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Rethinking
karang: Bagaimana ganggang dan karang cover mempengaruhi kehidupan mikroskopik
Rethinking the coral reef: How algal and coral cover affect the
microscopic life that call the reef home
Date:
July 3, 2014
Source:
San Diego State University
Summary:
Biologists have shown that inhabited coral islands
that engage in commercial fishing dramatically alter their nearby reef
ecosystems, disturbing the microbes, corals, algae and fish that call the reef
home.
..........................
A new study by biologists at San Diego State University and
Scripps Institution of Oceanography shows that inhabited coral islands that
engage in commercial fishing dramatically alter their nearby reef ecosystems,
disturbing the microbes, corals, algae and fish that call the reef home.
The study's
lead author, Linda Wegley Kelly, is a postdoctoral scholar in the lab of SDSU
virologist Forest Rohwer. She's been involved in some capacity with Rohwer's
lab for the past 13 years, beginning as a lab technician.
For the
study, she looked at seawater samples collected from the surfaces of reefs
surrounding all 11 of the Line Islands, a chain of atolls in the central
Pacific Ocean. Over the past five years, Kelly and her colleagues have made
sporadic trips to the islands, collecting the samples with a specially adapted
bilge pump that sucks up approximately 100 liters of water in a given area.
"It's
like vacuuming the reef," Kelly said.
Kelly
sequenced themicrobiomes of the samples to determine the DNA encoded by the
viruses, bacteria, archaea (tiny, single-celled microorganisms like Halobacteria),
and protists (similarly tiny eukaryotic microorganisms such as diatoms) all
living in the same space. Within these millions of DNA sequences, Kelly found
thatcertain types of bacteria predicted whether the reef was predominantly
composed up of coral or algae.
Algae or
coral?
The
preponderance of either of these organisms has huge ramifications for the
health of the surrounding sea.
"Corals
are fierce competitors for space on the reef," Kelly said. "In a
healthy marine environment, reefs support a vibrant population of corals and
other calcifying organisms that continuously build the reef skyward."
If reefs are
dominated by algae, however, the entire habitat dissolves over time and the
fish don't have anywhere to go, Kelly explained.
When she
sequenced the surfaces of algae-covered reefs, Kelly identified microbes that
may contribute to an ecological feedback loop which impairs coral growth. Her
study was published this week in the Proceedings of the National Academy of
Sciences.
Population
centers
Another
observation, that the reef microbiomes on unpopulated islands were more similar
to one another than to other geographically closer -- but populated -- islands,
suggests that the entire community of reef inhabitants, including the microbes,
is more significantly influenced by the degree of the reef's coral or algal
cover than researchers previously realized.
Her results
have implications for conservationists looking for ways to improve strategies
for managing coral reef ecosystems.
"How do
you create an environment for corals to thrive?" Kelly asked. "In
addition to practicing sustainable fishing, one way to rehabilitate a reef
would be to transplant corals to the site. This should promote an environment
more conducive to coral growth by fostering a beneficial community of microorganisms."
Story
Source:
The above
story is based on materials provided by San Diego State University. The original article was written
by Michael Price. Note: Materials may be edited for content and length.
Journal
Reference:
- L. W. Kelly, G. J. Williams, K. L. Barott, C. A. Carlson, E. A. Dinsdale, R. A. Edwards, A. F. Haas, M. Haynes, Y. W. Lim, T. McDole, C. E. Nelson, E. Sala, S. A. Sandin, J. E. Smith, M. J. A. Vermeij, M. Youle, F. Rohwer. Local genomic adaptation of coral reef-associated microbiomes to gradients of natural variability and anthropogenic stressors. Proceedings of the National Academy of Sciences, 2014; DOI: 10.1073/pnas.1403319111
