Temporal and spatial dynamics of large lake hypoxia: Integrating statistical and three‐dimensional dynamic models to enhance lake management criteria

Abstract

Hypoxia or low bottom water dissolved oxygen (DO) is a world‐wide problem of management concern requiring an understanding and ability to monitor and predict its spatial and temporal dynamics. However, this is often made difficult in large lakes and coastal oceans because of limited spatial and temporal coverage of field observations. We used a calibrated and validated three‐dimensional ecological model of Lake Erie to extend a statistical relationship between hypoxic extent and bottom water DO concentrations to explore implications of the broader temporal and spatial development and dissipation of hypoxia. We provide the first numerical demonstration that hypoxia initiates in the nearshore, not the deep portion of the basin, and that the threshold used to define hypoxia matters in both spatial and temporal dynamics and in its sensitivity to climate. We show that existing monitoring programs likely underestimate both maximum hypoxic extent and the importance of low oxygen in the nearshore, discuss implications for ecosystem and drinking water protection, and recommend how these results could be used to efficiently and economically extend monitoring programs.

Drought alters the biogeochemistry of boreal stream networks

“…The magnitude and duration of episodic declines in stream O 2 concentrations varied across catchments, but all nine headwater streams had at least one documented excursion of O 2 below 50% saturation, five streams had one or more excursions below 25% saturation, and one remained anoxic for a large part of the summer. Hypoxic events, as well as their consequences for aquatic life, are well documented for estuaries and oceans 43 , lakes 44 , and large rivers 45,46 , but in contrast, have been less of a focus in small streams. However, our results highlight drought as a mechanism that has the potential to cause O 2 stress in streams draining carbon-rich, headwater catchments.…”

On the Role of a Large Shallow Lake (Lake St. Clair, USA‐Canada) in Modulating Phosphorus Loads to Lake Erie

“…ELCOM is a 3‐D hydrodynamic model that serves as the hydrodynamic driver for CAEDYM, a model capable of simulating a wide range of ecological processes and state variables (Hipsey, ; Hipsey & Hamilton, ). ELCOM‐CAEDYM, with different levels of ecological complexity, has been used widely for large North American lakes, including Lakes Winnipeg, Ontario, Erie, and St. Clair, for investigation of different aspects of nutrient and phytoplankton dynamics (e.g., Leon et al, ), relationship between transport time scales and nutrient losses (Bocaniov & Scavia, ), hypoxia (Bocaniov et al, ; Bocaniov & Scavia, ), the relative importance of meteorological forcing parameters (e.g., Bocaniov et al, ; Liu et al, ), winter conditions (e.g. Oveisy et al, ), and the role of mussels in shaping temporal and spatial pattern of phytoplankton biomass (Bocaniov et al, ) or interactions between hypoxia and spatial distribution of mussels (Karatayev et al, ).…”

Opportunities and Limits of Using Meteorological Reanalysis Data for Simulating Seasonal to Sub-Daily Water Temperature Dynamics in a Large Shallow Lake

“…This can result in larger horizontal than vertical gradients in shallow lakes [9,10]. Pronounced spatial patterns also have been observed for the occurrence of hypoxic zones, which lead to the dissolution of reduced metals and, thus, water quality deterioration (e.g., [11,12]).…”