Lakes in cold ecoregions

– Indicators for Climate Change Impacts –

Interactions between Climate Change, other stressors and the biota are complex. What are the main impacts? Which simple parameters are suited to detect them?

Here we suggest indicators, which reflect the main effects of Climate Change on freshwater ecosystems.

Within the Euro-Limpacs consortium there is an ongoing discussion about the best suited indicators. On this page you find a first selection, which will frequently be updated and improved within 2008.

• Biological parameters

  • Acidification effects on phytoplankton

    Climate Region	Cold
    Ecosystem type	Shallow lakes
    Stressor type	Temperature
    Responding parameter group	Biological parameters
    Responding parameter	Acidification effects on phytoplankton

    Response description

    Droughts are related to El Nino. Acidification pulses occur due to draught (El Nino). Acidification pulses will cause changes in phytoplankton richness and biomass.

    Secondary effects

    Pulse or increase acidification events will also cause changes in diversity and/or biomass of other sensitive biota groups.

    Specification of relevant ecosystem type

    Limited to lakes with silicious catchments prone to acidification.

    Relevant ecoregion(s) according to Illies

    Borealic Uplands (20), Tundra (21), Fennoscandian Shield (22), Taiga (23)

    Suggested indicator

    pH; biotic acid indices

    Justification of indicator

    pH is easy to record and often incorporated in water chemistry monitoring. As pH varies seasonally and daily, biotic indices are often more stable and better reflect the acidification status of a lake.

    Reference(s)

    Arnott, S.E., B. Keller, P.J Dillon, N. Yan, M. Paterson & D. Findlay (2003): Using temporal coherence to determine the response to climate change in boreal shield lakes. Environmental Monitoring and Assessment 88: 365-388.

  • Water temperature effects on cold water fish

    Climate Region	Cold
    Ecosystem type	Deep lakes
    Stressor type	Temperature
    Responding parameter group	Biological parameters
    Responding parameter	Water temperature effects on cold water fish

    Response description

    Higher water temperatures (especially in the epilimnion) lead to the progressively reduction of thermal habitats for e.g. Salvelinus namaycush. As a result, cold water species will disappear from littoral areas in spring and summer. Furthermore, higher water temperatures will reduce reproduction success of cold water species and increase parasitic and predator pressure on the egg and young life stages.

    Secondary effects

    Warm water species might invade cold water region lakes with subsequently changes in food webs.

    Specification of relevant ecosystem type

    Relevant for all small lakes in cold ecoregions.

    Relevant ecoregion(s) according to Illies

    Borealic Uplands (20), Tundra (21), Fennoscandian Shield (22), Taiga (23)

    Suggested indicator

    Summer water temperature or air temperature

    Justification of indicator

    Water temperature is easy to measure, but even air temperature reflects warming up of mixed layer temperature, since increases in mean mixed layer temperatures correspond to 85% of increases in air temperatures.

    Reference(s)

    McDonald, M.E., A.E. Hershey & M.C. Miller (1996): Global warming impacts on lake trout in arctic lakes. Limnology and Oceanography 41(5): 1102-1108. Nyberg,P., E. Bergstrand, E. Degerman & O. Enderlein (2001): Recruitment of pelagic fish in an unstable climate: studies in Sweden´s four largest lakes. Ambio 30/8: 559-564.

  • Water temperature effects on phytoplankton

    Climate Region	Cold
    Ecosystem type	Shallow lakes
    Stressor type	Temperature
    Responding parameter group	Biological parameters
    Responding parameter	Water temperature effects on phytoplankton

    Response description

    Increasing water temperatures lead to increased relative abundance of diatoms, but also to even higher early summer bacterial biomass with subsequently shift from a dominance of diatoms and cryptophtes to cyanbacteria. This effect is especially pronounced at temperatures > 20°C, since cyanobacteria (especially large, filamentous) and green algae are favoured at higher temperatures.

    Secondary effects

    Higher temperatures and shift in phytoplankton community composition leads to higher probability of cyanobacteria blooms with subsequent oxygen depletion in the hypolimnion and effects on zooplankton and benthic fauna.

    Specification of relevant ecosystem type

    Effect might be strongest in shallow and/or eutrophic lakes with anoxic hypolimnia.

    Relevant ecoregion(s) according to Illies

    Borealic Uplands (20), Tundra (21), Fennoscandian Shield (22), Taiga (23)

    Suggested indicator

    Phytoplankton biomass and composition, cyanobacterial algal blooms.

    Justification of indicator

    The shift in community composition gives information about the response of biota to changed lake characteristics as water temperatures. Phytoplankton community composition is routinely monitored for the Water Framework Directive.

