DDT causes this occurrence. It was used to cool and insulate electrical devices and to strengthen wood or cement. PCB's may be responsible for the declining fertility and behavioral changes in seals and a deadly viral epidemic among dolphins in the Mediterranean. To learn more about synthetic organic chemicals Solid Waste Plastic is a large amount and danger of solid waste. Plastic is not biodegradable and therefore effects the oceans for long periods of time.
Sea turtles mistake plastic bags for jellyfish and die from internal blockages.
Seals and sea lions starve after being muzzled by six-pack rings or entangled by nets. Sewage Sewage sludge, a mixture of organic matter containing viruses and bacteria, synthetic organic chemicals, and toxic metal compounds, is dumped into the ocean. Sludge can combine with oxygen to produce an oxygen poor environment where few animals can survive. During storms some of this material washes up on local beaches, contaminates shellfish beds and causes disease outbreaks among people.