Geospatial variability of krill and top predators within an Antarctic submarine canyon system
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The spatial distribution patterns of krill, seabirds (penguin, petrel and albatross), fur seals and baleen whales were mapped in nearshore waters (<50 km from land) to investigate their habitat selection within two adjacent submarine canyons near Livingston Island, Antarctica. Three shipboard surveys were conducted (February 2005–2007), and an echosounder was used to measure the distribution and abundance of krill while simultaneously conducting visual surveys to map seabird and marine mammals. Using a multispecies approach, we test the hypothesis that spatial organization of krill and top predators co-vary according to fine-scale changes in bathymetry in the nearshore marine environment. GAMs are used to examine the effect of sea depth, slope and distance to isobaths on the spatial distribution and abundance of krill and predators. Spatial distribution patterns of krill and predators relate to fine-scale (1–10 km) changes in bathymetry and exhibit cross-shelf gradients in abundance. Krill were concentrated along the shelf-break and abundant within both submarine canyons. Predators exhibited different preferences for locations within the submarine canyon system that relates to their foraging behavior. Penguins concentrated closer to shore and within the head of the east submarine canyon immediately adjacent to a breeding colony. Whales were also concentrated over the head of the east canyon (overlapping with penguins), whereas albatrosses and fur seals were concentrated in the west canyon. Fur seals also showed preference for steep slopes and were concentrated along the shelf-break. Petrels exhibited peaks in abundance throughout both submarine canyons. Owing to their orientation, size and proximity to the coastline, submarine canyons provide important habitat heterogeneity for krill and a variety of predators. This study highlights the multispecies approach for studying spatial ecology of top predators and krill and has implications for marine spatial management of the Scotia Sea.
KeywordsFishing Vessel South Shetland Island Humpback Whale Submarine Canyon Chinstrap Penguin
We greatly appreciate the effort of Michael P. Force and Douglas J. Futuyma for collecting predator observations, the assistance of Anthony C. Cossio for processing acoustic data and Valerie J. Loeb for measuring krill length–frequency. We thank three anonymous reviewers for their comments that helped strengthen the paper. Support for this project was provided by NOAA’s Antarctic Marine Living Resources program (contracts to JAS) and the Office of Polar Programs at the National Science Foundation (OPP-9983751 to RR Veit and OPP-0633939 to Joseph Warren and David Demer).
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