Threats to Marine Ecosystems

Marine ecosystems make up slightly more than 70 percent of the Earth's surface. These highly diverse ecosystems are important to the health of the planet, but they are threatened by a variety of human activities.

Overexploitation

Oceans were once considered an endless supply of resources. However, improvements in fishing gear, more efficient fishing vessels, and rapid increases in human population have decreased many fish stocks. Excessive harvesting and accidental capture of noncommercial or restricted species decrease aquatic biodiversity, threaten the ecosystem, and damage local economies.

Pollution

Marine pollution comes from many sources, such as oil spills, industrial waste, and cruise ships. According to the organization See the Sea, only 10 percent of the oil in our oceans is from natural sources; the rest comes human activities, including tanker accidents, routine maintenance, runoff, and air pollution. Industrial waste, including mercury, lead, and pesticides, is absorbed by fish and passed upward through the food chain, including to humans.

Aquaculture

According to the organization Slow Food, aquaculture or fish farming threatens marine ecosystems by dumping fecal matter into surrounding water, creating environments that promote parasites and disease and escapes by fish no longer suited to the wild. Wild fish are threatened by excessive algae caused by the fecal matter, killed by disease, and lose both resources and genetic diversity to their farmed cousins.

References

• U.S. EPA: Marine Ecosystems
• U.S EPA: Threats to Aquatic Biodiversity
• Greenpeace USA: Overfishing
• See the Sea: Toxic Pollution
• U.S EPA: Overexploitation of Species
• Slow Food: Aquaculture