Study

Integrated submerged aquatic vegetation management in an urban New Zealand river

  • Published source details Schwarz A. & Snelder T. (1999) Integrated submerged aquatic vegetation management in an urban New Zealand river. Hydrobiologia, 415, 235-241.

Summary

Action: Use cutting/mowing to control problematic plants

A study in 1996–1997 in a lowland river invaded by curlyleaf pondweed Potamogeton crispus in Christchurch, New Zealand (Schwarz & Snelder 1996) reported that over 20 months after cutting and removing aquatic macrophytes from the centre of the channel, cover of native stonewort Nitella hookeri increased. Statistical significance was not assessed. A first cut was made in March (autumn) 1996. Over the following winter and spring, the dominant macrophyte was curlyleaf pondweed (66–98% cover). Stonewort cover was only 0–3%. Total aquatic macrophyte cover was 76–98%. A second cut was made in September (spring) 1997. In the following two months, the dominant macrophyte was stonewort (66–68% cover) with little curlyleaf pondweed (5–22% cover). Total aquatic macrophyte cover was 86–99%. Methods: The study took place in a stretch of the Avon River (maximum depth 1.5 m), in which aquatic macrophytes had historically been cut (twice annually, with weed-cutter boats) across the whole 20-m-wide channel. In March 1996 and September 1997, only the central 10-m-wide strip was cut. Aquatic macrophytes were surveyed at 1 m intervals across the river until November 1997.

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