A three year study was undertaken during 2002 to 2004 from May to September to estimate abundance and density of harbour porpoises on the north coast of Anglesey, Wales, UK. There were no ecological data regarding the harbour porpoises in Anglesey waters so the ability to influence conservation measures was highly constrained.Boat based transects using distance sampling techniques were applied so a robust estimate of density and abundance could be attained. The study area consisted of a block approximately 489 km2 extending from the east of Point Lynas to the west of South Stack on north coast of Anglesey. The study area was divided into 5 blocks consisting of 31 perpendicular transect lines to the shore. Each of the transect lines were surveyed 1–5 times by the end of the three year study.Based on the assumption that g(0) = 1 the density of harbour porpoises for the 489 km2 study site was estimated to be 0.630 individuals/km2 (CV = 0.20) and the abundance is estimated to be 309 individuals (CV = 0.20). Heterogeneity in density and abundance was observed across the 5 blocks which showed Point Lynas and South Stack to have the highest densities. This distribution was closely associated to fine-scale oceanographic features which cause prey to be concentrated and may facilitate foraging for harbour porpoises. The study showed that Anglesey provides coastal habitats for the harbour porpoise and was the first study of this kind in North Wales, UK.
The Irish Sea is an important area for Norway Lobster Nephrops norvegicus fisheries, which are the most valuable fishing resource in the UK. Norway lobster are known to ingest microplastic pollution present in the sediment and have displayed reduced body mass when exposed to microplastic pollution. Here, we identified microplastic pollution in the Irish Sea fishing grounds through analysis of 24 sediment samples from four sites of differing proximity to the Western Irish Sea Gyre in both 2016 and 2019. We used µFTIR spectroscopy to identify seven polymer types, and a total of 77 microplastics consisting of fibres and fragments. The mean microplastics per gram of sediment ranged from 0.13 to 0.49 and 0 to 1.17 MP/g in 2016 and 2019, respectively. There were no differences in the microplastic counts across years, and there was no correlation of microplastic counts with proximity to the Western Irish Sea Gyre. Considering the consistently high microplastic abundance found in the Irish Sea, and the propensity of N. norvegicus to ingest and be negatively impacted by them, we suggest microplastic pollution levels in the Irish Sea may have adverse impacts on N. norvegicus and negative implications for fishery sustainability in the future.
<p>Oceanic and coastal fronts are well-documented as accumulators of microplastic debris; however the impact of estuarine fronts and their associated secondary flows on microplastic concentrations are less well-known. An investigation into the dynamics of microplastic behaviour within estuarine systems will allow for a greater understanding of plastic retention and exportation to coastal and offshore environments. This study combines high resolution modelling of estuarine processes with realistically parameterized microplastic particles to determine local exposure levels, residence times and temporal variability.&#160;</p>
<p>We present a validated, three-dimensional, D-Flow Flexible mesh (D-Flow FM) model of a well-mixed estuary (Conwy Estuary, Wales, UK), demonstrating the regular development of an axial convergent front following high tide. A Lagrangian particle tracking model has been applied to simulate the behaviour of microplastic in these frontal systems and analyse how this behaviour may change as a response to various river discharge levels and tidal phases. The results of the ocean model and Lagrangian particle tracking model will be presented.&#160;</p>
<p>Understanding how estuarine fronts impact microplastic concentration and dispersal within estuaries will increase the accuracy of modelling and in-situ estuarine microplastic studies alike, helping to quantify the contribution of well-mixed estuaries to regional and global microplastic budgets, and bridging the gap between terrestrial and marine environments.</p>
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