In 2014 a benthic infauna survey was carried out in Swansea Bay (Wales, UK), an industrialised embayment with a long history of shipping, industrial and domestic pollution, fishing, dredging and spoil disposal. The purpose of the survey was to generate up-to-date baseline information about the benthic communities in the area, and also to compare the current situation with a similar survey carried out 30 years ago. In 2014 grab samples were retrieved at 101 positions in the wider Swansea Bay area to analyse the infauna benthos as well as sediment grain size distribution. Grab samples were taken with a 0.1m2 Day grab. About 200g of surface sediment were removed for particle size analysis, and the remaining sediment was washed through a sieve with 1mm mesh. The sieve residue was fixed in 4% formaldehyde and stained with Rose Bengal. All benthic fauna was sorted from the samples, identified to species level if possible, and counted. Sediment samples were air dried and passed through a series of sieves from 2mm to 63µm according to the Wentworth-Udden classification scale to determine particle-size distribution.
The survey revealed spatially discrete benthic communities including a biodiversity hotspot. Habitat characteristics including sediment properties and the proximity to a sewage outfall explained 17-35% of the variation in the community structure. A group of five common species was found to be particularly persistent over time (Nucula nitidosa, Spisula elliptica, Spiophanes bombyx, Nephtys hombergii, Diastylis rathkei). According to the Infauna Quality Index (IQI) linked to the EU Water Framework Directive (WFD) the average ecological status for 2014 was 'moderate', but eleven samples showing 'poor' and 'bad' status indicated possible negative impacts of dredge spoil disposal.
Here the 2014 set of data is made publically available. The comparison of the 2014 data with the 30-year old data was published at http://dx.doi.org/10.3389/fmars.2016.00141.
