Biogeochemistry and community ecology in a spring-fed urban river following a major earthquake

Wells, Naomi
Clough, Timothy
Condron, LM
Baisden, WT
Harding, JS
Dong, Y
Lewis, GD
Lear, G
Journal Article
Fields of Research
ANZSRC::0402 Geochemistry , ANZSRC::040299 Geochemistry not elsewhere classified , ANZSRC::04 Earth Sciences , ANZSRC::0406 Physical Geography and Environmental Geoscience , ANZSRC::040603 Hydrogeology , ANZSRC::0602 Ecology , ANZSRC::060204 Freshwater Ecology , ANZSRC::0605 Microbiology , ANZSRC::060504 Microbial Ecology
In February 2011 a Mw 6.3 earthquake in Christchurch, New Zealand inundated urban waterways with sediment from liquefaction and triggered sewage spills. The impacts of, and recovery from, this natural disaster on the stream biogeochemistry and biology were assessed over six months along a longitudinal impact gradient in an urban river. The impact of liquefaction was masked by earthquake triggered sewage spills (∼20,000 m³ day⁻¹ entering the river for one month). Within 10 days of the earthquake dissolved oxygen in the lowest reaches was <1 mg l⁻¹, in-stream denitrification accelerated (attenuating 40–80% of sewage nitrogen), microbial biofilm communities changed, and several benthic invertebrate taxa disappeared. Following sewage system repairs, the river recovered in a reverse cascade, and within six months there were no differences in water chemistry, nutrient cycling, or benthic communities between severely and minimally impacted reaches. This study highlights the importance of assessing environmental impact following urban natural disasters.
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