Adaptive Management of Barriers in European Rivers

Improving ecological connectivity in rivers: barrier removal, bypasses and other

biota-passage solutions

Martyn Lucas

University of Durham, Department of Biosciences, UK

Connecting Rivers, People and Partnerships – IFM workshop, Loughborough, UK, March 2018

Estuarine barrage Large valley dam

Low-head barrier Levees

Breakages of longitudinal and lateral connectivity restrict or alter movements of water, nutrients, sediment, biota - and dramatically alter habitat

'Growthpe riod'

Re si de nceare a

'W in te ring'

Fe e din gare a

Daily acti vi tyare a

Re si de nceare a

Fe e din gare a

Daily acti vi tyare a

Spawni nggrounds

Re fuge Fe e din g

JUVENILES

Ontogeneticshifts

LARVAE

Fe e din gRe fugeSeasonalshiftsJUVENILES

and ADULTS

ADULTS

Functional Life Units of fishes• Using fishes as an example for groups of biota

• Recognising fishes as the most mobile group of freshwater animals

Lucas & Baras(2001)

Diverse and natural habitat conditions → diverse community

“Transparent barriers”

Sensu Alex Haro!

The Holy Grail !

Barrier being made ‘transparent’ to

whole fish-community passage!

Embrey Dam, Rappahannock River, Virginia

New opportunities for restoring river connectivity

Advances in science of dam removal“The lack of studies cries out for new research and peer-reviewed papers by experts in social, economic, and ecological fields.” Babbit, 2002

Bioscience special issue on dam removal, 2002

WFD: Ecological Status of European Lakes & Rivers

Good

Bad

EEA 2015

Many failures due to fragmentation & habitat loss

Crude estimate: 0.8-1.6 million dams and weirs(AMBER project)

Story of a weir removal for ecological reasons

• Flat-V flow-gauging weir, built 1978• River Nidd, tributary of Yorkshire Ouse (Humber basin)• First obstacle upstream of Ouse confluence• Dominated by rheophilic cyprinid community (Leuciscus, Rutilus, Barbus etc)

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Angler catch data - Kirk Hammerton

catch rate % NOT catching

weir constructed

1978

The utility of baseline data and evidence…..Series of timed angling competitions held historically, upstream of the planned site of weir – data recorded

Hats off to Steve Axford and Paul Frear! (Yorkshire Water Authority /

National Rivers Authority / Environment Agency) [though we can debate whether angler catches objectively reflect fish stocks]

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Angler catch data - Kirk Hammerton

catch rate % NOT catching

Subsiduary weir

constructed 1984

The utility of baseline data and evidence…..

BACI – Before , After , Control, Intervention

Anglers not happy – believe weir is cause of reduced catches, due to restricted upstream movement rather than changes in habitat • They wanted the “Tommy Cooper Method”

The Tommy Cooper Method of Dam/Weir removal –

“Just Like That!”

But rarely favoured by government agencies, budget holders, scientists – prefer evidence gathering, and/or “Elastoplast” methods

Radio-tracking of barbel (Barbus barbus) on the Nidd• Showed seasonal migrations – downstream to deeper, slower areas in

autumn-winter, upstream to riffles in spring

Lucas & Batley (1996)

J. Applied Ecology

Lucas & Frear (1997) J.

Fish Biology

Submerged gravel beds

Longitudinal movements – potamodromous fishesMany lowland river fishes are spring migrants, temperatureincreases often coincide with flow declines, making passage harder

Lucas & Batley (1996) J. Appl. Ecol.Lucas & Frear (1997) J. Fish Biol.

“Thin” flow, > 2 m/s over weir face

Attachment of baffles (1995) actually decreased fish (video + radiotrack)

Weir removed 1999Sampling angling catches stopped in 2002 – an error, financial necessity or convenience?? Whatever! Naturalises sediment transport etc

The utility of standardised time series data…(from S. Axford & P. Frear)

• Assessments of species available and species use, attraction and passage

Reconnection without dam removal?• Technical fishways for migratory fish – most designed for salmonids,

shads and a few other spp. (certainly the case for UK)• Most designed for upstream passage - “fish ladders”• Don’t reinstitute hydromorph processes or facilitate natural habitat• A weak compromise? Value for money?

Swim performance of Atlantic salmonids

Adult (sexually immature) river lamprey (Lampetrafluviatilis) migrating upstream in a river in northern England in winter (at night).

Anadromous river lamprey migration and barriers

NB – Unlike Pacific lamprey, European river lamprey and sea lamprey do not exhibit suck-and-climb ascent behaviour at steep smooth inclines

EU Habitats and Species Directive – EU-wide part protection, threatened species

• Sea lamprey*• European river

lamprey*• European brook

lamprey

Image: Iain Russon

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Number of Visits to Fish Pass Entrance (Days)

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Number of Visits to Fish Pass Entrance (Days)

Fish Pass

Design

Attraction

Efficiency

Passage

Efficiency

Denil baffle (u/s) 87% 0%

Pool & Spill (d/s) 47% 5.4%

Passage efficiency for river lamprey at two technical fish passes

300 river lamprey captured, PIT-tagged, released below fishways (Yorks.

Derwent) & studied over one full migration season (autumn to spring, ~6 months)

No spawning habitat d/s of Pool & Spill fishway, but spawning habitat at Denil

Foulds & Lucas (2013)Ecological Engineering

Buttercrambe flow-gauging weir, built 1975 – Yorkshire DerwentSpecial Area of Conservation (lamprey = a primary reason)Change to ultrasonic gauging – weir redundant – remove?? (best for lamprey and ecology and hydromorph)XX – flood risk concern, facilitate commercial HEP on site

Instead, installed Larinier superactive baffle fishway• Environment Agency’s recent preferred choice of technical pass at low-head sites for upstream passage of wide range of sizes and species.•Lamprey passage efficiency determined by telemetry

DownstreamPIT antenna

Velocity over disused gauging weir ca. 3m/s

Fishway attraction efficiency: 90.7%

Fishway passage efficiency: 0.3%!!!

