Rivers in warm 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

  • Eutrophication

    Climate Region	Warm
    Ecosystem type	Small rivers
    Stressor type	Temperature
    Responding parameter group	Biological parameters
    Responding parameter	Eutrophication

    Response description

    Eutrophication is promoted by nutrient input (e.g. by ferilizers) and high water retention time through low discharge.

    Secondary effects

    Oxygen depletion at night times

    Specification of relevant ecosystem type

    Relevant for all small rivers in warm ecoregions.

    Relevant ecoregion(s) according to Illies

    Iberian Peninsula (1), Italian Peninsula (3), Dinaric Western Balkan (5), Hellenic Western Balkan (6), Eastern Balkan (7)

    Suggested indicator

    Total phosphorus concentration, current velocity

    Justification of indicator

    Phosphorus is in many cases limiting primary production.

  • Increase of biomass

    Climate Region	Warm
    Ecosystem type	Small rivers
    Stressor type	Temperature
    Responding parameter group	Biological parameters
    Responding parameter	Increase of biomass

    Response description

    Nutrient availability is increased due to higher mineralisation rates at higher temperatures, enhancing macrophyte growth and biomass.

    Secondary effects

    Eutrophication

    Specification of relevant ecosystem type

    Relevant for all small rivers in warm ecoregions.

    Relevant ecoregion(s) according to Illies

    Iberian Peninsula (1), Italian Peninsula (3), Dinaric Western Balkan (5), Hellenic Western Balkan (6), Eastern Balkan (7)

    Suggested indicator

    Macrophyte coverage

    Justification of indicator

    Macrophyte coverage is simple to record and well correlated to biomass.

  • Increased macrophyte/algae growth

    Climate Region	Warm
    Ecosystem type	Small rivers
    Stressor type	Temperature
    Responding parameter group	Biological parameters
    Responding parameter	Increased macrophyte/algae growth

    Response description

    Higher water temperatures and lower discharge enhance macrophyte and algae growth. Furthermore, higher temperatures increase mineralisation processes and deliver more nutrients for macrophyte and algae growth.

    Secondary effects

    Oxygen depletion during night time and oxygen over-saturation at day time will affect aquatic communities.

    Specification of relevant ecosystem type

    Relevant for all small rivers in warm ecoregions.

    Relevant ecoregion(s) according to Illies

    Iberian Peninsula (1), Italian Peninsula (3), Dinaric Western Balkan (5), Hellenic Western Balkan (6), Eastern Balkan (7)

    Suggested indicator

    Water temperature (mean monthly values)

    Justification of indicator

    Mean monthly temperatures indicate overall temperature increase.

• Hydromorphological parameters

  • Change of permanent to intermittent regime

    Climate Region	Warm
    Ecosystem type	Small rivers
    Stressor type	Hydrology / Morphology
    Responding parameter group	Hydromorphological parameters
    Responding parameter	Change of permanent to intermittent regime

    Response description

    Due to less precipitation and increased demand for freshwater, higher temperatures and higher transpirations many small rivers will become intermittent with long dry phases in summer.

    Secondary effects

    The aquatic communities (fish, invertebrates, macrophytes) will change completely because many species do not survive dry periods.

    Specification of relevant ecosystem type

    Relevant for all small rivers in warm ecoregions.

    Relevant ecoregion(s) according to Illies

    Iberian Peninsula (1), Italian Peninsula (3), Dinaric Western Balkan (5), Hellenic Western Balkan (6), Eastern Balkan (7)

    Suggested indicator

    Drought periods

    Justification of indicator

    As gauging stations are not installed in most small headwater streams, drought periods can be easily recorded by visiting the respective streams.

  • Changes in life strategies

    Climate Region	Warm
    Ecosystem type	Small rivers
    Stressor type	Hydrology / Morphology
    Responding parameter group	Hydromorphological parameters
    Responding parameter	Changes in life strategies

    Response description

    If small rivers become intermittent, species with a bivoltine life cycle can not survive and the community will change to univoltine species with an early emergence period.

