TAMUG researchers work to unlock secrets in Yucatán’s underground rivers

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Scientific teams from Texas A&M University at Galveston and the National Autonomous University of Mexico in Mexico City are working jointly to explore and investigate the Ox Bel Ha System, the world’s longest underwater cave, which extends across 150 miles in very remote areas away from tourists.

With a funded cooperative research grant from Texas A&M and CONACyT — the Mexican National Science Foundation — this binational project combines the research of professors and students from both universities.

Tom Iliffe, marine biology professor at TAMUG, feels that pressure on the fragile ecosystems of the Yucatán Peninsula because of rapid, extensive development for tourism could become an environmental disaster.

Specifically, the teams will attempt to determine what promotes diversification of eyeless, albino cave fish and crustaceans utilizing three approaches — determining the water chemistry, examining potential food sources and investigating the biodiversity of these ecosystems.

The northern portion of the Yucatán Peninsula lacks surface rivers or streams so that all runoff is subterranean. Along the Caribbean coastline, partially totally submerged caves, known as cenotes, contain fresh to slightly brackish water at the surface separated by a well-defined boundary of underlying seawater.

Groundwater from cenotes (or wells) is the primary source of drinking water but developing mega-resorts for tourism has led to resource overexploitation.

Further, disposal of solid waste in jungle pits and liquid waste injected deep underground can pollute the caves. Cave systems and their cenote entrance pools link all the region’s ecosystems stretching from the rain forest, through mangroves to coral reefs.

In a domino effect, pollution of the caves and groundwater adversely impacts the local population and all of the area’s ecosystems.

To date, only limited research has been conducted on these submerged cave systems, but 46 new species have already been discovered. In the current investigation, four different cenotes are being studied on a seasonal basis before this area undergoes planned development.

Previous research by A&M scientists revealed that organic matter from the soil layer above the caves and the open cenote pools provide at least some of the nutrients for cave inhabitants.

“Chemoautotrophic bacteria are another possibility,” Ph.D. student David Brankovits said. “These microorganisms create their own food by oxidizing inorganic molecules.”

Two of the joint project’s research trips have been completed. A third is scheduled for December.

Scientific cave divers are using electronic water quality analyzers to detect changes in water chemistry as the underground rivers flow to the coast.

Biological specimens are also collected to determine the diversity and relative abundance of life in the caves, while isotopic analysis (that is, determining ratios of various forms of elements such as carbon and nitrogen) provides a means for establishing the cave food web.

“We are looking at how the micro and macro biology of caves interact,” Iliffe said. “One theory is that the unique distribution of cave-adapted fish and crustaceans within Yucatán cave systems may be a direct function of the types of microorganisms inhabiting specific sections of the caves.”

Source: http://www.galvestondailynews.com

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