Fewer than 500 now survive in the St. Lawrence River, down from an estimated 10,000 in the early 1900s. Although their decline was caused originally by over-hunting, the population did not rebound after hunting was banned in 1978. Scientists suspect that substances in the water of the St. Lawrence are partly responsible. The aquatic habitat of the St. Lawrence has been seriously polluted, mostly by industries in the Great Lakes basin and along the river itself in the mid-1980s, researchers found high levels of toxins in beluga whale tissue, as well as tumours, cancers and lesions. Acid Rain Travels.
Acid rain can affect an entire ecosystem.
Acid rain has damaged lakes thousands of kilometres away from the industries that caused it. One victim of this habitat pollution is the Common Loon. Increased acid levels kill insect larvae and young fish that are the food supply for waterbirds and especially for loon chicks. Common Loon populations are now in serious decline through most of their range. A single teaspoon of soil may support 10 million bacteria and over 2 km of microscopic fungal filaments that recycle nutrients and feed plants.