17A- Special issue: Climate change in the Indian Ocean
This special open-access issue of Phelsuma considers the impacts of climate change on species, ecosystems, islands and projects in the Western Indian Ocean, including reviews of probable climate change scenarios, impacts on different organisms and ecosystems, different types of conservation and management projects and the effects of sea-level rise, changes in ocean and atmospheric temperatures, weather patterns and ocean acidification. Papers will be made available here as they are completed for publication throughout 2009 and 2010.
Will climate change affect terrapin (Pelusios subniger parietalis and P. castanoides intergularis) conservation in Seychelles?
- P. Bombi, M. D’Amen, J. Gerlach & L. Luiselli Abstract:
We report a modeling study on habitat suitability and predicted distribution shifts of two species of Seychelles’s freshwater turtles (Pelusios castanoides
and Pelusios subniger
) under a climate change scenario. We utilized data from the entire species distribution for modeling habitat suitability of the two species under current and future climate conditions, by using the MAXENT algorithm. At the continental scale, it appeared that P castanoides
will shift its range towards more coastal areas, whereas P. subniger
will move towards more southern sites. In the Seychelles archipelago scale, habitat suitability for P. castanoides
will decrease significantly, mainly in the interior areas of Mahé Island. On the contrary, the climatic conditions are predicted to remain suitable for P. subniger
, which will enjoy a significantly increased habitat suitability in Seychelles.
Climate change, extinction and ecosystem collapse
- J. Gerlach Abstract:
Climate change models have predicted many environmental impacts, but there have beenrelatively few published studies of ecosystem or population changes. Three studies of ecosystemsand populations are reported here from the Seychelles islands. A study of a seagrass and lagoonecosystem on Silhouette island, shows that rising sea-levels are causing changes in current patternsover the reef. Local increases in current speed act as a stress on the seagrass, leading to death ofthe plants over much of the reef-flat and loss of the stabilising function of the seagrass. Silt iseroded off the reef-flat and into the lagoon, removing habitat for some lagoon-dwelling animals.Significant changes in fish populations have been recorded, including the possible extinction of thegoby Asterropteryx gubbina
; this is the first report of possible species extinction for which sea-levelrise appears to be the primary cause. Sea-level rise is also causing increased marine incursion intoestuarine habitat, this has led to declines in populations of the dartfish Parioglossus multiradiatus
,which should be considered to be Critically Endangered. Climate change impacts are also apparentin terrestrial systems: the destablisation of a hybrid zone, leading to the extinction of the snailPachnodus velutinus
in 1994 followed a period of reduced rainfall. This is in accordance withpublished models that predict increased frequency of extreme weather patterns in the region. Thesestudies indicate that rapid population and ecosystem changes are occurring. If such patterns arerepresentative then climate change may already be one of the primary drivers of extinction.