    Secondary effects

    Overall change of aquatic community

    Specification of relevant ecosystem type

    Relevant for all small rivers in warm ecoregions.

    Relevant ecoregion(s) according to Illies

    Iberian Peninsula (1), Italian Peninsula (3), Dinaric Western Balkan (5), Hellenic Western Balkan (6), Eastern Balkan (7)

    Suggested indicator

    Drought periods

    Justification of indicator

    As gauging stations are not installed in most small headwater streams, drought periods can be easily recorded by visiting the respective streams.

  • Changes of discharge patterns

    Climate Region	Warm
    Ecosystem type	Small rivers
    Stressor type	Hydrology / Morphology
    Responding parameter group	Hydromorphological parameters
    Responding parameter	Changes of discharge patterns

    Response description

    For humid warm areas of Europe higher precipitation in winter months is predicted. This will cause more frequent and higher floods.

    Secondary effects

    Sediment erosion and deposition will alter channel patterns and habitat availability.

    Specification of relevant ecosystem type

    Relevant for all small rivers in warm ecoregions.

    Relevant ecoregion(s) according to Illies

    Iberian Peninsula (1), Italian Peninsula (3), Dinaric Western Balkan (5), Hellenic Western Balkan (6), Eastern Balkan (7)

    Suggested indicator

    Discharge in winter months

    Justification of indicator

    Floods will mainly be restricted to winter months.

  • Changes of invertebrate communities

    Climate Region	Warm
    Ecosystem type	Small rivers
    Stressor type	Hydrology / Morphology
    Responding parameter group	Hydromorphological parameters
    Responding parameter	Changes of invertebrate communities

    Response description

    More frequent winter floods will enhance catastrophic drift of invertebrates and change the community to more r-strategy species tolerating floods.

    Secondary effects

    Decrease of species number due to loss of K-strategists.

    Specification of relevant ecosystem type

    Relevant for all small rivers in warm ecoregions.

    Relevant ecoregion(s) according to Illies

    Iberian Peninsula (1), Italian Peninsula (3), Dinaric Western Balkan (5), Hellenic Western Balkan (6), Eastern Balkan (7)

    Suggested indicator

    Discharge in winter months

    Justification of indicator

    Floods will mainly be restricted to winter months.

• Physico-chemical and biological parameters

  • Oxygen depletion

    Climate Region	Warm
    Ecosystem type	Small rivers
    Stressor type	Temperature
    Responding parameter group	Physico-chemical and biological parameters
    Responding parameter	Oxygen depletion

    Response description

    Higher water temperatures lead to increased phytobenthos and macrophyte growth and to oxygen depletion at night times.

    Secondary effects

    Many aquatic species are intolerant of oxygen depletion and suffocate.

    Specification of relevant ecosystem type

    Relevant for all small rivers in warm ecoregions.

    Relevant ecoregion(s) according to Illies

    Iberian Peninsula (1), Italian Peninsula (3), Dinaric Western Balkan (5), Hellenic Western Balkan (6), Eastern Balkan (7)

    Suggested indicator

    Oxygen concentration in summer month.

    Justification of indicator

    In well oxygenated rivers the oxygen concentration is around 100 %. Oxygen content decreases with water temperature, thus, summer months are the critical phase.
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  Large rivers

  Biological parameters

  • Increase of biomass

    Climate Region	Warm
    Ecosystem type	Large rivers
    Stressor type	Temperature
    Responding parameter group	Biological parameters
    Responding parameter	Increase of biomass

    Response description

    Nutrient availability is increased due to higher mineralisation rates at higher temperatures, enhancing macrophyte growth and biomass.

    Secondary effects

    Eutrophication

    Specification of relevant ecosystem type

    Relevant for all large rivers in humid warm ecoregions.

