Review: Reef Fishes in Biodiversity Hotspots Are at Greatest Risk from Loss of Coral Species
In the article, “Reef Fishes in Biodiversity Hotspots Are at Greatest Risk from Loss of Coral Species”, Holbrook and other researchers bring to the readers attention the importance of coral reef systems that are currently under attack from numerous global and anthropogenic changes. The researchers hypothesize that the effect of damaging habitats will be the strongest where there is the highest biodiversity because of the specialization by the fishes there. Although there were experiments done on similar hypothesis, the author pointed out that their specific hypothesis has not been tested yet. Therefore, the study’s main research question is “How will different geographically diverse communities respond to identical changes to the diversity of the corals in the region?”
In the article, the researchers conducted the main study with building 45 different patch reefs with different levels of coral diversity on large flat sandy areas with no other habitat in the same area in three locations with different levels of biodiversity. Over a course of 8-12 months, divers recorded the different species that were on or interacted with the patch reefs four times. After the collection, the data were analyzed by using the total number of species on each patch during the final survey. The researchers used canonical analysis of principal coordinates (CAP) to find the influence of the coral species on the fish communities. The sample size was different in the three locations so Type III Sums of Squares was also used to find statistical significance.
The researchers found that the relationship between biodiversity and habitat providing corals correlates positively with the size of the regional species pool. They argue that species that are specific to their habitat in areas with high biodiversity are at a higher risk of local extinction compared to the regions with lower species richness because those areas are faced with many global environmental changes. The researchers also bring up two points that may contribute to the higher risk of local extinction. One, fish that that have high specialization often also often exist in small population sizes, which escalates local extinction. Second, co-occurring coral species differ in the biodiversity of the species they support. Therefore, if these corals that have a high habitat providing functions are depleting, the species there will also have a local extinction risk. Lastly, the author also argues that if communities with high diversity are vulnerable to a greater extinction risk, then this implies that regions of lower biodiversity will be more resistant to the reductions in coral species.
The information in the article is consistent with previous knowledge about coral reefs ecosystems and the different threats they face. Overall, the researchers make valid conclusions from the analysis of the data, however, some inferences cannot be completely justified. The communities with lower diversity will be more resistant to reductions in the diversity of the coral habitats is a weak argument because ‘resistance’ implies that they are actively against the reductions whereas the data only shows that there is a higher chance of local extinction in species-rich areas. Information from this article would be most beneficial to other scientists that focus on future implications of the global and anthropogenic changes on the extinction rates of various species.
Coral reefs currently house one-third of the marine species in the world and often exist in areas with high biodiversity. Research has found that areas with high biodiversity are at a higher risk for local extinction of species because of the specialization of the species there. With this new information, we can better understand the repercussions of the changes we impose on the environment and work to correct those for future generations.
Literature Cited
Holbrook SJ, Schmitt RJ, Messmer V, Brooks AJ, Srinivasan M, Munday PL, et al. (2015) Reef Fishes in Biodiversity Hotspots Are at Greatest Risk from Loss of Coral Species. PLoS ONE 10(5): e0124054. doi:10.1371/journal.pone.0124054
