ESPECIES

Effects of nesting yellow-legged gulls (Larus cachinnans Pallas) on the heavy metal content of soils in the Cies Islands (Galicia, North-west Spain)

Enlace mardeaves Larus michahellis,PUBLICACIÓN CIENTÍFICA,REPOSITORIO ,,

Otero Pérez, X. L. Effects of nesting yellow-legged gulls (Larus cachinnans Pallas) on the heavy metal content of soils in the Cies Islands (Galicia, North-west Spain). Marine Pollution Bulletin 36, 267–272 (1998).

Cd, Cr, Cu, Pb and Zn levels were determined in faeces of the yellow-legged gull Larus cachinnans in Galicia (NW Spain), and in soils from three breeding and one reference site. The levels of Cd, Cu, Zn and Pb in the soil were significantly higher at the site with highest gull density and with the longest history of use as a breeding site (Percha) than at the reference site. Zn levels were higher than levels of the other metals in all soil and faeces samples. Mean levels of metals in faeces were 305 mg kg-1 (Zn), 60 mg kg-1 (Cu), 40 mg kg-1 (Pb), 9.8 mg kg-1 (Cr) and 5.8 mg kg-1 (Cd).

Monitoring polycyclic aromatic hydrocarbon pollution in the marine environment after the Prestige oil spill by means of seabird blood analysis

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

Pérez, C., Velando, A., Munilla, I., López-Alonso, M. & Oro, D. Monitoring Polycyclic Aromatic Hydrocarbon Pollution in the marine environment after the Prestige oil spill by means of seabird blood analysis. Environmental Science & Technology 42, 707–713 (2008).

In this studywetested the use of seabird blood as a bioindicator of polycyclic aromatic hydrocarbon (PAH) pollution in the marine environment. Blood cells of breeding yellow-legged gulls (Larus michahellis) were able to track spatial and temporal changes consistent with the massive oil pollution pulse that resulted from the Prestige oil spill. Thus, in 2004, blood samples from yellow-legged gulls breeding in colonies that were in the trajectory of the spill doubled in their total PAH concentrations when compared to samples from unoiled colonies. Furthermore, PAH levels in gulls from an oiled colony decreased by nearly a third in two consecutive breeding seasons (2004 and 2005). Experimental evidence was gathered by means of an oil ingestion field experiment. The total concentration of PAHs in the blood of gulls given oil supplements was 30% higher compared to controls. This strongly suggested that measures of PAHs in the blood of gulls are sensitive to the ingestion of small quantities of oil. Our study provides evidence that seabirds were exposed to residual Prestige oil 17 months after the spill commenced and gives support to the nondestructive use of seabirds as biomonitors of oil pollution in marine environments.

Parental food conditions affect sex-specific embryo mortality in the yellow-legged gull (Larus michahellis)

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

Pérez, C., Velando, A. & Domínguez, J. Parental food conditions affect sex-specific embryo mortality in the yellow-legged gull (Larus michahellis). Journal of Ornithology 147, 513–519 (2006).

Different mortality of males and females during early post-hatching development in sexually size-dimorphic bird species is usually attributed to different nutritional requirements of the sexes, because mortality is mostly biassed toward the larger sex. We investigated whether sex-specific embryo mortality in the yellow-legged gull (Larus michahellis), a size-dimorphic seabird, depends on parental condition. To test this, we experimentally modified parental nutritional conditions by supplementary feeding of yellow legged gulls during egg formation, to evaluate sex-biassed environmental sensitivity of gull embryos. We found that eggs were larger in supplemented clutches, but egg size did not affect embryo survival. Survival of male gull embryos was more related to parental food conditions than was survival of female embryos. Survival of male embryos in supplemented clutches was greater than in unsupplemented clutches whereas survival of female embryos was similar in both groups. Because size at hatching was similar in both sexes our results suggest that male phenotype disadvantage is not exclusively linked to the energy demands of size-dimorphic development at the embryo stage.

Oil pollution increases plasma antioxidants but reduces coloration in a seabird

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

Pérez, C., Lores, M. & Velando, A. Oil pollution increases plasma antioxidants but reduces coloration in a seabird. Oecologia 163, 875–884 (2010).

