Nearly a month after the fuel spill in the Galapagos Islands, only nine animals are known to have died, thanks to intensive clean-up efforts and favorable ocean currents. But scientists may not know the real impact on the areas plants and animals, many of which are unique to these islands, for years to come. "The birds and mammals are the most visible, but they only constitute a small fraction of the ecological system," Wayne Landis of Western Washington University observes. "The [chemicals] that are toxic to birds and mammals are also toxic to the invertebrates and algae and other things that are in aquatic systems. So a lot of the damage isnt readily observed in these kinds of spills." Invertebrates, and photosynthetic organisms like phytoplankton, although not nearly so noticeable as other Galapagos inhabitants, are eaten by the larger creatures. Thus, if they are affected, down the road the more conspicuous creatures will be too.

To monitor long-term effects of the spill on the Galapagos ecosystem, researchers are turning to ground- and satellite-based tools. NASAs Sea-viewing Wide Field-of-view Sensor (SEAWiFS) satellite, for example, will supply data on how the phytoplankton in particular fares in the aftermath of the event. With a resolution of one square kilometer, SEAWiFS assesses phytoplankton levels by measuring the color of the water: the greener the water, the more phytoplankton it contains. (The image pictured above, taken by the SEAWiFS satellite, shows the spill as it appeared five days after fuel began leaking from the shipwreck.)

Researchers at the Charles Darwin Foundation expect that a systematic evaluation of the fuel spills short-term impact will take up to three months. Evaluation of its long-term ecological repercussions, however, is likely to continue for two to three years.