REPOSITORIO

Seabird abundance and distribution off western Iberian waters estimated through aerial surveys

Enlace mardeaves Calonectris diomedea,ESPECIES,Morus bassanus,PUBLICACIÓN CIENTÍFICA,Puffinus mauretanicus,REPOSITORIO ,,,,,,,,
Araujo, H., Correia-Rodrigues, P., Bastos-Santos, J., Ferreira, M., Pereira, A.T., Martinez-Cedeira, J., Vingada, J. and Eira, C., 2022. Seabird abundance and distribution off western Iberian waters estimated through aerial surveys. Marine Ornithology, 50, pp.71-80.

Western Iberian waters are important migratory flyways, stopover sites, and wintering areas for several of the world’s seabird species. To describe seabird species composition, distribution, and abundance in these waters, we performed six aerial surveys in September and/ or October of each year, 2010–2015, covering 74840 km2. Using line-transect methodology, 27396 seabird sightings from 17 taxonomic groups were recorded along 10496.3 nautical miles (19 433 km). Using the program “Distance,” annual and overall abundance estimates were obtained for nine taxonomic groups: Balearic Shearwater Puffinus mauretanicus, Great Shearwater Ardenna gravis, Cory’s Shearwater Calonectris borealis, shearwaters, Northern Gannet Morus bassanus, Sabine’s Gull Xema sabini, Great Skua Stercorarius skua, storm petrels, and Red Phalarope Phalaropus fulicarius. For the six-year period, Northern Gannet was the most abundant species (89 630 individuals, coefficient of variation [CV] = 6.28%), followed by Cory’s Shearwater (25 044 individuals, CV = 7.56%) and Balearic Shearwater (13 632 individuals, CV = 20.81%). The remaining taxonomic groups exhibited variable abundances. Results confirm that the study area is important to several seabird species, providing baseline estimates to inform conservation policies and instruments, such as the Birds Directive and the Marine Strategy Framework Directive.

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Light received by embryos promotes postnatal junior phenotypes in a seabird

Enlace mardeaves ESPECIES,Larus michahellis,PUBLICACIÓN CIENTÍFICA,REPOSITORIO ,,,,,
Ruiz-Raya, F., Noguera, J.C. and Velando, A., 2022. Light received by embryos promotes postnatal junior phenotypes in a seabird. Behavioral Ecology, 33(6), pp.1047-1057.

Light is a salient and variable ecological factor that can impact developmental trajectories of vertebrate embryos, yet whether prenatal light environment can act as an anticipatory cue preparing organisms to cope with postnatal conditions is still unclear. In asynchronous birds, last-laid eggs are particularly exposed to sunlight as parental incubation behavior becomes intermittent after the hatching of senior chicks. Here, we explore whether natural variations in prenatal light exposure shape the distinctive phenotype showed by last-hatched chicks of a semi-precocial seabird, the yellow-legged gull (Larus michahellis), potentially preparing them to cope with the postnatal competitive context. To do this, we manipulated the amount of light received by last-laid eggs (within a natural range) during last stages of embryonic development. Prenatal exposure to light cues promoted the development of the resilient “junior phenotype” exhibited by last-hatched gull chicks, characterized by accelerated hatching, increased begging behavior and a slower growth rate. These developmental and behavioral adjustments were accompanied by down-regulation of genes involved in metabolism and development regulation (SOD2 and TRalpha), as well as changes in the HPA-axis functioning (lower baseline corticosterone and robust adrenocortical response). Junior chicks exposed to light cues during the embryonic development showed longer telomeres during the early postnatal period, suggesting that light-induced adjustments could allow them to buffer the competitive disadvantages associated with hatching asynchrony. Our study provides evidence that postnatal junior phenotypes are, at least in part, prenatally shaped by light cues that act during a critical temporal window of developmental sensitivity.

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Maternal testosterone affects offspring telomerase activity in a long-lived seabird

Enlace mardeaves ESPECIES,Larus michahellis,PUBLICACIÓN CIENTÍFICA,REPOSITORIO ,,,,,,,
Noguera, J.C. and Velando, A., 2022. Maternal testosterone affects offspring telomerase activity in a long‐lived seabird. Ecology and Evolution, 12(9), p.e9281.

