Cave diving scientists study a subterranean estuary to reveal methane and other dissolved organic carbon form the foundation of a complex food web system.  

USGS Biogeochemist John Pohlman and Texas A&M Postdoctoral Scientist David Brankovits, along with an international research team, studied submerged flooded cave systems of Ox Bel Ha in the Northeastern Yucatan.  The team discovered an ecosystem in the groundwater where living organisms were feeding on methane as a primary source.  “It is an interesting way that life is able to subsist in an extreme environment”, Pohlman said.   

Deep in the underwater caves Tilt Current Meters were deployed in different areas of the cave system affixed to simple dive weights to measure the current velocity of two distinctly different water columns: shallow water that is loaded with dissolved methane and deeper water  below with oxygen.  The current meters are retrieved every six months and the data that is collected will help to understand the hydrodynamics of the differing water masses and how they are mixing.  According to Pohlman, the TCM’s were “very easy to install and super reliable.”  The economical meters were easy to deploy by divers and were left in locations where there was a risk of loss or theft.  The meters were configured to collect 1 minute current and temperature records for the 6-month deployments.

The TCM’s are able to provide the data we require to answer the scientific questions we have”, Pohlman said, “The current measurements allow us to quantify how the ingredients for the life of bacteria exist.”