Buried Treasure: Mesophotic Coral Ecosystems (MCE’s) of the Hawaiian Archipelago
By Farrah Leone
The Twilight Zone was not just a hit TV series by Rod Serling. But the counterpart which shares its name, “Coral Reef Twilight Zone”, captivates audiences just as much.
The National Oceanic and Atmospheric Association (NOAA) conducted research on Hawai’i’s mesophotic reef systems from September 2007 through August 2012. The premise of the research was to investigate the chemical, biological, and physical connections these ecosystems have with shallower corals that lie more towards the surface.
Hawai’i’s mesophotic coral ecosystem averages about 98 - 150 meters below sea level. The deepest reef explored in this study was found all at an astounding 153 meters! The diversity of corals and morphology is not completely lost with penetration of light. The “massive, laminar, branching, and foliose” design provides habitat and shelter for smaller and juvenile organisms.
It had been concluded that, “Of the fish species documented on these deep coral or mesophotic reefs, 43 percent were endemic, species found only in the Hawaiian Islands, which is more than double the 17 percent of endemic species found on shallow Hawaiian reefs.” Endemic species are only found in certain pockets of the world and cannot be found anywhere else. Organisms may be similar across ecosystems, but not 100% genetically the same. For example, Las Vegas has a replica of the Effiel Tower, but we all know that a different one is in Paris.
100% endemism existed at the northern tip of the Papahānaumokuākea Marine National Monument within the Au’au channel, which is the highest on Earth! However, these species have shown to be genetically similar to those found at shallower depths and might have the potential to restock abundance in lacking areas. Shelter provided by the reef also may be linked to a sanctuary for juveniles and small species. Genetic similarity and increased chance of survival are two key factors to repopulating stock.
MCE’s show great potential for nourishing our degrading marine ecosystems but they do face their own challenges. The cooler waters of the twilight zone are thought to slow growth rate which also correlates with reduced calcification, making ocean acidification a large problem.
However, this month’s theme features many women who are hard at work to protect our reefs. On behalf of all the mermaids, we thank you for your perseverance!