Abstract:
A series of permanent line transects established on fourteen reefs on the eastern
seaboard of the Gulf of Thailand were monitored through a three-year period (1995-
1998) using a video transect method. Hierarchical cluster analysis shows three distinctive
reef community types dominated by 1) Porites, 2) Acropora and 3) zoantharians. The
reefs are developed under naturally turbid conditions and relatively low salinity due to
the proximity of four major river outlets located in the uppermost area of the gulf. The
number of Acroporid species on the reefs is positively correlated with distance from the
major flver outlets. Eighty-seven species of scleractinian coral were found on the
transects.
Over the three-year period, the comparison of 1995-97-98 matched stations using
Repeated Measures ANOV A reveals no significant time-dependent change in percent
area cover of reef components except for an overall significant reduction in the faviid
coral component. In the 1997-98 matched station comparison, statistical tests reveal
significant increases in both Acropora and Porites components that translated into an
overall increase in total living coral cover.
These findings indicate that the overall environmental conditions have been
favorable for coral growth. Outcompetition of massive corals by faster growing corals on
several reefs also indicates conditions favorable for reef expansion. Growth of newlyformed
Porites colonies over primary rock substrate and dead coral skeleton was
presumably responsible for its rapid increase.
Although these reefs are in an area of rapid industrialization and population
growth, resultant anthropogenic effects have not yet stopped active coral accretion.