    Reference(s)

    Findlay, D.L., S.E.M. Kasian, M.P. Stainton, K. Beaty & M. Lyng (2001): Climatic influences on algal populations of boreal forest lakes in the Experimental Lakes Area. Limnology and Oceanography 46(7): 1784-1793.  Weyhenemeyer, G.A., T. Bleckner & K. Pettersson (1999): Changes of the plankton spring outburst related to the North Atlantic Oscillation. Limnology and Oceanography 44(7): 1788-1792.

• Hydromorphological parameters

  • Ice cover

    Climate Region	Cold
    Ecosystem type	Shallow lakes
    Stressor type	Temperature
    Responding parameter group	Hydromorphological parameters
    Responding parameter	Ice cover

    Response description

    Higher air and thus higher water temperature leads to a shorter ice cover period and to an earlier ice-breakup. The relationship between air temperature and timing of lake ice-breakup shows an arc cosine function. This nonlinearity results in marked differences in the response of ice-breakup timing to changes in air temperature between colder and warmer regions. Furthermore, there is thinner ice and snow cover due to elevated air and water temperature.

    Secondary effects

    Shorter ice cover periods and earlier ice-breakup results in thermal instability and also in changes of food-web dynamics. Earlier ice-breakup results in earlier phytoplankton growth and thus earlier clearwater timing. Thinner ice and snow cover favours phytoplankton growth in winter below ice resulting in increasing chlorophyll levels.

    Specification of relevant ecosystem type

    Relevant for all small lakes in cold ecoregions.

    Relevant ecoregion(s) according to Illies

    Borealic Uplands (20), Tundra (21), Fennoscandian Shield (22), Taiga (23)

    Suggested indicator

    Ice cover duration, timing of ice-breakup, ice thickness.

    Justification of indicator

    Ice cover duration is simple to monitor, e.g. by remote sensing.

    Reference(s)

    Pettersson, K. & K. Grust (2002): Seasonality of nutrients in Lake Erken - effects of weather conditions. Verh. Internat. Verein. Limnol. 28: 731-734. Pettersson, K., K. Grust , G. Weyhenmeyer & T. Blenckner (2003): Seasonality of chlorophyll and nutrients in Lake Erken - effects of weather conditions. Hydrobiologia 506: 75-81. 

  • Precipitation/evapotranspiration

    Climate Region	Cold
    Ecosystem type	Shallow lakes
    Stressor type	Temperature
    Responding parameter group	Hydromorphological parameters
    Responding parameter	Precipitation/evapotranspiration

    Response description

    Lower precipitation and higher evaporation changes water residence time. Lower precipitation means also less snow and earlier thawing which affects light conditions in the water.

    Secondary effects

    Changes in residence time and mixing processes lead to decreased nutrients entrainment. A higher residence time has effect on the availability of eutrophying substances. Changes in light conditions will lead to earlier phytoplankton growth and an increase in biomass.

    Specification of relevant ecosystem type

    Relevant for all small lakes in cold ecoregions.

    Relevant ecoregion(s) according to Illies

    Borealic Uplands (20), Tundra (21), Fennoscandian Shield (22), Taiga (23)

    Suggested indicator

    Water temperature (maximum monthly values)

    Justification of indicator

    Water temperature is easy to measure, but even air temperature reflects warming up of mixed layer temperature, since increases in mean mixed layer temperatures correspond to 85% of increases in air temperatures.

    Suggested indicator 2

    Phytoplankton

    Justification of indicator 2

    Autotrophs are considered to respond quickly to changes in nutrient concentrations.

    Reference(s)

    Schindler, D.W., K.G. Beaty, E.J. Fee, D.R. Cruikshank, E.R. DeBruyn, D.L. Findlay, G.A. Linsey, J.A. Shearer, M.P. Stainton, M.A. Turner (1990): Effects of Climatic warming on lakes of the Central Boreal Forest. Science 250: 967-970. 

  • Stratification

    Climate Region	Cold
    Ecosystem type	Shallow lakes
    Stressor type	Temperature
    Responding parameter group	Hydromorphological parameters
    Responding parameter	Stratification

    Response description

    Higher temperatures result in earlier onset and prolongation of summer stratification. As a result, changing mixing processes occur and systems may change from dimictic to warm monomictic. A lack of full turnover in winter might lead to a permanent thermocline in deeper regions (below shallow seasonal thermocline).

    Secondary effects

    Changes in mixing processes lead to decreased nutrients entrainment. Less intense mixing and increased thermal stability result in oxygen depletion in deeper regions with subsequently phosphate and ammonium (i.e. nutrients in general) release from the sediment. Anoxia in the hypolimnion leads to benthic species extinctions, especially sensitive chironomids. Nutrient (N, P) availability leads to eutrophication with several effects such as increased algae growth, (further) oxygen depletion during night times, extinction of sensitive species such as brown trout (Salmo trutta).