Androgens are a group of steroid hormones that have long been proposed as a mechanism underpinning intergenerational plasticity. In birds, maternally allocated egg testosterone, one of the main androgens in vertebrates, affects a wide variety of offspring phenotypic traits but the mechanisms underlying this form of intergenerational plasticity are not yet well understood. Recent in vitro and animal model studies have shown that telomerase expression and activity are important targets of androgen signaling. The telomerase enzyme is known for its repair function on telomeres, the DNA–protein complexes at the ends of chromosomes that are involved in genomic integrity and cell aging. However, the role of maternal testosterone in influencing offspring telomerase levels in natural populations and its consequences on telomere length and potentially on offspring development is still unknown. Here, by experimentally modifying the level of egg testosterone in a natural population of yellow-legged gull (Larus michahellis), we show that chicks hatched from testosterone-treated eggs had higher average levels of telomerase and faster growth than controls during the first week of life. While testosterone-treated chicks also tended to have longer telomeres than controls at hatching this difference disappeared by day 6 of age. Overall, our results suggest that maternal testosterone may have a potential adaptive value by promoting offspring growth and presumably telomerase levels, as this enzyme plays other important physiological functions (e.g., stress resistance, cell signaling, or tissue genesis) besides telomere lengthening. Nonetheless, our knowledge of the potential adaptive function of telomerase in natural populations is scarce and so the potential pathways linking maternal hormones, offspring telomerase, and fitness should be further investigated.

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Global deposition of potentially toxic metals via faecal material in seabird colonies

Enlace mardeaves PUBLICACIÓN CIENTÍFICA,REPOSITORIO ,,,,,,,,,
De La Peña-Lastra, S., Pérez-Alberti, A., Ferreira, T.O., Huerta-Díaz, M.Á. and Otero, X.L., 2022. Global deposition of potentially toxic metals via faecal material in seabird colonies. Scientific Reports, 12, p.22392.

Seabirds are known to play an important role in the geochemical cycling of macronutrients; however, their role in cycling elements of environmental interest has not been investigated. Guano is an important source of marine-derived nutrients and trace metals in seabird nesting areas, but most of the available information on this topic is derived from local studies. In the present study, we used a bioenergetic model to estimate the amounts of cadmium (Cd), mercury (Hg) and lead (Pb) that are deposited via faecal material in seabird colonies worldwide. The findings showed that the seabirds excreted 39.3 Mg (Mg = metric ton or 1000 kg) of Cd, 35.7 Mg of Hg and 27.2 Mg of Pb annually. These amounts are of the same order of magnitude as those reported for other fluxes considered in the geochemical cycling of these elements (e.g. sea-salt spray, cement production, soil loss to oceans). Most of the deposition occurs in circumpolar zones in both hemispheres and, interestingly, high proportions of the metals in the excrements occur in geochemically labile forms, which can be easily leached into coastal waters and assimilated by marine organisms.

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Soil eutrophication in seabird colonies affects cell wall composition: Implications for the conservation of rare plant species

Enlace mardeaves ESPECIES,Larus michahellis,PUBLICACIÓN CIENTÍFICA,REPOSITORIO ,,,,,,,
Otero, X.L., Fernández-Balado, C., Ferreira, T.O., Pérez-Alberti, A. and Revilla, G., 2021. Soil eutrophication in seabird colonies affects cell wall composition: Implications for the conservation of rare plant species. Marine Pollution Bulletin, 168, p.112469.

Seabird colonies exert a strong influence on coastal ecosystems, increasing soil nitrogen bioavailability and modifying plant communities. Previous studies have evidenced that increased N in soils leads to changes in plant cell wall composition; however, this effect has not been assessed in seabird colonies. The main objective of this study was to determine the influence of seabird colonies on nitrogen, cellulose and lignin content in cell walls. For this purpose, analyses were performed on droppings, soils and three native plant species (Armeria pubigera, Armeria pungens and Corema album) growing in yellow-legged gull colonies. The results showed that N excreted by yellow-legged gull is assimilated by plants, increases N content in plant tissues and reduces cellulose and lignin synthesis, therefore potentially altering plant resistance against phytoparasites.

