The adverse effects of the continued warming of the Earth's climate may no longer be limited to just terrestrial species. A new study conducted by the University of Adelaide in Australia has found that carbon emissions are placing a deadly stranglehold on fisheries and ocean ecosystems as well.

A team of marine experts from Adelaide, led by Professor Sean Connell and Associate Professor Ivan Nagelkerken, carried out the first international analysis of marine responses to increasing CO2 emissions from human populations.

They discovered that the projected acidification of the oceans and the warming of the climate could potentially lead to a significant reduction in the diversity and populations of marine species, which are vital to the balance of ecosystems in different parts of the world.

Nagelkerken said that the "simplification" of the world's oceans will likely produce severe repercussions on people's current way of life, especially for those living in coastal areas and populations that depend on the food and trade that the oceans provide.

Climate Change and Ocean Acidification

To find out the extent of changes brought on by the warming climate on the world's oceans, the Adelaide ecologists meta-analyzed data collected from 632 different studies on arctic and tropical waters. They also examined a wide range of marine ecosystems, including coral reefs, through kelp forests and open oceans.

"We know relatively little about how climate change will affect the marine environment," Connell said.

"Until now, there has been almost total reliance on qualitative reviews and perspectives of potential global change."

Connell added that their study combines data collected from different experiments in order to identify the impact of multiple stressors on communities as a whole, such as interactions between species and various response measures to the changing climate.

The marine experts discovered that the acclimation of aquatic life to warmer temperatures and ocean acidification could possibly occur in a limited scope.

Only a small number of marine species will be able to avoid the adverse effects of increasing levels of CO2, which would result in a large-scale reduction in the diversity and abundance of species all over the world.

The researchers believe the only marine creatures that will not be affected by this event are microorganisms, which experts believe will grow in diversity and population.

Effect of Warming Water Temperatures on Microorganisms

When the expected acidification of oceans is to be analyzed from a food web point of view, the primary food production from the smallest species of plankton would increase in warmer water temperatures, while secondary production from smaller fish and zooplankton would decrease.

Nagelkerken explained that with higher rates of metabolism in warmer waters, which often result in greater food demand, carnivorous species would have less food available to them. These include larger fish that fisheries industries depend on.

Nagelkerken said this would cause a collapse of species, beginning with those at the top of the food chain down to the creatures at the bottom.

The results of the study suggest that, in the event of warming water temperatures or an increase in acidification or even both, habitat-forming species such as mussels, oysters and corals would be the ones most affected.

It is believed that even the slightest changes in the health of marine habitats would already cause a far-reaching impact on a multitude of species living in reefs.

The findings of the University of Adelaide study are featured in the journal Proceedings of the National Academy of Sciences.

Photo: Shek Graham | Flickr 

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