Investigating blue-green algae in Lake Taupo

Investigating blue-green algae in Lake Taupo

Acacia Bay is a key area of Lake Taupo for recreation and drinking water. NIWA is investigating what controls the occurrence of blue-green algae there, in a step towards the development of a tool for water managers to predict blue-green algal blooms.

Based on overseas research, we expect the key contributing factors to include:

• Presence of over-wintering seed populations of blue-green algae in the sediments. We have collected sediments from the bay and undertaken laboratory experiments to look at the germination patterns of the algae under conditions similar to those in Lake Taupo in summertime.
• Physical structure of the water column, particularly the surface layer. We have put a set of temperature recorders in the bay which give us information about the layering of the water throughout the summer.
• Local weather patterns. We are using weather data from three sites around the lake to look at the influence of weather patterns on the physical structure of the water and the occurrence of blue-green algae.
• The concentration and form of nutrients such as nitrogen and phosphorus in the bay. We are collecting samples fortnightly, analysing nutrient levels and algal counts.

The research is being conducted from December to June, when historical data show us that blue-green algal blooms are most likely to occur. From February to April, which is the highest risk period, Environment Waikato is also monitoring blue-green algae and nutrient concentrations in Whakaipio and Kinloch Bays. This will provide data for a comparative study of key recreational areas on Lake Taupo.