Rivers 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.

• Small rivers

  Biological parameters

  • Increase of algae growth rates

    Climate Region	Cold
    Ecosystem type	Small rivers
    Stressor type	Temperature
    Responding parameter group	Biological parameters
    Responding parameter	Increase of algae growth rates

    Response description

    With increasing water temperatures, growth of benthic algae will stop later in autumn and start earlier in spring.

    Secondary effects

    Increased food availability for grazers in the macroinvertebrate community. Increased grazer abundance.

    Specification of relevant ecosystem type

    Relevant for all small rivers in cold ecoregions.

    Relevant ecoregion(s) according to Illies

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

    Suggested indicator

    Water temperature (maximum and minimum monthly values) in winter

    Justification of indicator

    Algae growth in winter is inhibited by water temperatures.

  • Increase of species number

    Climate Region	Cold
    Ecosystem type	Small rivers
    Stressor type	Temperature
    Responding parameter group	Biological parameters
    Responding parameter	Increase of species number

    Response description

    Low temperatures are a migration and physiological barrier for many aquatic species. With temperature increase several species can invade.

    Secondary effects

    Changes in community composition

    Specification of relevant ecosystem type

    Relevant for all small rivers in cold ecoregions.

    Relevant ecoregion(s) according to Illies

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

    Suggested indicator

    Number of species (e.g. fish, selected invertebrates groups)

    Justification of indicator

    The increase of species numbers is best evaluated by a simple richness index, e.g. the number of species, which can easily inferred from routine monitoring results.

    Reference(s)

    Jacobsen, D., R. Schultz & A. Encalada (1997): Structure and diversity of stream invertebrate assemblages: the influence of temperature with altitude and latitude. Freshwater Biology 38: 247-261.

  • Replacement of cold water species (fish, macroinvertebrates)

    Climate Region	Cold
    Ecosystem type	Small rivers
    Stressor type	Temperature
    Responding parameter group	Biological parameters
    Responding parameter	Replacement of cold water species (fish, macroinvertebrates)

    Response description

    Many fish and invertebrate species in cold regions are highly adapted to cold water temperatures and vanish with higher temperatures.

    Secondary effects

    Species more tolerant to warm temperatures will invade the formerly cold water areas; thus, the entire community will change.

    Specification of relevant ecosystem type

    Relevant for all small rivers 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

    Physiologic barriers are mainly determined by extremes. For cold water species these are too warm temperatures in crucial phases of their life cycle.

    Reference(s)

    Hauer, F.R., J.S. Baron, D.H. Campbell, K.D. Fausch, S.W. Hostetler, G.H.Leavesley, P.R. Leavitt, D.M. Macknight & & J.A. Stanford (1997): Assessment of climate change and freshwater ecosystems of the Rocky Mountains, USA and Canada. Hydrological Processes 11: 903-924.

  • Replacement of salmonid by cyprinid fish species

    Climate Region	Cold
    Ecosystem type	Small rivers
    Stressor type	Temperature
    Responding parameter group	Biological parameters
    Responding parameter	Replacement of salmonid by cyprinid fish species

    Response description

    Higher water temperatures will reduce reproductive success of salmonid species and increase parasitic and predator pressure on the egg and young larval stages. Warm water cyprinid species will invade in cold water regions.

    Secondary effects

    Food webs will change if salmonid species as main predators of macroinvertebrates will be reduced.

    Specification of relevant ecosystem type

    Relevant for all small rivers in cold ecoregions.

    Relevant ecoregion(s) according to Illies

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

    Suggested indicator

    Water temperature (maximum and minimum monthly values); fish species composition

    Justification of indicator

    The eggs of salmonid species need high oxygen concentrations which will be reduced by higher water temperatures. Parasites and fungi benefit of high temperatures.

  • Standing stock of cold water fish

    Climate Region	Cold
    Ecosystem type	Small rivers
    Stressor type	Temperature
    Responding parameter group	Biological parameters
    Responding parameter	Standing stock of cold water fish

    Response description

    Brook trout populations could either benefit from increased growth rates in spring and fall, or suffer from shrinking habitat and reduced growth rates in summer, depending on the magnitude of temperature change and on food availability. A stream temperature increase of 2 °C or less likely increase brook trout growth, while the effect of larger temperature increases is less predictable. A 15 to 20% increase in food consumption would be required to maintain growth rates with an increase of 2 °C, and 30 to 40% increase in food consumption would be required with an increase of 4 °C.

    Secondary effects

    Increased food consumption by trout.

    Specification of relevant ecosystem type

    Relevant for all small mountain rivers in cold ecoregions.

    Relevant ecoregion(s) according to Illies

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

    Suggested indicator

    Abundance and biomass of brook trout

    Justification of indicator

    Brook trout is a keystone species in most Northern European countries.

