The Mushroom Corals of Singapore: Global vs. Local Challenges
Hoeksema, B.W. and Koh, E.G.L. 2009. Depauperation of the mushroom coral fauna (Fungiidae) of Singapore (1860s-2006) in changing reef conditions. The Raffles Bulletin of Zoology (Supplement 22): 91-101.
Against this backdrop, Hoeksema and Koh studied the characteristics of mushroom corals (Scleractinia: Fungiidae) that had either been collected from the coastal waters of Singapore or merely photographed in situ, based on historical records and specimen collections maintained at Singapore's Raffles Museum of Biodiversity Research, which were provided by researchers in the 1860s, 1890s, 1970, 1986-1991 and 2006, with the goal of identifying all of the species that were present at each of the times of observation.
Results indicated that all of the records together yielded a total of 19 species, but that "four species represented in collections made before 2006 were not observed during the 2006 survey." In addition, they say that three of the four species "are usually absent on reefs close to river outlets and most abundant on offshore reefs (Hoeksema and Moka, 1989; Hoeksema, 1990,1993)," which suggests, in their words, that these species "are less capable to withstand sedimentation" and, therefore, that the "increase in sediment load at Singapore is a likely cause for their disappearance."
Changing gears slightly, Hoeksema and Koh state that "although Singapore's reefs suffered severe coral bleaching in 1998, some species (including Fungia spp.) were also known to have recovered quite soon," citing Chou (2001). Likewise, they say that "coral populations in the offshore Thousand Islands off Jakarta showed recovery after the 1983 bleaching event (Brown and Suharsono, 1990; Hoeksema, 1991)," and that "during a coral reef survey in 2005 species richness of mushroom corals in the same area showed no visible decrease in species numbers." Therefore, as they continue, "coral bleaching is not a likely cause for a decrease in fungiid species richness in Singapore."
As Idso et al. (2000) have long maintained, sediment delivery and associated chemical insults to reef environments -- such as are caused by the rising levels of nutrients and toxins in coastal waters due to runoff from agricultural activities on land and activities such as those cited in the introduction to this Journal Review -- are a much greater threat to earth's corals than are rising temperatures and atmospheric CO2 concentrations, which conclusion is essentially the same as what Hoeksema and Koh concluded: "The observed loss in mushroom coral species in Singapore is most likely linked to an increased sediment load of the water and the reefs as a result of land reclamation projects in the harbor of Singapore (Hilton and Chou, 1999) and deforestation of Singapore's hinterland (Brook et al., 2003)."
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