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Thursday, October 16th, 2008
Fertiliser kills marine life
Alumeci Nakeke/Fiji Daily Post
In the past, a typical Fijian household would have a knife, fork and spade to till the land. In today's commercial agriculture modern technology and chemicals have been added to the normal tools to ease the burden of everyday cutting and digging. This includes spray tanks, weedicides and fertiliser.
For coastal communities and those who live by rivers, these chemicals are a hazard to the marine environment.
The University of the South Pacific's Institute of Applied Sciences (IAS) environment unit manager Dr Bale Tamata says surplus supply of fertiliser will leach nutrients into the soil and run-off into the creeks ending up in the sea.
She said when it gets into the sea, the nutrients from the fertiliser causes overgrowth of seaweeds. The seaweeds will then cover the corals and smother them, destroying them.
"When it dies it uses up dissolved oxygen in the water so the fish are deprived of their supply of oxygen. It therefore kills fish or causes fish migration from that area," said Dr Tamata.
"Before, there was balance between the algae and the corals but fertilisers are providing more food for the algae which will overgrow and smother or suffocate the corals."
Dr Tamata said another proof was the introduction of phosphate- free Coral detergent in Fiji and this was done to save the corals.
"When there is an increase in nutrients there is a dying coral reef and increase of seaweeds," she said.
"Phosphate affects the skeleton of the coral because it prevents its build-up and that means you will not get your coral reef. Phosphate and nitrate are food for the plant on land only."
Run off of fertiliser and soil is a situation the people living along both sides of Natewa Bay in Vanua Levu have long been experiencing.
Apolosi Silaca, a project officer for the Cakaudrove Yaubula Management Support Team, which is part of the Fiji Locally Managed Marine Area Network, said marine life in the Natewa Bay had been badly affected by chemical runoffs.
Another issue was the illegal logging practices used by contractors which resulted in soil erosion which washes sediments into water ways, rivers and into the sea. Areas mainly affected are Navatu and Korotasere.
Because of these practices, Silaca said there had been a gradual decrease in the number fish and seafood previously caught by villagers. Dead corals have also been noticed in large numbers in these areas.
"There are semi-commercial farmers who plant a lot of dalo and use weedicides and fertilisers like MPK and others.
"People are now lazy to use the knife and depend more on weedicides. These are dangerous because when it rains it seeps into the soil and run-offs into the river and into the sea," he said.
He also blamed the Agriculture Department for not addressing the side-effects of over usage of fertilisers and weedicides.
"The Agriculture Department is only promoting faster harvest, more yields, more export and more income for the people. What they do not consider is how the weedicides and fertiliser will affect the land and the surrounding areas like water and the sea and what lives in them," said Silaca.
"They do not conduct any workshop on how to properly use fertiliser and weedicide. The farmers need awareness programmes because they need to know sustainable management of resources.
"The use of weedicide and fertiliser affects the land and after four or five years, soil fertility decreases."
For soil runoffs, he said, the silt or soil settles on the reef and covers the coral from the rays of the sun. Corals have algae on them which need the sun for the process of photosynthesis just like trees to make their food.
Meanwhile, he said people farming near the rivers have also been advised that they allow 30 metres from the edge of the river as buffer zone.
"This stops the soil from running into the rivers but farmers still cut those trees. I had told the Forestry Department here about it but they blamed the Agriculture Department for the felling of those trees," said Silaca.
"They (Forestry) said people were doing that to clear the forest so they could plant more food and sell more."
However, Agriculture director research Moti Lal Autar said those allegations were peoples' own assumptions as there were no concrete information based on scientific findings to support it.
"We control the importation, distribution and use of weedicides in Fiji. In Cakaudrove very low amount of fertiliser is used only on taro crop and paraquat weedicide is used which does not leach as it is bonded to day particles as soon as it comes in contact with soil," Autar said.
"The Agriculture Department has a regular programme on training of farmers, its staff, farm demonstration and field days around the country. Awareness is generated during the above mentioned programmes on the topic."
Autar said farmers could also use whatever methods they knew like cow dung, compost their plant thresh and use, manual weeding, crop rotation."
"Fertiliser and chemicals are a part of the input that assists in increasing production. The crop on its own will not be able to do it. Every country in the world is practicing similar concept in farming," he said.
Autar added that the amount of fertilisers and weedicides used was very low as they were costly and most are of low impact to human health and the environment.
And they do not bring into the country highly toxic weedicide.
However, Dr Tamata refuted Autar's claims, saying there was scientific proof that fertilisers impacted the ocean.
"There have been studies on the Great Barrier Reef in Australia, Florida Keys and Hawaii that showed that high nutrient levels from fertilisers resulted in high algal dominance," said Dr Tamata.
She said it was the Ministry of Agriculture's responsibility to advise farmers of the fertilisers' detrimental effects.
"They (farmers) should also know how much the soil needs and there should be an education and awareness on the importance of adding enough. Any surplus will leach into the soil into the creeks and end up in the sea," said Dr Tamata.
"In the sea there are phytoplankton (algae) that you cannot see with your eyes, all the nutrients will be eaten by them and by the seaweeds causing them to overgrow.
The overgrown seaweed will cover the coral and smother them. When they die they will use up the dissolved oxygen in the water and deprive fish of their supply. Fish kills like the one in Qawa river (Labasa) happens due to lack of oxygen and fish migration could also happen."
From a study she did in the Coral Coast, Dr Tamata had similar findings.
She said there was also a safe water level but when this was excessive it led to coral degradation.
To solve the problem she suggested that the CYMST organise awareness progrmammes and the two ministries to stop blaming each other.
"We need to reduce and control fertile input and there is a need to do some baseline water quality to find out how much nutrient is already there," said Dr Tamata.
"Maybe the levels are already exceeding the safe levels and if they are, they should start checking how much fertiliser is being added by farmers.
Timing of application was another important factor, she said.
"They should also see to the timing of the additional fertiliser because it has been proven when it rains it is time of the flushing out of these nutrients. So it would be best that they are added during dry period and not in the wet season."
"It has also been found that the nutrient loading in the creeks and rivers is highest during rainy season. So Agriculture should monitor the timing and the amount applied," said Dr Tamata.
She added that mangroves, marshland and creepers that grew along the shores also acted as natural filters so people should not cut them.
Moreover, piggeries and development also contribute to the imbalance in the nutrient level.
Silaca also mentioned nutrients from piggeries near the rivers and seashores in those villages also affected corals.
Those rearing pigs should have been advised by the Veterinary department on how to drain its wastes.
"I had also informed those who attend our tikina council meetings about the problem of piggery but villagers are slow to take action," he said.
"People should remember that when you do something, one has to consider the next generation."
He said many thought rearing animals would alleviate poverty but they do not think of the bigger poverty that is going to follow.
"Animals are not really good means of economical benefits because in the villages animals are mostly used for traditional ceremonies. Those animals are not eaten regularly but rather for special occasions only," said Silaca.
He said what communities have put in their management plan should be followed especially regarding piggeries and the use of fertilisers.
And its effects on corals should be their main concern because it is the sea that most depend on for their daily sustenance and livelihood, said Silaca.
Alumeci Nakeke is an Ocean Science Reporter with SeaWeb. SeaWeb is a non-government organisation that helps the media promote a healthy ocean.
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