SOLVE magazine Issue 01 2020 - Page 17

SUSTAINABILITY AND THE ENVIRONMENT: LIVING SEAS nurseries for important commercial fish stocks. But oysters today are struggling to perform these roles because they have been all but wiped from the wild. A deadly combination of overfishing, pollution and disease and has seen the world lose 85 per cent of its oyster reefs. For marine scientists the scale of this depletion highlights the urgent need to restore this almost-forgotten ecosystem. At the University of Portsmouth, researchers have embarked upon an ambitious project to restore oyster reefs to the Solent and provide a case study for similar restoration programmes elsewhere. The 20-mile strait between mainland England and the Isle of Wight was once home to millions of native oysters – in fact, it was once Europe’s largest oyster fishery – but by 2013 was so depleted that even collecting oysters from the area had to be banned. In 2017 a University of Portsmouth survey of 300 seabed samples in three harbours found just three native oysters. This echoed the stock assessments by the Southern Inshore Fisheries and Conservation Authority (SIFCA) that set in motion a major recovery programme – The Solent Oyster Restoration Project, a collaboration with the Blue Marine Foundation, 1851 Trust, MDL Marinas, Ineos, and UK oyster fisheries. Led by Dr Joanne Preston, the programme provides an evidence-based strategy and cutting-edge restoration science to restore a healthy reefs ecosystem to Solent and UK waters. To begin repopulating the strait, the research team suspended oyster-filled cages from pontoons. Oyster larvae produced in what some journalists dubbed aquatic ‘love hotels’ – a nod perhaps to Aphrodite – are now re-settling the seabed. This is an achievement in itself, but showing just how interconnected the marine web of life is, their cages were promptly occupied by other creatures. The team has discovered 95 species in the cages, including endangered European eels. Data from the cage study are now being used to recommend ways for marinas around the country to become involved in oyster restoration. Oysters are coming home, and they are saving our seas. Ecosystem engineers Dr Preston describes oysters as ‘ecosystem engineers’, their reefs and beds contributing substantially to inshore biodiversity by providing protection and nursery grounds for juvenile fish and other species. Oyster reefs are ‘biogenic’, meaning they are solid structures created by living organisms; in this case by shells mounting up as oysters die, and as new oysters settle on each other. This creates a 3D hard structure that supports a whole new ecosystem. The restoration project, begun in late 2016, hopes to reseed the Solent with millions of oysters over the next few years to restore the the native oyster’s role in lifting and sustaining ecosystem health, increase biodiversity and improve water quality. Dr Preston’s research also covers molecular ecology and evolution, which involves looking at the DNA sequences of organisms to identify relationships. “Organisms’ DNA tells Ecosystems provide us with food, oxygenated water, and other natural resources we humans depend on. And ecosystems depend on biodiversity. – Joanne Preston us what’s related and what isn’t, and we use this to understand true biodiversity. By pinpointing how much genetic variation is out there, you can estimate how likely those organisms can adapt and survive in the future. “Essentially, the less genetic variation, robustness and resilience there is, the higher the chance of extinction,” she says. Dr Preston says overfishing has caused the gene pool (or genetic diversity) of many marine species to shrink. This includes oysters and one of the concerns being addressed by The Solent Oyster Restoration Project is the level of genetic diversity within the remaining population, and whether the population is diverse enough to enable the oysters to survive and adapt to the changed marine environment there. If the oyster populations cannot be sustained, then multiple other species that depend on oyster reefs for food and shelter are also in trouble. Dr Preston’s Portsmouth team works closely with Southampton University, Essex University, Heriot-Watt University, Roslin Preserving the Mary Rose Dr Joanne Preston isn’t just preserving marine life. She has also used her expertise to stabilise the remains of King Henry VIII’s warship, the Mary Rose, when it was raised from the Solent after hundreds of years underwater. The struggle to preserve it has been challenging. Dr Preston explains that the Mary Rose was producing tonnes of sulphuric acid due to the oxidation of iron and sulphur in the wood and bolts after being exposed to air again. The acid was eating away at the ship and had to be stopped. Dr Preston used her DNA expertise to discover iron-oxidising bacteria in the wood, along with acidophilic bacteria, which live off the iron and sulphur. “It took three months trying to get environmental DNA out of one piece of archaeological wood. After amplifying a specific gene from all the microbes that were inside the wood, I sequenced these to identify what species were living there, as well as growing microbes using microbiology culturing techniques. We discovered several species of iron and sulphur organisms present in the Mary Rose, and tested ways of stopping them.” For Dr Preston, variety is the spice of scientific life: “I always recommend scientists go off-piste and challenge themselves by trying new areas of research and collaborating with people in different fields. The Mary Rose work opened up a whole new world for me in terms of microbiology and microbial ecology, and it feeds into my oyster restoration work.” Institute, the Centre for Environment, Fisheries and Aquaculture Science in the UK, and other research partners across Europe to achieve a Europe-wide restoration and revive the lost memory of thriving oyster reefs in this part of the world. � www.nativeoysternetwork.org www.noraeurope.eu www.noraeurope.eu/wp-content/uploads/2018/Berlin-Oyster- Recommendation-Part-1.pdf ISSUE 1 / 2020 17