Identifying and characterizing biological hotspots in the northern California Current

摘要

Understanding how marine animals utilize their environment and identifying important habitats are crucial for understanding how marine ecosystems function. The goal of the present study is to identify biologically rich areas within the northern California Current and to determine the environmental characteristics occurring within these areas. We analyzed how surface nekton are distributed in the northern California Current, not only in space and time but also with reference to species assemblages, habitat characteristics, and environmental factors. Sampling was conducted during June and August of 2000 and 2002 as part of the US GLOBEC mesoscale surveys from Newport, Oregon, in the north to Crescent City, California, in the south. A geostatistical approach was used to create surfaces to be used in a GIS to determine the presence or absence of biological hotspots throughout the region. Two biological hotspots were identified and determined to persist in space and time, yet differed with respect to biological and physical features and in the amount of area covered. We used indicator species analyses (ISA) and non-metric multidimensional scaling (NMS) to explore patterns in community structure. Results indicate that although the locations of the biological hotspots persisted over the course of the study, the habitat characteristics and nekton community composition within each hotspot varied over time. The most consistent environmental parameters explaining the distributions were sea-surface temperature, salinity, and density, indicating the likely structuring mechanism of the hotspots is related to the flow through the region and differing patterns of circulation.