Marine Environmental Effects

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The phenomenon of global climate change is widely considered fact. Studies have shown that the world’s average surface temperature has been accelerated by human activities which has led to the increase in production of greenhouse gases into the atmosphere, chiefly carbon dioxide, methane and CFCs. The repercussions of this phenomenon are the increase of global sea levels, the thinning of the ozone layer, changes of annual precipitation, and an overall increase in variability and intensity of seasons, climate and weather patterns. The southern African region is undergoing the same climate changes. These changes will have an effect on the marine ecosystem and its marine fish stocks, however, only probable scenarios and predictions have been presented…show more content…
The global surface temperatures are increasing at a rate of about 0.15°C per decade and the observed changes in southern Africa seem to follow the global trend. The sea surface temperature off the southern African coasts has increased by 1°C since the 1940s. This water temperature increase has taken place in the deep ocean as well where in the span of thirty years, it has increased by 0.17°C. Water temperature increases have devastating effects on the marine ecosystems such coral reefs, where the microorganisms responsible for the production of coral are under environmental stress and lose their intracellular endosymbionts. This phenomenon is known as coral bleaching and results in an overall loss of an ecosystem for many marine organisms that rely on coral reefs as a food source and protection. This it shows that even the slightest change in water temperature can have large consequences. Most aquatic organisms are thermoconformers and therefore do not have body temperatures-independent from their environment, making them susceptible to any change in the ambient temperature. Small shifts in water temperatures will be observable in South Africa, where fish species will respond to the changing temperatures by modifying their distribution patterns. It is predicted that as water temperatures increase, tropical fish species from the north will shift their distribution further south, while species already in…show more content…
This will have significant effects on the estuaries and river systems as well as the marine environment surrounding them due to many marine organisms relying on these systems to continue their life cycles. They provide nursery and feeding grounds for fish species, such as the dusky kob, as they are sheltered habitats. Lower rainfall leads to lower runoff. This will result in many estuaries being blocked by sand bars and reducing tidal exchange. The frequency at which river mouths will open will lower and therefore negatively affect fish species that rely on them as a haven for offspring. Removing a life cycle component will end in a smaller population of a species. Interestingly, increasing water levels will have little impact on the ecology and functioning of the marine environment and might even benefit from it. It might compensate for the lack of water run-off in river systems, and open up river mouths, making estuaries more
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