Groundwater: a living resource - Graham Fenwick

Post on 20-Jun-2015

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Graham FenwickPrincipal ScientistNIWA

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Groundwater:a living resource

Fauna discovered in 1880s by Charles Chilton at Eyreton, Canterbury

NZ:•Live in all groundwaters throughout NZ•Some highly local•Currently >100 named species, most endemic•Another >90 await description•Anticipate >500 species

Groundwater biodiversity:high diversity

Groundwater biodiversity:in all aquifer systems

N. Boustead, NIWA

Groundwater biodiversity:curiosities or ecological keystones?

Groundwater ecosystemconceptual food web

water percolating from soil surface

Dissolved org CParticulate org C

Groundwater surface

Org C in biofilms

browsed by animals

predatorsfaeces,death

microbes?

D org CP org C

microbes

net losses as CO2

from respiration

Excessive loadings kill the animals

Sewage effluent: effects

0

50

100

150

200

250

-180 -100 12 20 400 430

distance from ponds (m)

nu

mb

ers

/20 l

0

100

200

300

400

500

600

-180 -100 12 20 400 430

distance from ponds (m)

nu

mb

ers

/20 l

Mollusca

Nematoda

Annelida

Acarina

Ostracoda

Syncarida

Nauplii

Copepoda

Amphipoda

SummerIncreases

•copepodsDecreases

•Acarina

AutumnIncreases

•annelids,•amphipods•Acarina &•nematodes

Decreases •copepods

Carbon & nutrients from land use:

a subsidy/stress gradient in groundwater ecosystems

Invertebrate biomass

Organic enrichment

Dissolved oxygen

Ecosyste

m function

Organic carbon

Excess organic matter &/or reduced dissolvedoxygen lead to dead stygofauna &

clogged, anoxic sediments

Groundwater ecosystem services:vital to aquifer sustainability

Groundwater is a living resource

– Contains significant biodiversity

Performs vital ecological services

– Consumes some potentially harmful microbes

– Removes organic carbon from sediments

– Stygofauna feeding and movement:

• Maintains aquifer flow and water quality

• Enhances surface water quality

Face increasing human threats

Must manage as living system to sustain the

physical resource

Must manage groundwater as a living system

Life-supporting capacity

Water qualityAquifer yield