"It's not only important that things are shifting," Caitlin Fong said, "but when macroalgae is abundant, it seems logical to consider the species traits of the dominant spaceholders." She worked with the area's four most dominant species: Dictyota bartayresiana, Padina boryana, Galaxaura fasciculata and Halimeda opuntia.
"I've actually been back to Moorea every two years and the shift to these fleshy species of macroalgae has been even more extreme," she noted. "In 2010, Padina was a lot more contained in space but now it has carved a large part of the back reef area where we work."
The results showed that inappropriate functional form groupings altered the ability to detect important controlling factors. Scale also seemed to affect the detection of ecological processes. "This may be because different ecological processes act at different scales," Caitlin Fong said. "The resultant loss of information, in turn, masked strong interactions between herbivory and nutrients that were not included in the models."
The research attributes the limitations of existing models of functional form dominance to the rapid and catastrophic changes in ecosystems caused by humans, which have been documented worldwide. "We postulate that functional-group models may need to be reformulated to account for shifting baselines," she concluded. "If you don't want to lose ecological resolution, you need to ensure that the defined groups that you use are true groups as opposed to arbitrary groups without underlying assumptions."
|Contact: Julie Cohen|
University of California - Santa Barbara