    Specification of relevant ecosystem type

    Relevant for all small lakes in cold ecoregions.

    Relevant ecoregion(s) according to Illies

    Borealic Uplands (20), Tundra (21), Fennoscandian Shield (22), Taiga (23)

    Suggested indicator

    Duration of summer stratification as reflected by water temperature

    Justification of indicator

    Water temperature well reflect the status of lake stratification.

    Reference(s)

    Pettersson, K. & K. Grust (2002): Seasonality of nutrients in Lake Erken ? effects of weather conditions. Verhandlungen Internationale Vereinigung Limnologie 28: 731-734.
    Bleckner, T., A. Omstedt & M. Rummukainen (2002): A Swedish case study of contemporary and possible future consequences of climate change on lake function. Aquatic Sciences 64: 171-184. 

• Physico-chemical parameters

  • Salinity

    Climate Region	Cold
    Ecosystem type	Shallow lakes
    Stressor type	Temperature
    Responding parameter group	Physico-chemical parameters
    Responding parameter	Salinity

    Response description

    Warmer winters cause extreme rainstorms and heavy sea-salt deposition. Storms will lead to frequent turnover and changed stratification times, whereas increased salt deposition might affect water chemistry.

    Secondary effects

    Heavy sea salt deposition increase acidifying substances which will have effects on the entire food web.

    Specification of relevant ecosystem type

    Limited to lakes with silicious catchments prone to acidification.

    Relevant ecoregion(s) according to Illies

    Borealic Uplands (20), Tundra (21), Fennoscandian Shield (22), Taiga (23)

    Suggested indicator

    acidifying substances

    Justification of indicator

    These parameters are easy to record and often incorporated into routine water chemistry monitoring.

    Reference(s)

    Andersen, D.O. (2003): Impacts of warm winters and extreme rainstorms on the base consumption in a limed lake, southern Norway. The Science of the Total Environment 313: 127-139.

  • Sulphate concentration

    Climate Region	Cold
    Ecosystem type	Shallow lakes
    Stressor type	Temperature
    Responding parameter group	Physico-chemical parameters
    Responding parameter	Sulphate concentration

    Response description

    With less precipitation in El Nino- years and resulting droughts, stored reduced S in anoxic zones (wetlands) are oxidised during drought, with subsequently high sulphate export rates after droughts. Elevated sulphate concentrations in lakes (in spite of decreased atmospheric sulphate) will be the results. Sulphate concentrations in lakes are strongly predicted by regional/global scale climate indices (SOI, ENSO) and sulphate deposition indices. Large-scale climate factors play a major role in determining the response of lakes to sulphate deposition and recovery.

    Secondary effects

    Elevated sulphate concentration confounds recovery of lake ecosystems from acidification.

    Specification of relevant ecosystem type

    Limited to lakes with silicious catchments prone to acidification

    Relevant ecoregion(s) according to Illies

    Borealic Uplands (20), Tundra (21), Fennoscandian Shield (22), Taiga (23)

    Suggested indicator

    Sulphate concentration

    Justification of indicator

    ; Directly reflecting the responding parameter; Often incorporated into routine water quality monitoring

    Reference(s)

    Aherne, J., T. Larssen, P.J. Dillon, B.J. Cosby (2004): Effects of climate events on environmental fluxes from forested catchments in Ontario, Canada: Modelling drought-induced redox processes. Water, Air and Soil Pollution: Focus 4: 37-48.
    Dillon, P.J., K.M. Somers, J. Findeis & M.C. Eimers (2003): Coherent response of lakes in Ontario, Canada to reductions in sulphur deposition: the effect of climate on sulphate concentrations. Hydrology and Earth Sytem Sciences 7(4): 583-595. 

  • TOC run-off patterns

    Climate Region	Cold
    Ecosystem type	Shallow lakes
    Stressor type	Temperature
    Responding parameter group	Physico-chemical parameters
    Responding parameter	TOC run-off patterns

    Response description

    Warmer winters produce higher levels of run-off TOC release with subsequently increasing TOC water concentrations.

    Secondary effects

    Changes in water colour might cause changes in light conditions which will have an effect on phytoplankton growth and oxygen concentrations in the profundal.

    Specification of relevant ecosystem type

    Relevant for all small lakes in cold ecoregions.

    Relevant ecoregion(s) according to Illies

    Borealic Uplands (20), Tundra (21), Fennoscandian Shield (22), Taiga (23)

    Suggested indicator

    TOC levels and/or absorbance (water colour).

    Justification of indicator

    Water TOC concentrations reflect changes in run-off and input of allochtonous material.

    Reference(s)

    Wright, R.F. and Jenkins, A. (2001): Climate change as a confounding factor in reversibility of acidification: RAIN and CLIMEX projects. Hydrology and Earth System Sciences 5(3): 477-486.