Lake edge plants could help small lakes
Lake Okareka, in the Rotorua district, still has clear water, but is showing early signs of deterioration. A NIWA study is investigating the importance of vegetation growing on the lake edge in protecting the water quality – with potential application to other lakes.
Bands of tall, emergent plants such as raupo, kuta, and jointed twig rush grow in parts of Lake Okareka out to about 3 m depth. Such vegetation used to be common in many small New Zealand lakes. International researchers have suggested the plants are effective in reducing algal blooms in small lakes, because the emergent plant tissues decompose more slowly and retain nutrients more strongly than other plants. Now NIWA is starting to test this in New Zealand conditions.
The work is being funded by the Foundation for Research, Science & Technology and Environment Bay of Plenty, and is contributing to the Lake Okareka Catchment Management Action Plan.