Mangroves are the unsung hero’s of our marine environment. They provide numerous ecosystem services estimated to be worth over US$186million per year. Think nurseries for fisheries that feed millions, tourism and protection of the coastline from erosion to name a few.
They’re also considered a tree with ‘super powers’ and an evolutionary success story given that they can survive in the harsh elements on an intertidal environment. But it seems that scientists have discovered a chink in their armour (sigh…). While they can adapt to changing tides and salinity levels they may not be that flexible when it comes to climate change and sea level rise.
And apparently this all comes down to genetics… and the lack thereof.
Biologists from Sun Yat-sen University in Guangzhou, surveyed the genetic material of several mangrove species, around the Gulf of Thailand and China’s Hainan Island. What they discovered was a surprisingly low genetic diversity, so much so that individual trees seemed identical. What does this mean for our humble mangroves? Sadly, less chance of adapting to a changing world than more diverse species.
How could this possible happen? After all mangroves are the ultimate survivors, choosing to live, survive and thrive where no other trees or shrubs dares to go. They’ve survived changes in sea levels as the oceans have risen and fallen with the ice ages over the last several hundred thousand years. Well this was until sea levels rose quickly over 20,000 years ago, killing off our silt bound super hero’s. With these deaths, the genetic diversity also died. The remaining warriors that survived represented only a fraction of the original genetic diversity, which scientists refer to as a genetic bottleneck. Sadly they’re yet to recover.
Scientists explored this concept further and the relationship of the mortality of mangroves, discovering that those species with the lowest genetic diversity where hardest hit when it came to climate change. Given the role that these trees play in the ecosystem, the loss of these humble trees will be felt far and wide, transforming our coastlines and oceans.
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