Changes in Coral Cover (Diaseris distorts and Porites sverdrupi) at Isla Catalana, Gulf of California, Mexico

Changes in Coral Cover (Diaseris distorts and Porites sverdrupi) at Isla Catalana, Gulf of California, Mexico

Diaseris distorta is a free-living, solitary fungiid coral that occupies sand and mud habitats throughout the tropical waters of the Red Sea, Indian and Pacific Oceans. However, there is little data on their biology and ecology, particularly in the widely scattered and small Eastern Pacific populations. Information about the status of these coral populations will help determine if protection is warranted for this important resource. On two dates (June 2008, November 2009), population density, mean size, and total live tissue surface area were documented off the coast of Isla Catalana in the Gulf of California, which is the northern-most limit for this coral in the Eastern Pacific. For each survey, 30 randomly located 0.25m photo quadrats (7.5m total area) were analyzed using CPCe software. Data were compared for differences using paired sample, two tailed T-tests, and all results were significant. The mean number of individuals increased from 15.2 — 27.3 corals per m- (p<<0.001), and live tissue cover increased from 0.010 — 0.013% (p<<().()()l). However, their mean size decreased from 1.63 — 1.16cm (p=0.()25). A possible explanation is favorable conditions allowed larger individuals to reproduce asexually through fragmentation, increasing their numbers but decreasing their average size. In addition, the rare, endemic branching coral Porites sverdrupi was observed, with 3 colonies found in 2008 and 2 in 2009 (mean surface area of 3.8cm and 2.3cm , respectively). Further research on these corals will help clarify the factors that cause population changes providing important information for resource managers.