Journal articles: 'Hypolimnetic anoxia'

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Quinlan, Roberto, John P. Smol, and Roland I. Hall. "Quantitative inferences of past hypolimnetic anoxia in south-central Ontario lakes using fossil midges (Diptera: Chironomidae)." Canadian Journal of Fisheries and Aquatic Sciences 55, no. 3 (March 1, 1998): 587–96. http://dx.doi.org/10.1139/f97-279.

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The ability to infer long-term changes in hypolimnetic oxygen levels is important for ecological studies of eutrophication and the impacts of climatic change on freshwater lakes. We examined the distributions of fossil midge (Diptera: Chironomidae) assemblages in the surface sediments of 54 south-central Ontario lakes and, using canonical correspondence analysis (CCA), determined if fossil chironomid assemblages could be used to reconstruct levels of hypolimnetic anoxia in thermally stratifying Laurentian Shield lakes. Anoxia was expressed as the anoxic factor (AF), which represents the days per season that a sediment area equal to a lake's surface area is overlain by anoxic water. Forward selection in CCA showed that AF, maximum depth, [SO4], [Na], and watershed area all explained significant portions of species variation. A weighted-averaging regression and calibration model of the chironomid-anoxia relationship was developed which suggests that it is possible to infer AF from fossil chironomid assemblages ( (r2appar ) = 0.70, bootstrapped RMSE = 6.5 days/summer). Quantitative reconstruction of past changes in anoxia using fossil Chironomidae should provide a new and useful tool for paleoecological assessments of lake ecosystems.

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Liu, Chang, Shiyan Wang, Xiaobo Liu, Huaidong Zhou, Budong Li, Yanliang Du, and Liang Wang. "Characteristics of water quality response to hypolimnetic anoxia in Daheiting Reservoir." Water Science and Technology 85, no. 7 (November 12, 2021): 2065–75. http://dx.doi.org/10.2166/wst.2021.491.

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Abstract Anoxia is a common phenomenon at the bottom of large reservoirs during thermal stratification. In an anoxic environment, an increasing amount of reducing substances and nutrients are released and settle at the hypolimnion of the reservoir, leading to water quality deterioration and eutrophication. This work presents a case study on Daheiting Reservoir, a part of the Water Diversion Project from the Luanhe River to Tianjin city. With the monitored data of the water temperature and dissolved oxygen content in the reservoir, and based on the mechanism of redox reactions, the water quality response to the hypolimnetic anoxia in Daheiting Reservoir was systematically analyzed. It was found that the release of total phosphorus from the sediments in Daheiting Reservoir was a joint effect of the biological and chemical processes, and the redox reaction in the anoxic zone boosted release of phosphorus. Anoxia in the reservoir caused the ammonia nitrogen released from sediments in the reservoir to accumulate at the hypolimnion, which increased the concentration of ammonia nitrogen in the water. Anoxia in the reservoir led to an increase in the concentration of iron and manganese, which accounts for the major driving factor of release of iron and manganese.

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Nürnberg, Gertrud. "Coping with Water Quality Problems due to Hypolimnetic Anoxia in Central Ontario Lakes." Water Quality Research Journal 32, no. 2 (May 1, 1997): 391–405. http://dx.doi.org/10.2166/wqrj.1997.025.

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Abstract Many lakes experience oxygen depletion in their hypolimnia during summer or winter stratification. This study investigates the remedial actions that are available to combat the harmful effects of hypolimnetic anoxia in three types of Central Ontario lakes with different trophic states. In more eutrophic lakes, e.g., Lake Wilcox, southern Ontario, much phosphorus accumulates in the hypolimnion during anoxia and represents ca. 60% of the annual P budget. To diminish the detrimental effects of such a high internal phosphorus load, withdrawal of the hypolimnetic waters, together with damming of the surface water outflow, has been suggested. In oligo- to mesotrophic Chesley Lake, on the Niagara Escarpment, phosphorus accumulation in the hypolimnion is only slight and metals with a binding capacity for phosphorus are available. Here a hypolimnetic oxygenation has been suggested to alleviate the stress on fish and also to prevent further P release from the sediments. Lakes in the District of Muskoka are softwater lakes because of their location on the Canadian Shield. Although the geochemistry of the catchment typically renders these lakes nutrient poor and oligotrophic, long-term development on their shores has led to phosphorus accumulation in the sediments that is released under anoxic conditions in some lakes. To prevent the deterioration of the water quality in these lakes, water quality models to manage and control future development in its watersheds, as those of the district municipality, should include anoxia and internal P recycling in a quantitative manner.

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Verschoor, Mark J., Chistopher R. Powe, Eric McQuay, Sherry L. Schiff, Jason J. Venkiteswaran, Jiahua Li, and Lewis A. Molot. "Internal iron loading and warm temperatures are preconditions for cyanobacterial dominance in embayments along Georgian Bay, Great Lakes." Canadian Journal of Fisheries and Aquatic Sciences 74, no. 9 (September 2017): 1439–53. http://dx.doi.org/10.1139/cjfas-2016-0377.

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Previous work suggests that a high rate of internal ferrous iron (Fe2+) loading from anoxic sediments into overlying waters favours cyanobacteria dominance (>50% of the phytoplankton biomass) over eukaryotic algae. This Cyanobacteria–Ferrous conceptual model was assessed along the Georgian Bay coastline of Lake Huron, Ontario, in one meso-eutrophic and three oligotrophic embayments that experience natural hypolimnetic anoxia. Cyanobacteria dominated all embayments in the relatively warmer summer of 2012 but not in the much cooler summer of 2014, although hypolimnetic anoxia and internal Fe2+ loading were observed in both summers in all embayments. A cyanobacteria bloom large enough to turn the lake visibly green was observed only in warmer 2012 in the meso-eutrophic embayment. Results show that warm summer temperatures and internal Fe2+ loading are necessary preconditions for cyanobacteria dominance, while high nutrient levels are needed to form large blooms. There were no consistent patterns between dominance and total and dissolved phosphorus (P), total nitrogen, ammonium, and nitrate. Internal P loading was not a necessary precondition for dominance. While P removal programs will decrease phytoplankton biomass in eutrophic waters, oxidized surficial sediments must be maintained throughout an aquatic system to prevent cyanobacteria dominance.

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Tu, Luyao, Paul Zander, Sönke Szidat, Ronald Lloren, and Martin Grosjean. "The influences of historic lake trophy and mixing regime changes on long-term phosphorus fraction retention in sediments of deep eutrophic lakes: a case study from Lake Burgäschi, Switzerland." Biogeosciences 17, no. 10 (May 20, 2020): 2715–29. http://dx.doi.org/10.5194/bg-17-2715-2020.