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Influence of fisheries on the spatio-temporal feeding ecology of gulls along the western Iberian coast

Enlace mardeaves ESPECIES,Larus michahellis,PUBLICACIÓN CIENTÍFICA,REPOSITORIO ,,,,,,,
Calado, J.G., Veríssimo, S.N., Paiva, V.H., Ramos, R., Vaz, P.T., Matos, D., Pereira, J., Lopes, C., Oliveira, N., Quaresma, A. and Ceia, F.R., 2021. Influence of fisheries on the spatio-temporal feeding ecology of gulls along the western Iberian coast. Marine Ecology Progress Series, 661, pp.187-201

Gulls are highly opportunistic seabirds, and the exploitation of fishery discards has led to many population increases worldwide. We investigated the importance of fish in the diet of yellow-legged Larus michahellis and Audouin’s gulls L. audouinii and assessed the influence of fishery discards on their feeding ecology. We collected pellets from 4 islands along the western Iberian coast during pre-breeding, breeding, and post-breeding seasons from 2014 to 2018. Stable isotopes (from adult blood, and chick and adult feathers) were used to investigate spatial, seasonal, and inter-annual differences in their feeding ecology. We used pellet, stable isotope (δ15N, δ13C, and δ34S), and biochemical (triglycerides, uric acid, total protein, and carotenoids in adult plasma) analyses to investigate their relationships with fish landings across the annual cycle. Results revealed that the fish species consumed by gulls matched those landed by local fisheries on all study islands, and there was a positive association of pelagic and demersal fish diets with fish landing quantities for 2 islands. δ34S values suggest different self-feeding and chick-provisioning strategies in relation to fisheries. δ15N values exhibited strong negative correlations with fish landings, and triglycerides were positively correlated with pelagic but not with demersal fish landing quantities, suggesting that gulls fed more on lower trophic level and higher energetic content pelagic fish than on demersal fish. Overall, our results based on several techniques suggest that gull feeding ecology was linked to fishery discards, which in view of the new EU landing obligation may have major implications for both gull populations across Europe.

Seabird colonies as the main source of nutrients for the coastal ecosystems in the Atlantic Islands of Galicia National Park (NW Spain)

Enlace mardeaves ESPECIES,Larus michahellis,PUBLICACIÓN CIENTÍFICA,REPOSITORIO ,,,,,,,
De La Peña-Lastra, S., Pérez-Alberti, A. and Otero, X.L., 2021. Seabird colonies as the main source of nutrients for the coastal ecosystems in the Atlantic Islands of Galicia National Park (NW Spain). Chemosphere, 275, p.130077.

Seabirds form large colonies during the reproductive period, producing substantial changes in coastal ecosystems. The present study quantifies the amount of N and P deposited in colonies of yellow-legged gull (Larus michahellis) in the Atlantic Islands of Galicia National Park (AINP). Based on the composition of droppings, the amount of total N (TN), total P (TP) and bioavailable P (Pbio) deposited directly on the area occupied by the colony was determined. In addition, the amount of NH3 released into the atmosphere was also estimated by applying a bioenergetic model. The results indicated that 5.35 t total N, 3.35 t total P and 1.24 t bioavailable P are deposited in the colony annually. The archipelagos that received the greatest amount of nutrients were the Cíes Islands (2.37 t TN y−1, 1.48 t TP y−1, 0.55 t Pbio y−1), Sálvora (1.94 t TN y−1, 1.22 t TP y−1, 0.55 t Pbio y−1) and Ons (1.04 t TN y−1, 0.65 TP y−1, 0.24 t Pbio y−1). Rainwater from the colonies showed higher values of nutrients than in the control plot, possibly also due to gull influence. Therefore, the yellow-legged gull colony seems to be the most important source of nutrients at a local level, exerting a clear influence on the N and P cycles in this National Park. Another aspect worth taking into consideration is that increased N and P bioavailability may have a negative effect on the conservation of rare or threatened habitats and species by promoting the expansion of non-native ruderal species.

The importance of marine resources in the diet of urban gulls.

Enlace mardeaves ESPECIES,Larus michahellis,PUBLICACIÓN CIENTÍFICA,REPOSITORIO ,,,,,
de Faria, J.P., Vaz, P.T., Lopes, C.S., Calado, J.G., Pereira, J.M., Veríssimo, S.N., Paiva, V.H., Gonçalves, A.M. and Ramos, J.A., 2021. The importance of marine resources in the diet of urban gulls. Marine Ecology Progress Series, 660, pp.189-201.

