Increasing lake primary production and organic carbon sequestration in tropical Mexican lakes during the past century

Lake primary production and organic carbon (OC) sequestration represent globally important ecosystem services, yet their responses to global change remain obscure. This is especially true in understudied regions, such as the tropics. We investigated multidecadal patterns and controls of lake primary production and OC burial rates in five tropical crater lakes spanning Central Mexico, addressing prevailing spatial and temporal data biases. Sediment biogeochemical trends since the late 1800s were assessed relative to lake morphometry and catchment land use, as well as population and climate trends. The lakes displayed overall trends of increasing primary production and OC burial rates during the past century, reshaped by heterogeneous natural and cultural landscapes. No single anthropogenic predictor was consistently related to the lake productivity shifts. Rather, productivity increases likely arose from the interacting effects of nutrient enrichment and lake-level reductions driven by increasing evaporative demand and water use. The timing and extent of the OC burial increases did not align with spatial and temporal lake productivity trends, despite the predominantly autochthonous origin of the sediment carbon pools. Rather, OC burial rates increased in tandem with detrital erosional inputs during the latter half of the last century, promoting the burial of the labile autochthonous OC. The largest productivity increases were associated with the smallest lakes, whereas the extent of OC burial increases showed no consistent connection to lake morphometry. Our results show how increasing regional human pressures and climate change have fundamentally shaped critical lake ecosystem functions in Central Mexico