Cockles of My Heart?

Here we go again! The local news is full of images of deaths of '6000 tonnes' of cockles in the Burry inlet (http://news.bbc.co.uk/1/hi/wales/south_west/7454536.stm) and about a possible petition to the National Assembly Government for a Public Inquiry. The current claims that the shellfish deaths might be related to 'a mystery bug' or to sewage from a water treatment plant are understandable but highly speculative. In relation to the second possibility, the Chairman of the Carmarthen River Festival has been quoted as saying "We want to know what's causing the cockles to die and how much sewage is going into the estuary". That statement inevitably links the deaths and sewage. Historically, however, the cockle numbers initially boomed in this location (possibly wiping out oyster and mussel stocks at that time) when the amount of human waste going into the river was high (before the development of the hi-tech £50m sewage treatment plant). The actual release of organic material into the river will have declined in recent times, meaning that there is less 'food' for these detritus feeders. The causes for the current problems are likely to be complex and could even involve (more speculation) the liberation of toxic heavy metals from river deposits (these highly coloured sands were generated as a result of smelting operations in the Industrial Revolution and subsequently buried over decades by river movements but changes in the river channel [its no longer controlled] could have made them more accessible). It's perhaps pertinent to note that I seem to remember declines in adult cockle numbers in years gone by being initially blamed on the voracious appetites of the Oyster catcher (a bird that was shot in large numbers). The crushing of cockle spat by 4-wheel drives and tractors used in 'harvesting' eventually appeared to be implicated in these local shortages. Cause and effect are never easy to establish in such cases.