Flushed

Natural History, Nov, 2003 by Peter Brown

Just when you thought you'd become so jaded about assaults on the natural environment that you'd heard it all, along comes a story that manages to stir shock, depression, and outrage anew. Thousands of miles out to sea, in a remote region of the North Pacific Ocean where even sailors seldom venture, is a vast floating mass of plastic junk, stretching across an area the size of Texas. Plastic bleach bottles, tops of spray cans, discarded TV picture tubes, polypropylene lines from fishing nets, plastic cigarette lighters, even toy "rubber duckies" have collected in a huge mass of slowly rotating seawater known as the North Pacific subtropical gyre, which--if you'll forgive the metaphor--has come to resemble a giant toilet bowl of swirling waste.

Is this the secret dumping ground of some evil junkyard Mafia? In fact, according to Charles Moore (see "Trashed," page 46), the effect is a natural one. Rivers of plastic objects are carried by great ocean currents from North America, Japan, and other lands along the North Pacific rim into the gyre. There, much of the detritus, most prominently the plastic, becomes trapped until it can decay--a process that, by some estimates, could take 500 years.

Worse, this environmental disaster is not merely an eyesore and a health hazard for seabirds. Japanese investigators have discovered that plastics can concentrate hydrophobic chemicals a millionfold. Those chemicals include such toxic substances as DDT, PCBs, and other oily poisons that have already been dispersed in the oceans. No one knows how such concentrations might affect plankton, fish, or other parts of the food web, but it seems unlikely that any good will come of it.

Not everyone will find the face of the komodo monitor pictured on this month's cover as endearing as I do, but the creature is certainly a poster child for a group of predatory lizards so wily and intelligent that the epithet "mammal-like" has become a cliche among herpetologists. Ecosystems don't even harbor small monitors and small placental carnivores at the same time. According to Samuel S. Sweet and Eric R. Pianka ("The Lizard Kings," page 40), the reason may be that the two groups play such similar roles.

What I find particularly fascinating about small monitors is their success as cold-blooded (more aptly called ectothermic) animals. They can move about all day, and they can strike like lightning when the circumstances call for it--yet they generally spend far less energy simply living than do their mammalian counterparts. The monitor story spotlights a basic lesson of biology: there are many ways to thrive in a threatening world.