Preserving Coastal Ecosystems: study shows loss of mangroves and salt marshes releases long-stored CO2

Surfbird News reports on all things related to coastal surfbirds and the environments that support them. The site recently reported on the findings of an international consortium of scientists on the impact on CO2 sequestration with the loss of coastal ecosystems like mangroves and marshlands.

Urgent Action Needed To Halt Increasing Carbon Emissions from Destroyed, Degraded Coastal Marine Ecosystems

The destruction of coastal carbon ecosystems, such as mangroves, seagrasses and tidal marshes, is leading to rapid and long-lasting emissions of CO2 into the ocean and atmosphere, according to 32 of the world’s leading marine scientists.

That key conclusion highlights a series of warnings and recommendations developed by the new International Working Group on Coastal “Blue” Carbon, which convened its first meeting in Paris last month. The Working Group was created as an initial step in advancing the scientific, management and policy goals of the Blue Carbon Initiative, whose founding members include Conservation International (CI), the International Union for Conservation of Nature (IUCN), and the Intergovernmental Oceanographic Commission (IOC) of UNESCO.

Much of the carbon emitted when mangroves, seagrasses or tidal marshes are destroyed is estimated to be thousands of years old because the CO2 stored in these ecosystems is found not only in the plants, but in layer upon layer of soil underneath. Total carbon deposits per square kilometer in these coastal systems may be up to five times the carbon stored in tropical forests, due to their ability to absorb, or sequester, carbon at rates up to 50 times those of the same area of tropical forest. The management of coastal ecosystems can supplement efforts to reduce emissions from tropical forest degradation.

Dr. Emily Pidgeon, Marine Climate Change Director at Conservation International, and a leading blue carbon conservation scientist emphasized, “We have known for some time the importance of coastal ecosystems for fisheries and for coastal protection from storms and tsunamis. We are now learning that, if destroyed or degraded, these coastal ecosystems become major emitters of CO2 for years after the plants are removed. In the simplest terms, it’s like a long slow bleed that is difficult to clot. So we need to urgently halt the loss of these high carbon ecosystems, to slow the progression of climate change.”

“The capacity of coastal wetlands to reduce climate change by capturing and storing carbon dioxide is considerable, but has been overlooked” says Jerker Tamelander, Oceans and Climate Change Manager for IUCN. “If valued and managed properly, coastal ecosystems can help many countries meet their mitigation targets, while supporting adaptation in vulnerable coastal areas.”

Read the entire article in Surfbird News.

Fiddler Crabs: an unusual but important member of the salt marsh community

Fiddler crabs are small but striking members of the salt water marsh community. They are also a perfect example of the roles that different species play within a particular ecosystem and how these roles form a complex web of interdependency.

There are actually some 96 different species that fall within the fiddler crab genus. Reaching a maximum of only two inches, the fiddler crab gets its name from its disproportionately larger claw and how the crab uses it during feeding in what appears to be a violin-playing like motion. The claw is actually used for signaling potential mates as part of a "hey, look at me" courtship behavior in addition to battling possible rivals during the courting process. If the crab loses its large claw to a predator or a rival suitor, it will grow back but only as a much smaller claw. However, as if to make up for the loss, the crab's other smaller claw will increase in size.

Fiddler crabs feed by filtering sand and ingesting any algae, fungus, microbes, or detritus it finds. In so doing, it plays an important role in cleaning and aerating the salt marsh sediment. Unfortunately, being such a small crab makes it a delicious morsel for other predators, so the fiddler crab population is kept in check by shore birds, fishes, and larger crabs.

While adult fiddler crabs make a home by burrowing in the sand, the juvenile crab seeks shelter by using an empty snail shell, much like the hermit crab. But whereas the hermit crab carries its protective housing with it, juvenile fiddler crabs simply use the empty shells as temporary shelter. A recent study by researchers from the Georgia Southern University in Statesboro (United States) found that with every 100 snail shells, almost 80 would typically have baby fiddler crabs inside.

"Small mammals and reptiles feed on fiddler crabs as they move across the salt," said Prof. Sophie George, the study's leader. "An abundance of Littoraria irrorata [snail] shells [provide] a welcome refuge for juvenile fiddler crabs."

So, the tiny fiddler crab plays important functions both as a filter feeder of marsh sediment and as a prey item for other animals within the community. And its success depends on the presence of snails which provide sustenance to some predators and a temporary home to the juvenile fiddler crab.

Such is the complexity of nature's ecological web.

Read more about the fiddler crab in the BBC Earth News.