PUBLICACIÓN CIENTÍFICA

Status of the Balearic shearwater (Puffinus mauretanicus) on the Galician coast (NW Iberian Peninsula)

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Mouriño, J., Arcos, F., Salvadores, R., Sandoval, A. & Vidal, C. Status of the Balearic shearwater (Puffinus mauretanicus) on the Galician coast (NW Iberian Peninsula). Scientia Marina 67, 135–142 (2003).

This paper aims to assess the status of the threatened Balearic shearwater Puffinus mauretanicus along the Galician coast (NW Iberian Peninsula) by studying its movements and numbers. Balearic shearwaters are detected off Galicia during their annual cycle although they are uncommon between November and May. Overall, 44 groups of over 150 birds have been recorded in seven main areas since 1976, especially in the Vigo Ria and the Pontevedra Ria and along the coast of Bergantiños (Sisargas-Baldaio). Birds have been observed moulting primary and secondary feathers, mainly in June. North-eastward migration is evident along the Atlantic coast (capes Silleiro and Fisterra, daily maximum of 476 birds per hour) between June and August, where it seems to overlap with local movement. However, south-westward migration is far more frequent between September and October (daily maximum of 360 birds per hour) along the Cantabrian coast. The results might be biased due to the methodological problems, on account of the existence of irregular flows, an important inter-annual variability and local movements, probably brought about by the distribution of food resources.

A three-isotope approach to disentangling the diet of a generalist consumer: the yellow-legged gull in northwest Spain

Enlace mardeaves Larus michahellis,PUBLICACIÓN CIENTÍFICA,REPOSITORIO ,

Moreno, R., Jover, L., Munilla, I., Velando, A. & Sanpera, C. A three-isotope approach to disentangling the diet of a generalist consumer: the yellow-legged gull in northwest Spain. Marine Biology 157, 545–553 (2010).

The widespread omnivory of consumers and the trophic complexity of marine ecosystems make it difficult to infer the feeding ecology of species. The use of stable isotopic analysis plays a crucial role in elucidating trophic interactions. Here we analysed d15N, d13C and d34S in chick feathers, and we used a Bayesian triple-isotope mixing model to reconstruct the diet of a generalist predator, the yellow-legged gull (Larus michahellis) that breeds in the coastal upwelling area off northwest mainland Spain. The mixing model indicated that although chicks from all colonies were fed with a high percentage of fish, there are geographical differences in their diets. While chicks from northern colonies consume higher percentages of earthworms, refuse constitutes a more important source in the diet of chicks from western colonies. The three-isotope mixing model revealed a heterogeneity in foraging habitats that would not have been apparent if only two stable isotopes had been analysed. Moreover, our work highlights the potential of adding d34S for distinguishing not only between terrestrial and marine prey, but also between different marine species such as fish, crabs and mussels.

Seabird feathers as monitors of the levels and persistence of heavy metal pollution after the Prestige oil spill

Enlace mardeaves Larus michahellis,Phalacrocorax aristotelis,PUBLICACIÓN CIENTÍFICA,REPOSITORIO ,,,,

Moreno, R., Jover, L., Diez, C. & Sanpera, C. Seabird feathers as monitors of the levels and persistence of heavy metal pollution after the Prestige oil spill. Environmental pollution 159, 2454–2460 (2011).

We measured heavy metal concentrations in yellow-legged gulls (n=196) and European shags (n=189) in order to assess the temporal pattern of contaminant exposure following the Prestige oil spill in November 2002. We analysed Pb, Cu, Zn, Cr, Ni and V levels in chick feathers sampled at four colonies during seven post-spill years (2003-2009), and compared results with pre-spill levels obtained from feathers of juvenile shag corpses (grown in spring/summer 2002). Following the Prestige wreck, Cu (4.3-10 mg g-1) and Pb concentrations (1.0e1.4 mg g-1) were, respectively, between two and five times higher than prespill
levels (1.5-3.6 and 0.1-0.4 mg g-1), but returned to previous background concentrations after three years. Our study highlights the suitability of chick feathers of seabirds for assessing the impact of oil spills on heavy metal contamination, and provides the best evidence to date on the persistence of oil pollution after the Prestige incident.

