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Título del libro: Lake Alchichica Limnology: The Uniqueness Of A Tropical Maar Lake
Título del capítulo: The Deep Benthic Zone

Autores UNAM:
JAVIER ALCOCER DURAND; ELVA GUADALUPE ESCOBAR BRIONES; LUIS ALBERTO OSEGUERA PEREZ;
Autores externos:

Idioma:

Año de publicación:
2022
Palabras clave:

AnoxiaChironomus; Benthic-pelagic coupling; Candona; Deep benthos


Resumen:

The basin?s shape of Lake Alchichica resembles a cylinder, with a limited littoral and extended profundal zone. The deep benthic zone is somewhat homogenous. The sediment is clayey silts with a high content of organic matter and carbonates. Deepwater is also relatively uniform except for the dissolved oxygen concentration, which ranges from close to saturation during the mixing period to anoxia along the stratification period. There are just two species inhabiting the lake?s deep benthos, a chironomid midge (Chironomus alchichica) and an ostracod clam shrimp (Candona alchichica). The small ostracod dominates numerically, but the large chironomid in biomass. Candona alchichica remains along the entire annual cycle by entering diapause/latency in the juvenile stage. Simultaneously, Chironomus alchichica pupates and emerges massively at the onset of the deep benthic anoxia. There is an explicit benthic-pelagic coupling developing in Lake Alchichica. Through the mixing period, nutrient availability promotes a winter diatom bloom. At the spring stratification?s onset, nutrient depletion and water column stability led to the massive sinking of the winter diatom bloom. The high load of organic matter deposited at the deep benthic zone fosters the deep benthos development (particularly chironomids), and also drove the rapid development of hypolimnetic anoxia. Once established, anoxia prevents the permanence and development of the deep benthic fauna. The organic matter remineralization in the hypolimnion enhances nutrients concentration. Water column mixing brings back nutrients to the water column promoting the winter diatom bloom. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2022.


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