A team of scientists, in collaboration with Dark Zone Diving and XTC Dice Centre, conducted an expedition to explore and document the blue hole’s unique geomorphological features and depth.
Photo: Location of the TJBH in the western Caribbean inside Chetumal Bay: (A) Surrounding sinkholes or cenotes along Laguna Bacalar and the reported locations for the blue holes Poza A and Poza B within Chetumal Bay (Carrillo et al., 2009b), near the Mexico and Belize border (UTM 16Q), and (B) contour levels overlapped over underwater imagery of the blue hole obtained from georeferenced raster images taken by sidescan sonar recordings.
In April 2021, the second deepest blue hole in the world was discovered. The investigation involved using an echosounder, scuba dives, CTD profiling (conductivity, temperature, and depth), and water chemical sampling. Initially, its depth was estimated to be 274.4 meters, making it 13 metres shallower than the former deepest blue hole in the world, located in the South China Sea, which was discovered in 2016.
The recent project focused on a blue hole called Taam ja’, meaning “deep water” in Mayan, for further research and exploration. The dive team was composed of Krzysztof Starnawski, Javier Salas, Darius J. and Melodie Trevino, with Krzysztof breaking the record for the deepest dive in Taam Ja’ down to 207 meters. To the team’s surprise, the depth of the hole exceeded expectations as it measured at least 387 meters, making it the deepest blue hole worldwide.
Blue holes are sinkholes that form on karstic geological landforms. Changes in climate over time lead to the dissolution and eventual collapse of limestone. These changes occur during glacial and interglacial periods, causing fluctuations in sea level and eroding the lithography.
Taam ja’ exhibits specific geological features that attract a specialized ecosystem, relying on a brackish environment to support the entire marine community living within the blue hole. Maintaining the balance between freshwater and saltwater is crucial for the health of this niche ecosystem, as environmental stress caused by climate change could increase its vulnerability. The brackish water in the blue home creates a homogenous environment with minimal temperature and chemical fluctuations. The blue home is part of a tropical estuary on the west Caribbean coast, with adjacent underground aquifers and lagoons serving as the primary sources of freshwater that feed into the hole. The area experiences micro-tides that are too weak to cycle the biotic environment. Despite this, strong winds contribute to a dynamic turbulent system that facilitates water mixing.
The limited turbulence in the blue hole creates a hypoxic environment with a unique chemistry, influenced by the surrounding dissolving limestone. These conditions are conducive to the preservation of fossils and provide valuable insights into how the marine environment adapts to climate change. While no ice-age fossils have yet been discovered, the blue hole exhibits features such as rocky ledges, sediments, and biofilm.
Despite the efforts made in studying the blue, the available information remains limited, highlighting the need for further research in the near future. There is still much to be explored and understood about this fascinating ecosystem.
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