Hydromorphology & Ecology within river restoration Name: Dr Judy England Job title: Hydromorphology Research Scientist Date: 9th September 2014

Contents

Processes affecting aquatic ecology Interactions Understanding habitats How to use your knowledge of habitats in RR What can affect ecological recovery? Where to go for more information

What is ecology? “Ecology is the study of the relationships between plants and animals and the environment in which they live.” Owen, 1980

Why is hydromorphology important?

Physical habitat (hydromorphology) is one of the key supporting components of a healthy aquatic ecosystem

Ecological response to hydromorphological change

2006 1997 2001

Longitudinal processes: Hydrology Fluvial geomorphology

Lateral processes: Interactions with riparian zones & floodplains

Vertical processes Connectivity with groundwater

Internal processes: Predation, competition etc.

Hydromorphology influences ecology

Mechanisms of ecological change to natural hydrological regime of a river

Source: Bunn and Arthington, 2002

Influence of hydrology on invertebrates

Velocity category

Freq

uenc

y

0

10

20

30

40

50

60

70

Spate Fast Moderate Slow Slack

Sialis lutaria

Velocity category

Freq

uenc

y

0

10

20

30

40

50

60

70

80

Spate Fast Moderate Slow Slack

Simulium sp.

Some species have flow preferences, relating to feeding preferences, physical adaptations,

Black fly larvae, filter feeders. Preferred velocities - a balance between those that bring food particles and being dislodged.

Alder fly larvae, burrowing predator. Preferred velocities – a balance where prey can be found and being dislodged.

Alder fly photo

Influence of geomorphology

Impacts on substrate size Impacts on substrate patchiness Impacts on substrate movement Impacts on substrate depth

20 40 60 %

0

20

40

60

Dep

th c

m

Caddis flies

20 40 60 %

0

20

40

60

Dep

th c

m

Stone flies

20 40 60 %

0

20

40

60

Dep

th c

m

May flies

After Bretschko 1981

Influence of substrate on invertebrates

Median phi

Num

bers

0

10

20

30

40

50

60

70

-3.5 -3.0 -2.5 -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5

Med

ium

gra

vel

Fine

grav

el

Ver

y fin

e gr

avel

Ver

y co

arse

san

d

Coa

rse

sand

Med

ium

san

d

Fine

san

d

Ver

y fin

e sa

nd

Silt

Simulium spp.

Black fly larvae, filter feeders. Found in larger substrate sizes providing stable substrate.

Alder fly larvae, burrowing predator. Found in finer, softer sediment.

Median phi

Num

bers

0

10

20

30

40

50

-3.5 -3.0 -2.5 -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5

Med

ium

gra

vel

Fine

gra

vel

Ver

y fin

e gr

avel

Ver

y co

arse

sand

Coa

rse

sand M

ediu

m sa

nd

Fine

sand

Ver

y fin

e sa

nd

Silt

Sialis lutaria

Hydrological & morphological interaction

Velocity category

Freq

uenc

y

0

10

20

30

40

50

60

70

80

Spate Fast Moderate Slow Slack

Simulium sp.

Median phi

Num

bers

0

10

20

30

40

50

60

70

-3.5 -3.0 -2.5 -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5

Med

ium

gra

vel

Fine

grav

el

Ver

y fin

e gr

avel

Ver

y co

arse

san

d

Coa

rse

sand

Med

ium

san

d

Fine

san

d

Ver

y fin

e sa

nd

Silt

Source: Haslam 1978

Interaction between plants & sediment

Hydrological and morphological interaction influence ecological quality

Antecedent low flow conditions

Low High

Eco

logi

cal q

ualit

y fo

r m

acro

-inve

rtebr

ates

Lateral processes Margins & riparian zone

habitats refuges food – leaf & insects

Large wood channel forming

Shade temperature climate change adaptation

Floodplains

Large wood (debris?)

Branches, large limbs, root boles or entire trees (>1m in length and 0.1m diameter) that have fallen into rivers are commonly referred to as Large Wood (LW).

A major contributor to processes

Create lateral scour, helping to form meanders Raises levels upstream, increasing floodplain connectivity Retains fine sediment, reducing entrainment into spawning gravels Changes velocity patterns

It helps create diversity

Changes in velocity sorts fine and coarse sediment Promotes habitats variation: ideal conditions for spawning salmonid and rheophilic coarse fish (barbel, chub and dace) Cover for fish 147 invertebrates, some rare, strongly associated with woody (Godfrey, 2003)

Vertical interactions

Water quantity up-welling & down-welling

Water quality temperature chemical quality

Habitat & refuge flood, droughts & pollutions specialist species salmonid redds

Internal processes Physio-chemical processes

Nurient cycling

Biological interactions: Competition Herbivory Predation Life cycles

Source www.epa.gov

Degraded site Control site

The more complex the food-web the more stable it is and the greater the ecological resistance and resilience.

Complex interactions

Source: Newson and Newson 2000

Understanding habitats:

Physical Biotopes Marginal dead water Glide Riffle

Functional Habitats Tree roots Sand Gravel Cobbles/ pebbles Rocks

Physical Biotopes Marginal dead water Run

Functional Habitats Sand Submerged Plants Gravel Pebbles Marginal plants

Habitats for plants Channel & bank morphology Flow regime

Low water level

Bank full water level

Submerged vegetation

emergent narrow leaf vegetation

emergent broad leaf

vegetation

floating leaf vegetation

semi –terrestrial vegetation

terrestrial vegetation tree

roots

Habitats for invertebrates - physical

Pool

Riffle

Large woody debris

Exposed riverine sediments

Glide

Groundwater

Hyporheos

Water table

Bank

Marginal dead-water

Marginal damp areas

Water surface

Habitat considerations for mammals

Bats roost, feeding

Water voles burrows, feeding, latrines

Otters holts, cover,

How to use habitat awareness in RR

Concentrate on restoring processes Habitats should be appropriate – use reference sites Assess biota in relation to the habitat changes Important to monitor changes in relation to the reference/control site

Restoring processes Substrate size is important to the distribution of invertebrates How stable will the substrate be? Will the inundation pattern be correct for the desired plants?

