How is algae grown?
The facility at the Cawthron Aquaculture Park produces about 2000 litres of microalgae cultures per day, in a combination of continuous and batch culture. Most of the algae used to feed the larval stages of shellfish is grown in continuous culture, as this is a cost-effective way of growing the 'gourmet' algae required at these early life stages.
Research and development feeds shellfish
Cawthron carries out research and development on the continuous production of fastidious microalgae species. For example, the team have succeeded in the continuous culture of Chaetoceros calcitrans, a very small diatom that is an important diet component of many shellfish larvae. This work requires the combination of microbiological, chemical and process engineering expertise.
Where is our algae grown?
We grow our algae in large ponds at the Cawthron Aquaculture Park, which is an ideal environment.
- The seawater is of constant quality because there is no major freshwater inflow nearby, and there is little suspended matter in the water during rare northerly storms.
- The land behind Nelson's Boulder Bank lies below spring high tide, which fills the ponds with fresh seawater at no cost.
- The Glen, where the aquaculture park is located, is one of the sunniest spots in New Zealand – meaning plenty of sunlight for phytoplankton production in the ponds. Phytoplankton is used to grow shellfish spat and to condition broodstock such as adult shellfish used in Cawthron's breeding programmes.
The technologies developed to produce algae in continuous, batch or pond culture can be adapted to grow algae that produce bioactive compounds of commercial interest (see microalgae production and extraction for bioactives).