Graham Fenwick Principal Scientist NIWA

1. 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

2. Groundwater biodiversity:
high diversity

3. Groundwater biodiversity:
in all aquifer systems
N. Boustead, NIWA

4. Groundwater biodiversity:
curiosities or ecological keystones?

5. Groundwater ecosystem
conceptual food web
water percolating from soil net losses
surface as CO2
Dissolved org C from
Particulate org C respiration
Groundwater surface
D org C Org C in biofilms
P org C
microbes
microbes? browsed by animals
faeces,
death predators
Excessive loadings
kill the animals

6. Sewage effluent: effects
600 Summer
500 Mollusca Increases
Nematoda •copepods
numbers /20 l
400
300
Annelida
Acarina
Decreases
Ostracoda •Acarina
200
Syncarida
100 Nauplii
Copepoda
0
Amphipoda
-180 -100 12 20 400 430
distance from ponds (m)
250
200
numbers /20 l
Autumn 150
Increases
•annelids, 100
•amphipods 50
•Acarina &
•nematodes 0
-180 -100 12 20 400 430
Decreases
•copepods distance from ponds (m)

7. Carbon & nutrients from land use:
a subsidy/stress gradient in groundwater
ecosystems
Dissolved oxygen
Ecosystem function
Organic carbon
Invertebrate biomass
Organic enrichment

8. Excess organic matter &/or reduced dissolved
oxygen lead to dead stygofauna &
clogged, anoxic sediments

9. 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

10. Must manage groundwater as a
living system
Life-supporting capacity
Aquifer yield Water quality