River Chess, Buckinghamshire

Habitat restoration should be appropriate Recreate habitats in comparison with reference conditions. Increase ecological resistance and resilience

The distribution of exposed boulders in 1994 and 1995 – national RHS survey

Getting the target right

Assess biota in relation to the habitat changes

River Rib, Hertfordshire

“Control” section

Degraded section

0%10%20%30%40%50%60%70%80%90%

100%

Emergent Veg Submerged Veg

Fast Gravel Slow Gravel Sand Silt

% c

ompo

sitio

n

Fuctional Habitat

Flies

Caddisflies

Alderflies

Beetles

Bugs

Stoneflies

Mayflies

Shrimps & Hoglice

Hydracarina

Leeches

Worms

Mussels

Snails

Flatworms

Macro-invertebrate composition of different mesohabitats

Vegetation only Gravel only Fast Gravel only Slow Gravel only Sand only

Polycelis felina Lymnaea palustris Lymnaea truncatula Acroloxus lacustris Centroptilum luteolum Baetis vernus Hydrometra stagnorum

Velia capri Gerris sp. Haliplus wehnckei Octhebius minimus Helophorus brevipalpis Helophorus minutes Limnephilus lunatus

Chelifera sp. Nemurella picteti Dicronota sp. Leuctra fusca

Hydroptila sp. Limnophora sp.

Athripsodes cinereus

Pericoma trivialis Rhycophila dorsalis Tinodes waeneri Hydropsyche sp.

Functional Habitat

Restored section Control section

Before After Before After

Emergent Vegetation

Submerged Vegetation

Fast Gravel

Slow Gravel

Sand

Silt

Flow Scale: 20 metres

Control site:

Restoration site:

Functional Habitat:

Emergent vegetation Submerged vegetation Fast gravel Slow gravel Sand Silt

The theory:

“…..If natural hydrology and morphology are recreated, with careful consideration given to the hydraulic aspects, then there is every possibility that natural ecological recovery will follow….”

Brookes, A. and Shields, F.D. (1996)

What can affect ecological recovery?

Catchment context Inappropriate aims Complex processes Timescales Multiple pressures:

Water quality Alien species

Catchment context

Source

Impact

Impact

Source

Catchment context Catchment and riparian land use control local habitat conditions Restoration is more likely to be successful, if upstream physical habitat degradation and land use impacts are low Deal with the main pressure – other pressures inhibit benefits Local restoration, undertaken without consideration of other pressures acting on river, is often unsuccessful

Getting the aims right Understanding the catchment context Interactions with other pressures Identifying project aims Identifying monitoring aims See PRAGMO

Practical River Restoration Appraisal Guidance for Monitoring Options (PRAGMO)

Available from the RRC website

Linking morphology and ecology

Complex processes

Macrophyte links

Invertebrate links

Timescales - Lagtime Hydromorphology operates over long timescales

River may be moving sediment from last week or last ice age - long history of natural change Long legacy of physical modification

Recovery timescales Time lag between physical restoration & ecological response? Initial improvement but not long term? Benefits of restoration may take a long time to be realised

Can be difficult to quantify

Time scale of recovery Colonisation processes - invertebrates Source of colonists Ability to colonise Succession/biological interactions

Interactions with other pressures eg water quality

Poor water quality will inhibit biota Amend objectives May not increase richness or diversity but can increase numbers – fish food!

Brent at Tokyngton Park

Water depth <5cm - >1m

Water velocity slow - spate

No substrate No cover /

habitat

Water quality

Water depth varied

Water velocity varied

Substrate varied

Habitat & refugia

“I think it’s been really good. We used to come to the park before the restoration and after the restoration, and the difference I think, it has made to the neighbourhood has been a big change. I think before people did not use the park as much as they do now.”

“It shows what can be done with time, effort and funding along with the support of the local community and partnerships with other organisations. It gives hope, not only to improve the water quality and local environs of the River Brent but sets a statement of what can be achieved with other polluted or heavily modified rivers within London.”

Social reaction:

Mbeke (2008) “Those St Raphael people are a nuisance. They are the scum of the earth. I think the foot bridges are a problem.”

Non-native species

Hydromorphology uncertainty

Ecological response to hydromorphological change

Quantifying and understanding the processes

Effectiveness of measures on hydromorphology and ecological response

Where to go for more information:

Ecological preferences & ecology www.freshwaterecology.info

Environment Agency

www.environment-agency.gov.uk

UK Technical Advisory Group (TAG) www.wfduk.org

Restoring Europe’s Rivers

www.restorerivers.eu

Hydromorphology REstoring rivers FOR effective catchment Management

www.refromrivers.eu

Further reading:

General aquatic ecology: Rivers: Holmes & Raven Ecology of freshwaters: Moss Britain’s Freshwater Fish: Everard Stream Ecology: Allan & Castillo

Restoration Stream and watershed restoration: Roni & Beechie River restoration: Darby & Sear River Conservation and Management: Boon & Raven

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Any questions?