suelos

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

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

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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.

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

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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.

Soil under dead or live organic matter systems: Effect of: European shag (Phalacrocorax aristotelis L.) nesting on soil nematodes and nutrient mineralization

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Aira, M. e Domínguez, J., 2020. Soil under dead or live organic matter systems: Effect of European shag (Phalacrocorax aristotelis L.) nesting on soil nematodes and nutrient mineralization. Soil Ecology Letters, https://doi.org/10.1007/s42832-020-0023-9

Here we studied whether soil systems differ if they are under the influence of live (plants) or dead organic matter systems (nest) in terms of C and N mineralization, microbiological characteristics and nematode trophic group structure. We analyzed physicochemical and microbiological properties of soils inside and outside nests of the European shag (Phalacrocorax aristotelis L.) on the Cíes Islands (NW Spain). We sampled fresh soil below dead (nests) and live organic matter (plants) (paired samples, n = 7). Soil of nests had lower organic matter and higher electric conductivity and dissolved organic C and extractable N contents than the soil of plants. Microbial biomass and activity were greater in soil of nests than in soil of plants. The abundance of nematode trophic groups (bacterivores, fungivores, omnivores and herbivores) differred between soils of nests and plants, and the soil of plants supported a more abundant and diverse nematode community. The present results points to that source of organic matter promote differences in the decomposer community, being more efficient in soil of nests because C mineralization is greater. Further, this occurred independently of the complexity of the systems, higher in the soil of plants with more groups of nematodes.

Enrichment of trace elements in colonies of the yellow-legged gull (Larus michahellis) in the Atlantic Islands National Park (Galicia-NW Spain)

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De La Peña-Lastra, S., Pérez-Alberti, A. e Otero, X.L., 2019. Enrichment of trace elements in colonies of the yellow-legged gull (Larus michahellis) in the Atlantic Islands National Park (Galicia-NW Spain). Science of The Total Environment, 648, pp.1536-1548.

Marine-derived nutrients are known accumulate in seabird breeding colonies due to the deposition of nutrient-rich biological materials, thus greatly altering the functioning and dynamics of these terrestrial ecosystems. Here we present the results of a sampling survey carried out during three years in yellow-legged gull colonies in the Atlantic Islands of Galicia National Park (NW Spain) with the aim of evaluating the influence of the colonies on the accumulation of trace elements, including micronutrients (Cu, Zn, Se, Co, Mo, Ni) and toxic elements (Cr, Cd, Hg, Pb, As, Ag), in the surrounding environments. For this purpose, we analysed samples of biological materials produced by the seabirds (pellets, excrement, feathers, eggs) and of soil, plants and inland water from several different subcolonies and control zones without seabirds.

The concentrations of most of the elements were higher in excrement and pellets (mean values: Zn: 152, As: 50 mg kg−1, Cd: 6, Co: 5 mg kg−1) than in feathers and eggs. The flow of trace elements into the breeding colonies, considering only the excrement, revealed a very high level of trace element deposition for a supposedly pristine environment (Zn: 2667, Cd: 70, Cu: 315, As: 64 g ha−1). The total concentrations of trace elements in soil were consistent with the long-term impact of the seabirds. Thus, the values in areas which this impact was greatest were significantly higher than in the control zones, particularly considering the most labile geochemical fractions of the soil. The concentrations of some elements (i.e. Co, As, Cd) were also higher in the inland waters in the colonies than in control zones. Finally, the concentration of trace elements in plants varied depending on the species and element considered.

Influencia de la colonia de gaviota patiamarilla (Larus cachinnans Pallas) sobre el contenido de nutrientes (amonio y fósforo) en los suelos de los acantilados del Parque Natural de las Islas Cíes (SO de Galicia, NO de España).

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Otero Pérez, X. L. Influencia de la colonia de gaviota patiamarilla (Larus cachinnans Pallas) sobre el contenido de nutrientes (amonio y fósforo) en los suelos de los acantilados del Parque Natural de las Islas Cíes (SO de Galicia, NO de España). Thalassas 14, 57–62 (1998).

Los análisis realizados pusieron de manifiesto la presencia de concentraciones importantes de amonio (32.50 mg g-1) y de fósforo (16.58 mg g-1) en excrementos frescos de la gaviota patiamarilla (Larus cachinanns). Los resultados obtenidos para los suelos reflejaron un claro enriquecimiento en amonio cambiable y fósforo asimilable en los suelos de los acantilados donde se establece la colonia de esta especie. Las concentraciones de amonio presentaron diferencias entre las áreas de cría y la zona control (sin gaviotas), pero no entre las zonas de cría con densidades diferentes. Sin embargo, todas las áreas mostraron diferencias significativas entre ellas para el fósforo asimilable. Estos resultados parecen estar de acuerdo con el ciclo biogeoquímico de cada uno de estos dos nutrientes. El amonio puede ser oxidado pasando a la forma NO3- y este puede ser lavado fácilmente del suelo ya que apenas se encuentra absorbido por los coloides del suelo. Por el contrario los fosfatos pueden ser absobidos de manera específica por formas activas de Al y/o Fe o formando precipitados de Ca, Al, NH4+ y Fe3+ de baja solubilidad. Estos procesos favorecen su permanencia y acumulación en el suelo.

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.

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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.

Composición de la microfauna y características bioquímicas de los suelos en el interior y exterior de nidos de Cormorán Moñudo (Phalacrocorax Aristotelis, L.) en las islas Cíes, España

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Aira, M., Monroy, F. & Domínguez, J. Composición de la microfauna y características bioquímicas de los suelos en el interior y exterior de nidos de cormorán monudo (Phalacrocorax aristotelis, L.) en las Islas Cíes, España. Boletín de la Real Sociedad Española de Historia Natural Sección Biológica 101, 71–75 (2006).