It has been suggested that condition-dependent signals may be a useful measure of environmental quality. In this study, we tested the hypothesis that oil pollution enhances oxidative stress and impairs expression of a carotenoid-based signal in a wild population of the yellowlegged gull (Larus michahellis). During the courtship period, a group of gulls were fed a supplementary diet containing heavy fuel oil from the Prestige oil spill and were compared with control gulls fed a similar supplementary diet without fuel oil. Blood levels of polycyclic aromatic hydrocarbons, the most toxic components of crude oils, were higher (30%) in the Prestige oil-fed gulls than in the control gulls. Plasma concentrations of vitamin E and carotenoids were also significantly higher in the Prestige oil-fed gulls (31 and 27%, respectively). Although, the plasma levels of lipid peroxidation markers were higher (13%) in gulls fed with Prestige oil than in the control gulls, these differences were not significant, possibly because of the small number of gulls analyzed. The red bill spot was significantly smaller (16%) in the oil-fed gulls than in the control individuals. This study provides the first experimental evidence that a carotenoid-based signal in a freeliving seabird is affected by exposure to oil pollution and is hence indicative of environmental quality. Since the yellow-legged gull belongs to a complex of species widely distributed throughout the northern hemisphere, the method described may constitute a useful tool for evaluating sublethal effects of oil spills in seabirds.

Availability of nonpigmentary antioxidant affects red coloration in gulls

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

Pérez, C., Lores, M. & Velando, A. Availability of nonpigmentary antioxidant affects red coloration in gulls. Behavioral Ecology 19, 967–973 (2008).

Red, orange, and yellow carotenoid-based colorations displayed by fishes and birds may function as honest sexual signals of the bearer’s quality. However, the mechanisms underlying the expression of these traits and the information they convey are still controversial. Because carotenoids are antioxidants and carotenoid-based pigmentation is bleached as a consequence of oxidative processes, it has been suggested that the pigmentation may signal antioxidant status. We tested this hypothesis in the yellow-legged gull (Larus michahellis), a seabird that exhibits a carotenoid-based red spot on the lower mandible. The availability of a nonpigmentary antioxidant (i.e., vitamin E) to the gulls was modified before egg laying by means of a supplementary feeding experiment. During the incubation period, breeding pairs were captured to assess the intensity of the color and the size of the red bill spots. We measured the plasma level of lipid peroxidation, total antioxidant capacity, and carotenoids. We found that males that received vitamin E supplements had larger red spot than control birds but that color intensity was not affected by the supplements. Moreover, we found that only those plasma carotenoids involved in the red coloration were affected by the antioxidant supplementation, suggesting an active mechanism to increase red coloration. Overall, our results provide experimental evidence for the hypothesis that carotenoid-based coloration reflects the bearer’s antioxidant status in male gulls.

Sublethal effects on seabirds after the Prestige oil-spill are mirrored in sexual signals

Enlace mardeaves Larus michahellis,PUBLICACIÓN CIENTÍFICA,REPOSITORIO ,,

Perez, C., Munilla, I., Lopez-Alonso, M. & Velando, A. Sublethal effects on seabirds after the Prestige oil-spill are mirrored in sexual signals. Biology Letters 6, 33–35 (2010).

It has been suggested that sexual signals may be a useful measure of environmental quality as they represent the sum of environmental pressures on the animal. Accordingly, it has been proposed that carotenoid-based coloration may be especially valuable in monitoring and detecting the sublethal effects of toxic pollutants in the environment. Here, we evaluate whether the carotenoid-based coloration in the bill of adult yellow-legged gulls reflects oil-induced sublethal effects in breeding colonies affected by the Prestige oil spill. In 2004, we took blood samples from 27 adult birds at four insular breeding colonies located in the pathway of the Prestige oil spill. We measured the size of the red bill spot area and analysed plasma biochemical parameters indicative of sublethal effects of oil contamination in gulls, including glucose, total protein, creatinine, inorganic phosphorus, aspartate aminotransferase (AST) and gamma-glutamyl transferase. We showed that the size of their red bill spot area was positively related to body condition, while negatively related with AST levels, an enzyme that is commonly used as an indication of hepatic damage in birds. Hence, the present study provides support for the idea that carotenoid-based colour integuments may be a useful measure of environmental quality.

Phosphorus in seagull colonies and the effect on the habitats. The case of yellow-legged gulls (Larus michahellis) in the Atlantic Islands National Park (Galicia-NW Spain)

Enlace mardeaves Larus michahellis,PUBLICACIÓN CIENTÍFICA,REPOSITORIO ,,

Otero, X. L. et al. Phosphorus in seagull colonies and the effect on the habitats. The case of yellow-legged gulls (Larus michahellis) in the Atlantic Islands National Park (Galicia-NW Spain). Science of The Total Environment 532, 383–397 (2015).

