The main threat posed to living creatures is one of physical smothering by the persistent residues of spilled oils and water-in-oil emulsions, leading to death through the prevention of feeding, respiration and movement. As damage is caused by physical contact, marine life most at risk are marine mammals, reptiles and plants living close to shorelines, birds that feed by diving or flock at on the sea and plant and animals in aquaculture facilities and storage pens in tidal areas.
Coral reefs are at risk if they are directly exposed to floating oil during extreme tides or to high concentrations of dispersed oil. Rocky and coarse sand shorelines, exposed to wave action tend to self-clean rather rapidly, whereas fine sand and mud shorelines in sheltered areas soak up oil, which that then persist for decades. Saltmarshes and mangrove areas can take one to several decades to recover from a single oiling.
Texaco dumped some 4.3 million gallons per day of toxic oil waste water over a period of 20 years previous to 1999, in the Ecuadorean rainforest. The equivalent of three Exxon Valdez oil disasters. It is claimed that Texaco left behind 300 open waste pits contaminated with heavy metals and carcinogenic hydrocarbon compounds. It is estimated that Texaco saved $3 to $4 per barrel - close to $6 billion over 20 years in additional profits - by dumping the waste water rather than pumping it back beneath the earth's surface. Oil spills along the company's Trans-Ecuadorean Pipeline totaled an estimated 16.8 million gallons. Damages caused by Texaco's practices are estimated to be in excess of $1 billion.
On the 17/5/1999, thousands of barrels of oil spilled into the Peruvian Amazon rainforest after heavy rains triggered a landslide which broke the country's largest oil pipeline. The landslide wiped out 13 feet (four meters) of the 530-mile (850-km) pipeline owned by the state oil company, Petro-Peru. It was reported that the spill dumped 12,500 barrels of oil in the ecologically sensitive area.
It is conservatively estimated that the Niger Delta experiences about 300 separate oil spillages every year. Occurring from old worn- out flowlines which traverse several kilometers of mangroves and swamps through which oil companies transport crude oil from the scattered oil fields to their oil export terminals.