Groundwater: a living resource - Graham Fenwick

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Graham Fenwick
Principal Scientist
NIWA

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Groundwater: a living resource - Graham Fenwick

  1. 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. 2. Groundwater biodiversity: high diversity
  3. 3. Groundwater biodiversity: in all aquifer systems N. Boustead, NIWA
  4. 4. Groundwater biodiversity: curiosities or ecological keystones?
  5. 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. 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. 7. Carbon & nutrients from land use: a subsidy/stress gradient in groundwater ecosystems Dissolved oxygen Ecosystem function Organic carbon Invertebrate biomass Organic enrichment
  8. 8. Excess organic matter &/or reduced dissolved oxygen lead to dead stygofauna & clogged, anoxic sediments
  9. 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. 10. Must manage groundwater as a living system Life-supporting capacity Aquifer yield Water quality

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