Temperature and availability of water, oxygen, petroleum, and nutrients affect the rate of hydrocarbon biodegradation. The populations of hydrocarbon-degradation microorganisms increase rapidly at the beginning of an oil spill but their activity is quickly limited by the lack of nutrients. Application of fertilizers to the beaches affected by the spill enhanced biodegradation significantly. Dispersed oil may be ingested by aquatic organisms. The ingested oil may have acute effects including direct lethal toxicity, sub-lethal disruption of physiological or behavioral activities, and adsorption into the tissue of the organism.
Hydrocarbons tend to pass through zooplankton unchanged.
Although the plankton themselves are not adversely affected by the oil, oil-containing plankton and the fecal pellets may be ingested by other organisms in the food chain. Intertidal fish are affected by an oil spill in several ways. A parasite known as trichodinid ciliates, found in polluted waters at higher concentrations than in unpolluted waters, attaches to the gills of fish causing inflammation of the gills to the point that the fish cannot get enough oxygen. One of the most significant problems encountered by marine birds and mammals during an oil spill is the coating of their feather and fur by oil. The oil decreases the effectiveness of the fur to regulate the body temperature of the organism, and hypothermia is a common result.