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Abstract. Hypolimnetic anoxia in eutrophic lakes can delay lake recovery to lower trophic states via the release of sediment phosphorus (P) to surface waters on short timescales in shallow lakes. However, the long-term effects of hypolimnetic redox conditions and trophic state on sedimentary P fraction retention in deep lakes are not clear yet. Hypolimnetic withdrawal of P-rich water is predicted to diminish sedimentary P and seasonal P recycling from the lake hypolimnion. Nevertheless, there is a lack of evidence from well-dated sediment cores, in particular from deep lakes, about the long-term impact of hypolimnetic withdrawal on sedimentary P retention. In this study, long-term sedimentary P fraction data since the early 1900s from Lake Burgäschi provide information on benthic P retention under the influence of increasing lake primary productivity (sedimentary green-pigment proxy), variable hypolimnion oxygenation regimes (Fe∕Mn ratio proxy), and hypolimnetic withdrawal since 1977. Results show that before hypolimnetic withdrawal (during the early 1900s to 1977), the redox-sensitive Fe∕Mn-P fraction comprised ∼50 % of total P (TP) in the sediment profile. Meanwhile, long-term retention of total P and labile P fractions in sediments was predominantly affected by past hypolimnetic redox conditions, and P retention increased in sedimentary Fe- and Mn-enriched layers when the sediment-overlaying water was seasonally oxic. However, from 1977 to 2017, due to eutrophication-induced persistent anoxic conditions in the hypolimnion and to hypolimnetic water withdrawal increasing the P export out of the lake, net burial rates of total and labile P fractions decreased considerably in surface sediments. By contrast, refractory Ca–P fraction retention was primarily related to lake primary production. Due to lake restoration since 1977, the Ca–P fraction became the primary P fraction in sediments (representing ∼39 % of total P), indicating a lower P bioavailability of surface sediments. Our study implies that in seasonally stratified eutrophic deep lakes (like Lake Burgäschi), hypolimnetic withdrawal can effectively reduce P retention in sediments and potential for sediment P release (internal P loads). However, after more than 40 years of hypolimnetic syphoning, the lake trophic state has not improved nor has lake productivity decreased. Furthermore, this restoration has not enhanced water column mixing and oxygenation in hypolimnetic waters. The findings of this study are relevant regarding the management of deep eutrophic lakes with mixing regimes typical for temperate zones.

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Lawrence, Gregory A., J. M. Burke, T. P. Murphy, and E. E. Prepas. "Exchange of water and oxygen between the two basins of Amisk Lake." Canadian Journal of Fisheries and Aquatic Sciences 54, no. 9 (September 1, 1997): 2121–32. http://dx.doi.org/10.1139/f97-235.

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Amisk Lake was artificially oxygenated year-round by bubbling oxygen through a diffuser installed at the deepest point of its north basin. The hypolimnion of both basins became anoxic in summer before operation of the system whereas anoxia was never observed while it was fully operational (July 1990 until October 1993). The system increased the average hypolimnetic oxygen content of the south basin by an average of 83 tonnes (t) more than under natural conditions between 2 September and 18 May. This considerable increase is approximately accounted for by the transport of dissolved oxygen (DO) through the connecting channel by currents driven by the bubble plume ( approx 52 t) and by internal seiche pumping ( approx 17 t): both mechanisms are contingent on the thermocline depth being less than that of the connecting channel. Internal seiche pumping was possible because the connecting channel is shorter than the maximum distance across which hypolimnetic fluid moved between flow reversals. Other factors that may have been important include changes in the replenishment of DO during turnover, oxygen transfer during winter through the ice-free patch created by the bubble plume, and an increase in DO consumption.

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Ladwig, Robert, Paul C. Hanson, Hilary A. Dugan, Cayelan C. Carey, Yu Zhang, Lele Shu, Christopher J. Duffy, and Kelly M. Cobourn. "Lake thermal structure drives interannual variability in summer anoxia dynamics in a eutrophic lake over 37 years." Hydrology and Earth System Sciences 25, no. 2 (February 25, 2021): 1009–32. http://dx.doi.org/10.5194/hess-25-1009-2021.

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Abstract. The concentration of oxygen is fundamental to lake water quality and ecosystem functioning through its control over habitat availability for organisms, redox reactions, and recycling of organic material. In many eutrophic lakes, oxygen depletion in the bottom layer (hypolimnion) occurs annually during summer stratification. The temporal and spatial extent of summer hypolimnetic anoxia is determined by interactions between the lake and its external drivers (e.g., catchment characteristics, nutrient loads, meteorology) as well as internal feedback mechanisms (e.g., organic matter recycling, phytoplankton blooms). How these drivers interact to control the evolution of lake anoxia over decadal timescales will determine, in part, the future lake water quality. In this study, we used a vertical one-dimensional hydrodynamic–ecological model (GLM-AED2) coupled with a calibrated hydrological catchment model (PIHM-Lake) to simulate the thermal and water quality dynamics of the eutrophic Lake Mendota (USA) over a 37 year period. The calibration and validation of the lake model consisted of a global sensitivity evaluation as well as the application of an optimization algorithm to improve the fit between observed and simulated data. We calculated stability indices (Schmidt stability, Birgean work, stored internal heat), identified spring mixing and summer stratification periods, and quantified the energy required for stratification and mixing. To qualify which external and internal factors were most important in driving the interannual variation in summer anoxia, we applied a random-forest classifier and multiple linear regressions to modeled ecosystem variables (e.g., stratification onset and offset, ice duration, gross primary production). Lake Mendota exhibited prolonged hypolimnetic anoxia each summer, lasting between 50–60 d. The summer heat budget, the timing of thermal stratification, and the gross primary production in the epilimnion prior to summer stratification were the most important predictors of the spatial and temporal extent of summer anoxia periods in Lake Mendota. Interannual variability in anoxia was largely driven by physical factors: earlier onset of thermal stratification in combination with a higher vertical stability strongly affected the duration and spatial extent of summer anoxia. A measured step change upward in summer anoxia in 2010 was unexplained by the GLM-AED2 model. Although the cause remains unknown, possible factors include invasion by the predacious zooplankton Bythotrephes longimanus. As the heat budget depended primarily on external meteorological conditions, the spatial and temporal extent of summer anoxia in Lake Mendota is likely to increase in the near future as a result of projected climate change in the region.

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Prepas, Ellie E., Tom P. Murphy, W. Paul Dinsmore, Janice M. Burke, Patricia A. Chambers, and Sharon Reedyk. "Lake Management Based on Lime Application and Hypolimnetic Oxygenation: the Experience in Eutrophic Hardwater Lakes in Alberta." Water Quality Research Journal 32, no. 2 (May 1, 1997): 273–94. http://dx.doi.org/10.2166/wqrj.1997.020.

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Abstract Many water bodies in western Canada experience high internal phosphorus recycling rates and excessive primary production, with associated water column anoxia and restricted fisheries habitat. Lime (Ca(OH)2 and CaCO3) application and hypolimnetic oxygenation were investigated in Alberta as nontoxic, inexpensive management alternatives. In hardwater lakes, multiple Ca(OH)2 applications at dosages <100 mg L-1 reduced chl a and TP concentrations by up to ~30 and 50%, respectively, often for several years. In contrast, high flushing rates in stormwater retention basins made repeated Ca(OH)2 treatment necessary. Hypolimnetic oxygenation in Amisk Lake from 1988-93 increased hypolimnetic dissolved oxygen concentrations from 0.9 to 4.6 mgL-1 in the treated basin while maintaining thermal stratification. Epilimnetic whole-lake chl a and TP concentrations were reduced by 55 and 13%, respectively. Deep-water habitat was improved for fish, zooplankton and macroinvertebrates. Our research shows that water quality can be improved in lakes that are naturally eutrophic (i.e., due to internal P cycling) and has implications for lake management projects worldwide.

