Can Mangroves Survive Our Rising Sea Levels?

CC BY 2.0. Sandie Marie

I've been reading a lot about mangroves recently. Having lent my support to a crowdfunding effort to replant mangroves in Madagascar, I've learned more and more about these unique forests and their ability sequester carbon and protect in-land communities from storm surges and sea level rise.

But what if the mangroves themselves fall victim to sea level rise?

A new study in the journal Nature suggests that's exactly what may happen in many parts of the Indo-Pacific region as land is lost to rising seas, and as the natural sediment flows that would normally replenish mangrove swamps and help them to keep up with sea level rise are disrupted by forest clearance and disturbance, and by inland damming. In fact, says the team of researchers led by University of Queensland ecologist Catherine Lovelock, 69% of the sites they studied showed insufficient soil sediment build up to keep up with current levels of sea level rise, and some of the sites with the lowest sediment build up and tidal range—in particular the Chao Phraya River delta in Thailand and the Mekong delta in Vietnam—could be inundated as early as 2070.

Ultimately, says Lovelock and two of her co-authors Neil Saintilan and Kerrylee Rogers in an article over at The Conversation, preventing mangrove loss requires restoring natural sediment flows and, where necessary, allowing for a planned shoreline retreat that gives mangroves the ability to adapt:

Appreciation of the financial contribution of mangroves has been slowing the trend of decline. However, long-term survival will require planning that includes both the continued provision of sediment supply, and in many cases the provision of retreat pathways, to allow mangroves to respond to sea level in ways they always have.

Of course, it might not be a bad idea to restore lost mangroves and put the brakes on sea level rise too. That last part, however, is easier said than done.