Passage over weir directly 13.8%

Tummers et al (2016) Ecological Engineering

Too much emphasis on passage of main migratory species• WFD fish biological quality indices measure fish community against reference• Many urban streams now clean enough for fish but recolonisation inhibited by

obstacles – so fish community remains poor (but habitat can be poor too)• Recolonisation is NOT a migration problem but a DISPERSAL problem• ALL fish species disperse – not all migrate – need to help poor dispersers too• WHY do we ignore ‘minor’ spp. when they often form main fish biomass in streams?

Structured Mark-Recapture + fancy analysisTummers et al. (2016)Science Total Environ.

Elastomer

Elastomer

S7 = control site

Back to nature – biomimetics• Rock ramps, Nature-like bypasses (Thanks Jungwirth, Harris and co.)• Heterogenous flow conditions, hydraulics and sediment• Can reinstitute local areas of near-natural habitat e.g. riffle• Facilitate natural hydromorph and ecological processes• Biota corridors - wide range of fish (multiple life stages), inverts etc

Lowland

Upland

De-congesting London – urban waterway reconnection for fishes!

Can Low-Cost Baffle Solution at 30%-slope weirs help stocked coarse fish disperse? and can wild fish us it?

Angus Lothian et al. poster on display(Durham Uni., SE Rivers Trust, EA)

Poutès Dam – River Allier, France• Important for conservation of Atlantic salmon • Upstream and downstream passage problems

due to dam• Habitat loss due to dam• Reduce height? Modify operation?

Difficulties in downstream migration at low-head barriers

• Downstream movement not expected to be a problem at open, ‘simple’ low-head

barriers, especially for ‘midwater’ fishes like salmonid smolts

• Little investment for assisting downstream migration – in UK it is assumed that small

barriers will not markedly affect downstream migration

•XX WRONG!

• Effects of low flows – at barriers vs. open reaches

•Telemetry of downstream migration of sea trout smolts

Philiphaugh weir,

River Tweed

system

2010 – low flow 2011 – normal flow

Sig. difference No sig. difference(note difference in y-scales on graphs)

Gauld, Campbell & Lucas (2013) Science of the Total Environ.

In cold lowland streams with salmonid populations, barriers can have major effects on those populations

Natural gradient and variation = healthy populations

Jan Nielsen, DTU, Denmark

Weir A

Natural stream

Distance from source

Stream bed Weir = barrier Flooded zone, often several km’s

Flooded / ponded zone

In lowland rivers weirs can have a great negative impact on rheophilic habitat

Dam/weir height and stream gradient have a major effect on ponded distance and loss of rheophilic fish habitat

Barriers at weirs for downstream migrating fish

(an overlooked problem ?)

Weir at Mean % smolt loss

Water mills 30

Fish farms 42

Hydropower stations 82

Confusion ?

Jan Nielsen, summarising multiple Danish studies

Re-establishment of natural spawning and nursery areas

in the flooded zone of the River Gudenaa - just by removal of the weir in 2008

Vilholt Mill Lake

Jan Nielsen, DTU, Denmark

The brown trout and natural spawning areas upstream of the former dam responded well

after 146 years of inactivity in the flooded zone

From Jan Nielsel, DTU Denmark, and from Birnie-Gauvin et al. (2017) JEM

~1 km upstream of dam

~1 km downstream of dam

From Jan Nielsen DTU, Denmark& Birnie-Gauvin et al. (2017) J. Env. Man.

Boxplots of densities of trout before and after removal of the dam

Young of Year

Parr / adults

See also:

Birnie‐Gauvin, K. et al (2017) Shining a light on the loss of rheophilic fish habitat in lowland rivers as a forgotten consequence of barriers, and itsimplications for management. Aquatic Conservation: Marine and Freshwater Ecosystems DOI: 10.1002/aqc.2795

Biota passage without good habitat will not give good populations and diversity

There can be good ecological reasons for not removing obstacles – or even for building new onese.g. slowing spread of Aquatic Invasive Species

Bioscience (2010) 60, 37-46 Bioscience (2013) 63, 362-372

Signal crayfish upstream dispersal barriers – can they work? effects on fish?

No field tests of intentional barriers published…..

Upper Clyde (Annan boundary)Installed but no data / tests (C. Bean, SNH)

Rosewarne et al. (2013) - River Glem, upstream movements at existing sloping weir reduced by 45% cf control section - but NOT designed to limit crayfish

2017: Kerr (Northumberland Rivers Trust) & Lucas – proposed installation and testing (fish vs signal crayfish movement) of full-width, sub-surface, vertical, lipped weirs in R. Pont – but (so far) little buy-in from Environment Agency and perceived flood risk / ecological ‘damage’

Restoring connectivity in rivers benefits from an adaptive management approach, for which barrier removal is only one option –and much less likely in urban environments

Birnie-Gauvin et al. (2017)

Thanks for listening, and for reconnecting rivers!

And a shameless plug forJournal of Ecohydraulics (Editors: Chris Katopodis & Paul Kemp)

• All aspects of interaction between river flows and biota / ecological processes

• Ecological aspects of dam/weir removal, aquatic connectivity restoration, fish passage etc are ideal for this journal

• Double peer review