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

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