Dangerous Pollutants

April 8, 2007
By Damond Benningfield

The odds of survival for a young fish aren’t very good. It needs to grow and develop in a hurry to evade predators and adapt to daily changes in the environment. But for fish whose mothers were exposed to industrial pollution, the odds are longer still. They may develop more slowly, making them easier targets -- endangering not only individual fish, but entire populations.

Larval Atlantic croaker (Micropogonias undulatus): 20 days old and 3.9 mm long. Photo: Lee Fuiman

One class of pollution that can have adverse effects is PCBs. These industrial chemicals were banned in the United States 30 years ago. But they’re still found in coastal sediments, and they’re likely to remain there for a long time. PCBs can impair the hormonal system, which controls growth, reproduction, and development.

A recent study documented the effects of a PCB on newly hatched Atlantic croaker. Researchers used the same low levels of PCB that the fish might encounter in the bays where it lives.

The study found that the chemical was concentrated in a female’s eggs. When a baby hatched and started consuming its yolk, it got a dose of the pollutant. At an age of 13 days, larvae from parents exposed to PCB were smaller than those that were not exposed. They also responded more slowly when they were startled. That would make them easier prey for other fish.

Another study has found similar effects for fish exposed to mercury. The studies provide evidence that pollution can endanger marine life in subtle and unexpected ways.


copyright 2006, The University of Texas Marine Science Institute