“We are witnessing the spread of marine life that cause problems – such as toxic jellyfish blooms and rotting algal mats. Pathogens like cholera don’t recognise national borders so seawater warming is a health issue for cities like London, and nobody knows what organisms will spread and cause problems as Arctic shipping routes open up,” says Professor Jason Hall-Spencer, a marine scientist at Plymouth university, Devon, UK.
A rise in the carbon dioxide (CO2) levels in the Earth’s atmosphere corresponds not just to a warmer planet or sea level rising , but also increasingly acidic oceans that pose a threat to marine life. In the tropics for example, coral reefs face multitude of interconnected problems (bleaching, disease, invasive species) that are all caused by rising CO2 levels.
Ocean acidification occurs when atmospheric CO2 gets absorbed and is carried to the depths by the oceanic currents.
However, recent research suggests that ocean acidification, rather than adversely affecting many invasive species of algae, jellyfish, crabs and shellfish, may as well be helping them thrive.
A study conducted by Professor Hall-Spencer & his team at various volcanic sites in the Mediterranean, shows various invasive algal species and jellyfish being capable of flourishing in the high CO2 emission levels precdicted for this decade. Their study was published in Research and Reports in Biodiversity Studies.
The report suggests a direct & dangerous consequence of the continual increase in degree of ocean acidification is the movement of invasive species to new areas with destructive impact. The ‘Killer algae’ (Caulerpa taxifolia) for example, is a global threat and is but a single parasitic specimen in a plethora of trespasser species. These algae are caplable of thriving at elevated CO2 levels but are otherwise extremely toxic to native herbivores, who prefer starving to death rather than eating them. Other species capable of adjusting to evlevated CO2 levels include the Japanese kelp (Undaria pinnatifida) and stinging jellyfish (Pelagia noctiluca).
Part of an explanation for the adaptabiltiy of these invasive species may be that, jelly-like creatures tend to be more resistant to rise in CO2 levels, than those like corals with solid shells and exoskeletons, as they tend to dissolve in acidic conditions.
Their studies, however do highlight that in some species ocean acidification both helps and hinders it. Of noteworthy mention are the American slipper limpet (Crepidula fornicate) – one out of the 100 most invasive species in Europe, the Red King Crab – invaded the Barents Sea, and the predatory snail Urosalpinx cinera – currently in the north east Atlantic and Pacific, are specimens exhibiting significant reduction in larval surival and growth. This in turn has an adverse effect on the oyster and scallop aquaculture industries.
“Observations show there will be winners as well as losers as CO2 levels ramp up, just as there were in previous mass extinctions. The spread of harmful marine organisms should be factored into risks of rising CO2 emissions,” states Ro Allen, a researcher.
Kenath Priyanka Prasad, Biotechin Asia, 18 November 2015. Article.