    Relevant ecoregion(s) according to Illies

    Iberian Peninsula (1), Italian Peninsula (3), Dinaric Western Balkan (5), Hellenic Western Balkan (6), Eastern Balkan (7)

    Suggested indicator

    Macrophyte coverage

    Justification of indicator

    Macrophyte coverage is simple to record and well correlated to biomass.

  • Increase of invertebrate predators (e.g. beetles)

    Climate Region	Warm
    Ecosystem type	Large rivers
    Stressor type	Hydrology / Morphology
    Responding parameter group	Biological parameters
    Responding parameter	Increase of invertebrate predators (e.g. beetles)

    Response description

    Summer drought change rivers to pool chains. Highly mobile predators like many beetle species use these pools to hunt and scavenge.

    Secondary effects

    Change of aquatic community composition.

    Specification of relevant ecosystem type

    Relevant for all large rivers in humid warm ecoregions.

    Relevant ecoregion(s) according to Illies

    Iberian Peninsula (1), Italian Peninsula (3), Dinaric Western Balkan (5), Hellenic Western Balkan (6), Eastern Balkan (7)

    Suggested indicator

    Share of predators in the invertebrate community

    Justification of indicator

    The share of predators in river invertebrate samples is typically around 10%. In pools the share increase up to 30%.

  • Low flow

    Climate Region	Warm
    Ecosystem type	Large rivers
    Stressor type	Hydrology / Morphology
    Responding parameter group	Biological parameters
    Responding parameter	Low flow

    Response description

    High summer temperatures and high transpirations rate in conjunction with less precipitation will lead to the desiccation of river stretches or low flows.

    Secondary effects

    Species adapted to high current velocities or intolerant of low oxygen concentrations will vanish and the aquatic communities will change completely.

    Specification of relevant ecosystem type

    Relevant for all large rivers in humid warm ecoregions.

    Relevant ecoregion(s) according to Illies

    Iberian Peninsula (1), Italian Peninsula (3), Dinaric Western Balkan (5), Hellenic Western Balkan (6), Eastern Balkan (7)

    Suggested indicator

    Discharge in the summer months.

    Justification of indicator

     Periods of low flow usually occur during the summer months.

  • Parasitic infestation

    Climate Region	Warm
    Ecosystem type	Large rivers
    Stressor type	Temperature
    Responding parameter group	Biological parameters
    Responding parameter	Parasitic infestation

    Response description

    Parasites mobility and reproduction rate increase with temperature. Thus, parasitic infestation of fishes and invertebrates will increase.

    Secondary effects

    Survival and reproduction of hosts will be affected.

    Specification of relevant ecosystem type

    Relevant for all large rivers in humid warm ecoregions.

    Relevant ecoregion(s) according to Illies

    Iberian Peninsula (1), Italian Peninsula (3), Dinaric Western Balkan (5), Hellenic Western Balkan (6), Eastern Balkan (7)

    Suggested indicator

    Water temperature (mean monthly values)

    Justification of indicator

    Mean monthly temperatures indicate overall temperature changes between years.

• Hydromorphological parameters

  • Changes of invertebrate communities

    Climate Region	Warm
    Ecosystem type	Large rivers
    Stressor type	Hydrology / Morphology
    Responding parameter group	Hydromorphological parameters
    Responding parameter	Changes of invertebrate communities

    Response description

    Winter floods will lead to catastrophic drift of invertebrates, will change the community to more r-strategists tolerating frequent floods and lead to the loss of bivoltine species.

    Secondary effects

    Decrease of species number

    Specification of relevant ecosystem type

    Relevant for all large rivers in humid warm ecoregions.

    Relevant ecoregion(s) according to Illies

    Iberian Peninsula (1), Italian Peninsula (3), Dinaric Western Balkan (5), Hellenic Western Balkan (6), Eastern Balkan (7)

    Suggested indicator

    Frequency and magnitude of floods in winter months.

