Rivers in cold ecoregions - indicators for climate change
The raising temperatures and changes in precipitation patterns due to climate change will result in complex cause–effect chains, linked by many interacting environmental parameters. The degree of ecosystem response will depend on the ecoregion (cold, temperate or warm) and ecosystem type (lakes, rivers or wetlands), and on species-specific adaptations of different organisms.
The purpose of this section is to suggest indicators for the effects of climate change on lake, river and wetland ecosystems that reflect the direction of their pathways, relative importance, and magnitude of change.The term ‘indicator’ is used here simply to describe a detectable signal of a complex process that can be used as an early warning of ecosystem change. Indicators may be chemical, hydrological, morphological, biological or functional parameters, which reflect key processes influenced by climate change and are relatively simple to monitor.
The purpose of this section is to suggest indicators for the effects of climate change on lake, river and wetland ecosystems that reflect the direction of their pathways, relative importance, and magnitude of change. It addresses the three ecosystem types and the three climatic regions always with four categories of indicators: (a) abiotic variables; (b) primary producers; (c) macroinvertebrates; and (d) fish.
Physico-chemical
Eutrophicating substances
Ecoregion:
Cold
Category:
Physico-chemical
Indicators:
Eutrophicating substances
Why measure:
Climate change is expected to have profound effects on the nitrogen (N) dynamics in the cultivated landscape as well as on N transport in streams and the eutrophication of lakes. N loading from land to streams is ex-pected to increase in North European temperate lakes due to higher winter rain-fall and changes in cropping patterns.
How to measure:
Nutrient levels (such as nitrate, total N and phosphate) are routinely monitored in most water bodies. An increase of baseline concentration should provide an-early signal.
Water temperature
Ecoregion:
General
Category:
Physico-chemical
Indicators:
Water temperature
Why measure:
Temperature is a key variable in determining physical properties of the water (such as oxygen solubility), duration of water stratification in lakes and biotic properties such as life history traits, reproduction success and metabolic rates. River temperatures in Europe have increased over the last 20?30 years. For example, in upland Wales, Scotland, southern English chalk streams, the upper Rhone, the Swiss Alps and Austria, by up to 1oC per decade.
How to measure:
Using in-situ fixed gauging stations, routine fieldwork or remote-sensing techniques (where possible) can provide data on changes in water temperature regime.
Biological
Bryophyte biomass
Ecoregion:
Cold
Category:
Biological
Indicators:
Bryophyte biomass
Why measure:
As global temperatures increase, animal husbandry and perhaps crop agriculture are likely to increase in cold regions. Temperature will directly influence the stream communities, but its secondary effects, manifested through agricultural eutrophication, are likely to be much greater.
How to measure:
bryophyte biomass will increase due to the combined effects of high temperature and nutrients
References:
Gudmundsdottir, R., Olafsson, J. S., Palsson, S., Gislason, G. M., & Moss, B. (2011). How will increased temperature and nutrient enrichment affect primary producers in sub-Arctic streams? Freshwater Biology, 56(10): 2045?2058.
DOI:
doi:10.1111/j.1365-2427.2011.02636.x
Macroinvertebrate taxa abundance
Ecoregion:
Cold
Category:
Biological
BQE:
Macroinvertebrates
Indicators:
Macroinvertebrate taxa abundance
Why measure:
Changes in alpine stream macroinvertebrate community composition as meltwater contributions decline were associated with lower suspended sediment concentration, and higher water temperature, electrical conductivity and pH
How to measure:
ß diversity (between-sites). Expected to increase with as snow melt and glacier melt decrease
References:
Brown LE, Hannah DM, Milner AM (2007) Vulnerability of alpine stream biodiversity to shrinking glaciers and snowpacks. Global Change Biology 13:958?966
DOI:
doi: 10.1111/j.1365-2486.2007.01341.x
Macroinvertebrate taxa richness
Ecoregion:
Cold
Category:
Biological
BQE:
Macroinvertebrates
Indicators:
Macroinvertebrate taxa richness
Why measure:
Changes in alpine stream macroinvertebrate community composition as meltwater contributions decline were associated with lower suspended sediment concentration, and higher water temperature, electrical conductivity and pH
How to measure:
a diversity (at a site). Expected to increase with as snow melt and glacier melt decrease
References:
Brown LE, Hannah DM, Milner AM (2007) Vulnerability of alpine stream biodiversity to shrinking glaciers and snowpacks. Global Change Biology 13:958?966
DOI:
doi: 10.1111/j.1365-2486.2007.01341.x
Occurance of Jungermannia exsertifolia
Ecoregion:
Cold
Category:
Biological
BQE:
Marchantiophyta (Liverwort)
Indicators:
Occurance of Jungermannia exsertifolia
Why measure:
As global temperatures increase, animal husbandry and perhaps crop agriculture are likely to increase in cold regions. Temperature will directly influence the stream communities, but its secondary effects, manifested through agricultural eutrophication, are likely to be much greater.
References:
Gudmundsdottir, R., Olafsson, J. S., Palsson, S., Gislason, G. M., & Moss, B. (2011). How will increased temperature and nutrient enrichment affect primary producers in sub-Arctic streams? Freshwater Biology, 56(10): 2045?2058.
DOI:
doi:10.1111/j.1365-2427.2011.02636.x
Pulmonate freshwater snail diversity
Ecoregion:
Cold and Temperate
Category:
Biological
BQE:
Macroinvertebrates
Indicators:
Pulmonate freshwater snail diversity
Why measure:
The changes associated with the global warming would have diverse consequences on pulmonates? survival. Increasing evaporation will cause prolonged periods of drought, preferentially at lower latitudes, leading to partial habitat loss there. Higher water temperatures are inevitably associated with less oxygenated waters, which will impact species demanding high water oxygenation. A reduction in the sutibale habitats for pulmonate snails in predicted across central European countries (such as Germany, France and Poland)
How to measure:
The number of pulmonate genera in the macroinvertebrate assemblage. An increase in pulmunate sp. is expected in cold-regions
References:
Cordellier, M., Pfenninger, a., Streit, B. & Pfenninger, M. (2012) Assessing the effects of climate change on the distribution of pulmonate freshwater snail biodiversity. Marine Biology. Published on-line Feb. 2012.
DOI:
DOI: 10.1007/s00227-012-1894-9
Tolerant/sensitive fish species
Ecoregion:
Cold
Category:
Biological
BQE:
Secondary production
Indicators:
Tolerant/sensitive fish species
Why measure:
Metrics based on a ratio between sensitve and tolerant species would be indicative+ to shifts in the assemblage structure, as individuals naturally occurring in cold areas would be replaced by individuals that are better adapted to the modified environmental conditions
How to measure:
Ratio between the of number of small oxygen-intolerant fishes to number of warmwater and/or tolerant species
References:
Logez M. and Pont D. (2011). Development of metrics based on fish body size and species traits to assess European coldwater streams. Ecological Indicators 11 (5): 1204?1215
DOI:
http://dx.doi.org/10.1016/j.ecolind.2010.12.023