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Bédard, Charles, and Roger Knowles. "Hypolimnetic O2 Consumption, Denitrification, and Methanogenesis in a Thermally Stratified Lake." Canadian Journal of Fisheries and Aquatic Sciences 48, no. 6 (June 1, 1991): 1048–54. http://dx.doi.org/10.1139/f91-123.

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Hypolimnetic O2 consumption, methanogenesis, and denitrification were estimated from concentration changes in O2, CH4, and nitrogen oxides (NO3−, NO2−, N2O), respectively, in the eastern basin of Lake St. George, Ontario, during thermal stratification from 1980 to 1984. NH4+ accumulated in the hypolimnion throughout the period of stratification and provided an overall measure of organic matter mineralization. Anaerobic metabolism, particularly methanogenesis, predominated because anoxia was total within less than 2 mo of spring water column turnover and nitrogen oxides were always completely depleted before fall turnover. The time of onset and rate of NO3−, depletion varied considerably between years and were not always directly correlated with O2 concentration. It was estimated that, on average, O2 consumption, denitrification, and methanogenesïs accounted for approximately 80% of hypolimnetic organic C mineralization in the periods surveyed.

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Regnell, Olof, Tommy Hammar, Anders Helgée, and Bo Troedsson. "Effects of anoxia and sulfide on concentrations of total and methyl mercury in sediment and water in two Hg-polluted lakes." Canadian Journal of Fisheries and Aquatic Sciences 58, no. 3 (March 1, 2001): 506–17. http://dx.doi.org/10.1139/f01-001.

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Between May and December 1996, monthly samples of surface sediment (01 cm), settling matter, and water were taken at a shallow site and a deep site in each of two consecutive Hg-polluted riverine lakes. In the upper lake, the sediment was polluted also with cellulose fiber. Both hypolimnia turned anoxic, but sulfide was detected only in the upper lake. When sulfide appeared, hypolimnetic methyl mercury (MeHg) increased and reached 47 pM (9.4 ng·L1), whereas MeHg in the sediment below decreased. The increase in hypolimnetic inorganic Hg (IHg = total Hg MeHg), which reached a peak of 40 pM (8.0 ng·L1), was slower, possibly because mobilized IHg was methylated. In the lower lake, hypolimnetic MeHg and IHg increased less dramatically during summer stratification, reaching only 5 and 24 pM (1.0 and 4.8 ng·L1), respectively. There was no detectable concomitant decrease in sediment MeHg. In both lakes, MeHg appeared to increase simultaneously with total Fe and Mn in the hypolimnion, as did IHg in the lower lake. Our observations suggest that the presence of hydrous ferric and manganese oxides decreased the mobility of Hg in both lakes but increased MeHg production in the upper lake.

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Beutel, Marc W. "Hypolimnetic Anoxia and Sediment Oxygen Demand in California Drinking Water Reservoirs." Lake and Reservoir Management 19, no. 3 (September 2003): 208–21. http://dx.doi.org/10.1080/07438140309354086.

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Snortheim, Craig A., Paul C. Hanson, Katherine D. McMahon, Jordan S. Read, Cayelan C. Carey, and Hilary A. Dugan. "Meteorological drivers of hypolimnetic anoxia in a eutrophic, north temperate lake." Ecological Modelling 343 (January 2017): 39–53. http://dx.doi.org/10.1016/j.ecolmodel.2016.10.014.

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Little, Joanne L., Roland I. Hall, Roberto Quinlan, and John P. Smol. "Past trophic status and hypolimnetic anoxia during eutrophicaton and remediation of Gravenhurst Bay, Ontario: comparison of diatoms, chironomids, and historical records." Canadian Journal of Fisheries and Aquatic Sciences 57, no. 2 (February 1, 2000): 333–41. http://dx.doi.org/10.1139/f99-235.

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Quantitative paleolimnological inferences of diatom-inferred total phosphorus and chironomid-inferred hypolimnetic oxygen levels (measured as the anoxic factor) were compared along with historical records for Gravenhurst Bay, Ontario, prior to and following sewage treatment. Water quality declined dramatically following European settlement in the mid-1800s and reached its highest inferred nutrient concentrations during the first half of the twentieth century. After treatment of sewage began in 1972, surface water total phosphorus rapidly returned to near oligotrophic conditions. Diatom assemblages reflected the period of nutrient enrichment, as well as the subsequent recovery. Chironomid assemblages exhibited trends consistent with decreased availability of dissolved oxygen to deepwater habitats since ca. 1886, with profundal taxa being largely absent since ca. 1958 when deepwater anoxia became more severe. Despite remediation efforts, Gravenhurst Bay still experiences long periods of anoxia, and chironomid assemblages have shown no sign of recovery to the improved surface water quality. We suggest that chironomid assemblages responded more strongly to changes in deepwater oxygen availability than to epilimnetic nutrient concentrations, especially during periods of pronounced hypoxia. This study demonstrates the advantages of using both chironomids and diatoms in paleolimnological assessments of eutrophication, as the indicators track changes in different lake strata.

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Downes, M. T. "Nitrogen transformations in a mesotrophic lake during the transition to hypolimnetic anoxia." SIL Proceedings, 1922-2010 23, no. 1 (January 1988): 617–18. http://dx.doi.org/10.1080/03680770.1987.11897992.

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Dawidowicz, Piotr, Andrzej Prejs, Andrzej Engelmayer, Andrzej Martyniak, Jacek Kozłowski, Lech Kufel, and Małgorzata Paradowska. "Hypolimnetic anoxia hampers top-down food-web manipulation in a eutrophic lake." Freshwater Biology 47, no. 12 (November 19, 2002): 2401–9. http://dx.doi.org/10.1046/j.1365-2427.2002.01007.x.

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Sánchez-España, Javier, M. Pilar Mata, Juana Vegas, Mario Morellón, Juan Antonio Rodríguez, Ángel Salazar, Iñaki Yusta, Aida Chaos, Carmen Pérez-Martínez, and Ana Navas. "Anthropogenic and climatic factors enhancing hypolimnetic anoxia in a temperate mountain lake." Journal of Hydrology 555 (December 2017): 832–50. http://dx.doi.org/10.1016/j.jhydrol.2017.10.049.

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Nürnberg, Gertrud K. "Quantified Hypoxia and Anoxia in Lakes and Reservoirs." Scientific World JOURNAL 4 (2004): 42–54. http://dx.doi.org/10.1100/tsw.2004.5.

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Hypoxia and anoxia occur frequently in freshwater systems and have biological and chemical implications.Anoxiacan be expressed and quantified as the anoxic factor;hypoxia, for a specific level of oxygen depletion, can be expressed as the hypoxic factor in lakes, reservoirs, and river sections. These methods summarize information of individual dissolved oxygen profiles as annual values or factors that facilitate comparison between and within lakes. Therefore, these factors are useful in the formulation and testing of hypotheses related to the dissolved oxygen status in water bodies. Methods of calculating different factors for different oxygen levels and water layers, including those applying separately to the epilimnion and hypolimnion, are presented in detail. Proven and potential applicability include: (1) the quantification of relationships with lake water quality variables and lake classification (trophic state), (2) the evaluation of restoration techniques with respect to their effects on hypolimnetic oxygen depletion, (3) the determination of internal phosphorus loading in stratified and polymictic lakes, (4) the exploration of habitat constraints due to hypoxia (e.g., fish species richness and winterkill), (5) forecasting potential effects of climatic change on oxygen content and internal phosphorus loading, and (6) the establishment and examination of criteria and guidelines with respect to hypoxia by custom-made definitions.

