DENMARK n HOW SUCCESSFUL HAVE WE BEEN IN CREATING HABITATS FOR - - PowerPoint PPT Presentation

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HELCOM MEETING, 29. MAY 2017

AARHUS UNIVERSITET

AU

STREAM RESTORATION IN DENMARK

HOW SUCCESSFUL HAVE WE BEEN IN CREATING HABITATS FOR RARE AND ENDANGERED STREAM SPECIES?

ANNETTE BAATTRUP-PEDERSEN AND JES J. RASMUSSEN

HELCOM MEETING, 29 MAY 2017

• A. BAATTRUP-PEDERSEN

AARHUS UNIVERSITET

AU

• The species diversity pr. area

is higher in freshwater ecosystems compared to any

• ther ecosystem on the earth
• The number of endangered

species is much higher in freshwater compared to

• ther ecosystems

THE DIVERSITY IS HIGH IN FRESHWATER BUT MANY SPECIES ARE ENDANGERED

Gentegnet fra Strayer & Dudgeon (2010). J. N. Am. Benthol. Soc.

HELCOM MEETING, 29 MAY 2017

• A. BAATTRUP-PEDERSEN

AARHUS UNIVERSITET

AU

SPECIES IN THE GENUS POTAMOGETON ARE RAPIDLY DECLINING IN DANISH STREAMS

The presence of Potamogeton was investigated on the same 13 sites in the three periods.

Potamogeton praelongus

Fram Baattrup-Pedersen et al. 2010. Vand og Jord .

HELCOM MEETING, 29 MAY 2017

• A. BAATTRUP-PEDERSEN

AARHUS UNIVERSITET

AU

REASONS FOR SPECIES DECLINE: HABITATS ARE LOST

• The total stream length in Denmark has been

significantly reduced (40-50%)

• Some types of habitats are almost eradicated
• Backwater habitats and oxbow lakes
• The habitat diversity (riffle, run and pool)

has declined. Riffle habitats have been lost.

HELCOM MEETING, 29 MAY 2017

• A. BAATTRUP-PEDERSEN

AARHUS UNIVERSITET

AU

WHAT ARE THE REASONS FOR SPECIES DECLINE: MANY STRESSORS

• There are many interacting

stressors in streams:

• Hydrological alterations
• Nutrients and other pollutants like

pesticides

• Weed cutting and dredging
• Straightening, widening and

deepening of the stream channel and altered substrate characteristics

• Waste water
• Ochre
• …

Gentegnet fra Dudgeon et al. (2006) : Biol. Rev.

HELCOM MEETING, 29 MAY 2017

• A. BAATTRUP-PEDERSEN

AARHUS UNIVERSITET

AU

HAVE WE BEEN SUCCESFUL IN STREAM RESTORATION PROJECTS IN DENMARK?

HELCOM MEETING, 29 MAY 2017

• A. BAATTRUP-PEDERSEN

AARHUS UNIVERSITET

AU

OVERVIEW – COMPARATIVE STUDIES

• Generally before-after studies are

few and have only been performed 1-2 years after the restoration

• Restoration succes has mostly been

evaluated based on species richness, Danish Stream Fauna Index, and density of throut. The number and density of endangered species or species with a high conservation value have not been the focus

• Restoration succes has been limited

if we consider the number of endangered species as a parameter for succes

Fra: Pedersen et al. 2014. Plos One

Based on comparative studies over number and abundance of endangered macroinvertebrate species in 6 channelized, 6 natural and 6 restored streams in Denmark

HELCOM MEETING, 29 MAY 2017

• A. BAATTRUP-PEDERSEN

AARHUS UNIVERSITET

AU

EXAMPLE: SKJERN Å

• Restoration of River Skjern has created a

number of new habitats. However, the stream width and the area with backwaters is still low and oxbow lakes are missing compared to former conditions (1871)

• The number of endangered macrophyte

and macroinvertebrate species is lower than in the reference period (1942-1963). Species that are missing are those associated with backwater habitats and the river margin habitats.

• For the macrophytes app. 40% of the

species are still missing when comparing to the reference period, especially Potamogeton species.

Fra: Wiberg-Larsen et al. 2013. Vand og Jord

HELCOM MEETING, 29 MAY 2017

• A. BAATTRUP-PEDERSEN

AARHUS UNIVERSITET

AU

WHY IS RESTORATION SUCCES LIMITED WHEN IT COMES TO RARE AND ENDANGERED SPECIES?

HELCOM MEETING, 29 MAY 2017

• A. BAATTRUP-PEDERSEN

AARHUS UNIVERSITET

AU

ARE WE APPLYING APPROPRIATE METHODS?

• Addition of coarse substrata

(stone and gravel) to the stream bottom is the most commonly applied restoration method in Danish streams

• This method also stabilizes the

channel form and impede natural hydrodynamic processes in forming new stream habitats.

HELCOM MEETING, 29 MAY 2017

• A. BAATTRUP-PEDERSEN

AARHUS UNIVERSITET

AU

WHAT HAPPENS WHEN WE ADD COARSE SUBSTRATE ?

• Some species like e.g.

Heptagenia sulphurea (mayfly), Agapetus ochripes (caddisfly) andElmis aenea (beetle) benefit from the created habitats

• Habitats for macrophytes are

missing

• Some species like

e.g.Metretopus borealis (mayfly) associated with macrophytes will not benefit from the created habitats

Regional species pool Local species pool

HELCOM MEETING, 29 MAY 2017

• A. BAATTRUP-PEDERSEN

AARHUS UNIVERSITET

AU

THE NUMBER OF ENDANGERED SPECIES CONFINED TO COARSE SUBSTRATES IS LIMITED

• Approximately 25% of the endangered species

are associated with gravel

• Half of the endangered species are more or less

specifically associated with plants and woody debris

• Half of the endangered species are more or less

specifically associated with bank and backwater habitats

• Approximately 25% of the endangered species
• ccur only in bank and backwater habitats

HELCOM MEETING, 29 MAY 2017

• A. BAATTRUP-PEDERSEN

AARHUS UNIVERSITET

AU

RESTORATION PROJECTS MAY ALSO FAIL IF OTHER STRESSORS STILL OPERATE

• In a comparative study of plant

communities in channelized, restored and natural reaches it was observed that weed cutting was the most important factor for species composition independent of the restoration performed

• If the proportion of streams with

a high weed cutting intensity was left out of the analysis then habitat diversity (current velocity and substrate composition) turned out to be more important.

HELCOM MEETING, 29 MAY 2017

• A. BAATTRUP-PEDERSEN

AARHUS UNIVERSITET

AU

RESTORATION IN THE FUTURE

HELCOM MEETING, 29 MAY 2017

• A. BAATTRUP-PEDERSEN

AARHUS UNIVERSITET

AU

THE REFERENCE CONCEPT IN RESTORATION:

• Geology
• Stream slope and substrates
• Bio-engineering – macrophytes and dead wood
• Natural, dynamic processes that create habitat

variability should be in focus

Dead wood and macrophytes are natural bio- engineering elements in lowland streams and likely play an important role for the overall diversity

HELCOM MEETING, 29 MAY 2017

• A. BAATTRUP-PEDERSEN

AARHUS UNIVERSITET

AU

RESTORATION PRIORITIES

• Probably higher chance for success

when restored stream reaches are situated in catchments with multiple source populations

• Restoration projects can then be

planned to maximize the potential for dispersal succes to restored reaches

AARHUS UNIVERSITET

AU