In my previous post, I quickly looked at climate change migration response of species and barriers to that movement which will have an adverse effect on biodiversity. I’m going to carry on from this and comment on the future of coastal wetlands and associated lowlands. In respects to the previous piece, these environments are probably less likely to be able to migrate being often heavily reliant on the local water / land balance which means that the land and ocean barriers are too large to overcome. Another issue will obviously complicate the situation. This is of course rising sea levels.
Right off that bat, I’ll admit that inspiration for this section came from a very recent paper by Traill et al. (2010). With projections of sea level rise ranging from centimetres to many metres over the next century, Traill el al. (2010) modeled what effect this would have on the habitat of a keystone waterbird species, the magpie goose (Anseranas semipalmata) which rely on subcoastal floodplains in northern Australia and New Guinea. Using relatively coarse (90m) digital elevation models (DEM), they suggested a sudden tipping point in population numbers after 100-150 years (Traill et al. 2010). They note a number of weaknesses to their study – the most important being the coarseness of their DEM, which does not give true indication of intrusion through finer channels (Traill et al. 2010).
The major transferable elements that I took away from this paper where that; 1) inundation and habitat lost is likely to occur more rapidly that species adaptation, 2) nutrient value of the current floodplains are the result of millennia and will both be lost through inundation and be unavailable in remaining areas, 3) although storm surges were not included in this study, they are likely to exacerbate this intrusion of sea water, and 4) the removal of one keystone species will have a detrimental effect on other species as well socio-economic factors (Traill et al. 2010).
Any near coastal land within the different projection sea level heights and most islands are very likely to face nutrient loss, habitat loss and ultimately an increase in local (if not global) extinction of various species as a result of sea water inundation. With very little flow reaching the Murray mouth and Coorong region a persistent problem and dredging a continuous management strategy (MDBC, 2008), here is a local example of a Ramsar listed area, already under considerable stress which will be at high risk of habitat and nutrient loss as sea levels rise. Unless flows are restored, it is also likely that sea water would be able to change the water chemistry further upstream, impacting on both agricultural land and wetlands.
Grinstead et al. (2010) have recently suggested that IPCC projections for sea level rise by 2090-2099 might be an underestimate by close to a factor of 3 and that the rate of sea level change over the coming century is greater than that of the last 2000 years.
As temperatures are noticeably on the rise, sea levels are following and the potential for an increase in storm surges (Woth et al. 2006) there is little question that this will have a detrimental affect on not only island ecosystems, but indeed all coastal wetlands, many of which are already subject to anthropogenic impact stresses (Michener et al. 1997). Many of the wetlands at risk are Ramsar listed and home to migratory birds (which would suggest the ramifications are far reaching in nutrient distribution) and other keystone species that provide various ecological survives that include socio-economic benefits (Traill et al. 2010). Without proper recognition of wetlands and the above impacts, we won’t risk being short of wetlands (there will be plenty of inundation), but risk losing economically and ecologically important wetland environments and sudden disappearance of once abundant species.