity

The long-term damage caused to valuable fishing grounds by offshore wind farms could be more costly to the environment and to economies than realised by environmentalists.

With the controversy of offshore wind farms looks set to grow as governments in developed countries insist that wind energy is a natural replacement for carbon fuelled electricity but have they the full facts of what offshore man-made structures are doing to the marine environment.

Could offshore wind farms cause more damage to the marine environment than governments are letting on? Is it a case of robbing Peter to pay Paul? We may take carbon from the skies but what are the long term effects on our fish and other marine life?

In January this year, a seminar held in the European Parliament specifically looked at the issue of whether fisheries and offshore wind farms can coexist.

The event was hosted by MEP Peter van Dalen (NL-EPP group), vice-president of the Fisheries Committee, and co-organised by Europêche, VisNed, EMK and Collectif Pêcheurs Artisans.

It was proposed that long-term sustainable fisheries are under threat due to the building of offshore wind farms. The EU has made an investment to make fishing operations economically and ecologically better but areas where offshore wind farms are built have already seen damage to fish stocks and the surrounding environment.

Fishing fleets in the EU and the UK look set to lose valuable fishing grounds to these invasive structures despite evidence that there could be a huge price to pay for carbon free electricity.

The effects of offshore wind farms have been highlighted before. The structures affect biodiversity, damage the seabed, change the currents and create a constant vibration, all of which are detrimental to the natural fish stocks. It can also mean that invasive species can gain a foothold on grounds where they would otherwise not prosper.

In the Netherlands, when fishermen complained about offshore wind farms being built on traditional fishing grounds, Hans Timmers from the Dutch Wind Energy Association Association who participated in the agreement said “I understand the fishermen’s plea, but they can of course go fishing in different places on the North Sea.”

This is an attitude held by many environmentalists who believe offshore wind power is the long-term solution to our energy needs. Government Planning Departments often do not consider the rights of fishermen who would historically fish where they want to plant an offshore wind farm.

Is the lifespan of an offshore wind turbine is estimated to be between 20 and 25 years worth damaging valuable fishing grounds for an eternity? That is the question environmentalists and wind farm companies should pose to themselves.

A recent study on the effects that man-made structures have on our marine environment has recently been released and makes interesting reading.

Man-made structures have been built into our coastal and marine environments as we respond to the need to generate even more energy. Installed across several soft sediment environments, these structures range from oil and gas installations to harbour walls, wrecks, pipelines, and offshore wind farms.

Inevitably, these structures host fouling communities that are often new to the offshore regions – potentially serving as stepping-stones for non-indigenous species as well as providing habitat and shelter for a variety of marine species.

The altered local biodiversity affects biological and biogeochemical processes from the water column to the seafloor, either directly (e.g. scouring, organic matter export from piles) or indirectly (e.g. closure or displacement of fisheries) and, hence, ecosystem functioning is also affected at various spatial and temporal scales. ​

But what should happen to these structures when they have been decommissioned? This debate provides the focus of the latest themed article set in ICES Journal of Marine Science, which presents a compilation of new evidence. Decommissioned offshore man-made installations has been spearheaded by Silvana Birchenough, Cefas​, and Steven Degraer, Royal Belgian Institute of Natural Sciences​.  “There are 14 peer-reviewed papers helping to shape the science-based evidence”, says Birchenough, “This new research will support ongoing discussions to inform marine spatial planning and future policy decisions on the use and protection of marine resources”. The ecological best practice in decommissioning, rigs/renewables-to-reefs, the influence of man-made infrastructures on fish population dynamics, and commercial fisheries losses arising from offshore pipelines are a few of the research topics included.​​

RESEARCH

Joop Coolen, Wageningen Marine Research, has been working on the impact of offshore infrastructure for many years and is very pleased with such an interesting collection of scientific work put together for this themed set. “I work mostly on fouling biodiversity on oil and gas installations. Whether or not the artificial reef role these structures play should be considered in decommissioning decisions has been an important discussion point.” The research Coolen presents facilitates this discussion. ​

A contribution by Jennifer Dannheim​, Alfred Wegener Institute, addresses the lack of understanding and research on the cause-effect-relationships by the implementation of artificial structures in benthic systems. With her co-authors, she identifies knowledge gaps on how marine renewable energy installations affect the ecosystem functioning and services of the benthic system. “In particular”, she says, “these are about (a) hydrodynamic changes possibly resulting in altered primary production with potential consequences for filter feeders, (b) the introduction and range expansion of non-native species (through stepping stone effects) and, (c) noise and vibration effects on benthic organisms. Our results further provide evidence that benthic sensitivity to offshore renewable effects is higher than previously indicated”.

Dannheim concludes that, “Knowledge and understanding of the cause-effect relationship and how the benthos is affected by the implementation of man-made structures is a prerequisite to the development of sustainable management plans in order to know which effects may disappear or may last on the benthos by decommissioning”​.

INSITES

The timely publication contributes to the scientific knowledge base on the impacts of man-made structures on marine ecosystems with the specific aim to generate new evidence-based debate over decommissioning. Richard Heard is Programme Director of INSITE (INfluence of man-made Structures In The Ecosystem) which specifically looks at understanding the influence of man-made structures on the North Sea ecosystem. With INSITE phase I complete, Heard states that, “The publication of this ICES Journal of Marine Science themed set is perfectly timed to showcase some of the INSITE phase I research and development and prepare us for INSITE phase II in the summer”.

MATURING SCIENCE

Birchenough and Degraer are thrill​​ed to have been involved in producing this contribution and thank all the enthusiastic authors for their support. Their introduction provides the reader with a comprehensive overview and is a good starting point to dive into the topic.

Degraer concludes, “There is an urgent need for a robust understanding of the effects of artificial hard substrate and the consequences of its removal (e.g. through decommissioning) to marine biodiversity. The science needs to move at a faster pace and has yet to develop to maturity”. ​

​Read Decommissioned offshore man-made installations in ICES Journal of Marine Science.

Source: Offshore Structures: to remove or nor to remove?

What are the effects of man-made structures on the marine environment?

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