Nuclear power and coastal birds: predicting the ecological consequences of warm-water outflows

Local alteration of species abundance in natural communities due to anthropogenic impacts may have secondary, cascading effects on species at higher trophic levels. Such effects are typically hard to single out due to their ubiquitous nature and, therefore, may render impact assessment exercises difficult to undertake. Here we describe how we used empirical knowledge together with modelling tools to predict the indirect trophic effects of a future warm-water outflow on populations of shorebirds and wildfowl. Of the main potential benthic prey used by the birds in this instance, the clam Macoma balthica was the only species suspected to be adversely affected by a future increase of temperature. Various scenarios of decreases in prey energy content, simulating various degrees of temperature increase, were tested using an individual-based model, MORPH, in order to assess the effects on birds. The survival and body condition of eight of the 10 bird species modelled, dunlin, ringed plover, turnstone, redshank, grey plover, black-tailed godwit, oystercatcher and shelduck were shown to be not influenced even by the most conservative prey reduction scenarios. Most of these species are known to feed primarily on polychaete worms. For the few bivalve-feeding species, the larger size-classes of polychaete worms were predicted to be a sufficient alternative food. Only knot was predicted to have a lower survival under the two worst case scenario of decreased M. balthica energy content. We believe that this is the first time such predicted cascade effects from a future warm-water outflow have been shown

Using remote sensing to quantify fishing effort and predict shorebird conflicts in an intertidal fishery.

Accurate estimates of fishing effort are necessary in order to assess interactions with the wider ecosystem and for defining and implementing appropriate management. In intertidal and inshore fisheries in which vessel monitoring systems (VMS) or logbook programmes may not be implemented, quantifying the distribution and intensity of fishing can be difficult. The most obvious effects of bottom-contact fishing are often physical changes to the habitat, such as scarring of the sediment following dredging or trawling. We explored the potential of applying remote sensing techniques to aerial imagery collected by an unmanned aerial vehicle, or drone, in an area of intertidal mud flat (0.52 km2) in Poole Harbour, UK, where shellfish dredging is widely carried out and conflicts between commercial fishing interests and the conservation of internationally important shorebird populations are a concern. Image classification and image texture analysis were performed on imagery collected during the open dredge season in November 2015, in order to calculate measures of fishing intensity across three areas of the harbour subject to different management measures. We found a significant correlation between results of the image texture analysis and official sightings records collected during the dredging season, indicating that this method most accurately quantified dredging disturbance. The relationship between shorebird densities and food intake rates and the results of this analysis method were then investigated to assess the potential for using remotely sensed measures of fishing effort to assess responses of overwintering shorebird populations to intertidal shellfish dredging. Our work highlights the application of such methods, providing a low-cost tool for quantifying fishing effort and predicting wildlife conflicts

Differential survival in adult Eurasian oystercatchers Haematopus ostralegus

I explored the fitness implications of individual and sex differences in foraging strategy in the Eurasian oystercatcher Haematopus ostralegus by monitoring the survival of individually colour-ringed birds of known sex and known feeding specialisation. Over the period of this study, adult female annual and overwinter survival was significantly lower than adult male survival. However, contrary to previous findings, no differences in survival were found between birds of different feeding specialisations. Lower female survival was not due to sex differences in feeding specialisation. Possible mechanisms for sex differences in survival and the survival implications of different feeding specialisations are discussed. I conclude that sex differences in survival may be due to differences in social status. I also suggest that worm/clam feeders and mussel-stabbers, feeding specialisations previously associated with lower survival rates, may have benefited more than mussel-hammerers from milder winter temperatures in recent years

Predicting the effect of local and global environmental change on shorebirds: a case study on the Exe estuary, U.K.

We used an individual-based model to assess site quality and to predict the effect of local (i.e. disturbance from a cycle path) and global (i.e. climate change) environmental change on the survival of six species of overwintering shorebirds on the Exe estuary, U.K. We also compare site quality on the Exe estuary with three other estuary Special Protection Areas (SPAs) and compare our predictions for the effects of climate change with predictions made for another southern U.K. estuary, Poole Harbour. Prey biomass densities in the Exe estuary were high for all six shorebirds, being as high as or higher than those found on other estuary SPAs. Simulations of increased levels of disturbance from a proposed cycle path along the side of the estuary predicted that disturbance of upper mudflat areas was unlikely to affect shorebird survival but that increased disturbance of nearby fields would reduce curlew survival. Shorebirds on the Exe estuary were far less seriously affected than those in Poole Harbour by reductions in mean daily temperatures, loss of terrestrial habitats and simulated sea-level rise. We conclude that the Exe estuary is a high quality estuary and that the shorebird populations modelled were less susceptible to climate change than those in Poole Harbour