Ten Years after the Prestige Oil Spill: Seabird Trophic Ecology as Indicator of Long-Term Effects on the Coastal Marine Ecosystem

Enlace mardeaves Phalacrocorax aristotelis,PUBLICACIÓN CIENTÍFICA,REPOSITORIO ,,,,

Moreno, R., Jover, L., Diez, C., Sardá, F. & Sanpera, C. Ten Years after the Prestige Oil Spill: Seabird Trophic Ecology as Indicator of Long-Term Effects on the Coastal Marine Ecosystem. PLoS ONE 8, e77360 (2013).

Major oil spills can have long-term impacts since oil pollution does not only result in acute mortality of marine organisms, but also affects productivity levels, predator-prey dynamics, and damages habitats that support marine communities. However, despite the conservation implications of oil accidents, the monitoring and assessment of its lasting impacts still remains a difficult and daunting task. Here, we used European shags to evaluate the overall, lasting effects of the Prestige oil spill (2002) on the affected marine ecosystem. Using δ15N and Hg analysis, we trace temporal changes in feeding ecology potentially related to alterations of the food web due to the spill. Using climatic and oceanic data, we also investigate the influence of North Atlantic Oscillation (NAO) index, the sea surface temperature (SST) and the chlorophyll a (Chl a) on the observed changes. Analysis of δ15N and Hg concentrations revealed that after the Prestige oil spill, shag chicks abruptly switched their trophic level from a diet based on a high percentage of demersal-benthic fish to a higher proportion of pelagic/semi-pelagic species. There was no evidence that Chl a, SST and NAO reflected any particular changes or severity in environmental conditions for any year or season that may explain the sudden change observed in trophic level. Thus, this study highlighted an impact on the marine food web for at least three years. Our results provide the best evidence to date of the long-term consequences of the Prestige oil spill. They also show how, regardless of wider oceanographic variability, lasting impacts on predator-prey dynamics can be assessed using biochemical markers. This is particularly useful if larger scale and longer term monitoring of all trophic levels is unfeasible due to limited funding or high ecosystem complexity.

Influence of trophic ecology and spatial variation on the isotopic fingerprints of seabirds

Enlace mardeaves Phalacrocorax aristotelis,PUBLICACIÓN CIENTÍFICA,REPOSITORIO ,,

Moreno, R., Jover, L., Velando, A., Munilla, I. & Sanpera, C. Influence of trophic ecology and spatial variation on the isotopic fingerprints of seabirds. Marine Ecology Progress Series 442, 229–239 (2011).

Notwithstanding the potential applications of stable isotopes in feeding and migration studies, the simultaneous influence of diet, foraging behavior and spatial variation on the stable isotope signatures of seabirds is poorly understood. Many studies have interpreted their isotopic signatures without considering local baseline and prey isotopic signatures; consequently, the main factors causing isotopic differences between populations have frequently not been discerned. To examine the influence of these factors on the stable isotopic signatures of seabirds, we analyzed the δ15N, δ13C, δ34S and Hg concentrations of chick feathers of the European shag Phalacrocorax aristotelis, its main fish prey and baseline indicator organisms (mussels), all sampled in 2 sectors of northwest coastal Spain with marked differences in primary productivity. Our results show that the δ15N signature and Hg concentration of shags are influenced by both feeding ecology and spatial variation. The δ13C and δ34S signatures, however, mainly related to spatial differences and can thus be used as reliable geographic markers. Our findings also highlight the importance of assessing spatio-temporal variation in baseline isotopic signatures and their progressive
integration through the food web. Omission of potential prey and baseline values, or application of only a single baseline to the food webs of the 2 sectors, assuming isotopic homogeneity because of geographical proximity, would have led to significantly distorted interpretations of feeding ecology of shag chicks.

Are edge bird populations doomed to extinction: A response to Munilla et al.

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Martínez Abraín, A. Are edge bird populations doomed to extinction: A response to Munilla et al. Biological Conservation 191, 843–844 (2015).

Munilla et al. (2007) defended the idea that the population crash of common guillemots (Uria aalge) in Atlantic Spain, between 1960 and 1974, was not due to food scarcity associated to climate change, but to decreased adult survival caused by human-related factors, such as the generalization of the use of synthetic fishing nets, illegal shooting and oil spills. I strongly agree with them regarding the relevance of not using climate change as a default scapegoat for conservation problems. Often, proximate ecological factors are responsible for population declines, and can be managed if identified. However, regarding the quasi-extinction of common guillemots in NW Iberia the authors did not rule out convincingly the possibility that the local population crash was not due to massive adult emigration, rather than to reduced adult survival. In fact they admitted in their discussion that local adult survival in their population models also included adult emigration, and that they could not discard at all this possibility, although they considered it unlikely.

