A new study has uncovered the important role that
humble sea cucumbers play in the balance of coral reefs, as it turns out
their acidic gastric emissions cause coral reefs to dissolve.
Researchers at One Tree Island on Australia’s Great
Barrier Reef originally made measurements of seawater that showed that
during the night, a significant portion of the coral reef dissolved away
– and they didn’t know why. But they did notice that there were a lot
of sea cucumbers hanging out in the area, and they wondered if they
perhaps were to blame.
In
the tropics these unprepossessing tubular relatives of starfish and sea
urchins, spend much of their lives laying about on the seabed acting
like living vacuum cleaners, slurping up mouthfuls of sand and coral
rubble, and squirting out – from the other end - piles of cleaned up
sediment. In the process they release dissolved calcium carbonate into
the water.
The team, led by Kenny Schneider from the Carnegie
Institution for Science in California took some sea cucumbers into the
lab and essentially measured what went in and what went out of them.
And they estimate that sea cucumbers are responsible
for around half the carbonate dissolution every night on the coral
reef. That might sound bad, but in fact sea cucumbers are doing a vital
job of recycling nutrients back into the ecosystem to make them
available to primary producers.
The dissolved calcium carbonate they release also
helps to buffer against the rising levels of acidity in the oceans
that’s taking place because of increasing levels of carbon dioxide
dissolving from the atmosphere.
It goes to show that there is still so much we need
to learn about the complex interactions of species in ecosystems like
coral reefs, and emphasizes the importance of maintaining all those
different species – because even if they look like just harmless
critters, lounging about on the seabed, they could be playing a very
important role in the overall health of the ecosystem.
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