Hola amigos: AL VUELO DE UN QUINDE EL BLOG., hemos recibido información del National Science Foundation NSF, sobre la vida en un pequeño arrecife de Coral y como las esponjas de coral son sometidas a un predator que es un pes llamado: the "yuk factor." en la Pequeña Isla Caymán.
Les invito a lEer la versión original en inglés del National Science Foundation NSF
Giant barrel sponges off Little Cayman Island in the Caribbean dwarf researchers.
Credit: Joe Pawlik, UNCW
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Scientists research chemical defenses in tube sponges off Little Cayman Island.
Credit: Joe Pawlik, UNCW
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Predatory fish prevent orange sponges from smothering corals.
Credit: Joe Pawlik, UNCW
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Sponge growth experiment underway on Conch Reef, Key Largo, Florida.
Credit: Joe Pawlik, UNCW
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Gray tube sponge with "bite marks" from angelfish off Grand Cayman Island.
Credit: Joe Pawlik, UNCW
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Reef-building corals overgrown by orange sponges on an overfished reef off Martinique.
Credit: Joe Pawlik, UNCW
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When is insult added to injury for a Caribbean coral reef?
When overfishing removes predatory fish that feed on sponges, according to results reported this week in the journal PLOS ONE.
Using the undersea habitat Aquarius--moored
on Conch Reef off Key Largo, Florida--marine scientist Joseph Pawlik of
the University of North Carolina Wilmington (UNCW) and colleagues found
that these predator-fish are the same brightly colored angelfish and
parrotfish that attract scuba divers and glass-bottom boat tourists.
Pawlik is first author of the PLOS ONE paper; co-authors, all from UNCW, are Tse-Lynn Loh, Steven McMurray and Christopher Finelli.
Chemical warfare beneath the waves
The fish prey on sponges without chemical defenses--sponges missing what might be called the "yuk factor."
"Sponges that manufacture metabolites that are distasteful to fish are largely left alone," says Pawlik.
"That
being said, when overfishing by humans removes these predatory fish,
reefs shift toward faster-growing sponges that can out-compete reef
corals for space.
"That further hinders corals' chances of recovery."
Coral cover on Caribbean reefs is at historic lows due to disease, heat stress from warming waters and waves from storms.
Undersea garden of sponges
"Coral
reefs, especially in the Caribbean, have undergone many changes in the
past few decades," says David Garrison, program director in the National
Science Foundation's (NSF) Division of Ocean Sciences, which funded the
research.
"With the decline of reef-building corals, sponges
are becoming the main organisms on many reefs. These findings provide
important information about interactions between sponges and predatory
fish in coral reef communities."
Previous research showed that
Caribbean sponge communities were primarily structured by the
availability of plankton, or tiny floating plants and animals, rather
than by predators.
But sponge growth experiments performed by
Pawlik and colleagues--research that used cages to exclude
predators--show the opposite.
"Overfished reefs that lack
spongivores [sponge-eating fish] soon become dominated by
faster-growing, chemically undefended sponge species, which better
compete for space with reef-building corals," says Pawlik.
Endangered corals: threatened by 'new game in town'?
That has implications for fisheries management throughout the Caribbean.
"Some
coral species are listed as critically endangered on the IUCN
[International Union for Conservation of Nature] Red List, with four
reef-building corals on the top ten list for risk of extinction."
Sponges are already overrunning certain coral reefs.
"As
the effects of climate change and ocean acidification disrupt marine
communities," says Pawlik, "it's likely that reef-building corals will
suffer greater harm than sponges, which don't form at-risk limestone
skeletons [as corals do]."
Hence, he believes, Caribbean reefs of the future are likely to be made up increasingly of sponges.
Scuba divers and glass-bottom boat tourists may visit not to view coral reefs, but to see the new game in town: the sponges.
| -- | Cheryl Dybas, NSF (703) 292-7734 cdybas@nsf.gov |
Related Websites
NSF Discovery Article: Trouble in Paradise: Ocean Acidification This Way Comes: http://www.nsf.gov/discoveries/disc_summ.jsp?cntn_id=122642&org=NSF
NSF Discovery Article: Trouble in Paradise: Ocean Acidification This Way Comes: http://www.nsf.gov/discoveries/disc_summ.jsp?cntn_id=122642&org=NSF
Guillermo Gonzalo Sánchez Achutegui
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