    Justification of indicator

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

  • Increase of turbidity

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

    Response description

    Floods will increase turbidity of the water.

    Secondary effects

    Sediment accumulation rate in the interstitial will increase and lead to oxygen depletion at the river bottom.

    Specification of relevant ecosystem type

    Relevant for all large rivers in humid warm ecoregions.

    Relevant ecoregion(s) according to Illies

    Iberian Peninsula (1), Italian Peninsula (3), Dinaric Western Balkan (5), Hellenic Western Balkan (6), Eastern Balkan (7)

    Suggested indicator

    Suspended sediment

  • Reduced water quality

    Climate Region	Warm
    Ecosystem type	Large rivers
    Stressor type	Hydrology / Morphology
    Responding parameter group	Hydromorphological parameters
    Responding parameter	Reduced water quality

    Response description

    Due to an increased temperature and decrease in precipitation the runoff volume will decrease, particularly in summer. Consequently oxygen will decease and BOD increase.

    Secondary effects

    Community shift from sensitive to tolerant taxa.

    Specification of relevant ecosystem type

    Relevant for all large rivers in humid warm ecoregions.

    Relevant ecoregion(s) according to Illies

    Iberian Peninsula (1), Italian Peninsula (3), Dinaric Western Balkan (5), Hellenic Western Balkan (6), Eastern Balkan (7)

    Suggested indicator

    Saprobic Index in the summer months

    Justification of indicator

    Saprobic indices reflect the organic load in rivers and eventually the oxygen content. Thus, if the organic load increases the saprobic indices will decrease. Species with a high oxygen demand respectively low saprobic value will disappear and species with a low oxygen demand respectively high saprobic value will increase.

    Reference(s)

    Truscott, A.M., C. Soulsby et al. (2006): The dispersal characteristics of the invasive plant Mimulus guttatus and the ecological significance of increased occurrence of high-flow events. Journal of Ecology 94(6): 1080-1091.

  • Sedimentation/erosion

    Climate Region	Warm
    Ecosystem type	Large rivers
    Stressor type	Hydrology / Morphology
    Responding parameter group	Hydromorphological parameters
    Responding parameter	Sedimentation/erosion

    Response description

    Increasing precipitation in the winter months lead to higher floods which enhance erosion and sedimentation processes in the rivers.

    Secondary effects

    Invertebrate communities will respond with catastrophic drift.

    Specification of relevant ecosystem type

    Relevant for all large rivers in humid warm ecoregions.

    Relevant ecoregion(s) according to Illies

    Iberian Peninsula (1), Italian Peninsula (3), Dinaric Western Balkan (5), Hellenic Western Balkan (6), Eastern Balkan (7)

    Suggested indicator

    Frequency and magnitude of floods in winter months.

    Justification of indicator

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

    Reference(s)

    Brookes, C.J., J.M. Hooke et al. (2000): Modelling vegetation interactions with channel flow in river valleys of the Mediterranean region. Catena 40(1): 93-118.

• Physico-chemical parameters

  • Oxygen depletion

    Climate Region	Warm
    Ecosystem type	Large rivers
    Stressor type	Temperature
    Responding parameter group	Physico-chemical parameters
    Responding parameter	Oxygen depletion

    Response description

    Higher water temperatures lead to increased phytobenthos and macrophyte growth and to oxygen depletion at night times.

    Secondary effects

    Many aquatic species are intolerant of oxygen depletion and suffocate.

    Specification of relevant ecosystem type

    Relevant for all large rivers in humid warm ecoregions.

    Relevant ecoregion(s) according to Illies

    Iberian Peninsula (1), Italian Peninsula (3), Dinaric Western Balkan (5), Hellenic Western Balkan (6), Eastern Balkan (7)

    Suggested indicator

    Oxygen concentration in summer month.

    Justification of indicator

    In well oxygenated rivers the oxygen concentration is around 100 %. Oxygen content decreases with water temperature, thus, summer months are the critical phase.