Wellington Scoop

Warning: chemicals in seaweed will create a threat to human health


Wellington fishermen are warning that an increase in commercial harvesting of seaweed from beaches will create a threat to human health.

The increase is being proposed by the Ministry of Fisheries and Biosecurity New Zealand. But they have been warned by the Wellington Recreational Marine Fishers’ Association that the seaweed is scientifically proven to absorb toxic petroleum or endocrine chemicals – and if it is used as a fertilizer or in food products, the chemicals will be passed into the human food chain.

“The seaweed on the beach on either side of the waste-water pipe in Lyall Bay and either side of the Hutt City pipe at Pencarrow provides a perfect example of chemically-destroyed seaweed,” writes Jim Mikoz, vice-president of the association, in a submission to the two government bodies.

The submission states that a number of science papers have been published describing how chemicals are absorbed into seaweed; one was a study of the Hutt River. It makes an alarming connection between the poisoning of seaweed and pollution in the water around Wellington. “Beach-cast seaweed is continually being drowned in chemicals.”

In an earlier submission to the Wellington City Council, the association opposed the discharge of waste-water into water less than 50 metres deep or 500 metres from highly-used recreational reefs. “There is no waste-water plant able to remove endocrine and petroleum chemicals or human diseases – they flow out of waste-water pipes which are all in water less than 50 metres deep.

“Some waste-water plants have to add a class eight chemical to meet the required ph levels; in Wellington, that is 38,000 litres a week unless it rains, when the quantity is trebled. The plant’s capacity is then exceeded and untreated waste-water at 4200 litres a second flows onto every rock for over 15 miles.

“Chemical contamination of our coastline is a national disaster, with rivers such as the Manawatu collecting waste from two cities and a number of dairy-related industries that use chemicals which cannot be removed. At times of flood these chemicals combine with cyanobacteria resulting in toxic algae blooms sometimes causing massive fish kills but other times killing whales. There are over 30 science papers published a year describing how chemicals are killing fish, dolphins, sealions and whales, while in some rivers fish larvae are being hatched with two heads.

“The chemicals from waste-water and the chemicals that arrive with high river flows contaminate our shoreline’s inter-tidal zone and flow into seaweed beds, stunting their growth or turning the seaweed black.”

The fishers’ submission states: “Biosecurity and MFish – you have been warned that if you allow these chemicals and diseases into our food chain by allowing the harvesting of beach-cast seaweed for commercial use … you will have become a party to promoting a toxic product for human consumption.”

Jim Mikoz adds a personal story about dolphins.

“In my experience,” he writes, “dolphins know they are entering an area contaminated with endocrine chemicals and human diseases. They will not pass through the waste-water slicks from the Hutt City outfall at Pencarrow or the Wellington City Council outfall in Lyall Bay. I have photographed a pod of dolphins that immediately changed course as they entered the waste-water chemical slick coming past Island Bay.”


  1. Aimee M., 7. August 2009, 12:26

    …….it sounds like ‘what goes round, comes round’……if the danger of toxicity from the seaweed ( to be collected for distribution in our food sourse,) is in the chemicals washed into their environment, then the chemicals are already distributed in the environment we are living in in the first place to get washed down to the seaweed beds. It’s a far bigger issue than stopping the collection of the seaweed “at the bottom of the cliff.”

  2. Celia Wade-Brown, 10. August 2009, 9:25

    Endocrine disrupting chemicals (EDCs) were addressed in the Moa Point Assessment of Environmental Effects (AEE) and in evidence presented at the Moa Point resource consent application hearing. EDCs are trace organic contaminants that have the potential to adversely affect aquatic fauna by mimicking hormones in a process termed “endocrine disruption”. EDCs can be expected in the influent to wastewater treatment plants. Investigations into removal of EDCs in wastewater treatment plants in NZ, Australia and internationally shows concentrations of most EDCs are greatly reduced by sewage treatment processes. Modern activated sludge plants such as at Moa Point and Seaview would typically remove 80-100% of most EDCs. Residual concentrations in treated wastewater are typically measured in “parts per trillion” and are often undetectable. Subsequent dilution in the receiving waters ensure that discharges from Moa Point and Seaview WWTPs present no significant risk to the aquatic ecology (or to human health).

    Wellington City, Hutt Cities and Porirua City Councils have modern wastewater treatment plants that discharge fully stabilized and disinfected effluents into the sea. The level of treatment given is as good as or if not better than most treatment plants discharging effluents to the sea. In terms of treatment there is little more that can be done apart from perhaps improving the actual location of the points of disharge.

    Because of the buffer capacity of marine waters there is no need for pH correction and in any event all the discharges have a near neutral pH value anyway

    Cr Celia Wade-Brown
    Wellington City Councillor
    Environment Portfolio Leader