Many nuclear power stations in the UK are built on the coast, where the easy availability of sea water offers a natural solution to cooling the carbon dioxide used to moderate the reactor temperature. Hinkley Point B station is situated on the Bristol Channel for just this reason, and as one adventitious consequence, its water intakes have been a rich source of biological data for the last 30 years.
Tidal currents in the Bristol Channel can be strong (witnessed in the Severn Bore, which forms further upstream), and fish feeding on the coastal mudflats may be pulled into the station’s water intakes. They aren’t allowed, of course, to reach the station itself – fish not being a very good coolant – and are instead caught in filter screens. Since the early 1980s, the catches in these screens have been used as population samples for the wider habitat, with numbers and species – and since the 2000s, also weights – of the caught fish being recorded once a month.
This kind of long-running population survey allows analyses that wouldn’t be possible on a shorter timescale, and one of these has just been published by the Magurran lab in BMC Biology. Partitioning the data into natural seasonal patterns over the course of each year, the authors asked whether these seasonal patterns are important in maintaining increased biodiversity (“fluctuation-mediated coexistence” is the technical term). As might be predicted if they were, the data show an increase in diversity (as measured by typical habitat occupancy of each species) during the winter and spring months, when resources are at their lowest compared with the more bountiful summer and autumn.
The 30+ years of data were necessary to enable the authors to draw conclusions about seasonal fluctuation that are robust to yearly differences, and the paper is a reminder of the importance of these kind of long-term biological datasets to ecology.