The term aquatic pertains water in general. However, marine is specific to those things in and around ocean or sea water. Marine life encompasses a broad range of plants and animals living in various ocean ecological systems throughout the world. Numerous things can affect marine life, including pollution, temperature, ocean currents and the sea’s chemical balance.
Experts contend that water contamination or pollution is the greatest factor that affects marine life. This contamination can come from a variety sources, including radioactive material, oil, excess nutrients and sediments. Many times, radioactive material comes in the form of discarded industrial and military waste or atmospheric debris. These substances can cause disease directly to marine life or indirectly by entering a food chain that adversely affects organisms within the chain. The second greatest ocean polluter comes from land-based resources such as vehicles; however, the majority of the sea's oil pollution comes from oil tankers and shipping operations. Even though oil contamination has decreased by more than 50 percent since 1981, it is still an issue that requires constant supervision and regulation. In addition to causing illness, oil pollution is known to kill marine life ranging from larvae to larger animals.
Excess nutrients (such as nitrogen oxides) come from sewage and residuals from power plants and land utilization (farming and forestry). These airborne or land-based contaminants feed algal blooms which releases toxins and depletes oxygen from sea water. This in turn kills various forms of marine life, including plants and fish. Erosion from mining, coastal dredging and land utilization forms sediment that inhibits photosynthesis in sea plants, clogs fish gills and severely damages ecosystems. Sediment is also a carrier of excess nutrients and toxins.
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Changes in ocean temperature can be attributed to numerous factors, including general climate conditions, the earth’s tectonic plate and core activity, and global warming. Rising sea temperatures cause a bleaching effect to corals, forcing its marine population to find new homes and food sources. An increase in temperature also increases the amount of zooplankton in an ecosystem, which through a domino effect, adversely impacts the food chains within that system.
Currents have a great impact on marine life by transporting microscopic and large organisms. They affect ecosystems by circulating surface heat and distributing nutrients and oxygen throughout the ocean.
Variations in the sea’s chemical composition are common due to factors including pollution, atmospheric conditions and physiological changes of marine life (such as decay, biological emissions, etc.). Saline and carbon dioxide levels are two of the components in the sea’s chemical balance are studied frequently by experts. While salinity will vary among marine ecosystems, a sustained increase or inconsistency in saline levels can prove to be detrimental to some marine species that are more salt intolerant–or stenohaline – such as finfish. Substantive increases in atmospheric carbon dioxide have been attributed to the burning of fossil fuels. As more CO2 is absorbed into the ocean, it lowers the pH balance of the water, causing it to be more acidic. Experts cite that this impedes the ability of certain marine animals--such as coral, shellfish and some species of phytoplankton--to create their shells and skeletons from calcium carbonate components.