The availability of anthropogenic food subsidies has promoted an increase in generalist opportunistic gull species, which currently breed and forage on predictable anthropogenic resources (e.g. landfills). Here we investigated whether marine resources are still important to urban-dwelling gulls. We studied 4 natural and 2 urban yellow-legged gull Larus michahellis colonies and compared (1) diet composition (through pellet analysis) and (2) isotopic niches of adults and chicks, (3) diet delivered to chicks of different ages, and (4) fatty acid (FA) composition of fledglings, in order to assess diet composition, diversity and quality, and the relevance of marine prey for natural and urban gull populations. Adult urban gulls consumed considerably lower proportions of marine prey when compared to gulls from natural colonies; however, they fed their younger chicks (<20 d old) mostly with fish, representing 61-80% of their chick food deliveries. Refuse items were mostly delivered to chicks older than 20 d. Overall, urban isotopic niches were not completely distinct from those of natural colonies, in some cases sharing ca. 50% of their niche space. Fledglings from the most urbanized colony presented overall higher FA concentrations and diversity, but they were lacking some omega-3 FAs relevant to their physiology. Our results highlight the importance of marine resources in the diet of urban gulls, particularly during early chick rearing, the relevance of food sources in the area around the breeding colonies and the fact that urban gulls benefit from year-round reliable anthropogenic food resources

Levels of Zinc, Cadmium, and Lead in liver, kidney, and feathers of Atlantic Puffins (Fratercula arctica) from Spain.

Enlace mardeaves ESPECIES,Fratercula arctica,PUBLICACIÓN CIENTÍFICA,REPOSITORIO ,,,,,,,
Barrales, I., Hernández-Moreno, D., Fidalgo, L.E., López-Beceiro, A., Martínez-Morcillo, S., Sánchez-Montero, L., Prado Míguez, M., Soler, F. e Pérez-López, M., (2021). Levels of Zinc, Cadmium, and Lead in liver, kidney, and feathers of Atlantic Puffins (Fratercula arctica) from Spain. Toxicological & Environmental Chemistry, pp.1-24.

Zinc, cadmium, and lead in livers, kidneys, and feathers of 48 young and adult Atlantic puffins found dead or dying off the coast of Galicia (Northwest Spain) were determined. The most abundant between the three elements was the essential metal zinc, with highest mean levels (173±9mg/kg dry weight) in livers. For the two non-essential metals, the highest mean levels of cadmium were found in kidneys (22.1 ± 1.0 mg/kg dry weight), and of lead in feathers (1.31±0.10mg/kg dry weight). For some birds, concentrations of zinc and cadmium exceeded established risk levels. The concentrations of the three metals were positively cor- related in livers. In kidneys and livers, cadmium levels were correlated. With respect to age, the levels of the three metals in adults were higher than in young animals. Female birds showed significantly higher levels than males. The results are useful for establishing baseline data of the concentrations of the three metals for this species.

Effects of a yellow legged gull (Larus michahellis) colony on soils and cliff vegetation in the Atlantic Islands of Galicia National Park (NW Spain)

Enlace mardeaves ESPECIES,Larus michahellis,PUBLICACIÓN CIENTÍFICA,REPOSITORIO ,,,,
De La Peña-Lastra, S., Gómez-Rodríguez, C., Pérez-Alberti, A., Torre, F. and Otero, X.L., 2021. Effects of a yellow legged gull (Larus michahellis) colony on soils and cliff vegetation in the Atlantic Islands of Galicia National Park (NW Spain). Catena, 199, p.105-115.

Seabirds are powerful environmental modulators, generating major changes in soil properties and vegetation in areas where their breeding colonies are established. One of the largest yellow-legged gull colonies in the world is found in the Atlantic Islands of Galicia National Park. In this study, we performed seasonal monitoring, over a period of 5 years, of the flora and soil in eight subcolonies characterized by different densities of gulls. Soil nutrient concentrations differed significantly between the control site and the subcolonies, as well as between seasons; the concentrations of N-NO3– and bioavailable P were highest in samples obtained at the end of the breeding season. Principal Component Analysis (PCA) transformed the environmental variables into three main components following varimax rotation. The PCA components were used as potential predictors in distance-based Redundancy Analyses (db- RDA) to explain turnover and also nestedness patterns in plant assemblages. Species turnover was explained by both natural (salinity) and nutrient gradients, while none of the relationships were significant in the nestedness analysis. Floristics inventories clearly revealed ruderalization of vegetation in the densest subcolonies, which led to total replacement of the most representative vascular plant species by eutrophic and ruderal species. PERMANOVA analysis showed that seagull density in 1991, when the seagull population was at its highest, could be used to group similar plant assemblages; however, this relationship was not observed for seagull density in 2011, which was 70–90% lower than in 1991. The study findings indicate that the environmental effects of seabird colonies are long lasting and that disappearance of the birds does not lead to restoration of the previous vegetation. The gull colony has irreversibly transformed the soil and vegetation of cliffs, generating a new environmental system.