Aquaculture Environmental Monitoring: Wilsons Bay

This monitoring programme studies water quality, mussel growth and condition, benthic communities and sediment, currents and wave action, hydrodynamic modeling and biotoxins inside and outside the marine farm. The purpose is to determine the environmental effects of marine farm development in Wilsons Bay, Coromandel.

Water quality – temperature, salinity, transparency, chlorophyll a, phytoplankton and microzooplankton community composition and biomass, inorganic nutrients, and suspended solids. Mussel condition and growth monitoring – total green weight, total cooked weight, cooked meat weight, shell length Benthic community and sediment monitoring – video images (benthic fauna presence and activity, sediment characteristics) and sediment grabs (organic matter, particle size).

Wilsons Bay

Wilsons Bay – E2726260 N6476246, NZMG, !:20000, AREA

Water quality – Five sites sampled using 'tube' sampler to give an averaged sample of dissolved and particulate materials from the surface to the chosen sampling depth. Additional sample taken a one site at a depth of 25 m. On completion of each stage of development of the mussel farm water column parameters of the wider area will be mapped providing a three-dimensional view of any change in phytoplankton, nutrients or other suspended loads – two sample runs made over high and low water periods, which traverse a minimum of 5 transects. Twenty discrete samples will be taken per run. Mussel condition and growth – 20 mussels collected from pre-set droppers at minimum of 3 sites (upstream, middle and downstream of development - + control site?). Measured for total green weight, total cooked weight, cooked meat weight, and shell length. Growth is measured monthly from the length of the 20 uppermost mussels on five dropper lines and compared with results from the Marlborough Sounds. Benthic community and sediment – video transects cover within the farm and run 6 km away from the farmed area, covering upstream and downstream regions. Geogrphic and depth referenced video images of the seabed are interpreted by trained staff to identify animals on the seafloor, their activities, presence of shell material, high organic accumulations, sandiness or muddiness. Initial sampling by divers of the density and diversity of animals on the surface was undertaken to relate structures on the seafloor to specific animals. This enables changes in the density of certain structures to be linked to changes in certain animals. Video data is supplemented by 60 sediment grab samples (2 replicates at 6 locations on 5 transects). Modifcations to monitoring from 2006 onwards have seen replacement of video surveys with Sediment Profile Imagery (SPI). Currents and wave action – deployment of wave gauges and current meters. Biotoxin monitoring - will follow the standard procedures as required by MAF Regulatory Authority Biotoxin Monitoring Programme. Frequency of collection: Water quality – fortnightly sampling (+ surveys of the wider area of the eastern Firth of Thames for temp, salinity, transparency, chl a, and nutrients will be undertaken at each stage of farm development). Mussel condition and growth – fortnightly and monthly sampling

Not reported

reports, electronic

Sustainable marine farm management

see NIWA and/or the Wilsons Bay Consortium. Reports are publicly available, raw data is commercially sensitive

Ongoing video sampling

Additional comments: Publicly available report based on results from above monitoring to be produced.