In the cold light of day: the potential importance of under-ice convective mixed layers to primary producers

Pernica, Patricia; North, Rebecca L.; Baulch, Helen M.

doi:10.1080/20442041.2017.1296627

Cited by 49 publications

(71 citation statements)

References 47 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…In early spring from 9 March, air temperatures reached up to 9°C during daytime, so that the ice would have become partially transparent to solar radiation after the highly reflective snow cover had melted. At the same time, this radiation warms the surface layer making an unstable stratification, as previously seen in Lake Simcoe on 9 February, 9 March, and 14 March in 2011, just before ice-out on 24 March 2011 (Pernica et al, 2017). In previous years, it was calculated that this led to an eightfold increase of the mean photosynthetically active radiation (Kim et al, 2015).…”

Section: Data and Resultsmentioning

confidence: 61%

“…Our calculations of density for the Thorpe scales assume a constant salinity with a value of 420 μS/cm. Based upon conductivity measurements made by the MOECC in 2011 and in 2016, and by Pernica et al (2017), we have assumed that there were no significant salinity gradients in the upper water column.…”

Section: Methodsmentioning

confidence: 99%

“…The combined presence of ice cover and a stable stratification in winter has traditionally been assumed to inhibit vertical transport of oxygen from the atmosphere, and hence in shallow lakes, winter anoxic fish kills can occur (Golosov et al, 2007). More recent studies show that increased light levels in late winter lead to under-ice phytoplankton growth (Kim et al, 2015;Obertegger et al, 2017;Phillips & Fawley, 2002;Salmi & Salonen, 2016), which produces oxygen in the upper water column (Pernica et al, 2017). It is likely that the physical processes under the ice (Kirillin et al, 2012) are linked to the timing of the frequent presence of Geophysical Research Letters 10.1002/2017GL075373 large plankton concentrations observed in many lakes during winter (Hampton et al, 2017;Salmi & Salonen, 2016;Twiss et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

High‐Frequency Observations of Temperature and Dissolved Oxygen Reveal Under‐Ice Convection in a Large Lake

Yang

Young

Brown

et al. 2017

Geophysical Research Letters

View full text Add to dashboard Cite

Detailed observations of thermal structure over an entire winter in a large lake reveal the presence of large (10-20 m) overturns under the ice, driven by diurnal solar heating. Convection can occur in the early winter, but the most vigorous convection occurred near the end of winter. Both periods are when our lake ice model suggest thinner ice that would have been transparent. This under-ice convection led to a deepening of the mixed layer over time, consistent with previous short-term studies. During periods of vigorous convection under the ice at the end of winter, the dissolved oxygen had become supersaturated from the surface to 23 m below the surface, suggesting abundant algal growth. Analysis of our highfrequency observations over the entire winter of 2015 using the Thorpe-scale method quantified the scale of mixing. Furthermore, it revealed that changes in oxygen concentrations are closely related to the intensity of mixing.

show abstract

Section: Data and Resultsmentioning

confidence: 61%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

High‐Frequency Observations of Temperature and Dissolved Oxygen Reveal Under‐Ice Convection in a Large Lake

Yang

Young

Brown

et al. 2017

Geophysical Research Letters

View full text Add to dashboard Cite

show abstract

“…Factors which affect light attenuation in winter include albedo effects on incident irradiance, snow cover (thickness, quality, and distribution), and ice thickness and characteristics. Snow thickness has the most influence on under‐ice photosynthetically active radiation (PAR) (Bertilsson et al ); snow depth and quality can strongly influence light limitation of under‐ice primary producers (Pernica et al ) and subsequent reduction in growth rates (Jewson et al ).…”

Section: Measurements Of Physical Conditionsmentioning

confidence: 99%

The unique methodological challenges of winter limnology

Block

Denfeld

Stockwell

et al. 2018

Limnology & Ocean Methods

View full text Add to dashboard Cite

Winter is an important season for many limnological processes, which can range from biogeochemical transformations to ecological interactions. Interest in the structure and function of lake ecosystems under ice is on the rise. Although limnologists working at polar latitudes have a long history of winter work, the required knowledge to successfully sample under winter conditions is not widely available and relatively few limnologists receive formal training. In particular, the deployment and operation of equipment in below 0 C temperatures pose considerable logistical and methodological challenges, as do the safety risks of sampling during the icecovered period. Here, we consolidate information on winter lake sampling and describe effective methods to measure physical, chemical, and biological variables in and under ice. We describe variation in snow and ice conditions and discuss implications for sampling logistics and safety. We outline commonly encountered methodological challenges and make recommendations for best practices to maximize safety and efficiency when sampling through ice or deploying instruments in ice-covered lakes. Application of such practices over a broad range of ice-covered lakes will contribute to a better understanding of the factors that regulate lakes during winter and how winter conditions affect the subsequent ice-free period.

show abstract

“…These representative water heights are not known, reflecting complications from highly dynamic and depth-penetrating mixing patterns that have been revealed in recent winter research (Pernica et al 2017;Bruesewitz et al 2014). Because nitrification is thought to be a benthic-dominated process in these lakes ), estimates of ecosystem-level oxygen consumption by nitrification may be obtained through knowledge of the sediment surface area associated with a given depth.…”

Section: Potential Oxygen Consumption By Nitrifiersmentioning

confidence: 99%

Nitrification contributes to winter oxygen depletion in seasonally frozen forested lakes

et al. 2017

Self Cite

View full text Add to dashboard Cite

In lakes that experience seasonal ice cover, understanding of nitrogen-oxygen coupling and nitrification has been dominated by observations during open water, ice-free conditions. To address knowledge gaps about nitrogen-oxygen linkages under ice, we examined long-term winter data (30 ? years, 2-3 sample events per winter) in 7 temperate lakes of forested northern Wisconsin, USA. Across lakes and depths, there were strong negative relationships between dissolved oxygen (DO) and the number of days since ice-on, reflecting consistent DO consumption rates under ice. In two bog lakes that routinely experience prolonged winter DO concentrations below 1.0 mg L -1 , nitrate accumulated near the ice surface mainly in late winter, suggesting nitrification may depend on biogenic oxygen from photosynthesis. In contrast, within five oligotrophicmesotrophic lakes, nitrate accumulated more consistently over winter and often throughout the water column, especially at intermediate depths. Exogenous inputs of nitrate to these lakes were minimal compared to rates of nitrate accumulation. To produce the nitrate via in-lake nitrification, substantial oxygen consumption by ammonium oxidizing microbes would be required. Among lakes and depths that had significant DO depletion over winter, the stoichiometric nitrifier oxygen demand ranged from 1 to 25% of the DO depletion rate. These estimates of nitrifier-driven DO decline are likely conservative because we did not account for nitrate consumed by algal uptake or denitrification. Our results provide an example of nitrification at temperatures \ 5 degrees C having a substantial influence on ecosystem-level nitrogen and oxygen availability in seasonally-frozen, northern forested lakes. Consequently, models of under-ice dissolved oxygen dynamics may be advanced through consideration of nitrification, and more broadly, coupled nitrogen and oxygen cycling.

show abstract

In the cold light of day: the potential importance of under-ice convective mixed layers to primary producers

Cited by 49 publications

References 47 publications

High‐Frequency Observations of Temperature and Dissolved Oxygen Reveal Under‐Ice Convection in a Large Lake

High‐Frequency Observations of Temperature and Dissolved Oxygen Reveal Under‐Ice Convection in a Large Lake

The unique methodological challenges of winter limnology

Nitrification contributes to winter oxygen depletion in seasonally frozen forested lakes

Contact Info

Product

Resources

About