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James, William F., Robert H. Kennedy, and Robert F. Gaugush. "Effects of Large-Scale Metalimnetic Migration Events on Phosphorus Dynamics In a North-Temperate Reservoir." Canadian Journal of Fisheries and Aquatic Sciences 47, no. 1 (January 1, 1990): 156–62. http://dx.doi.org/10.1139/f90-016.

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In Eau Galle Reservoir, Wisconsin, early in the stratified period of 1982, hypolimnetic anoxia developed, soluble reactive phosphorus concentrations increased above the profundal sediment surface, and internal total phosphorus loading was high. Shortly thereafter, the passage of a cold front with high wind power resulted in mixing and a pronounced descent of the metalimnion. During this event, previously anoxic water within the metalimnion and upper hypolimnion became reoxygenated, internal total phosphorus loading declined to a minimum, and a loss of total phosphorus mass occurred from the metalimnion and hypolimnion. Total phosphorus mass in the epilimnion remained constant during this period. A similar pattern occurred during a large, wind-driven migration of the metalimnion in early August. During such events, phosphorus sedimentation rates increased in the hypolimnion, reflecting the loss of total phosphorus mass from the water column. In contrast, other investigations of lakes have reported that phosphorus is entrained into the epilimnion during metalimnetic migrations, rather than lost through sedimentation. Phosphorus sedimentation during large metalimnetic migration events in Eau Galle Reservoir may occur because previously anoxic water containing iron becomes reoxygenated, causing the coprecipitation and sedimentation of oxidized iron and phosphorus.

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Dickman, M. D. "Evidence of Recent Eutrophication of an Urban Lake in Nanjing, China." Water Quality Research Journal 27, no. 2 (May 1, 1992): 311–26. http://dx.doi.org/10.2166/wqrj.1992.022.

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Abstract There is very little known about urban lakes in China, and for this reason this paper provides a synthesis of palaeolimnological and past and present phytoplankton studies of Xuanwu Lake, an urban lake near the center of Nanjing, in Jiangsu Province, China. Documented changes in biotic species diversity and water chemistry in this urban lake over the last thirty years have been attributed to progressive eutrophication associated with lake in-filling, commercial harvesting of plants and fish and intense industrial and urban activities within the lake's watershed. During the last decade, phytoplankton biomass in Xuanwu Lake has increased ten fold. This has resulted in a steady shallowing of the lake's photic zone to a depth of less than 0.7 m with Secchi transparencies of 0.3 to 0.4 m. Wind-generated currents prevent anoxia from occurring in this shallow wind-swept lake no matter how eutrophic the lake. As a result, many of the negative impacts of hypertrophication, such as anoxia, fish kills and noxious odors, are avoided. Thus, shallow lakes like Xuanwu Lake can become eutrophic without producing long periods of hypolimnetic anoxia such as those frequently reported for deeper eutrophic lakes. It was concluded that it is important to treat deep urban lakes differently from shallow urban lakes as the latter systems rarely display extended periods of anoxia, fish kills and noxious odors.

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Zawiska, Izabela, Inta Dimante-Deimantovica, Tomi P. Luoto, Monika Rzodkiewicz, Saija Saarni, Normunds Stivrins, Wojciech Tylmann, Anna Lanka, Martins Robeznieks, and Tom Jilbert. "Long-Term Consequences of Water Pumping on the Ecosystem Functioning of Lake Sekšu, Latvia." Water 12, no. 5 (May 20, 2020): 1459. http://dx.doi.org/10.3390/w12051459.

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Cultural eutrophication, the process by which pollution due to human activity speeds up natural eutrophication, is a widespread and consequential issue. Here, we present the 85-year history of a small, initially Lobelia–Isoëtes dominated lake. The lake’s ecological deterioration was intensified by water pumping station activities when it received replenishment water for more than 10 years from a eutrophic lake through a pipe. In this study, we performed a paleolimnological assessment to determine how the lake’s ecosystem functioning changed over time. A multi-proxy (pollen, Cladocera, diatoms, and Chironomidae) approach was applied alongside a quantitative reconstruction of total phosphorus using diatom and hypolimnetic dissolved oxygen with chironomid-based transfer functions. The results of the biotic proxy were supplemented with a geochemical analysis. The results demonstrated significant changes in the lake community’s structure, its sediment composition, and its redox conditions due to increased eutrophication, water level fluctuations, and erosion. The additional nutrient load, particularly phosphorus, increased the abundance of planktonic eutrophic–hypereutrophic diatoms, the lake water’s transparency decreased, and hypolimnetic anoxia occurred. Cladocera, Chironomidae, and diatoms species indicated a community shift towards eutrophy, while the low trophy species were suppressed or disappeared.

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James, William F., William D. Taylor, and John W. Barko. "Production and Vertical Migration of Ceratium hirundinella in Relation to Phosphorus Availability in Eau Galle Reservoir, Wisconsin." Canadian Journal of Fisheries and Aquatic Sciences 49, no. 4 (April 1, 1992): 694–700. http://dx.doi.org/10.1139/f92-078.

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Seasonal production of Ceratium hirundinella and its diel migratory patterns were examined in relation to phosphorus (P) availability in eutrophic Eau Galle Reservoir, Wisconsin (USA). During mid-June, hypolimnetic P gradients (0.030–1.045 mg∙L−1) developed as internal P loading was high (14.7–18.0 mg∙m−2∙d−1). Ceratium migrated as much as 4 m into the upper hypolimnion at night. Subsequent increases in Ceratium biomass, gross primary productivity, and chlorophyll a indicated retrieval of hypolimnetic P for production. During early July, anoxia restricted vertical migration of Ceratium into the hypolimnion. Surplus cellular P was low during this period, while alkaline phosphatase activity increased to a maximum, suggesting P limitation of Ceratium production. During late July and August, P-rich interflows from the Eau Galle River entered the reservoir at the base of the epilimnion. Ceratium migrated into these interflows at night, with corresponding increases and decreases in surplus cellular P and alkaline phosphatase activity, respectively. Ceratium production increased to a maximum in early September, following these periods of high external P input. These results directly support the hypothesis that Ceratium can access multiple P sources through vertical migration.

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Doubek, Jonathan P., Kylie L. Campbell, Kaitlyn M. Doubek, Kathleen D. Hamre, Mary E. Lofton, Ryan P. McClure, Nicole K. Ward, and Cayelan C. Carey. "The effects of hypolimnetic anoxia on the diel vertical migration of freshwater crustacean zooplankton." Ecosphere 9, no. 7 (July 2018): e02332. http://dx.doi.org/10.1002/ecs2.2332.

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Peltomaa, E., P. Zingel, and A. Ojala. "Weak response of the microbial food web of a boreal humic lake to hypolimnetic anoxia." Aquatic Microbial Ecology 68, no. 2 (January 10, 2013): 91–105. http://dx.doi.org/10.3354/ame01602.

