Improved estimates of digestion correction factors and passage rates for harbor seal (Phoca vitulina) prey in the northeast Atlantic

Diet composition in pinnipeds is widely estimated using hard prey remains recovered from feces. To estimate the size and number of prey represented in fecal samples accurately, digestion correction factors (DCFs) must be applied to measurements and counts of fish otoliths and cephalopod beaks. In this study, 101 whole prey feeding trials were conducted with six harbor seals (Phoca vitulina) and 18 prey species. We derived species- and grade-specific estimates of digestion coefficients (DCs) and species-specific recovery rates (RRs) to account for partial and complete digestion, respectively. Greater than 98% of otoliths were passed within three days of consumption. RRs were smallest for Atlantic salmon smolts (RR = 0.306, SE = 0.031) and increasingly larger for sandeels (RR = 0.494, SE = 0.017), flatfish (RR = 0.789, SE = 0.033), and large gadoids (RR = 0.944, SE = 0.034). Species-specific otolith width DCs were smallest for Trisopterus species (DC = 1.14, SE = 0.015) and increasingly larger for flatfish (DC = 1.27, SE = 0.045), large gadoids (DC = 1.32, SE = 0.067) and sandeels (DC = 1.57, SE = 0.035). RRs were similar to those from gray seals (Halichoerus grypus), but harbor seal species- and grade-specific DCs were generally smaller. Differences in partial and complete digestion rates among prey species and between seal species highlight the importance of applying DCFs when reconstructing diet.PostprintPeer reviewe

Responses of two marine top predators to an offshore wind farm

Quantifying the likely effects of offshore wind farms on wildlife is fundamental before permission for development can be granted by any Determining Authority. The effects on marine top predators from displacement from important habitat are key concerns during offshore wind farm construction and operation. In this respect, we present evidence for no significant displacement from a UK offshore wind farm for two broadly distributed species of conservation concern: common guillemot (Uria aalge) and harbor porpoise (Phocoena phocoena). Data were collected during boat-based line transect surveys across a 360 km2 study area that included the Robin Rigg offshore wind farm. Surveys were conducted over 10 years across the preconstruction, construction, and operational phases of the development. Changes in guillemot and harbor porpoise abundance and distribution in response to offshore wind farm construction and operation were estimated using generalized mixed models to test for evidence of displacement. Both common guillemot and harbor porpoise were present across the Robin Rigg study area throughout all three development phases. There was a significant reduction in relative harbor porpoise abundance both within and surrounding the Robin Rigg offshore wind farm during construction, but no significant difference was detected between the preconstruction and operational phases. Relative common guillemot abundance remained similar within the Robin Rigg offshore wind farm across all development phases. Offshore wind farms have the potential to negatively affect wildlife, but further evidence regarding the magnitude of effect is needed. The empirical data presented here for two marine top predators provide a valuable addition to the evidence base, allowing future decision making to be improved by reducing the uncertainty of displacement effects and increasing the accuracy of impact assessments

Resolving the Trophic Relations of Cryptic Species: An Example Using Stable Isotope Analysis of Dolphin Teeth

Understanding the foraging ecology and diet of animals can play a crucial role in conservation of a species. This is particularly true where species are cryptic and coexist in environments where observing feeding behaviour directly is difficult. Here we present the first information on the foraging ecology of a recently identified species of dolphin (Southern Australian bottlenose dolphin (SABD)) and comparisons to the common bottlenose dolphin (CBD) in Victoria, Australia, using stable isotope analysis of teeth. Stable isotope signatures differed significantly between SABD and CBD for both δ13C (−14.4‰ vs. −15.5‰ respectively) and δ15N (15.9‰ vs. 15.0‰ respectively), suggesting that the two species forage in different areas and consume different prey. This finding supports genetic and morphological data indicating that SABD are distinct from CBD. In Victoria, the SABD is divided into two distinct populations, one in the large drowned river system of Port Phillip Bay and the other in a series of coastal lakes and lagoons called the Gippsland Lakes. Within the SABD species, population differences were apparent. The Port Phillip Bay population displayed a significantly higher δ15N than the Gippsland Lakes population (17.0‰ vs. 15.5‰), suggesting that the Port Phillip Bay population may feed at a higher trophic level - a result which is supported by analysis of local food chains. Important future work is required to further understand the foraging ecology and diet of this newly described, endemic, and potentially endangered species of dolphin

International genome-wide meta-analysis identifies new primary biliary cirrhosis risk loci and targetable pathogenic pathways.

Primary biliary cirrhosis (PBC) is a classical autoimmune liver disease for which effective immunomodulatory therapy is lacking. Here we perform meta-analyses of discovery data sets from genome-wide association studies of European subjects (n=2,764 cases and 10,475 controls) followed by validation genotyping in an independent cohort (n=3,716 cases and 4,261 controls). We discover and validate six previously unknown risk loci for PBC (Pcombined<5 × 10(-8)) and used pathway analysis to identify JAK-STAT/IL12/IL27 signalling and cytokine-cytokine pathways, for which relevant therapies exist

Robust digestion and passage rate estimates for hard parts of grey seal (<em>Halichoerus grypus</em>) prey

Application of digestion correction factors to measurements and counts of fish otoliths and cephalopod beaks recovered from seal scats is required before the size or quantity of prey consumed can be accurately estimated. We carried out 86 feeding trials with seven grey seals (Halichoerus grypus) and 18 prey species to derive estimates of digestion coefficients (to account for partial digestion), recovery rates (to account for complete digestion), and passage rates (to estimate the time between consumption and excretion of an item). Mean digestion coefficients were greatest for sandeel (Ammodytes marinus) and then less for large gadoid, flatfish, and Trisopterus spp. otoliths; and finally squid (Loligo forbesii) beaks. Recovery rates were greatest for squid beaks and then less for large gadoid, Trisopterits spp., flatfish, and sandeel otoliths. Greater than 95% of otoliths and beaks recovered were passed within 4 days (similar to 88 h) of consumption. The large differences in partial and complete digestion rates found among prey species reinforce the importance of obtaining robust estimates of these quantities. Results from this study are the most comprehensive and systematically obtained for any species of pinniped and will allow accurate and precise estimation of the number and size of fish represented by otoliths recovered from grey seal scat samples collected in the wild.</p