During the period 1980–2000, the yellow-legged gull population underwent exponential growth due to an increase in the availability of anthropogenic food resources. The aim of this study was to highlight the effect of the gull colonies on the P soil cycle and the associated effects on coastal ecosystems. Samples of soil, water and faecal material were collected in a colony of yellow-legged gulls (Cíes Islands) and in a control area. Four sampling plots were installed in the study areas, and samples were collected in summer and winter in 1997 and 2011. Sample analysis included soil characterization and determination of the total P content (TP), bioavailable-P and fractionated-P forms in the soils and faecal material. The 31P NMR technique was also used to determine organic P forms. Clear differences between the gull colony soils and the control soil were observed. The TP was 3 times higher in the gull colony soil, and the bioavailable P was 30 times higher than in the control soil. The P forms present at highest concentrations in the faecal material (P-apatite, P-residual and P-humic acid) were also present at high concentrations in the colony soil. The absence of any seasonal or annual differences in P concentration indicates that the P has remained stable in the soil over time, regardless of the changes in the gull population density. The degree of P saturation indicated that soils are saturated with P due to the low concentration of Fe/Al-hydroxides, which is consistent with a high P concentration in the run-off from the colonies. The P output from the colony soils to coastal waters may cause eutrophication of a nearby lagoon and the disappearance of a Zostera marina seagrass meadow. Similarly, the enrichment of P concentration in dune system of Muxieiro may induce irreversible changes in the plant communities.

Nitrógeno (NH4+, NO3), fósforo asimilable y metales traza (Hg, Cd, Pb, Zn. Ni y Cu) en suelos de la colonia de la gaviota patiamarilla (Larus cachinnans) en el parque natural de las Islas Cies.

Enlace mardeaves Larus michahellis,PUBLICACIÓN CIENTÍFICA,REPOSITORIO ,,

Otero, X. L. & Mouriño, J. Nitrógeno (NH4+, NO3), fósforo asimilable y metales traza (Hg, Cd, Pb, Zn. Ni y Cu) en suelos de la colonia de la gaviota patiamarilla (Larus cachinnans) en el parque natural de las Islas Cies. Cuadernos de la Sociedad Española de Ciencias Forestales (2002).

La gaviota patiamarilla (Larus cachinnans) presenta en el Parque Natural de las Islas Cíes su mayor colonia de cría con una población aproximada de 20.000 parejas reproductoras. En el presente trabajo se pretende evaluar el efecto que sobre el contenido en nutrientes y metales traza en el suelo puede tener esta colonia. Para ello se seleccionaron tres acantilados en las islas Cíes y una zona control en cabo Home (sin presencia de gaviotas). Los resultados obtenidos han puesto de manifiesto que los suelos de los acantilados de la Percha, zona donde la gaviota patiamarilla lleva criando con densidades elevadas por lo menos desde los años 70, presenta para el nitrógeno, fósforo asimilable y metales traza concentraciones significativamente más elevados que la zona control. Los otros dos acantilados de las islas Cíes (Campana y Figueiras) presentaron, en general, concentraciones intermedias entre las zona control y los suelos de los acantilados de la Percha.

Pre-fledgling oxidative damage predicts recruitment in a long-lived bird

Enlace mardeaves Phalacrocorax aristotelis,PUBLICACIÓN CIENTÍFICA,REPOSITORIO ,,

Noguera, J. C., Kim, S.-Y. & Velando, A. Pre-fledgling oxidative damage predicts recruitment in a long-lived bird. Biology letters rsbl20110756 (2011).

Empirical evidence has shown that stressful conditions experienced during development may exert long-term negative effects on life-history traits. Although it has been suggested that oxidative stress has long-term effects, little is known about delayed consequences of oxidative stress experienced early in life in fitness-related traits. Here, we tested whether oxidative stress during development has long-term effects on a life-history trait directly related to fitness in three colonies of European shags Phalacrocorax aristotelis. Our results revealed that recruitment probability decreased with oxidative damage during the nestling period; oxidative damage, in turn, was related to the level of antioxidant capacity. Our results suggest a link between oxidative stress during development and survival to adulthood, a key element of population dynamics.

Maternal testosterone influences a begging component that makes fathers work harder in chick provisioning

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

Noguera, J. C., Kim, S.-Y. & Velando, A. Maternal testosterone influences a begging component that makes fathers work harder in chick provisioning. Hormones and behavior 64, 19–25 (2013).

In species with biparental care, parents disagree evolutionarily over the amount of care that each of them is willing to provide to offspring. It has recently been hypothesised that females may try to manipulate their mates by modifying offspring begging behaviour through yolk hormone deposition, shifting the division of labour in their own favour. To test this hypothesis we first investigated how yellow-legged gull (Larus michahellis) parents feed offspring in relation to each component of complex begging behaviour and if feeding behaviour varies between sexes. Then we investigated the effect of yolk testosterone on chicks’ begging by experimentally increasing yolk testosterone levels. Our results revealed that yolk testosterone has a component-specific effect on chicks’ begging, specifically increasing the number of chatter calls. Parental feeding effort was influenced by the number of chatter calls emitted by chicks, but most importantly, the influence was stronger in male than in female parents. Moreover, chick body mass increased with the number of paternal feeds. In conclusion, these results show that female gulls may use yolk testosterone deposition to exploit their partners as predicted by the ‘Manipulating Androgen Hypothesis (MAH)’.