Water depth influences algal distribution and productivity in shallow agricultural lakes

Abstract

Agricultural activity can alter water quality and quantity resulting in lakes facing increasing interactive stressors including eutrophication, suspended sediment and water withdrawal. This study examined the relationships between water depth, water quality and algae in shallow agricultural lakes in the lower Mississippi River Basin (LMRB) to assess how lake depth influences algal structure and function, focusing on factors that typically regulate growth, that is, light, temperature and nutrients. Lake water and sediment cores were collected in shallow (mean = 0.8 m) and deep (mean = 1.7 m) locations in three lakes seasonally for 1 year. Additionally, interactive effects of light and temperature on algal growth were investigated through a laboratory experiment to determine the relative importance of each in regulating algal biomass and net oxygen production. In these shallow, turbid, eutrophic lakes, deeper water had lower nutrient concentrations and temperature across all seasons and clearer water in the summer. Shallow areas had more phytoplankton and periphyton. Water temperature had a stronger correlation than light with both phytoplankton and periphyton biomass. Algal biomass generally decreased with increasing water temperature, but biomass was better predicted by increasing nitrogen availability, and productivity declined with greater phosphorus availability. Water depth was therefore likely influencing different locations of the same lake towards different algal stable states. Mitigating excess algal production is an important goal towards limiting hypoxic conditions in the LMRB, and increasing water storage could help moderate temperature, nutrients and turbidity effects that contribute to algal blooms in lakes receiving agricultural runoff.

Photosynthetic Protein-Based Edible Quality Formation in Various Porphyra dentata Harvests Determined by Label-Free Proteomics Analysis

“…A previous study showed that the total soluble protein (TSP) content decreased while the growth rate increased with increasing light intensity and sunlight duration [ 16 ]. The relative photosynthetic response of the alga varies with regional climate and aquatic physicochemistry [ 17 ]. Observed differences in P. dentata photosynthesis are associated with biotic and abiotic stressors, including temperature extremes, ocean acidification, carbon fixation rates, tides, salinity level [ 18 , 19 , 20 ].…”

Surface Water Monitoring Systems—The Importance of Integrating Information Sources for Sustainable Watershed Management

“…Specifically, changes in wind direction are a significant factor influencing lake hydrodynamics [195]. The distribution of algal blooms with lower nutrient concentrations is influenced by water depth, water temperature and turbidity [196]. The result observation from Mei et al revealed that the temperature difference with 1.7 % average higher increased the nutrient concentrations [197].…”

Long-term trends in productivity across Intermountain West lakes provide no evidence of widespread eutrophication

“…In addition, hydrologic variables such as lake depth and lake area revealed that lakes trending eutrophic tended to be smaller and shallower than other lakes. Small, shallow lakes are often more productive than deeper lakes because of the effects that lake morphology can have on ecosystem structure (Richardson et al, 2022;Henderson et al, 2021).…”