Watershrew’s and wetland habitat quality

Dawn Scott & Fran Southgate

University of BrightonUniversity of BrightonUniversity of Brighton

Project background

• 2002-2005• Partnership – SROP & UOB• MPhil – Fran Southgate• 27 study sites over 3 catchments• Cuckmere, Ouse and Pevensey

Levels• Monitoring: Summer and Winter

for 3 years

                               

      

                               

      

                               

      

                               

      

                               

      

                               

      

                               

      

                               

      

                               

      

What is a water shrew?•Noemys fodiens

•Largest UK shrew: 13g•Dark, usually silver pale underside • Fringed tail and feet

Ecology: Breeding peak May & June (2 or < litters/season)

Life span 14-19 months

Aquatic/Riparian (but can be found away from water)

Insectivore: Diet 50: 50 terrestrial/aquatic invertebrates

Why focus on this species?

• Limited data on habitat requirements and distribution

• Conservation status? W&C act 1987

• Predominantly feeds on aquatic prey

• Intolerant to poor water quality ???

• Potential bio-indicator of water quality ??

Project aims

• Assess presence & abundance of water shrews across the 3 catchments and monitor these seasonally

• Assess habitat characteristics and habitat quality

• Assess presence and abundance of invertebrate prey base

• Record indicators of water quality

Methods• Shrew scat tubes:P/A and relative abundance • Wetland features: Bank slope, water body

• Plant diversity: Bank and in-stream

• Water quality:Temp,DO, pH, NH4, P, N

• Habitat assessment:Composition and structure

• Invertebrates:Diversity, BMWP, ASPT

Chart showing overall relative abundance - Pevensey catchmnent

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PMW PREA PNB POPC PHB PPW PBF PNS PHG

Site

Rel

ativ

e ab

unda

nce

Win 04

Sum 04

Win 03

Sum 03

Habitat Variable Ws relative abundance

rs P

Herb forb % cover -0.236 0.038

Grass % cover 0.044 0.700

Sedge % cover 0.230 0.038

Reed % cover 0.240 0.034

Litter % cover 0.215 0.058

Bare ground % cover 0.102 0.376

Shrub % cover 0.008 0.943

Rush % cover -0.004 0.969

Grass height (m) 0.257 0.023

Litter height (m) -0.013 0.910

Us/ds % tree cover -0.145 0.205

Us/ds % shrub cover -0.071 0.534

Us/ds tree density -0.100 0.385

Us/ds shrub density -0.032 0.781

Water parameters

• PH, temp. & DO showed no significant effect on water shrew presence over all sample seasons

• Only DO in summer ’03 showed a significant effect on water shrew presence where higher DO = higher abundance

• Higher water temperature was associated with lower water shrew presence in Summer 03 and Winter 04

• Data for phosphate, nitrates and ammonia showed no statistically significant relationships with water shrew abundance

Invertebrates

• Positive correlations between invertebrate diversity and richness scores and seasonal water shrew relative abundance in Summer 03, Winter 03 and Summer 04

• However, statistical analysis confirmed that neither water shrew presence nor relative abundance were associated with any of the derived BMWP and ASPT scores.

Family Common Name U value P Value

Calopterigidae (unknown) Damselfly larvae 844.5 0.002

Chironomidae Biting Midge larvae 986.0 0.011

Ecdyonuridae Flattened mayfly nymph 1020.0 0.038

Hydrobiidae (2) Snail 968.0 0.019

Hydrobiidae (3) Snail 986.0 0.011

Leptoceridae Caddis 917.5 0.037

Lymnaeidae Pond snail 1020.0 0.038

Mollannidae (1) Caddis 986.0 0.011

Philopotamidae Caddis 986.0 0.011

Physidae Aquatic snail 769.5 0.011

Polycentopaidae Caddis 1100.5 0.037

Coleoptera (Unidentified) Water beetle 1020.0 0.038

Tricoptera (unknown) Caddis 1100.5 0.037

Ephemoptera (Unidentified) Mayfly nymph 244.0 0.032

Hydracarina Water flea 218.0 0.049