In November 2002, the tanker Prestige broke in two and sank at the bottom of the ocean spilling about 70,000 t of fuel oil, which reached the coast of Galicia. It was considered the largest spill in maritime history, greatly affecting marine and related avian species. The spilled fuel oil contained high concentrations of polycyclic aromatic hydrocarbons (PAHs). Many species were affected and were found dead, although ongoing research is still being carried out on the sublethal effects. In this sense, little is known about the action of PAHs on Cholinesterase activity in seabirds. Consequently, the purpose of this study was to provide more information on the neurotoxicity of fuel oil on the seabirds most affected by the Prestige accident: common guillemot, Atlantic puffin and razorbill. On the other hand, data on normal values of acetylcholinesterase (AChE) activity were obtained to supply non-exposed values in seabirds. The oil spill produced a clear inhibitory effect on brain AChE activity in common guillemot (16%, p ≤ 0.01) and razorbill (22%, p ≤ 0.01), but not in Atlantic puffin (4%). Physiological levels of brain AChE, expressed in nmol acetylcholine hydrolysed min− 1 mg− 1 protein were similar in non-exposed common guillemot (388.6 ± 95.0) and Atlantic puffin (474.0 ± 60.7), however, razorbill values were higher (644.6 ± 66.9).
Seabirds are top consumers in marine foodchains which offer opportunities to detect and assess the toxicological effects of different inorganic elements on the marine ecosystem. In order to provide baseline data concerning trace element levels in seabird species from NW Spain, zinc, copper, arsenic, chromium, lead, cadmium and mercury concentrations were analyzed in liver of three different seabird species (common guillemot, Atlantic puffin and razorbill) affected by the Prestige oil spill in September 2002 on the Galician coast. In general, with the exception of mercury, levels of all the analyzed elements were similar or lower in comparison with those reported for the same species in other Atlantic areas, and did not exceed levels indicative of increased environmental exposure.
Bárcena, F. & Souza, J.A. Las colonias de aves marinas de la costa Occidental de Galicia. Características, censo y evolución de sus poblaciones. Ecología 1. (1987). ISSN 0214-0896
Munilla, I. & Velando, A. Plan Integral de Recuperación e Conservación das Aves Mariñas Ameazadas de Galicia. (Consellería de Medio Ambiente e Desenvolvemento Sostible, Xunta de Galicia, 2008).
Neste documento preséntase a memoria do “Plan Integral de Recuperación e Conservación das Aves Nidificantes en Cantís Costeiros: Uria aalge, Phalacrocorax aristotelis e Rissa tridactyla” ao abeiro do concurso público convocado pola Consellería de Medio Ambiente e Desenvolvemento Sostible da Xunta de Galicia, para a elaboración de planes de recuperación e conservación de diversas especies de fauna incluídas no catálogo galego de especies ameazadas (DOGA de 18 de xaneiro de 2007). Por tanto, contén a información biolóxica oportuna e as recomendacións de manexo necesarias para a conservación das poboacións galegas de tres aves mariñas: airo (Uria aalge), corvo mariño (Phalacrocorax aristotelis) e gaivota de tridáctila (Rissa tridactyla). O seu obxectivo último é garantir a persistencia desas especies en Galicia no longo prazo.
Munilla, I. & Velando, A. The Iberian guillemot population crash: A plea for action at the margins. Biological Conservation 191, 842 (2015).
We would like to thank Dr. Martínez-Abraín for his interest in our study on the collapse of the Iberian guillemots (Munilla et al., 2007) as it gives us the opportunity to comment on the importance of some of the issues concerning the conservation of marginal, rear edge populations. In our retrospective analyses of the quasi-extinction of Iberian guillemots, we found that the only demographic parameter which explained the dra- matic population crash that occurred between 1960 and 1974 was the disappearance of breeding adults.
Munilla, I., Díez, C. & Velando, A. Are edge bird populations doomed to extinction? A retrospective analysis of the common guillemot collapse in Iberia. Biological Conservation 137, 359–371 (2007).
In the first half of the XXth century, the common guillemot (Uria aalge) was the seabird with the largest breeding population in Atlantic Iberia (ca. 20,000 individuals), the low-latitude limit of the species breeding range. However, this population suffered a dramatic decline and is quasi-extinct at present. The decline was believed to be associated with reduced availability of pelagic prey fish due to climate change. In this study, we analyzed the population change of Iberian guillemots in the second half of the XXth century by means of a retrospective analysis. Our study showed that between 1960 and 1974 the guillemots in Iberia suffered a dramatic population crash (33.3% annual decline) and that subsequently, the population continued to decline at a slower annual rate (13.4%). Simulation models indicated that the factors driving the population crash should be related to adult survival, rather than reproduction. The analysis of environmental and fishery data suggested good climate conditions and higher or sustained availability of pelagic prey fish when the Iberian guillemots crashed. In contrast, relevant human-related factors were affecting adult mortality in that period, specially a rapid and large increase in the number of synthetic fishing nets. During the collapse, no conservation measures were undertaken to mitigate anthropogenic threats and it was assumed, in some extent, that this low-latitude edge population was somehow prone to extinction as a consequence of climate change. This study high- lights that to carelessly attribute the decline of rear edge populations to climate change could be highly misleading if the population is suffering from other, particularly human, threats.
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.