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'Poohsticks' is a game first
mentioned in The House at Pooh Corner, a Winnie-the-Pooh book by
A. A. Milne. It is a simple game which may be played on any bridge
over running water; each player drops a stick on the upstream side
of a bridge and the one whose stick first appears on the downstream
side is the winner.
The connection between the microbiological loading of Jersey seawater and this game is an obvious one, especially when we all know what bears do in the woods! The difference is where fiction stops and fact starts and that is easy with Winnie the Pooh but much harder with sewage contamination. It's worth getting a little technical to start off with so that everyone knows the main players. E.coli. This is a bacterium found in mammal and bird guts and their final product. It can cause food and water borne disease but its main role at present is as an indicator of the presence of sewage contamination. Shellfish like oysters can concentrate E.coli rapidly but can also discharge it fairly quickly. Birds are potentially big sources but like cattle, the Ecoli from them can be specifically identified when looked for. Norovirus (Norwalk). This is a specific human disease virus that causes 'winter vomiting bug'. The Ecoli indicator is really to detect the risk of virus presence such as this one. Shellfish concentrate norovirus very quickly but discharge it very slowly. This makes the use of Ecoli as an indicator a fairly crude means of determining shellfish safety and even worse the European criteria for safe shellfish is turning to virus detection very soon. Then we come to the fundamental paradox of Jersey seawater “How can we have the best bathing water quality and yet our shellfish have to be purified before they are safe to eat?” a sub-paradox is that according to the authorities, commercially produced shellfish are unsafe to eat directly but amateur collected shellfish are safe. No wonder the public are confused !
We will try and tease fact from fiction here. The bathing water sampling is undertaken at specific times and ways and is a point sample. The bathing beaches are usually sampled at high tide or near, think of Green Island or La Mare for instance. They are also sampled during daylight hours in the spring and summer when the sun's UV can kill some of the Ecoli, especially if the water has had to travel over warm rocks for a few hours. Can one be confident that the bathing water sampling is correct and that it is safe to swim there? The answer has to be yes. The shellfish samples are taken monthly and the results are very variable ranging from a very safe, less than 10 Ecoli /100g, to a 'must be relayed in clean water for more than three months' 40,000 Ecoli/100g. Unlike the bathing water quality samples these shellfish samples are not really point samples but 'time logs' indicating the level of recently absorbed bacteria against the rate of discharge. In the case of Ecoli most is discharged in 72 hours. This means that if a wave of sewage goes through the beds, 72 hours later there will be little indication of it. However, as this is only an indicator and the real disease causing organisms are viruses which take months to discharge the 'this is safe' message is an illusion. The new shellfish safety directives from the EU (to which Jersey producers must comply in order to sell abroad) which use virus detection, could sound the death knell for the oyster industry unless the viral load is reduced. Where does the sewage that affects the shellfish industry but not the bathing water quality, come from? The easiest way to start to answer this is to say where it doesn't come from or more correctly, mostly doesn't come from. The sea is an end point for a wide range of discharges and a large flock of birds, a failed septic tank or an errant cattle farmer, could all contribute massively to a problem. Birds. The Ecoli can be differentiated from human and some Jersey samples have shown that they can be a contributor as would be expected in a Ramsar site but the percentage is small. Cattle. Dairy farmers are responsible and have strict water pollution protocols to follow and very few discharge anything that would flow towards the south east coast. Septic Tank failure. Water Resources and others have frequently sampled the east coast (and other) outfalls. The picture is mixed, at times of heavy rain individual storm drains can produce occasional high levels. Water Resources have also analysed the rainfall data and compared it to shellfish contamination and shown a clear correlation between rainfall events and levels of contamination. Case Proven! Not Quite!! Below: Two conflicting Jersey Evening Post reports from the summer of 2009:
There is a scientific dictum 'Correlation does not infer causation'. During a heavy rainfall event in 2009 members of the shellfish industry using sterile bottles provided by Water Resources sampled a number of suspect outfalls. The result was illuminating. The Bellozanne outfall was producing thousands of times more Ecoli than all of the east coast discharges put together. Why was this and could this be the main source?. The Bellozanne outfall combines a stream flow and the sewage discharge which is UV treated. Seemingly at the time Water Resources did not sample this point and relied on Transport and Technical Services providing manufacturers specifications for the plant alone. At times of high rainfall the water becomes turbid (murky) restricting the effectiveness of the UV penetration and far exceeds the plants capability. The 'once in ten year event' discharge from the cavern also comes into play many times a year. So it does appear to be a 'smoking cannon'. Tidally, any discharge into St.Aubins Bay can under most tide conditions, end up moving up the La Sambue Gutter, past Le Hocq and into Grouville Bay. Incidentally the highest peak results come from the Green Island Beds and the lowest to the south of Seymour Tower which is a slightly different water column. When questioned on this during a Marine Resources Advisory Panel, the Minister for TTS retorted 'find £250 million and we will sort it out'. Even more telling was a comment to an external consultant by a TTS senior manager 'if we weren't being prosecuted by Water Resources over nitrate discharges into St.Aubins Bay we would have more money to sort out this problem'. In the meantime one oyster farmer had his only top grade harvesting area downgraded and was forced to spend £60,000 on temporary purification equipment. No grants, no aid, no apologies! Poohsticks!
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