    Reference(s)

    Ries, R.D. & S.A. Perry (1995): Potential effects of global climate warming on brook trout growth and prey consumption in central Appalachian streams, USA. Climate Research 5(3): 197-206.

• Hydromorphological parameters

  • Decrease in ice cover duration

    Climate Region	Cold
    Ecosystem type	Small rivers
    Stressor type	Hydrology / Morphology
    Responding parameter group	Hydromorphological parameters
    Responding parameter	Decrease in ice cover duration

    Response description

    Higher temperatures will reduce ice cover duration.

    Secondary effects

    Prolonged macrophyte and algae growth, increased primary production, eutrophication.

    Specification of relevant ecosystem type

    Relevant for all small rivers in cold ecoregions.

    Relevant ecoregion(s) according to Illies

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

    Suggested indicator

    Ice cover duration

    Justification of indicator

    Depending on the region ice cover duration is between three and four month. Ice cover is a key factor for the productivity of boreal aquatic ecosystems and easy to monitor.

    Reference(s)

    Finstad, A.G., T. Forseth, et al. (2004): The importance of ice cover for energy turnover in juvenile Atlantic salmon. Journal of Animal Ecology 73(5): 959-966.

• Physico-chemical parameters

  • Acidification

    Climate Region	Cold
    Ecosystem type	Small rivers
    Stressor type	Hydrology / Morphology
    Responding parameter group	Physico-chemical parameters
    Responding parameter	Acidification

    Response description

    Increased precipitation increases acid runoff from borealic coniferous forests leading to cascading acidification effects on aquatic biota.

    Secondary effects

    Disappearance of acid sensitive species.

    Specification of relevant ecosystem type

    Relevant for all small rivers in cold ecoregions.

    Relevant ecoregion(s) according to Illies

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

    Suggested indicator

    pH-value, invertebrate-based acid-indices.

    Justification of indicator

    pH-values decreases with increasing acid deposition. Since these events are of short duration, community based indices are often better reflecting acidification.

  • Increase of eutrophying substances

    Climate Region	Cold
    Ecosystem type	Small rivers
    Stressor type	Temperature
    Responding parameter group	Physico-chemical parameters
    Responding parameter	Increase of eutrophying substances

    Response description

    N flux in the runoff and decomposition of soil organic matter increases with temperature, which will increase the concentration of nutrients in the river.

    Secondary effects

    Algae growth will increase, leading to oxygen depletion at night times.

    Specification of relevant ecosystem type

    Relevant for all small rivers in boreal forest in cold ecoregions.

    Relevant ecoregion(s) according to Illies

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

    Suggested indicator

    Nitrate, total N, phosphate

    Justification of indicator

    Nutrients are routinely monitored in most European countries.

    Reference(s)

    Wright, R. F. (1998): Effect of increased carbon dioxide and temperature on runoff chemistry at a forested catchment in southern Norway (CLIMEX Project). Ecosystems 1: 216-225.

  • Increase of respiration rate

    Climate Region	Cold
    Ecosystem type	Small rivers
    Stressor type	Temperature
    Responding parameter group	Physico-chemical parameters
    Responding parameter	Increase of respiration rate

    Response description

    The metabolic rates of bacteria and fungi and the metabolic rates of detritivorous species will rise with increasing temperatures. The proportion between primary production and respiration will decrease.

    Secondary effects

    Less organic material (fine and coarse pariculate organic matter) will enter the downstream sections.

    Specification of relevant ecosystem type

    Relevant for all small rivers in cold ecoregions.

    Relevant ecoregion(s) according to Illies

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

    Suggested indicator

    Percentage of collectors in the invertebrate community

    Justification of indicator

    Collectors gather organic material, which is remineralised by fungi and bacteria. If this food source increases the percentage of collectors rises to about 40 %.
• 
  

  Large rivers

  Biological parameters

  • Replacement of salmonid by cyprinid fish species

    Climate Region	Cold
    Ecosystem type	Large rivers
    Stressor type	Temperature
    Responding parameter group	Biological parameters
    Responding parameter	Replacement of salmonid by cyprinid fish species

    Response description

    Higher water temperatures will reduce reproductive success of salmonid species and increase parasitic and predator pressure on the egg and young larval stages. Warm water cyprinid species will invade in cold water regions.

    Secondary effects

    Food webs will change if salmonid species as main predators of macroinvertebrates will be reduced.

    Specification of relevant ecosystem type

    Relevant for all large rivers in cold ecoregions.

    Relevant ecoregion(s) according to Illies

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

    Suggested indicator

    Water temperature (maximum and minimum monthly values); fish species composition.

    Justification of indicator

    The eggs of salmonid species need high oxygen concentrations which will be reduced by higher water temperatures. Parasites and fungi benefit of high temperatures.

