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Lakes in warm 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

Dissolved salts concentration
[id:19]

Ecoregion:

Cold and Warm

Category:

Physico-chemical

BQE:

Salinity

Indicators:

Dissolved salts concentration

Why measure:

Warmer winters cause extreme rainstorms and heavy sea-salt deposition together with increased evaporation in summer, might affect water chemistry and biotic structure

How to measure:

Direct measurments of salinity levels

Oxygen concentration at the bottom in summer
[id:15]

Ecoregion:

Warm

Category:

Physico-chemical

BQE:

Dissolved oxygen

Indicators:

Oxygen concentration at the bottom in summer

Why measure:

High temperatures will stimulate phytoplankton growth, which will lead to oxygen depletion of habitats. Dissolved oxygen will also decrease as a result of lower solubility in warmer waters and increased microbial activity

How to measure:

simple to monitor, easy to incorporate into routine monitoring

Hydrological parameters

Lake surface
[id:14]

Ecoregion:

Warm

Category:

Hydrological parameters

BQE:

Water level

Indicators:

Lake surface

Why measure:

Increased temperature and decreased precipitation in conjunction with intensive water use will decrease water volumes. This will lead to water level imbalances and, in many cases, to the complete loss of water bodies

How to measure:

simple to monitor, e.g. by remote sensing

Biological

Alien species
[id:24]

Ecoregion:

Temperate and Warm

Category:

Biological

BQE:

Secondary production

Indicators:

Alien species

Why measure:

Higher temperatures often favour alien fish, macrophytes or macroinvertebrate species. These may have a negative impact on local biota, including increased predation and competition for food and habitat.

How to measure:

Share of alien species in the community (macrophyte, macroinvertebrates, fish)

Macrophyte properties
[id:21]

Ecoregion:

Temperate and Warm

Category:

Biological

BQE:

Primary production

Indicators:

Macrophyte properties

Why measure:

Inter-annual variation in water temperature results in deeper macrophyte colonization, greater wet weight biomass, and an increase in whole lake biomass.

How to measure:

Macrophytes can be sampled routinely using WFD methodologies or using remote sensing techniques.

References:

Bucak T., Saraoglu E., Levi E.E., Tavsanoglu U.N.Y., Idil Çakiroglu A., Jeppesen E. & Beklioglu M., 2012. The role of water level for macrophytes growth and trophic interactions in Mediterranean shallow lakes: a mesocosms experiment with and without fish. Freshwater Biology 57(8): 1631-1642.?(2)



Climate Change and Freshwater
Online: http://www.climate-and-freshwater.info/climate_change/lakes/warm/indicators/
Date: 2017/10/23
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