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Clayer, François, Yves Gélinas, André Tessier, and Charles Gobeil. "Mineralization of organic matter in boreal lake sediments: rates, pathways, and nature of the fermenting substrates." Biogeosciences 17, no. 18 (September 18, 2020): 4571–89. http://dx.doi.org/10.5194/bg-17-4571-2020.

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Abstract. The complexity of organic matter (OM) degradation mechanisms represents a significant challenge for developing biogeochemical models to quantify the role of aquatic sediments in the climate system. The common representation of OM by carbohydrates formulated as CH2O in models comes with the assumption that its degradation by fermentation produces equimolar amounts of methane (CH4) and dissolved inorganic carbon (DIC). To test the validity of this assumption, we modelled using reaction-transport equation vertical profiles of the concentration and isotopic composition (δ13C) of CH4 and DIC in the top 25 cm of the sediment column from two lake basins, one whose hypolimnion is perennially oxygenated and one with seasonal anoxia. Furthermore, we modelled solute porewater profiles reported in the literature for four other seasonally anoxic lake basins. A total of 17 independent porewater datasets are analyzed. CH4 and DIC production rates associated with methanogenesis at the five seasonally anoxic sites collectively show that the fermenting OM has a mean (± SD) carbon oxidation state (COS) value of -1.4±0.3. This value is much lower than the value of zero expected from carbohydrate fermentation. We conclude that carbohydrates do not adequately represent the fermenting OM in hypolimnetic sediments and propose to include the COS in the formulation of OM fermentation in models applied to lake sediments to better quantify sediment CH4 outflux. This study highlights the potential of mass balancing the products of OM mineralization to characterize labile substrates undergoing fermentation in sediments.

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Ricciardi-Rigault, Mahaut, David F. Bird, and Yves T. Prairie. "Changes in sediment viral and bacterial abundances with hypolimnetic oxygen depletion in a shallow eutrophic Lac Brome (Quebec, Canada)." Canadian Journal of Fisheries and Aquatic Sciences 57, no. 6 (June 1, 2000): 1284–90. http://dx.doi.org/10.1139/f00-068.

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Two studies were conducted to examine changes in sediment viral and bacterial abundances following hypolimnetic oxygen depletion. Both studies, a spatiotemporal field study and a core incubation experiment set under controlled conditions, demonstrated that bacterial and viral abundances decreased significantly (43-48% for bacteria and 36-38% for viruses) and in a nearly identical pattern when submitted to changes in the oxygen status of their milieu. The consistency of the results strongly suggests that the shift in both population densities is essentially caused by the onset of anoxia, either directly or indirectly. We suggest that the decline in abundance is due to the disappearance of strictly aerobic bacteria and their associated viruses and not due to stress-induced viral lysis. We also show that the P content of the lysed microbial community can represent an important source of P released from the sediments.

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Jessen, Gerdhard L., Lin-Xing Chen, Jiro F. Mori, Tara E. Colenbrander Nelson, Gregory F. Slater, Matthew B. J. Lindsay, Jillian F. Banfield, and Lesley A. Warren. "Alum Addition Triggers Hypoxia in an Engineered Pit Lake." Microorganisms 10, no. 3 (February 26, 2022): 510. http://dx.doi.org/10.3390/microorganisms10030510.

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Here, we examine the geobiological response to a whole-lake alum (aluminum sulfate) treatment (2016) of Base Mine Lake (BML), the first pilot-scale pit lake established in the Alberta oil sands region. The rationale for trialing this management amendment was based on its successful use to reduce internal phosphorus loading to eutrophying lakes. Modest increases in water cap epilimnetic oxygen concentrations, associated with increased Secchi depths and chlorophyll-a concentrations, were co-incident with anoxic waters immediately above the fluid fine tailings (FFT) layer post alum. Decreased water cap nitrate and detectable sulfide concentrations, as well as increased hypolimnetic phospholipid fatty acid abundances, signaled greater anaerobic heterotrophic activity. Shifts in microbial community to groups associated with greater organic carbon degradation (i.e., SAR11-LD12 subclade) and the SRB group Desulfuromonodales emerged post alum and the loss of specialist groups associated with carbon-limited, ammonia-rich restricted niches (i.e., MBAE14) also occurred. Alum treatment resulted in additional oxygen consumption associated with increased autochthonous carbon production, watercap anoxia and sulfide generation, which further exacerbate oxygen consumption associated with on-going FFT mobilized reductants. The results illustrate the importance of understanding the broader biogeochemical implications of adaptive management interventions to avoid unanticipated outcomes that pose greater risks and improve tailings reclamation for oil sands operations and, more broadly, the global mining sector.

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Ito, Yuji, and Kazuro Momii. "Impacts of regional warming on long-term hypolimnetic anoxia and dissolved oxygen concentration in a deep lake." Hydrological Processes 29, no. 9 (October 16, 2014): 2232–42. http://dx.doi.org/10.1002/hyp.10362.

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Quinlan, Roberto, and John P. Smol. "Using fossil chironomid assemblages to infer changes in hypolimnetic anoxia in 24 south-central Ontario (Canada) shield lakes." SIL Proceedings, 1922-2010 27, no. 3 (November 2000): 1220–25. http://dx.doi.org/10.1080/03680770.1998.11901430.

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Bark, A. W. "Studies on ciliated protozoa in eutrophic lakes: 1. Seasonal distribution in relation to thermal stratification and hypolimnetic anoxia." Hydrobiologia 124, no. 2 (May 1985): 167–76. http://dx.doi.org/10.1007/bf00006798.

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Zander, Paul D., Giulia Wienhues, and Martin Grosjean. "Scanning Hyperspectral Imaging for In Situ Biogeochemical Analysis of Lake Sediment Cores: Review of Recent Developments." Journal of Imaging 8, no. 3 (February 25, 2022): 58. http://dx.doi.org/10.3390/jimaging8030058.

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Hyperspectral imaging (HSI) in situ core scanning has emerged as a valuable and novel tool for rapid and non-destructive biogeochemical analysis of lake sediment cores. Variations in sediment composition can be assessed directly from fresh sediment surfaces at ultra-high-resolution (40–300 μm measurement resolution) based on spectral profiles of light reflected from sediments in visible, near infrared, and short-wave infrared wavelengths (400–2500 nm). Here, we review recent methodological developments in this new and growing field of research, as well as applications of this technique for paleoclimate and paleoenvironmental studies. Hyperspectral imaging of sediment cores has been demonstrated to effectively track variations in sedimentary pigments, organic matter, grain size, minerogenic components, and other sedimentary features. These biogeochemical variables record information about past climatic conditions, paleoproductivity, past hypolimnetic anoxia, aeolian input, volcanic eruptions, earthquake and flood frequencies, and other variables of environmental relevance. HSI has been applied to study seasonal and inter-annual environmental variability as recorded in individual varves (annually laminated sediments) or to study sedimentary records covering long glacial–interglacial time-scales (>10,000 years).

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Outridge, PM. "Seasonal and spatial variations in benthic macroinvertebrate communities of Magela Creek, Northern Territory." Marine and Freshwater Research 39, no. 2 (1988): 211. http://dx.doi.org/10.1071/mf9880211.

