The Affects of Global Climate Change on Marine Life Behavior

Although we often refer to the Atlantic, Pacific, Indian and Arctic oceans as separate, they are all connected, encompassing the earth as one great ocean. Because of this, sea life from under the ice in Antarctica, in the emptiness of the middle ocean, and among the coral reefs are all interconnected in a finely balanced system of life. When one environment is effected by change, the organisms within respond behaviorally, and the entire ocean can feel this change. Global climate change, especially global warming, induced by the actions of humans, has profound effects on the ocean and the behaviors of marine life within it.
Elephant seals are an example of a mammalian marine creature that serves as a top predators in Antarctica. Elephant seals travel to the Antarctic shelf, where the females then travel away from the continent and forage within the marginal sea-ice zones. The males stay in a large, condensed group on the pack ice and forage primarily on the Antarctic shelf (Bailleul 2007). In one study, there was a striking correlation between the distance from the continent to sea-ice marginal zones, and the distance the females traveled away from the continent for foraging (Bailleul 2007). This suggests that the foraging behaviors of the elephant seals depend greatly upon the consistency of the Antarctic ice. Global warming has produced a great reduction in the extent of sea ice, with a recorded 12 – 20% decrease since the 1950’s (Barbraud 2006).
Avian species in Antarctica are also delicately connected to the balance of sea ice consistency. They have been laying their eggs on an average of 2.1 days later than in the 1950’s (Barbraud 2006). This significant change in phenological trends is connected to climate change via North Atlantic oscillation, weather conditions and seasonal temperatures (Barbraud 2006). The reduction in sea ice due to weather and temperature changes correlates with the decline in major food source abundances such as krill that are essential for the survival of Antarctic avian species (Barbraud 2006). Decreased food availability is the direct cause for a decrease in reproductive success, lower population abundances and changes in distribution (Moline 2008).
Climate change has also been shown to have severe consequences for the survival of scleratinian expand corals and their associated ecosystems. Changing oceanic temperatures reduces biological diversity, slows coral growth rates, and causes coral bleaching (Crabbe 2008). In one case in the Gulf of Mexico, change in winter air temperature averages at the flower garden banks were shown to connect to growth-rate changes of Montastea annularis coral (Crabbe 2008). Zooxanthellate coral communities in deep reefs ranging from 30 – 40 meters have compareable changes in species compositions that are “slowly but significantly decreasing” (Bak 2005). Coral mortality and species composition decreases are caused by bleaching due to extremely low temperatures, and tropical storms that are increasing with the onset of global warming (Bak 2005). The effects of tropical storms on coral reefs serves as a premiere example of oceanic interconnectedness. Storms do not directly affect the deep-sea coral, but they directly damage shallow coral. The sediment and debris that arises from the destruction of shallow reefs by storms, travels down the steep slopes into the deep-water reefs. The sediment rejection mechanisms of the coral species in the deep-reefs are not well developed and cannot efficiently remove sediment, reulting in coral mortality (Bak 2005).
The effects global climate change on coral reefs, elephant seals and Arctic avian species is seen clearly through a study on exploited, middle-ocean fish species. Water temperature has a significant impact on growth rates of deep-water fish (Thresher 2007). The mean annual growth rate for these fish have been shown to correlate with the summer mean SSTS explain near Maria Island (near Tasmania); the growth rates of the juvenile orange and deep-water oreostomatids expand are significantly less that their growth rates in the 1700’s (Thresher 2007). The study shows that with increased global warming, there will be a decrease in the fish’s population growth rates over the course of time and even a complete reversal (Thresher 2007). As explained earlier, the decrease in one marine population has a domino-like impact on a plethora of other marine and non-marine species alike. The decrease, and possible reversal of these deep-water fish populations will be felt by organisms all over the planet because of the vital co-dependence of our earth’s trophic levels.
The ocean is one body, one giant, organismal like structure that is balanced by the consistency of the systems within it. Global and regional warming causes a shift in zonal winds from the South Pacific, which then strengthens the East Australian Current and increased temperate SSTs regionally (Thresher 2007). If one system is cut off, such as the changing sea ice in the Antarctic, or one system is altered, such as the East Australian Current, than an innumerable amount of marine life are affected. Marine organisms are linked through the food chain to non-marine life, like sea birds and polar bears, that critically depend on them for survival. When global climate change affects one, seemingly insignificant factor of our oceans, in consequence, the entire world is thereby affected.