EGU2020-11490, updated on 15 Jun 2023
https://doi.org/10.5194/egusphere-egu2020-11490
EGU General Assembly 2020
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Ecological effects of sudden drainage of large karst lakes in the Lacandon Maya region, southern Mexico

Liseth Perez1 and the Selva Lacandona science team*
Liseth Perez and the Selva Lacandona science team
  • 1Technische Universität Braunschweig, Institut für Geosysteme und Bioindikation, Braunschweig, Germany (l.perez@tu-braunschweig.de)
  • *A full list of authors appears at the end of the abstract

Water levels in Lakes Metzabok and Tzibaná, two large karst lakes in the Lacandon Forest of southern Mexico, declined dramatically within a two-week period in July 2019. Lake Metzabok (0.83 km2; zmax = 25 m) dried completely, whereas in Lake Tzibaná (1.24 km2; zmax = 70 m) it fell by ~30 m. Analysis of satellite images in Lake Metzabok suggested a combined reduction in surface area of ~0.86 km2 and water volume loss of ~11.7 million m3. The sudden loss of such a large volume of water had negative impacts on local Lacandon Maya inhabitants, and profound ecological and environmental effects, in that it caused biodiversity loss.

We combined limnological and paleolimnological analyses to evaluate the ecological effects of the sudden loss of water from Lakes Metzabok and Tzibaná. We collected and analyzed remnant waters, surface sediments and short sediment cores from what remained of the water bodies to evaluate whether evidence for such drainage events is preserved in lake sediments. In situ water-column measurements yielded values similar to those from the previous six years when the lakes were filled, suggesting that evaporation was not the process responsible for lake level lowering, but rather that the lakes drained through fractures in the underlying karst bedrock. We collected phytoplankton and zooplankton samples from the remnant waters and found abundant diatoms, green algae, testate amoebae, crustaceans (copepods, cladocerans, ostracodes), insects (chironomids, trichopterans), collembolans, rotifers, tardigrades and nematodes. Environmental conditions in such small remnant ponds are probably stressful and unstable, but because many fish, the main predators in these ecosystems, did not survive the desiccation event, the aquatic environment is ideal for survival or recolonization by many invertebrate groups. Understanding the dynamics of this modern scenario with low lake levels is key for making paleolimnological inferences that use these aquatic bioindicators. We also investigated the commencing transition from an aquatic to a terrestrial habitat in Lake Metzabok. Abundant spiders colonized cracks in the dry sediment. Small, deep holes in surface mud were probably created by aquatic organisms when water levels decreased rapidly. Some cracks held rain water and were inhabited by tadpoles of the Gulf Coast toad (Incilius valliceps). The first plants to colonize the exposed lake beds belonged to the families Poaceae (grasses), Amaranthaceae (amaranths/chenopods) and Fabaceae (legumes), among others.

The sediment record from Lakes Metzabok and Tzibaná as well as testimonies of local Lacandon Maya inhabitants suggest that similar lake level lowering events occurred in the past. The hydrology of karst lakes is complex and unpredictable because multiple geological and hydrological factors control the water balance. The cause of this recent lake level lowering event remains unknown, but may be revealed by interdisciplinary studies of the limnology, paleolimnology, structural geology, geophysics, hydrology, geochemistry, genomics and geodesy of lakes and rivers in the region, as well as traditional environmental knowledge of the Lacandon Maya.

Selva Lacandona science team:

Matthias Bücker2, Antje Schwalb1, Johannes Buckel2, Theresia Lauke1, Johannes Hoppenbrock2, Alexander Correa-Metrio3, Mauricio Bonilla4, Rodrigo Martínez-Abarca5, Sergio Rodríguez3, Wendy Morales3, Óscar Escolero3, Margarita Caballero6, Socorro Lozano3, F. Romero3, Carlos Pita7, Adrián Flores8, Bárbara Moguel9, Mark Brenner10, 11, Jason Curtis11, William Kenney10, Robert van Geldern12, Christoph Mayr13, P. Hoelzmann14, Julieta Massaferro15, Fernanda Charqueño15, Karla Rubio-Sandoval16, Paula Echeverría1, Daniel Ochoa4, Claudia S. Romero-Oliva17, Jorge García Polo17, Santiago Landois18, Miguel García18, Arturo Chorley18. 1TU Braunschweig, Institute of Geosystems and Bioindication, Germany. 2TU Braunschweig, Institute for Geophysics and Extraterrestrial Physics, Germany. 3Universidad Nacional Autónoma de México, Instituto de Geología, Mexico. 4Universidad Nacional Autónoma de México, Posgrado en Ciencias Biológicas, Mexico. 5Universidad Nacional Autónoma de México, Posgrado en Ciencias de la Tierra, Mexico. 6Universidad Nacional Autónoma de México, Instituto de Geofísca, Mexico. 7Geotem Ingeniería S.A. de C.V., Mexico. 8TU-Wien, Department of Geodesy and Geoinformation, Research Group Geophysics, Austria. 9Universidad Nacional Autónoma de México, LIIGH, Mexico. 10 Land Use and Environmental Change Institute (LUECI), University of Florida, Gainesville, USA. 11 Department of Geological Sciences, University of Florida, Gainesville, USA. 12Geozentrum Nordbayern, Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany. 13Institut für Geographie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany. 14Institut für Geographische Wissenschaften, Freie Universität Berlin, Germany. 15CENAC, Bariloche, Argentina 16Marum, Center for Marine Environmental Sciences, Bremen, Germany 17Centro de Estudios Atitlán, Universidad del Valle de Guatemala, Guatemala 18Consejo Nacional de Áreas Naturales Protegidas, Mexico

How to cite: Perez, L. and the Selva Lacandona science team: Ecological effects of sudden drainage of large karst lakes in the Lacandon Maya region, southern Mexico, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11490, https://doi.org/10.5194/egusphere-egu2020-11490, 2020.

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