Abiotic Factors That Affect Organisms in the Surface Zone

Climate

The climate of a particular area of ocean will be determined largely by its position on the globe. Ocean closer to the poles will experience lower temperatures and greater variability in daylight hours. Length and intensity of sunlight determine the available energy for photosynthesis to take place. Temperature is one of the most influential factors on the species in the surface zone. It is directly important to organisms because they must have the correct metabolism and morphology to cope with a particular temperature, but it is also important in determining the concentration of dissolved gases that the water contains. Lack of dissolved gases is often the limiting factor in the growth of plant life.

Dissolved gases have already been mentioned as an abiotic factor, but other dissolved nutrients are also important. Phosphate and nitrate are particularly important. Lack of nutrients is often a limiting factor in the surface zone as those available are quickly taken by plants and moved toward the ocean floor when organisms die and sink. Nutrient availability will be determined by a number of factors including distance from shore, ocean depth, cycling of water by ocean currents and human activity.

Ocean currents play a crucial role in oceanic life. They are driven by a number of things, though primarily the cause is the force of the Earth rotating and the difference in temperature between the poles and the equator. Ocean currents play an important role in determining the climate of a given area and the cycling of nutrients from the sea bed toward the surface. The strength of ocean currents is also important for organisms which float freely in the surface zone such as plankton, as it will determine how they are distributed.

Most of what is defined as pollution is caused by humans, which are living, but the pollution itself is nonliving, so it counts as abiotic. Oil spills, acid buildup and radioactive waste are but some of the pollutants that affect life in the surface zone. Though in general, pollutants are harmful to life, some, at least in the short term, can boost the productivity of some species by providing excesses of nutrients. However, in the longer term this can result in destabilization of the ecosystem.