Oceanographic Factors Affecting Seabird Occurrence in the Tropical Pacific Ocean

点击翻译按钮获取中文摘要

The ecological structure of pelagic communities is not well known, except for portions of the zooplankton. Pelagic marine zooplankton communities may be organized differently than benthic or even terrestrial communities. Seabird abundance, species assemblages, assemblage constancy, and responses to habitat perturbation can be quantified more satisfactorily than for any other pelagic nektonic organisms. The EPOCS program, a large oceanographic project gathering data for prediction of El Nino events, will be used to quantify the link between seabird ecology and physical factors of the epipelagic environment. Seasonal periodicity and interannual variability of climate, a complex of well known water types in the eastern tropical Pacific, a non-migratory avifauna, and the EPOCS cruises dombine to provide natural experiments in which factors that structure pelagic seabird communities become clear. %%% Seabirds which depend upon pelagic organisms at the surface or near the surface of the sea often are found aggregated in particular areas of the ocean coincident with major features of the physical environment such as currents and fronts. Because seabirds can be seen and recognized at a distance, their abundance and presence in one area of the ocean or another is often indicative of a particular water mass carrying a particular group of pelagic organisms. In the Pacific Ocean, recent natural variation known as El Nino and cold anomalies, have shown that seabirds vary spatially in the same way as water masses influenced by El Nino. The distribution of birds and types of birds indicate not only what water mass is present in an area, but also the kind and abundance of plankton present which are the food resource of the birds. Bird ecology gives us a unifying overview of oceanic processes and their biological effect on the large scale.