The World's Seagrass Species: On the Road to Potential Extinction?
Short, F.T., Polidoro, B., Livingstone, S.R., Carpenter, K.E., Bandeira, S., Bujang, J.S., Calumpong, H.P., Carruthers, T.J.B., Coles, R.G., Dennison, W.C., Erftemeijer, P.L.A., Fortes, M.D., Freeman, A.S., Jagtap, T.G., Kamal, A.H.M., Kendrick, G.A., Kenworthy, W.J., La Nafie, Y.A., Nasution, I.M., Orth, R.J., Prathep, A., Sanciangco, J.C., van Tussenbroek, B., Vergara, S.G., Waycott, M. and Zieman, J.C. 2011. Extinction risk assessment of the world's seagrass species. Biological Conservation 144: 1961-1971.
In their own study, "for the first time," say the authors, "the probability of extinction is determined for the world's seagrass species under the Categories and Criteria of the International Union for the Conservation of Nature (IUCN) Red List of Threatened Species," which effort they describe as "a four-year process involving seagrass experts internationally, compilation of data on species' status, populations, and distribution, and review of the biology and ecology of each of the world's seagrass species." So what did they find?
The twenty-six seagrass experts -- hailing from eleven different countries -- determined that ten seagrass species (comprising 14% of all seagrass species) are at elevated risk of extinction, with three other species qualifying as Endangered. But what is the cause of the problem? Is it CO2-induced global warming and ocean acidification? Not much is said about these two villains; but the international team of experts name a number of others, including suspended sediments and siltation (Dennison et al., 1993; de Boer, 2007), coastal construction, land reclamation, shoreline hardening, and dredging (Erftemeijer and Lewis, 2006), damaging fisheries practices such as trawling and aquaculture (Pergent-Martini et al., 2006), mechanical damage from boats, boat moorings and docks (Burdick and Short, 1999; Kenworthy et al., 2002), introduced species (Williams, 2007) that compete for space and resources (Heck et al., 2000) and certain diseases (Rasmussen, 1997). Thus, they conclude that "the most common threat to seagrasses is human activity," particularly that of the type which is responsible for most of the threats listed above.
Short et al. go on to state that these "localized impacts to seagrass species will decrease their survival capacity in the face of global threats," such as "the effects of global climate change." Thus, it is only logical to conclude that if these localized impacts of human activity could somehow be dramatically reduced, there would be a correspondingly dramatic improvement in the ability of seagrasses to withstand the threats of anthropogenic-induced global warming and ocean acidification.
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