This year has been tough for marine creatures which are now facing extreme changes in their environment. Lately, there have been tragic die-off large volumes of coral at the treasured Great Barrier Reef and it was caused by too much warm water.
A team of researchers has revealed that another Australian coastal ecosystem which gets less attention had a dramatic ecosystem upheaval five years ago. Scientists call this phenomenon as "extreme marine heat wave."
In 2011, a surge of ocean temperatures between 37 and 41 degrees about normal -- conditions that for the kelp represented "the hottest in recorded history."
In the northern most latitudes, along southwest coast of Australia south of Kalbarri, kelp forests died off in dramatic numbers, suggesting that the temperatures had already "exceeded a physiological topping point for kelp forests."
The study, based on years of underwater surveys, shows that before the marine heat wave happened, in late 2010, kelp covered around 70% of reefs in the midwestern Australia coastal area -- but somewhat depleted by 43% in 2013.
Though kelps are expected to regrow afterwards, the sudden changes in water temperature lures invading fishes which mostly eat kelp. The study reports that more tropical species of fish seized the opportunity to colonize the warmer waters, including grazing fish that ate kelp as it started to regrow.
Source: St. Louis Post-Dispatch
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