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The New Zealand Herald

Int'l - Marine environment hit by floods as sediment flows

The biodiversity in a refuge for Hector’s dolphins could take up to a decade to recover from the Canterbury floods after large amounts of sediment smothered life along the coast.

The biodiversity in a refuge for Hector’s dolphins could take up to a decade to recover from the Canterbury floods after large amounts of sediment smothered life along the coast.

Rivers from South Canterbury to Waimakariri spewed massive amounts of turbid water, including forestry waste or refuse from dairy operations, into the marine environment after last week’s extreme rain, University of Otago Emeritus Prof Liz Slooten said.

And the sediment entering coastal waters would smother life in the Banks Peninsula Marine Mammal Sanctuary, Prof Slooten said.

She has studied threatened Hector’s dolphins there since 1984.

While the sediment would be unlikely to affect the dolphins directly, it would act on their food source, she said.

Offshore rocky reefs, often favoured by fishermen due to their productivity, would be hard hit.

Seaweed beds would be smothered.

And the sediment suspended in the water would block sunlight and stop photosynthesis from occurring.

The total amount of organisms in the area, its "biomass", would recover within a matter of years, she said.

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