Coral Reef Invaders

L.G. Eldredge psa at
Mon Jul 9 15:47:03 EDT 2001

Coral Reef Invaders

In temperate marine systems, invasive speceis are well documented causes of
environmental disturbance, disrupting native communiteis, and having a
negative impact on fisheries.  Less is known about the impact of invasive
speces in tropical marine environments, especially on coral reef systems.
Recent evidence from surveys indicate that  tropical and subtropical areas
are also susceptible to invasions but that detection of invasive species
may be hampered by our ability to make quick and accurate taxonomic
identifications.  Furthermore, most of the studies undertaken thus far have
been limited to surveys of harbors and ports, where environmental
conditions are usually quite different from those required by reef-building

Recent studies have included extensive biological inventories in
Hawaii--Pearl Harbor, Honolulu Harbor and adjacent embaymenst, Midway
Atoll, Johnston Atoll, and Kahoolawe--and current studies in Kaneohe Bay
and Waikiki.

Using the criteria of Carlton and Chapman, Jim Carlton and I have
calculated that more than 340 marine and brackish water species are not
native to the Hawaiian  waters--287 invertebrates, 24 algae, 20 fish, and
12 flowering plants.  The majority of these are thought to have been
introduced through hull fouling.

In Hawaiian waters the major problems have resulted through the intentional
introduction of nonnative algal species which have undergone massive
blooms, spreading rapidly and creating large areas of single species.
Through these "habitat shifts" there have been direct, negative impacts
upon the $800 million per year which Hawaii earns from marine tourism.  The
introduced blue-line snappers from French Polynesia are in direct
competition with some native fishes and are thought to be the source of a
parasitic roundworm now found in a native stream fish which passes part of
the life cycle in coastal waters.

Most of the introduced invertebrates have not been sufficiently studied to
determine negative imipacts.  Nonnative sponges from the Caribbean and the
Philippines are growing through upright branching reef corals.  At least
one introduced stomatopod species has replaced a native species.

Last October I convened a symposium "Coral Reef Nonindigenous and Invasive
Species" at the 9th International Coral Reef Symposium in Bali.  Here 12
papers were presented, outling regional studies including Hawaii, Guam,
French Polynesia, and Australia.  The majority of these papers will appear
in the journal "Pacific Science" early next year.  In May we held a
workshop in Honolulu on marine alien species and produced "A guidebook to
introduced marine species in Hawaii" sponsored by the Packard Foundation
and U.S. Fish and Wildlife Service.  The guidebook is being updated and
will be on the web by Fall.

Coral reef invasions do occur; their impacts are not fully recognized at
this point.  We must all be vigilant and observe changes which may occur
very subtely.  I should very much appreciate hearing from any of you who
have had further experience with coral reef invaders.

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