Sex-specific mortality of European shags after the Prestige oil spill: demographic implications for the recovery of colonies

Enlace mardeaves Phalacrocorax aristotelis,PUBLICACIÓN CIENTÍFICA,REPOSITORIO ,,,

Martínez-Abraín, A. et al. Sex-specific mortality of European shags after the Prestige oil spill: demographic implications for the recovery of colonies. Marine Ecology – Progress Series 318, 271–276 (2006).

Oil spills are extreme environmental perturbations (i.e. ecological catastrophes) affecting marine food webs and especially top predators, in which effects are likely amplified. As such, seabirds suffer from direct mortality and food depletion, with potentially important consequences for the population growth rate and probability of extinction. However, little is known about the effects of sex-skewed mortality (due to sex spatio-temporal differences in at-sea distribution) in seabird population
dynamics. We analyzed the mortality of European shags Phalacrocorax aristotelis after the Prestige oil spill and its effects on breeding colonies in Galicia (southwest North Atlantic). Most adults found dead were females (85%). The year after the spill, Monte Carlo simulations of population trajectories predicted a reduction of 11% in the number of breeding pairs when skewed mortality was considered, and a lower rate (8%) when assuming random sex distribution of adult mortality. The further reduction predicted with the sex-biased mortality was probably the result of unmated adults unable to reproduce. This difference, although slight, is a concern for conservation owing that the colonies studied were already showing a 5% annual decline due to other factors also related to human activities.

Differential effects of specific carotenoids on oxidative damage and immune response of gull chicks

Enlace mardeaves Larus michahellis,PUBLICACIÓN CIENTÍFICA,REPOSITORIO ,,,

Lucas, A., Morales, J. & Velando, A. Differential effects of specific carotenoids on oxidative damage and immune response of gull chicks. Journal of Experimental Biology 217, 1253–1262 (2014). doi: 10.1242/jeb.098004

Micronutrients are essential for normal metabolic processes during early development. Specifically, it has been suggested that diet-derived carotenoids can play a key role in physiological functions because of their antioxidant and immunostimulant properties. However, their role as antioxidants remains controversial. Additionally, it is also unclear whether oxidative stress mediates their immunostimulatory effects. In this field study, we separately supplemented yellow-legged gull (Larus michahellis) chicks with two carotenoids (lutein and β-carotene) with different molecular structures and different transformation pathways into other oxidative forms of carotenoids. We quantified their effect on the oxidative status and the immune response of chicks before and after an oxidative challenge with paraquat, a pro-oxidant molecule. Prior to oxidative challenge, none of the carotenoid treatments affected the oxidative status of chicks, but they enhanced the inflammatory response to an antigen compared with controls. The oxidative challenge enhanced plasma vitamin E levels (but not in β-carotene-supplemented chicks) and the antioxidant capacity in the short term. Interestingly, lutein-supplemented chicks showed lower oxidative damage to proteins than non-lutein-supplemented chicks. After the oxidative challenge, the positive effect of carotenoid supplementation on the immune response disappeared. Thus, these results suggest differential effects of two carotenoids with different molecular structures on the oxidative status. Lutein but not β-carotene helps to combat oxidative damage after a free-radical exposure. Additionally, the results indicate that the immunostimulatory effects of carotenoids are linked to oxidative status during early life.

Antioxidants safeguard telomeres in bold chicks

Enlace mardeaves Larus michahellis,PUBLICACIÓN CIENTÍFICA,REPOSITORIO ,,,,

Kim, S.-Y. & Velando, A. Antioxidants safeguard telomeres in bold chicks. Biology letters 11, 20150211 (2015). DOI: 10.1098/rsbl.2015.0211

Telomeres are sensitive to damage induced by oxidative stress, and thus it is expected that dietary antioxidants may support the maintenance of telomere length in animals, particularly those with a fast rate of life (e.g. fast metabolism, activity and growth). We tested experimentally the effect of antioxidant supplements on telomere length during early development in wild gull chicks with natural individual variations in behaviour pattern and growth rate. Proactive chicks had shorter telomeres than reactive chicks, but the penalty for the bold behaviour pattern was reduced by antioxidant supplementation. Chicks growing faster had longer telomeres during early growth, suggesting that inherited quality supports a fast life history.