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This study examined seasonal and spatial patterns of benthic macroinvertebrate communities in four billabongs and a perennial stream riffle in the Magela Creek catchment, Northern Territory. Chironomids, coleopterans, trichopterans and hydracarina were the most diverse and abundant taxa, although the mussel Velesunio angasi contributed over 98% of total standing crop in most billabongs. Diversity and standing crop were usually higher in littoral than in profundal areas of two shallow billabongs, probably because of the presence of macrophytes. Diversity, abundance and biomass declined sharply over the dry season, from maxima in May-July to minima in December. Recovery in the early wet season was rapid, commencing after the first creek flows in December. The decline and recovery were closely associated with the availability of sediment organic matter, which reflected inputs of mainly allochthonous (terrestrial) detritus over the wet season followed by losses due to intense microbial breakdown. Microbial respiration also seemed related to declines in benthic communities in the latter half of the wet season, by producing hypolimnetic anoxia during periods of reduced creek flow.

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Zhang, Yongdong, Huan Fu, Hanliang Liao, Huihui Chen, and Zhengwen Liu. "Geochemical records of Lake Erhai (South-Western China) reveal the anthropogenically-induced intensification of hypolimnetic anoxia in monomictic lakes." Environmental Pollution 299 (April 2022): 118909. http://dx.doi.org/10.1016/j.envpol.2022.118909.

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Giguet-Covex, Charline, Fabien Arnaud, Jérôme Poulenard, Dirk Enters, Jean-Louis Reyss, Laurent Millet, Jérome Lazzaroto, and Olivier Vidal. "Sedimentological and geochemical records of past trophic state and hypolimnetic anoxia in large, hard-water Lake Bourget, French Alps." Journal of Paleolimnology 43, no. 1 (March 18, 2009): 171–90. http://dx.doi.org/10.1007/s10933-009-9324-9.

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Abdulqader, N. N., B. S. İşgör, A. N. Genç, Enver Güler, and Vahide Cansu Seymenoğlu. "Modeling Surface Water Quality and Nutrient Correlation with Sediment Oxygen Demand at Dam Water Reservoirs." Nature Environment and Pollution Technology 21, no. 4 (December 1, 2022): 1783–806. http://dx.doi.org/10.46488/nept.2022.v21i04.034.

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The work presented here is a model approach based on WASP8 (Water analysis simulation program) a water quality model simulated to represent contaminants at the surface and bottom sediments of Kurtboğazı dam reservoir in Ankara city. However, our water quality output variables: are temperature, nitrate, total phosphorus, total Kjeldahl nitrogen, dissolved oxygen, Chlorophyll a, and ammonia. To ensure the model represents the actual case at the reservoir, the results from the simulation model were calibrated using actual data from the Kurtboğazı dam site, the calibration utilizes statistical techniques. The first method was the goodness-of-fit, R2 between model variables and field data, and the results were in the range of 0.86 to 1.0 indicating excellent linear association. The second technique was the RE, the values of which obtained were less than 1, elaborating acceptable results. The dam reservoir Kurtboğazı had been affected by the negative impact arising from dissolved oxygen depletion in the hypolimnetic layer during stratification periods and that had been well documented. However, the processes of oxygen consumption at the sediment-water interface are still difficult to grasp conceptually and mainly linked to sediment oxygen depletion and the phenomena of sediment oxygen demand SOD. The novelty of this research work is the development of a quality model to predict the reactions of state variables that are occurring at the water body and how they interact with each other and their influence on the overall quality status of the Kurtboğazı reservoir, and the crucial factors influencing the depletion of oxygen at the water column; secondly, the effect of anoxic condition on the benthic flux and the impact of anoxia condition on the ratio of nitrogen to phosphorus ratio at the reservoir. It was evident from the results of calibration that the model successfully simulated the correlation of the parameters influencing the anoxic condition, and benthic flux and ratio shift from nitrogen-limited during the summer to phosphorus-limited at the beginning of winter.

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Sorrel, Philippe, Kévin Jacq, Antonin Van Exem, Gilles Escarguel, Benjamin Dietre, Maxime Debret, Suzanne McGowan, Jules Ducept, Emilie Gauthier, and Hedi Oberhänsli. "Evidence for centennial-scale Mid-Holocene episodes of hypolimnetic anoxia in a high-altitude lake system from central Tian Shan (Kyrgyzstan)." Quaternary Science Reviews 252 (January 2021): 106748. http://dx.doi.org/10.1016/j.quascirev.2020.106748.

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Jones, Gary J., and Wojciech Poplawski. "Understanding and management of cyanobacterial blooms in sub-tropical reservoirs of Queensland, Australia." Water Science and Technology 37, no. 2 (January 1, 1998): 161–68. http://dx.doi.org/10.2166/wst.1998.0130.

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A three year study of two sub-tropical water supply (potable and irrigation) reservoirs - Baroon Pocket and Leslie - aimed to develop an improved understanding and effective management strategy for the control of low level toxic cyanobacterial ‘blooms’. The two reservoirs appear to be typical of those elsewhere in tropical and sub-tropical Australia, being strongly stratified and monomictic if deep, or polymictic to monomictic (depending on inter-annual climatic variation) if shallow. In both reservoirs, thermal stratification appeared to be the key factor influencing the onset and demise of cyanobacterial blooms. Hypolimnetic deoxygenation was rapid during periods of stratification, and high rates of nitrogen and phosphorus release from bottom sediments occurred during anoxia. External nutrient inputs were dominated by episodic storm in-flows following the passing of (sub)tropical depressions, carrying massive sediment and nutrient loads into the reservoirs. As a consequence of this, and coupled with the high degree of internal nutrient recycling and the low national targets for cyanobacterial control in Australia, we believe that reduction of external nutrient inputs alone, through improved catchment management, may not be sufficient to prevent cyanobacterial blooms. Therefore, more emphasis should be given to ‘in-lake’ control strategies such as destratification, biomanipulation and in situ sediment treatment.

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Ogutu-Ohwayo, Richard, and R. E. Hecky. "Fish Introductions in Africa and Some of Their implications." Canadian Journal of Fisheries and Aquatic Sciences 48, S1 (December 19, 1991): 8–12. http://dx.doi.org/10.1139/f91-299.

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Fish introductions in Africa have been made at various spatial scales from small fish ponds to the largest lakes, primarily to sustain or increase production, though some were to develop sport fisheries and to control unwanted organisms. Some introductions have fulfilled their objective in the short term, but several "successful" introductions have created uncertainties about their long-term sustainability. Lates niloticus, Oreochromis niloticus, O. leucostictus, Tilapia melanopleura and T. zilli were introduced into Lakes Victoria and Kyoga in 1950's and early 1960's; by the 1980's L. niloticus and O. niloticus dominated the fisheries, having virtually eliminated a number of endemic species. In Lake Victoria, the loss of genetic diversity has been accompanied by a loss of trophic diversity; the transformation of the fish community coincided with profound eutrophication (algal blooms, fish kills, hypolimnetic anoxia) which might be related to alterations of the lake's food-web structure. By contrast, the introduction of a planktivore, Limnothrissa miodon into Lake Kivu and the Kariba reservoir has established highly successful fisheries with little effect on the pre-existing fish community or trophic ecology. The endemic species-rich African Great Lakes may be particularly sensitive to introductions. Species extinctions, introgressive hybridization and ecosystem alterations may occur following introductions.

