A Review of Water Level Fluctuations on Aquatic Biota With an Emphasis on Fishes in Ice‐Covered Lakes¹

Abstract

The effects of water level fluctuations on fish and other aquatic biota, with an emphasis on winter water withdrawal in northern regions is reviewed. Water demands for population growth and development are adding pressure on water reserves, particularly when coupled with changing climatic conditions. Water level fluctuations can have adverse effects on the environment, most notably to hydrologic and biotic processes ranging in magnitude from the micro-scale to landscape level. Water level management of lakes and reservoirs can affect all forms of aquatic biota. The severity of effect is dependant on the magnitude, duration and timing of the fluctuation, and the species exposed. In northwestern Canada and northern Alaska, water is withdrawn from water bodies to construct ice-roads and other winter based developments. Biota in small, isolated water bodies are particularly sensitive to reductions in winter water levels. Water withdrawals can reduce the oxygen available to overwintering fish, while reduced water levels can reduce habitat for fish and furbearers, and freeze littoral areas killing plants, invertebrates, and fish eggs. Regulatory winter water withdrawal thresholds have been developed in the Northwest Territories and Alaska and continue to be refined as new data becomes available. The use of thresholds can help minimize or avoid negative impacts to the environment, particularly fish, from winter water withdrawal activities. Many different factors may influence the effect that winter water withdrawal has on a water body, such as basin shape, substrate and location. More research is warranted to better understand the linkages between anthropogenic and natural water level fluctuations and their combined effect on aquatic ecosystems. A general decision support system is proposed for minimizing risk to aquatic life from winter water withdrawal activities.(KEY TERMS: water withdrawal; ice roads; water level fluctuations; ice; lakes; northern resource development; water use; winterkill; aquatic biota.)

Burbot and large hydropower in North America: benefits, threats and research needs for mitigation

“…Lacustrine burbot spawn in shallow water (<2 m), and winter drawdown may reduce available spawning habitat and increase the likelihood of egg stranding and freezing (Cott et al . ; Stapanian et al . ).…”

“…Furthermore, hydropower facilities can result in direct losses to fish populations through turbine entrainment (the involuntary passage of fish through turbines; Coutant & Whitney ) and habitat losses through reservoir drawdown and habitat dewatering (Cott et al . ; Nagrodski et al . ).…”

Weekly dynamics of phytoplankton functional groups under high water level fluctuations in a subtropical reservoir-bay

“…Water level fluctuations have important effects on estuary (Costa et al 2009), wetland (Chow-Fraser et al 1998), lake (Osborne et al 1987;Gulati et al 2008;Coops et al 2003), reservoir (Naselli-Flores and Barone 1997; Donagh et al 2009;Arfi 2005;Cott et al 2008) and other ecosystems. It has been reported that water level was the main factor controlling phytoplankton biomass, species diversity, evenness and community change rate in the river, and in the lake, different phytoplankton groups (C-to S-strategists and R-strategists) responded to different water level phases (de Emiliani 1997).…”

Water level regulation affects niche use of a lake top predator, Arctic charr (Salvelinus alpinus)

“…In regulated lakes, the associated water level fluctuations typically lead to drastic changes in the physical, chemical, and biological characteristics of the littoral zone (e.g., Grimås, ; Nilsson ; Zohary & Ostrovsky, ). For example, freezing, drying, and heavy erosion of extensive bottom areas during the winter drawdown are typically followed by decrease or even local extinction of sensitive macrophyte, invertebrate, and fish species (Baxter, ; Cott et al , ; Zohary & Ostrovsky, , and references therein). Although these impacts are often prominent (e.g., Lindström, ; Supporting Information S1), there are very few empirical studies addressing how regulation may affect littoral benthic production and thereby energy flow pathways supporting top predators in lakes (but see Tikkanen et al , ; Freedman et al , ).…”