A comparison of Eastern Boundary Upwelling Ecosystems

Coastal upwelling along eastern boundaries has fascinated oceanographers for decades. The strong coupling between atmospheric forcing, ocean circulation, biogeochemical cycling, and food web dynamics encouraged oceanographers to conduct multidisciplinary scientific studies that have since become common. Following that tradition, an interdisciplinary approach is taken to highlight differences between the major Eastern Boundary Upwelling Ecosystems (EBUE's). Ocean basin-scale settings are important determinants of EBUE characteristics. First, trade winds accumulate heat and mass in the western side of the basins, deepening the thermocline in the west and raising it in the east. Second, and especially prominent in the Pacific, these properties are redistributed eastwards on interannual and multidecadal time scales, reducing the characteristically high biological productivity found in the eastern basin margins. Thirdly, north-south patterns of thermocline doming on the equator and deepening in the subtropical gyres, and high latitude weather-driven mixing makes latitude an important characteristic of each EBUE. As such each EBUE has 3-4 well-defined latitudinally distributed biomes. Many enigmas remain regarding EBUE's including: (1) Why do EBUE's differ dramatically in fish but not in primary production? (2) What nutrients or other physical properties limit EBUE primary production? (3) What roles do subsurface oxygen minimum zones play in EBUE ecosystems? (4) What role do euphausiids play in the transfer of energy through EBUE food webs? (5) What are the roles of EBUE food webs in the biogeochemical cycling of elements? (6) How inter-connected are biomes of EBUE ecosystems? and (7) Most importantly for society, how will EBUE's respond to climate and global change. (C) 2009 Elsevier Ltd. AM rights reserved.