Effect of electromagnetic fields from renewable energy subsea power cables on righting reflex and physiological response of coastal invertebrates.

Offshore renewables are expanding, yet more information is required to understand their possible impacts on the environment. Little is known about the effects of Electromagnetic Fields (EMF) from subsea power cables on marine life. This study simulated an EMF of 500 µT, as modelled for an export cable over a rocky shore, where the industry standard cable burial would not be possible. Righting reflex, refractive index of haemolymph/coelomic fluid, and total haemocyte/coelomocyte counts were measured for four coastal invertebrates (Asterias rubens, Echinus esculentus, Necora puber, and Littorina littorea). No significant differences were found in either behavioural or physiological responses. This was the first study to investigate EMF exposure on righting reflex, and the first ever EMF study on edible sea urchins and periwinkles, and only one of a couple for common starfish and velvet crabs. It therefore, provides valuable data for environmental impact assessments, marine spatial planning, and commercial fisheries.

Optimising recruitment in habitat creation for the native European oyster (Ostrea edulis): Implications of temporal and spatial variability in larval abundance.

European oyster (Ostrea edulis) restoration often requires the timely deployment of shell habitat for larval settlement. To inform this increasingly popular process, the present study investigated temporal and spatial abundance patterns of O. edulis larvae in a rare commercial fishery (Loch Ryan, Scotland, UK). Patterns in larval abundance were analysed against variability in temperature, salinity, chlorophyll, oxygen, tidal/moon phase, light, date, and location. 'Temperature sum' (sum total of degrees per day above 7 °C) was the most significant seasonal predictor of larval abundance; with a peak at 617 degree-days. Oyster larval abundance did not significantly vary between oyster bed and non-bed habitats but was significantly higher in the mid and near-surface part of the water column. The findings are discussed in the context of emerging international restoration initiatives and have implications for: where habitat restoration would be successful; the prediction of larval connectivity between sites; and a transferable indicator to optimise shell-habitat deployment timing.