Lucio Godinez Orta

Biological impact of Hurricane Ignacio (2003) in the eastern Pacific Ocean as observed through MODIS data

Strong winds associated with hurricanes generate upwelling of cold water and transfer nutrients to the sea surface, supporting the development of significant phytoplankton blooms. Here we study the effect of the passage of hurricanes on the fields of sea surface temperature and chlorophyll-a in the pelagic ocean. A case-study is given for Hurricane Ignacio, the first storm of the 2003 season in the Eastern Tropical Pacific Ocean, on the south-eastern waters of Baja California Peninsula. The net reduction of in situ water temperature was -10° C and the phytoplankton pigment increase was 10 fold. Detailed features of the distribution of both characteristics of the sea surface are evident in the synoptic satellite imagery (MODIS/Aqua), with extreme thermal changes of -6 °C and increases up to 25 fold in chlorophyll-a. The satellite-derived averaged changes computed in the area of impact (~45,000 km^2) show temperature reduction of -1.3 °C and 1.5 fold increase of phytoplankton biomass. The physical and biological features studied for Hurricane Ignacio are crucial for understanding the ecosystem function around the southern Baja California peninsula, a region with strong dynamics in the carbon cycle. The study demonstrates how hurricanes induce phytoplankton blooms, a critical resource in the food chain, in particular for the pelagic fisheries. Systematic use of satellite remote-sensing may be advantageous to quantify at short, middle and long term, the impact of hurricanes on ocean biology at spatial and temporal scales of local and regional interest.