Marine Farming - Biosecurity & Biohazards

The Top of the South Marine Biosecurity Partnership includes representation from Tasman District Council, Nelson City Council, Marlborough District Council, Ministry for Primary Industries, Department of Conservation, the aquaculture industry, port companies, tangata whenua and other stakeholders.

All New Zealanders have a role to play and the Partnership is open to any organisation or industry that wants to participate in reducing biosecurity risk in the Top of the South.
For further information go to www.marinebiosecurity.co.nz

Biotoxins | Phytoplankton are microscopic plants that live in the ocean. There are many different types of phytoplankton and they are the base of the food chain in the ocean, and just like the plants in your garden they contain chlorophyll that converts sunlight into energy. Some contain compounds called biotoxins, which if consumed in sufficient quantities can be toxic to fish, and animals. While the biotoxins are absorbed into the flesh of the shellfish they do not harm the shellfish.

Red Bloom | When the conditions are right the phytoplankton reproduce rapidly into vast populations. These are called blooms or often referred to overseas as "tides" or "red tides". The blooms are an entirely natural occurrence and in fact many are not even red. There is some evidence that blooms are increasing in frequency, possibly as a result of coastal pollution.

Red tides are recorded throughout man's history. The earliest reference is in the bible (Exodus 7:20) "all the water of the river was changed to blood.

The North American Indians were reputed to have watched the sea for streaks of red water during the day and luminescence at night. If luminescence or red streaks were seen, the chiefs forbade the taking of shellfish and posted guards to warn those not acquainted with the dangers.

There are four separate types of toxins and New Zealand is one of only a few countries to have identified all four types in our waters. That may of course be because we have more robust quality programmes. The results of biotoxin poisoning range from diarrhoea to paralysis and even death - so we are talking about a very serious issue.

LCMS | There are two parts to the biotoxin programme, the first is the testing of shellfish for the presence of toxins. In September 2001 MSQP became the first programme in the world to introduce chemical based testing. These new LCMS or Liquid Chromatography/Mass Spectrometry technologies were developed at the Cawthron Institute in Nelson, in conjunction with industry. The LCMS has provided more accurate and timely testing even though it is more expensive than the traditional methods. We are now on a quest to have LCMS adopted internationally.

The second part of the biotoxin monitoring is an early warning programme that measures the numbers of phytoplankton present in the water. Because there are different types within a species the initial identification is carried out using a microscope. But another newly developed method uses a "geneprobe" which analyses the DNA of the phytoplankton to determine if toxic types are present.

Sanitation | While the biotoxins are a natural occurrence, bacterial and viral contamination is the result of human activity. Bacteria are introduced directly by faecal contamination such as sewerage discharge from boats or ineffective septic tanks - a major concern for the industry. Bacteria from animal and human origin also enter the water in run off from land surrounding the growing areas. Viruses enter the water almost exclusively from faecal contamination and those of greatest concern are of human origin. We have tended to think that the ocean is the great cleanser - but we now know that's a fallacy. One paper shows that a single human stool in the Gulf of Mexico was enough to contaminate an area 1Km long by 100 metres wide and 2mm deep.