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Filling the groove: energy flow to seabirds in the Beagle Channel, Tierra del Fuego, Argentina

2001; Volume: 11; Issue: 2 Linguagem: Inglês

1667-782X

Andrea Raya Rey, Adrián Schiavini, Investigaciones Científicas,

Marine animal studies overview

We assessed the energy requirements and the food consumption of the seabird com- munity of the Beagle Channel in summer. We evaluated differences in energy flow among a priori established zones in the study area and among species. We converted data on densities of seabirds in the channel (February and March 1997) into energy demands. Energy flow to sea- birds in shallow waters was twice that of in deep waters. Average energy flow in the whole study area was 9.46×10 4 kJ.km -2 .day -1 . Energy intake rates ranged 4-13×10 4 kJ.km -2 .day -1 , being higher in zones that include breeding sites or close to them. Imperial Cormorant was the major con- tributor to energy flow in all the zones followed by the Black-browed Albatross. Kelp Gull was the major contributor in areas where food from human origin was available. Energy flow was similar in four zones, which may represent a saturation point for seabird biomass in the Beagle Channel. The factors that explain the observed energy flow distribution deal with the distribu- tion of shallow water areas in the channel, the presence of seabird's colonies, the proportion of diver and surface feeders, and the possible segregation of, at least, the most abundant species. Finally, food consumption varied from 1.71-3.42 ton/day, being higher near breeding colonies and lower in areas with more open waters. RESUMEN. Saturando el canal: flujo energetico de aves marinas en el Canal Beagle, Tierra del Fuego, Argentina: Se determinaron los requerimientos energeticos y el consumo de alimento de la comunidad de aves marinas del Canal Beagle durante el verano. Se evaluaron las diferencias en el flujo energetico entre seis zonas establecidas a priori en el area de estudio y entre especies. Se transformaron los datos de densidad de aves marinas del canal (febrero y marzo de 1997) en demanda energetica. El flujo energetico hacia las aves marinas en las aguas someras fue el doble del que se encontro en aguas profundas. El flujo energetico promedio en toda el area de estudio fue de 9.46×10 4