Rivers in temperate 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
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
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
Thermal-preference metrics
Ecoregion:
Temperate
Category:
Biological
BQE:
Macroinvertebrates
Indicators:
Thermal-preference metrics
Why measure:
Water temperature directly effect cold-water species. Their population could decrease as climate warmes up.
How to measure:
Proportion of cold-water species in a community
References:
Stamp, J. D., Hamilton, A. T., Zheng, L., & Bierwagen, B. G. (2010). Use of thermal preference metrics to examine state biomonitoring data for climate change effects. Journal of the North American Benthological Society, 29(4): 1410?1423. doi:10.1899/10-003.1
DOI:
http://dx.doi.org/10.1899/10-003.1