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Marcé, Rafael, Enrique Moreno-Ostos, and Joan Armengol. "The role of river inputs on the hypolimnetic chemistry of a productive reservoir: implications for management of anoxia and total phosphorus internal loading." Lake and Reservoir Management 24, no. 1 (March 2008): 87–98. http://dx.doi.org/10.1080/07438140809354053.

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Cadieux, Sarah B., Jeffrey R. White, and Lisa M. Pratt. "Exceptional summer warming leads to contrasting outcomes for methane cycling in small Arctic lakes of Greenland." Biogeosciences 14, no. 3 (February 7, 2017): 559–74. http://dx.doi.org/10.5194/bg-14-559-2017.

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Abstract. In thermally stratified lakes, the greatest annual methane emissions typically occur during thermal overturn events. In July of 2012, Greenland experienced significant warming that resulted in substantial melting of the Greenland Ice Sheet and enhanced runoff events. This unusual climate phenomenon provided an opportunity to examine the effects of short-term natural heating on lake thermal structure and methane dynamics and compare these observations with those from the following year, when temperatures were normal. Here, we focus on methane concentrations within the water column of five adjacent small lakes on the ice-free margin of southwestern Greenland under open-water and ice-covered conditions from 2012–2014. Enhanced warming of the epilimnion in the lakes under open-water conditions in 2012 led to strong thermal stability and the development of anoxic hypolimnia in each of the lakes. As a result, during open-water conditions, mean dissolved methane concentrations in the water column were significantly (p < 0.0001) greater in 2012 than in 2013. In all of the lakes, mean methane concentrations under ice-covered conditions were significantly (p < 0.0001) greater than under open-water conditions, suggesting spring overturn is currently the largest annual methane flux to the atmosphere. As the climate continues to warm, shorter ice cover durations are expected, which may reduce the winter inventory of methane and lead to a decrease in total methane flux during ice melt. Under open-water conditions, greater heat income and warming of lake surface waters will lead to increased thermal stratification and hypolimnetic anoxia, which will consequently result in increased water column inventories of methane. This stored methane will be susceptible to emissions during fall overturn, which may result in a shift in greatest annual efflux of methane from spring melt to fall overturn. The results of this study suggest that interannual variation in ground-level air temperatures may be the primary driver of changes in methane dynamics because it controls both the duration of ice cover and the strength of thermal stratification.

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Dreßler, Mirko, Thomas Hübener, Solvig Görs, Petra Werner, and Uwe Selig. "Multi-proxy Reconstruction of Trophic State, Hypolimnetic Anoxia and Phototrophic Sulphur Bacteria Abundance in a Dimictic Lake in Northern Germany over the past 80 Years." Journal of Paleolimnology 37, no. 2 (May 20, 2006): 205–19. http://dx.doi.org/10.1007/s10933-006-9013-x.

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Rogozin, D. Y., A. V. Darin, V. V. Zykov, I. A. Kalugin, and A. O. Bulkhin. "Seasonal sedimentation in saline Lake Shira (Siberia, Russia) and meromixis: implications for regional paleoclimate reconstructions." Limnology and Freshwater Biology, no. 4 (2022): 1547–49. http://dx.doi.org/10.31951/2658-3518-2022-a-4-1547.

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Abstract. Detailed studies of processes of sediment record formation are necessary for accurate sediment-derived paleo-environmental reconstructions. We conducted the multi-year seasonal sediment evolution of sediment fluxes of chemical elements, organic and inorganic carbon, total nitrogen, and photosynthetic pigments for a period from 2012 to 2017. In 2013, 2016, 2017, and 2018, we estimated the contents of photosynthetic pigments in the uppermost sediment layers frozen in situ with a freeze-corer. In 2015 and 2016, a rare event of transition from meromixis (i.e. long-term hypolimnetic anoxia) to holomixis was observed, which was accompanied by the temporary disappearance of hydrogen sulfide from the water column in spring and a decrease in hydrogen sulfide in other seasons compared to the meromictic state. We have demonstrated that okenone and Mo in the Lake Shira sediments reflect the presence of hydrogen sulfide in the water column. However, the okenone showed smoothened multi-year dynamics without a pronounced seasonal one. Therefore, the okenone can be a proxy of sulphidic conditions in photic zone and weakly depend on seasons whereas Mo can be used as an indicator of winter periods when analyzed in cores with annual resolution. Sedimentation fluxes of other substances showed typical seasonal dynamics with a minimum in winter and a maximum in late summer and autumn. All chemical elements in the sedimentation flow can be roughly divided into those associated with organic matter and terrigenous-chemogenous. The components of the second group showed a pronounced peak of sedimentation in autumn 2012 and summer 2017 presumably due to the increased amount of precipitation at that time. This demonstrates the relationship between the terrigenous components and the climate humidity for this lake. Besides, it reflects the irregularity of annual varves composition.

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Gemza, A. F. "Water Quality Improvements during Hypolimnetic Oxygenation in Two Ontario Lakes." Water Quality Research Journal 32, no. 2 (May 1, 1997): 365–90. http://dx.doi.org/10.2166/wqrj.1997.024.

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Abstract Two eutrophic lakes with seasonally anoxic hypolimnion were oxygenated utilizing hypolimnetic pure oxygen injection during 1995. Natural stratification was not disturbed. At Whittaker Lake, hypolimnetic oxygen levels were maintained between 4.0 and 5.0 ppm. Hypolimnetic total phosphorus concentrations did not increase beyond spring turnover levels, and lower concentrations of iron and manganese were measured, along with the elimination of all detectable hydrogen sulphide. The typical blue-green algal blooms fouling shorelines in the late summer and fall did not manifest themselves, but improvements in water clarity were not as dramatic as those observed at the second study site. During hypolimnetic oxygen injection in Heart Lake, where hypolimnetic oxygen levels were maintained at 2.0 ppm, the decline of zooplankton populations after a brief spring surge (clear water phase) was stopped and a shift to larger-bodied herbivorous cladocerans was observed — Bosminids were replaced by Ceriodaphnia species. Annual median water clarity improved from preaeration readings of 1.9 m to over 3.0 m. Small increases in hypolimnetic total phosphorus concentrations were observed in late summer under low level oxygenation, but were significantly less than pretreatment concentrations. The maintenance of an oxic hypolimnetic refugia not accessible to predator fish, but still able to oxidize sediments, was deemed important to the water clarity improvements. Historically low blue-green algal biovolumes and chlorophyll concentrations were recorded, and no beach closures due to algal blooms occurred. Hypolimnetic oxygenation is an effective tool which can improve lake water quality and ecosystem integrity.

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Eckley, C. S., C. J. Watras, H. Hintelmann, K. Morrison, A. D. Kent, and O. Regnell. "Mercury methylation in the hypolimnetic waters of lakes with and without connection to wetlands in northern Wisconsin." Canadian Journal of Fisheries and Aquatic Sciences 62, no. 2 (February 1, 2005): 400–411. http://dx.doi.org/10.1139/f04-205.

