Marine Mammal Habitat in Ecuador: Seasonal Abundance and Environmental Distribution

摘要

Marine mammals in the Eastern Equatorial Pacific play a vital ecological role toward structuring tropic systems and the distribution commercially valuable prey. However, scientific study of their populations within the waters surrounding Ecuador has been only infrequently conducted and largely neglected over the past decade. Our research including six marine mammal surveys will investigate the distribution of marine mammals inhabiting the oceanic areas between the Ecuadorian mainland and around the Galapagos Islands. Visual observers documented marine mammal sightings while aboard the Ecuadorian Navy's Oceanographic Vessel the (B/I) Orion last September/October 2008 and April 2009. The range of different species positively identified as well as the large proportion of sightings that could not be identified to species using current survey methodologies, suggests that the diversity and overall marine mammal abundance within Ecuadorian waters may be much higher than previously suspected. Four more surveys covering similar periods of the year will be conducted over the next two years. Biological patterns in this region are closely tied to physical features. Using satellite data, Palacios (2004) discerned seasonal patterns in the surface concentrations of chlorophyll off the West coast of the Galapagos Islands. Here, upwelling driven productivity (which is initiated by the subsurface derived macronutrients) is enhanced by iron inputs derived from the island platform. The confluence of the Equatorial Undercurrent and Peru Current create an area around the islands where enhanced levels of nutrients are available to the ocean's biology. Palacios' harmonic analysis of ocean color data showed that the seasonal cycle of warming and cooling is associated with the North-South migration of the ITCZ and that ocean color which is related to surface primary productivity follows these seasonal SST patterns.