Cayman Islands
Carrie Manfrino, Bernhard Riegl,
Christy Pattengill-Semmens, Jerome Hall, and Scientific Party
Preliminary Status Report
An international team of 11 scientists (and graduate assistants) completed
an AGRRA survey of 33 sites in the Cayman Islands from
June 1 - 25. As with many of the reefs in the Caribbean,
the reefs in the Caymans have been under continuous natural stresses caused by
bleaching (in 1998 nearly 80% of the corals on the wall were bleached), and
major storms and hurricanes (Hurricane Gilbert passed just north of the Caymans
in 1988). With increased human use (fishing, coastal development and mangrove
destruction, diving, etc.) concern about the survival of this important
resource has been growing.
The Cayman Islands are one of the most popular dive
and tourist destinations in the northern Caribbean
because of the luxurious reefs and spectacular walls. Eleven scientists
surveyed 19 study sites on Little Cayman and 14 study
sites on Grand Cayman Island.
A total of 4521 corals in 330 transects, 1807 algal quadrats, and 341 fish
transects were measured during the month of June, 1999. Sites were distributed
on all sides of the islands, but on Little Cayman, there
was a higher concentration of sites in the heavily dived areas such as Bloody
Bay and Jackson
Point. Reefs were assessed in all
of the different oceanographic settings of the two islands (protected windward
northern side, more exposed windward southern and eastern side, and the lower
energy leeward western side). Many of the reefs in the Caymans are regulated by
marine conservation laws so the study included sites in both managed and
non-managed reef areas. Important comparisons between the more populous Grand
Cayman and the still relatively pristine Little
Cayman Island will
be made in the final analysis.
The coral reefs of the two Cayman Islands appear to
be in similar good condition. Preliminary findings indicate that a major coral
mortality occurred some 10 years ago. However, strong, but patchy recovery
suggests that reefs are still capable of regeneration. Coral recruitment is
present but mostly at low levels and there are still many big massive coral
colonies (diameter over 2 m) though with partial mortality occur. No old Acropora
palmata stands occur, however, low density patchy new growth of A.
palmata occurs frequently. Fish diversity was moderate to high in
comparison to the tropical western Atlantic region. Algal competition does not
appear to be a problem for corals at most sites. However, in some sites, algal
encroachment and overgrowth with resultant coral mortality was observed.
Diseases were predominantly white syndromes but disease occurrence was very
low. Virtually no bleaching was recorded (< 1%). It appears that most corals
recovered from last years catastrophic bleaching event in 1998 when nearly 80%
of the corals on the wall were bleached.
The reefs differ between Little and Grand Cayman.
Overall, coral diversity and cover was high at the intermediate depths
surveyed, but low at shallow depths. On Little Cayman
average coral coverage was higher and colonies were bigger, but there was also
higher cover by macroalgae and turf algae. The frequency of coral diseases was
higher on Little Cayman but there was still less overall
coral mortality than on Grand Cayman. The average
density of grouper and snapper were considerably (3X) higher on Little
Cayman than on Grand Cayman. Grouper
spawning aggregations are still harvested in the Cayman Islands
and populations in the recent past have been still higher. Fish pots are
frequently seen on Grand Cayman (rare on Little
Cayman) and pose a potential problem for overall fish populations.
The project was coordinated by the Marine Environmental Research Institute
(MERI) with the assistance of several major organizations and institutions
including the Reef Environmental Education
Foundation (REEF), Cayman Islands Department of Environment, and the University of Miami.
Researchers included: Carrie Manfrino (Kean University and MERI
director), Bernhard Riegl (University of Graz, Austria and MERI director),
Jerome Hall (Texas A & M University and MERI director), Christy
Pattengill-Semmens (REEF), Kaho Hoshino (University of California, Santa
Barbara), Robert Graifman (MERI director), Brice Semmens (University of
Washington, Seattle), Casey Hermoyian (University of Michigan), Leslie Whaylen
(REEF), Belal Hansrod (University of South Dakota), and Marilyn Brandt (New
York University).
Cayman Survey Team.
Click photo to view full size.
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