Wednesday, August 4, 2010 - 8:00 AM

SYMP 12-1: Darwin's enchanted Isles under ENSO variability: scaling down a dynamic oceanography to approach key Galapagos conservation questions

Stuart Banks1, John Morrison2, and Angela Kuhn1. (1) Charles Darwin Foundation, (2) University of North Carolina Wilmington

Background/Question/Methods

The 133 000 Km2 Galapagos Marine Reserve positioned 1000 Km west of mainland Ecuador is renowned for its rich and varied marine biota provident from a confluence of westward flowing surface water from Indo-Pacific/Panama and Ecuador-Peru-Chile provinces. The surface currents driven by shifts within and between years by prevailing SE trade winds also interact precipitously with bathymetry, island topography and the upwelling of Equatorial Undercurrent (EUC) deep water generating meso-small scale productive eddies and spatially consistent yet temporally ephemeral cold productive cells. The sustained phytoplankton biomass is commensurate in magnitude with that of larger Eastern Current Boundary Systems (ECBS) (e.g. Peru-Chile/Benguela). Cold water refuge on the equator presumably encourages persistence of near shore cold adapted endemics of commercial and world heritage importance in otherwise inhospitable strongly stratified solar heated surface waters. Deep water filament propagation appears altered by considerable inter-decadal and El Niño Southern Oscillation (ENSO) variability in the Eastern Tropical Pacific (ETP), internal wave passage and potentially unqualified global warming effects. This can cause dramatic near shore habitat shifts, trophic adjustments with strong implications for coastal management. Through an 8 year review 2001-2009 including 4 GMR-wide oceanographic cruises, a sparse moored instrument array,  satellite derived ocean variables and subtidal monitoring of macrofauna and flora at 2 near coast depth strata we examine how prevailing oceanographic regimes and associated patterning of environmental correlates influence habitat stability over different scales. What are the connotations for biodiversity and management of ecosystem services to local communities?

Results/Conclusions

Strong biogeography patterning is evident over 100 Km scales across Galapagos subtidal communities, yet does not preclude small scale configurations of subtidal communities correlated with meso-small scale oceanographic features and the upwelling dynamic of colder EUC water against western shores. Underway analysis examines whether species distributions positioned at the limits of tolerance thresholds in small refuge zones are dependent upon the magnitude of shifts in environmental correlates over different spatial scales. Regional downscaling to increase resolution of small scale shelf circulation and mesoscale ocean dynamics has particular relevance for climate projections and management of small scale patterning of biodiversity (particularly cold water endemics), natural ecosystem function, and conservation measures promoting ecosystem resilience before large scale perturbations.