The Atlantic Lionfish has a New Friend:
A new species of coral has been discovered on one of the oil platforms just
southwest of the mouth of the Mississippi River. It is Tubastraea
micranthus, a western Indo-Pacific coral which has now gained a foot-hold in
the Gulf of Mexico. It has been sighted in the Grand Isle lease area, off
the Louisiana coast, southeast of Port Fourchon. What makes the sighting
particularly alarming is that its sister species, Tubastraea coccinea, also
invaded the southwestern Atlantic during the 1940s. Some fifty yrs later,
it had made its way to the northern Gulf of Mexico and has become the single
most abundant coral there. It has been recorded from the Americas, the
Antilles, the northern Gulf of Mexico (GOM), and on many of oil and gas
platforms in the northern Gulf – inhabiting a stretch from the Florida Keys
to Brazil. It is particularly successful on artificial substrata (bridges,
oil and gas platforms, breakwaters, etc.). The northern Gulf of Mexico now
boasts millions of these coral colonies. The question arises as to whether
this type of expansion will be repeated with Tubastraea micranthus, which
has used a different geographic entry point into the Atlantic than its
congener.
Paul Sammarco (Louisiana Universities Marine Consortium – LUMCON), Scott
Porter (same; and EcoLogic Environmental), and Stephen Cairns (Smithsonian
Institution, Washington, DC) have reported the first observation of this new
species – Tubastraea micranthus – in the western Atlantic. In a recently
released paper published in Aquatic Invasions1, they raise the question as
to whether this new introduction may pose a threat similar to that of its
sister species – Tubatraea coccinea.
Sammarco and Scott, together and independently, surveyed a total of 83
platforms, including deep-water, toppled, “Rigs-to-Reefs” structures, in the
northern Gulf of Mexico for coral colonization between 2000 and 2009.
(“Rigs-to-Reefs” platforms are those platforms which have been donated by
the oil companies to the government and have been toppled either in place or
towed elsewhere to be used as artificial reefs.) The surveys performed by
SCUBA divers stretched from Matagorda Island, Texas to Mobile, Alabama, USA,
between the depths of 7-37 m. Five platforms were surveyed by a Remotely
Operated Vehicle (ROV) to depths of up to 117 m. Tubastraea micranthus was
found on only one platform – Grand Isle 93C (GI-93C), off Port Fourchon,
Louisiana, near the mouth of the Mississippi River. This location is
particularly important because it occurs at the cross-roads of two major
shipping lanes (safety fairways) transited by large international commercial
ships. For this species to occur only on this one platform indicates that
the introduction is most likely recent. The coral probably invaded via
larvae carried in the ballast water of a ship from the Indo-Pacific or from
an adult colony which “hitch-hiked” on the hull of a vessel.
If the growth and reproductive rates of Tubastraea micranthus (sexual and
asexual) are similar to those of Tubastraea coccinea, it is possible that
this species could similarly become a dominant in the western Atlantic. In
addition, if its ability to out-compete its sister species and other reef
organisms that live on these hard bottoms, it is possible that local species
could be displaced.
In a sister recent study, Sammarco has determined that Tubastraea coccinea
is an “opportunistic species”. That is, it takes advantage of new,
disturbed, or unusual habitats and does not necessarily have the capability
of dominating natural, mature ecological communities, like well-developed,
well established coral reefs. This trait has prevented its dominating
natural reefs in western Atlantic. It is not yet known whether Tubastraea
micranthus is similarly restricted in its growth patterns.
The question is raised as to whether it might be possible to eradicate this
species. It is known that rapid eradication responses to new species
introductions can be highly effective, as has been the case several times in
California. On the other hand, it is also known that waiting too long to
respond can result in domination of the new species, as has happened with
Tubastraea coccinea, the fire ant, Nutria, and the Volitan lionfish, are
ineffective. Attempts at eradication long after integration of the new
species into the community can also cause more disturbance than the original
introduction itself. This was demonstrated recently by the removal of
thousands of feral cats from the Australian National Heritage Site,
Macquarie Island. This resulted in a population explosion of rabbits which
had otherwise been kept in check by the cats. This in turn resulted in the
loss of 40% of the vegetation on the island, which is now having negative
effects on nesting bird populations on the island. Eradication is more
effective sooner rather than later.
The fate of benthic (hard-bottom) communities in the northern Gulf of Mexico
and the western Atlantic in this case remains to be seen.
July 27, 2010
1Sammarco, P.W., S.A. Porter, and S.D. Cairns. 2010. New invasive coral
species for the Atlantic Ocean: Tubastraea micranthus (Cairns and Zibrowius
1997) (Colenterata, Anthozoa, Scleractinia): A potential major threat?
Aquat. Invasions 5: 131-140.
Paul W. Sammarco Scott
Porter
Louisiana Universities Marine Consortium Ecologic
Environmental
(LUMCON) & LUMCON
psammarco@lumcon.edu scottporter@ecorigs.org
Stephen D. Cairns
Smithsonian Institution
cairnss@si.edu
Paul W. Sammarco, Ph.D.
Executive Director
Association of Marine Laboratories of the Caribbean (AMLC)
and
Professor
Louisiana Universities Marine Consortium (LUMCON)
8124 Hwy. 56
Chauvin, LA 70344
USA
Tel: 1-985-851-2876
FAX: 1-985-851-2874
Email: psammarco@lumcon.edu
Website: www.lumcon.edu