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Rates of Hg methylation and demethylation were measured in anoxic hypolimnetic waters of two pristine Wisconsin lakes using stable isotopes of Hg as tracers. One of the lakes is a clear-water seepage lake situated in sandy terrain with minimal wetland influence. The other is a dark-water lake receiving channelized inputs from a relatively large terrestrial wetland. Methyl mercury (MeHg) accumulated in the anoxic hypolimnia of both lakes during summer stratification, reaching concentrations of 0.8 ng·L1 in the clear-water lake and 5 ng·L1 in the dark-water lake. The stable isotopic assays indicated that rate constants of Hg(II) methylation (Km) ranged from 0.01 to 0.04·day1 in the clear-water lake and from 0.01 to 0.09·day1 in the dark-water lake, depending on the depth stratum. On average, Km was threefold greater in the dark-water lake. Hypolimnetic demethylation rate constants (Kdm) averaged 0.03·day1 in the clear-water lake and 0.05·day1 in the dark-water lake. These methylation rates were sufficient to account for the observed accumulation of MeHg in hypolimnetic water during summer in both lakes. Despite substantial export of MeHg from the wetland to the dark-water lake, our study indicates that in-lake production and decomposition of MeHg dominated the MeHg cycle in both lakes.

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Aku, PMK, and W. M. Tonn. "Changes in population structure, growth, and biomass of cisco (Coregonus artedi) during hypolimnetic oxygenation of a deep, eutrophic lake, Amisk Lake, Alberta." Canadian Journal of Fisheries and Aquatic Sciences 54, no. 9 (September 1, 1997): 2196–206. http://dx.doi.org/10.1139/f97-118.

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Although most hypolimnetic oxygenation studies are designed to enhance cold-water fish populations, production-related responses have rarely been evaluated. We examined changes in density, biomass, and growth rate of cisco (Coregonus artedi) in Amisk Lake during 1989-1991, when one of the basins received hypolimnetic oxygenation, and in the nearby, untreated Baptiste Lake during 1990-1991. Variations in monthly density and biomass estimated using hydroacoustics suggested that as summer progressed, cisco in Amisk Lake responded behaviorally to hypolimnetic oxygenation by migrating from the hypoxic reference basin into the treated basin where oxygen concentrations remained high; by summer's end, the treated basin supported a density and biomass of fish that were twice as great as in the reference. Whole-lake fish density increased almost fivefold and biomass tripled in Amisk Lake during treatment, but there were no parallel changes in Baptiste Lake, where the hypolimnion remained anoxic each summer. Growth rate and condition of cisco in Amisk Lake decreased during treatment compared with pretreatment data, suggesting a density-dependent relationship with biomass; no coincident change in growth rate occurred in Baptiste Lake. These results suggest that hypolimnetic oxygenation can be an effective technique to enhance cold-water fish production, especially if combined with other management practices, such as regulated fish exploitation.

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45

Aku, PMK, L. G. Rudstam, and W. M. Tonn. "Impact of hypolimnetic oxygenation on the vertical distribution of cisco (Coregonus artedi) in Amisk Lake, Alberta." Canadian Journal of Fisheries and Aquatic Sciences 54, no. 9 (September 1, 1997): 2182–95. http://dx.doi.org/10.1139/f97-124.

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Using hydroacoustics and vertical gill nets, we evaluated the efficacy of hypolimnetic oxygenation as a lake management tool by quantifying summer vertical distributions of cisco (Coregonus artedi) in a treated and untreated basin of Amisk Lake, Alberta, during and after oxygenation (1988-1993) and in untreated Baptiste Lake, Alberta. In Baptiste Lake, the hypolimnion remained anoxic and cisco were restricted to epilimnetic waters. Oxygenation increased hypolimnetic dissolved oxygen (DO) concentrations in Amisk Lake, expanding habitat by up to 9 m. During oxygenation, hypolimnetic DO remained above concentrations avoided by cisco (<1.3 mg ·L-1) in the treated basin, but fell below this level by midsummer in the reference basin. Consequently, cisco were distributed up to 8 m deeper in the treated than in the reference basin. In August 1990, a metalimnetic oxygen minimum in the reference basin confined >70% of the cisco to the epilimnion, while >60% of the fish inhabited the metalimnion and hypolimnion in the treated basin. Although DO remained above avoidance concentrations throughout most of the treated basin, the highest densities of cisco occurred in water with mean ( ± SD) DO concentration and temperature of 3.1 ± 1.3 mg ·L-1 and 11.8 ± 2.1oC, respectively. Thus, the extent of habitat expansion for fish during oxygenation programs will also depend on the availability of suitable temperatures.

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Dinsmore, W. P., and E. E. Prepas. "Impact of hypolimnetic oxygenation on profundal macroinvertebrates in a eutrophic lake in central Alberta. II. Changes in Chironomus spp. abundance and biomass." Canadian Journal of Fisheries and Aquatic Sciences 54, no. 9 (September 1, 1997): 2170–81. http://dx.doi.org/10.1139/f97-123.

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Effects of hypolimnetic oxygenation on profundal (15-25 m depth) Chironomus spp. in double-basined Amisk Lake were studied from 1988 to 1991. Responses were species specific. Mean densities and biomasses of C. anthracinus at 25 m increased 55- and 109-fold, respectively, in the treated north basin over the study period. Densities also increased in the reference south basin, but mean larval weights and biomasses were significantly lower than in the treated basin (P < 0.001). Anoxic conditions in the hypolimnion (dissolved oxygen concentrations <1 mg ·L-1), rather than low hypolimnetic temperatures, appeared to limit C. anthracinus distribution in Amisk Lake. Major changes in C. anthracinus abundance were not apparent until 2 years after the treatment commenced. Densities and biomasses of C. cucini were higher in the reference basin than in the treated basin of Amisk Lake. Densities of the C. decorus and C. plumosus groups increased in the treated basin but remained of minor importance. In comparison, densities of the C. cucini and C. plumosus groups at 25 m in the reference south basin of nearby Baptiste Lake declined over the study period. Increased profundal Chironomus spp. abundance in Amisk Lake suggested an increase in potential fish food.

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Kesler, David H., and Gerrit L. Verschuur. "Hypolimnetic Oxygen Deficits and Anoxic Factors in Garner Lake, a West Tennessee Reservoir." Lake and Reservoir Management 12, no. 4 (December 1996): 462–67. http://dx.doi.org/10.1080/07438149609354286.

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Beutel, Marc W. "Inhibition of ammonia release from anoxic profundal sediments in lakes using hypolimnetic oxygenation." Ecological Engineering 28, no. 3 (December 2006): 271–79. http://dx.doi.org/10.1016/j.ecoleng.2006.05.009.

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49

Nürnberg, Gertrud K., Rosemary Hartley, and Edward Davis. "Hypolimnetic withdrawal in two north american lakes with anoxic phosphorus release from the sediment." Water Research 21, no. 8 (January 1987): 923–28. http://dx.doi.org/10.1016/s0043-1354(87)80009-x.

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Hamre, Kathleen D., Mary E. Lofton, Ryan P. McClure, Zackary W. Munger, Jonathan P. Doubek, Alexandra B. Gerling, Madeline E. Schreiber, and Cayelan C. Carey. "In situ fluorometry reveals a persistent, perennial hypolimnetic cyanobacterial bloom in a seasonally anoxic reservoir." Freshwater Science 37, no. 3 (September 2018): 483–95. http://dx.doi.org/10.1086/699327.

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Journal articles on the topic 'Hypolimnetic anoxia'

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