Dr Mel Austen PMLAs a marine ecologist I have always been interested in complexity and interactions. This started in earnest when I found out that just a handful of estuarine mud contained anything from 20 to 70 species of tiny nematode worms (smaller than a pin head)! Why are there so many species and what do they all do? (In partial answer they all feed on different things and live in minutely defined chemico-physical niches.)

I researched why some marine nematodes were more vulnerable to the things that humans throw at them (i.e. pollutants) than others. I also asked, who feeds on nematodes and how such sedentary organisms are so widely dispersed, given that they can only wriggle or move mere millimetres and they don’t even have a planktonic phase in their lifecycle. Tiny animals are difficult to study and we will probably never know precise answers to these questions.

Then I broadened my research to look at the rest of the animals living in the soft sediments on the seabed. I looked at why they had changed over recent decadal history (early signs of climate change), how they interacted with the whole of the physical, chemical and biological context of the water column above (which moves at different time and spatial scales to what happens in the sediments), what might happen in the future (working with mathematical ecosystem modellers) and considered what this might imply for people.

Adding ‘people’ created a whole new dimension of research. How do marine ecosystems function from a totally anthropocentric perspective, beyond the obvious provision of fish for us to eat? And how and why do we value the different services provided to us by the sea? Which brings me at last to energy.

From some people’s perspectives (and many of them are involved with UKERC) it seems that the ONLY thing of any importance is energy. Marine renewable energy supply is now even viewed by some as being an ecosystem service (although this ignores the definition of an ecosystem which embraces the interaction of both living and non-living components of the environment). However, the key thing for me is that the marine environment provides more than just energy.

It is a vital source of food, both directly from the sea through capture and also through aquaculture. It is a place to undertake leisure and recreation (I am a keen sailor and used to do a lot of scuba diving). It is a medium for transport (around 95% of goods entering or leaving the UK go by sea). We also take our seas for granted when we use them to discharge wastewater, like treated sewage, fertiliser/pesticide run-off from our highly intensive and much needed agriculture, and road surface water run-off – including all the chemicals released from the tyres and oils associated with transport. And of course the seas are a massive sink for our greenhouse gas emissions. I could go on still further about what the marine environment provides for us.

In recognition of this and of EU policy (The Maritime Directive, The Marine Strategy Framework Directive), the UK enacted legislation (Marine and Coastal Access Act 2009, Marine (Scotland) Act 2010) which introduced marine planning. This recognises that not only are the resources we exploit from our seas increasing, our seas are also becoming increasingly busy.

UK marine planners, who are based in the Marine Management Organisation and in Marine Scotland, have to consider the trade-offs between all the different services and resources that the marine environment provides. And of course they do this from a very anthropocentric perspective. When they look at the sea they have to weigh up not just the UK’s renewable energy targets, but also inter alia the need for food security, the need for security of transport, the need for local businesses and industry to sustain their local tourist and leisure income, the appreciation by the general public of the marine environment, and the legislative demands to protect and preserve aspects of the marine environment through creation of a network of protected areas (Marine Conservation Zones, Special Areas of Conservation).

Marine planners would be failing in their responsibilities if they only considered the need for a secure supply of energy to satisfy our demand. Similarly, we fail in our responsibilities as researchers if we consider low carbon energy supply in isolation, ignoring its interactions with the living and non-living aspects of the sea and with other users of the sea.

Some of these interactions can be positive – established wind-farms can potentially be areas of protection for marine life, for the enhancement of fish stocks and for local aquaculture to provide food. Some can be negative – wind farm arrays can interfere with the navigation of ships potentially endangering lives in the event of a collision, as well as increasing fuel consumption and costs to avoid the newly installed shipping hazards.

Also to be considered are the cumulative and interactive impacts on marine ecosystems of increasing deployment of offshore wind turbines, and in the future of wave and tidal energy devices, both with each other and with other uses of our seas. And then there can be the unanticipated public response to the deployment of energy infrastructure (fracking comes to mind here), where we still have little primary data to understand the motivations that lead to negative responses.

It doesn’t help that researchers consider the positive and negative impacts of marine renewable energy through the blurry lens of our limited information on this fast developing seascape. Our key source of knowledge of environmental impacts should be statutory monitoring, but much of it is inadequate and/or the results are not freely available for researchers, such that our rate of gain in knowledge of impacts is much slower than the speed of deployment.

Our clarity of understanding the impacts of renewable energy on marine ecosystems, on different industries and on the public, is not unlike the clarity of view you get when you stick your head underwater in the sea, open your eyes and try to make out the details of the different fish and seaweed that are all about you.

I have always loved complex problems and issues, and I have always loved the sea and its marine life. For me the research challenges associated with marine renewable energy are complex and important. Energy security and increasing the proportion of low-carbon energy supply are vital, but so are many of the other services provided by our seas.

Marine planners are rising to these challenges and so must the research community to support them, ensuring that the decisions they, and others, must make are based on the best available evidence and understanding.

Dr Melanie Austen is Head of Science for ‘Sea and Society’ at Plymouth Marine Laboratory. She is also a Co-Director at the UK Energy Research Centre (UKERC), leading the Energy and Environment theme.