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Ecologists study Te Mato Vai intake site streams


Lauren using a water quality probe to measure the waters' oxygen levels, pH and temperature

This week ecologists have begun an ecological survey of the Te Mato Vai intake site streams. The on-site stream assessments are expected to take five days.


The survey will contribute to the Environmental Impact Assessment (EIA) To Tatou Vai (TTV) has separately commissioned for the new water treatment system’s operation. This includes for PACl use, and to help inform the Cook Islands Government’s future decision on a preferred disinfection method.


GHD’s Dr Natalie Clark will lead the ecological study, which will assess the aquatic habitat and wildlife populations in the streams. Aquatic ecologist Lauren Pratt will be conducting on-site sampling and recording the stream environments. The team will then use the information gathered through the study to develop a detailed description of the streams’ condition.


What will the ecologists do?

The study will assess:

  • habitat diversity

  • the extent of habitat

  • suitability for aquatic animal groups

  • sensitivity to change

  • existing disturbances and/or modifications

  • condition of the stream area

  • water flow characteristics

  • any fish passage barriers (man-made or natural)

  • water quality.

Lauren and Andrew will photograph each site to record habitat conditions at the time of monitoring, and collect and record wildlife, including sampling for fish, where possible. They’ll also sample water to test its temperature, pH, electrical conductivity and dissolved oxygen at different depths, and its turbidity and alkalinity.

“Streams are home to hundreds of tiny animals called macroinvertebrates,” Lauren says. “These are animals including insects, crustaceans such as freshwater crayfish (koura), snails, mussels, worms and leeches. They live on and under rocks, water plants, wood or debris, so we’ll need to take a thorough look at the environment to get an understanding of the variety and quantity of their communities. We are looking forward to seeing what wildlife we find in each of the different streams.”

Once completed, the PMU will publish plain language versions of the ecological surveys on the project website.


About the ecology team

Dr Natalie Clark – Aquatic Ecology Team Lead

Natalie is an ecologist with 10 years’ experience in aquatic ecosystem monitoring, impact assessment and threatened species management. Natalie’s areas of experience include aquatic environment and fauna community monitoring, identifying site-specific passage requirements, developing fish passage design criteria and ecological input into fishway detailed design. Natalie will provide technical oversight and review of the ecological assessment


Lauren Pratt – Senior Aquatic Ecologist

Lauren is an ecologist with 10 years’ experience in aquatic ecosystem monitoring, including water and sediment quality, acid sulfate soil, macroinvertebrate, fish, turtle and stygofauna surveys. Lauren typically conducts this monitoring for baseline studies, receiving environment monitoring programs and environmental compliance. Lauren is highly experienced in macroinvertebrate identification and data quality assurance. Lauren is adept in research, interpreting data and providing easily understood technical reports for clients. Lauren will be responsible for undertaking the ecological field work and writing the ecological assessment.

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