Forecasting contamination risk for shellfish harvest and beach use

Tasman and Golden Bays on the 29 September 2014 with large sediment plumes from a storm event. © Cawthron Institute-generated image from Landsat-8 data (provided by the United States Geological Survey)

We have developed a near real-time forecasting tool for Tasman and Golden Bays to help predict when aquaculture sites and beaches are safe to access. 

Project leader: Ben Knight, Cawthron Institute

Duration: February 2017 – June 2019 
Budget: $450,000 
Status: Ongoing 

Seawater in Tasman and Golden Bays is periodically contaminated with bacteria, causing temporary closure of commercial shellfish harvest and public beaches. The aquaculture industry and regional councils want more accurate and timely forecasting to better predict and manage risk. We are creating the first near real-time forecasting tool for the region, which will improve the prediction of contamination risk. 

The coasts are at the ‘end of the pipe’ for discharge from local rivers and streams, so seawater quality is sometimes compromised by bacteria from land-based activities. This can affect the revenue of shellfish growing areas and close local beaches to public use. 

Although improved land management practices may ultimately reduce contamination risk, our research aims to improve forecasting so that beaches are not closed when bacterial levels are within safe limits and harvesting of shellfish is not unnecessarily delayed.  

Our team of national experts, from the Cawthron Institute, NIWA and MetOcean Solutions Limited, have built connected models from the land to the region’s main rivers to the sea. We have combined river flow estimates with river bacterial measurements to predict contaminant discharges on the coast. The model is a daily forecast – like a weather map – of river plumes entering the sea and contaminant measurements that accurately estimate contaminant risk. 

 

Latest news and updates

Interview: Stew Robertson, Abel Tasman Ecotours/Tasman Bay Guardians

Stew Robertson has been a participant in research workshops for projects focused in Tasman-Golden Bay. He is involved with the Nelson Biodiversity Forum and founded the Tasman Bay Guardians in 2017.

Understanding food webs to help manage coastal resources

A study of coastal food webs has revealed how ecosystem-based approaches to marine management could improve management of fish stocks and biodiversity in our changing coastal ocean.

Sharing our latest sedimentation science

In a workshop hosted in Wellington in early May, NIWA and Victoria University of Wellington researchers shared their latest findings on the effects of sediment on both shallow water and deep-sea species with iwi and stakeholders.