Coupling between subtidal prey and consumers along a mesoscale upwelling gradient in the Galápagos Islands

• DOI: 10.1890/08-1922.1
• Publication Date: 2010-03-01T19:49:38Z
• Authors: Jon D. Witman; Margarita Brandt; Franz Smith
• Keywords: 0106 biological sciences; 14. Life underwater; 01 natural sciences

Our understanding of how communities are regulated diminishes with increasing spatial scale. Because oceanographic processes supply food, transport propagules, and set abiotic conditions across broad areas, they may explain metacommunity food web functioning on large scales. Here we test for bottom‐up manifestations an process, upwelling, through production barnacle ( Megabalanus spp.) prey to top‐down control by whelks, fish, urchins a mesoscale (125 km) gradient 28–68% upwelling at 12 subtidal rock wall sites in the Galápagos from 2002 2005. Multivariate analysis situ flow measurements occurrence Equatorial Undercurrent (EUC) distinguished weak (WUP), intermediate (IUP), strong (SUP) site groups. Barnacle cover recruitment were significantly higher SUP than WUP decreased depth 6 15 m. High was persistent feature 2004. This related larval concentrations, vertical speeds, lesser extent, onshore offshore while growth rates barnacles highest three one IUP site. Three‐dimensional (3‐D) explained 39% variation growth. Therefore, effects occurred via as barnacles. Vertical most important component regime predicting these dynamics. Evidence population level predator–prey coupling provided significant linear relationships between densities whelk, Hexaplex princeps , both prey. In predation intensity experiment 33–100% eaten linking effects. Significantly more consumed sites. The broader context documented here topography sea floor offshore, maximum bottom slope within km predicted 40% duration. Eighty percent close steep slopes deep (>1100 m) water where internal waves EUC is likely.