Vertical distribution of picocyanobacteria in deep lakes: the influence of inorganic turbidity

SCHENONE, LUCA; MODENUTTI, BEATRIZ; BALSEIRO, ESTEBAN

AQUATIC SCIENCES

BIRKHAUSER VERLAG AG

Año: 2024 vol. 86

1015-1621

Picocyanobacteria(Pcy) represent the dominant photosynthetic fraction in aquatic systems,contributing significantly to global primary production and playing a key rolein global biogeochemical cycles. Based on a 20-years dataset of in situobservations in four deep Andean North-Patagonian lakes, we analyzed andpresented a simple model to understand how the input of inorganic particlesaffects light penetration and influences the vertical distribution offreshwater Pcy during summer stratification. The analyzed temporal seriesincludes two important events (volcanic eruption and glacial recession) thatsubstantially affected lake turbidity. Thus, our mechanistic model wasconstructed as a function of changes in light extinction coefficient (KdPAR)and mean irradiance of the mixing layer (Im). Our modeling approachusing Bayesian inference and a continuous non-monotonic function successfullypredicted changes in Pcy vertical distribution. The obtained model wassuccessful in fitting data of different minerogenic particles (volcanic ashesand glacial clay) and in predicting changes under sharp increases in turbidity(volcanic eruptions) as well as in more steady changes (glacial recession). Pcymaximum abundance increased with transparency (lower KdPAR values)and the amplitude of the vertical profile increased with higher Imvalues. Using our model, we achieved a full prediction of Pcy verticaldistribution under different scenarios of lake transparency and lake thermalstructures.