  • Spread of alien species

    Climate Region	Cold
    Ecosystem type	Large rivers
    Stressor type	Temperature
    Responding parameter group	Biological parameters
    Responding parameter	Spread of alien species

    Response description

    Higher temperatures often favour alien species that increasingly colonise small streams. These could be alien fish, macrophyte or macroinvertebrate species.

    Secondary effects

    Strong competitions with native species.

    Specification of relevant ecosystem type

    Relevant for all large rivers in cold ecoregions.

    Relevant ecoregion(s) according to Illies

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

    Suggested indicator

    Water temperature (maximum and minimum monthly values)

    Justification of indicator

    The survival and reproduction of several alien species in temperate ecoregions is controlled by minimum temperatures.

• Hydromorphological parameters

  • Decrease in ice cover duration

    Climate Region	Cold
    Ecosystem type	Large rivers
    Stressor type	Hydrology / Morphology
    Responding parameter group	Hydromorphological parameters
    Responding parameter	Decrease in ice cover duration

    Response description

    Higher temperatures will reduce ice cover duration.

    Secondary effects

    Prolonged macrophyte and algae growth, increased primary production, eutrophication.

    Specification of relevant ecosystem type

    Relevant for all large rivers in cold ecoregions.

    Relevant ecoregion(s) according to Illies

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

    Suggested indicator

    Ice cover duration

    Justification of indicator

    Depending on the region ice cover duration is between three and four month. Ice cover is a key factor for the productivity of boreal aquatic ecosystems and easy to monitor.

  • Increase of discharge

    Climate Region	Cold
    Ecosystem type	Large rivers
    Stressor type	Hydrology / Morphology
    Responding parameter group	Hydromorphological parameters
    Responding parameter	Increase of discharge

    Response description

    Due to overall higher precipitation overall discharge patterns of rivers will increase, leading to higher floods and less phases of low flow.

    Secondary effects

    Increased erosion in many rivers.

    Specification of relevant ecosystem type

    Relevant for all large rivers in cold ecoregions.

    Relevant ecoregion(s) according to Illies

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

    Suggested indicator

    Mean annual discharge

    Justification of indicator

    The discharge of most large rivers is already monitored with gauging stations.

    Reference(s)

    Eyre, M.D. (2006): A strategic interpretation of beetle (Coleoptera) assemblages, biotopes, habitats and distribution, and the conservation implications. Journal of Insect Conservation 10(2): 151-160.

• Physico-chemical parameters

  • Acidification

    Climate Region	Cold
    Ecosystem type	Large rivers
    Stressor type	Hydrology / Morphology
    Responding parameter group	Physico-chemical parameters
    Responding parameter	Acidification

    Response description

    Increased precipitation increases acid runoff from borealic coniferous forests leading to cascading acidification effects on aquatic biota.

    Secondary effects

    Disappearance of acid sensitive species.

    Specification of relevant ecosystem type

    Relevant for all large rivers in cold ecoregions.

    Relevant ecoregion(s) according to Illies

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

    Suggested indicator

    pH-value, invertebrate-based acid-indices.

    Justification of indicator

    pH-values decreases with increasing acid deposition. Since these events are of short duration, community based indices are often better reflecting acidification.

  • Change in macroinvertebrate feeding type composition

    Climate Region	Cold
    Ecosystem type	Large rivers
    Stressor type	Temperature
    Responding parameter group	Physico-chemical parameters
    Responding parameter	Change in macroinvertebrate feeding type composition

    Response description

    As food sources change (increasing rate of leaf litter breakdown and respiration rates in upstream reaches) less food for shredders and filter feeders is transported downstream and available in large rivers is available.

    Secondary effects

    Consequences for the food web, e.g. less fish production.

    Specification of relevant ecosystem type

    Relevant for all large rivers in cold ecoregions.

    Relevant ecoregion(s) according to Illies

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

    Suggested indicator

    Share of filter feeding organisms

    Justification of indicator

    Filter feeders are characteristic for large rivers in most ecoregions. The share of filter feeding organisms can be inferred from routine monitoring of benthic macroinvertebrates.

  • Increase of turbidity

    Climate Region	Cold
    Ecosystem type	Large rivers
    Stressor type	Temperature
    Responding parameter group	Physico-chemical parameters
    Responding parameter	Increase of turbidity

    Response description

    Due to leaching and mineralisation of soil organic matter turbidity increases with rising air temperatures.

    Secondary effects

    In times of high turbidity primary production will decline.

    Specification of relevant ecosystem type

    Relevant for all large rivers in cold ecoregions.

    Relevant ecoregion(s) according to Illies

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

    Suggested indicator

    DOC concentration, suspended sediment