With the water levels back to normal, today we have been assessing the damage from last week’s surge tide. Compared with some coastal sites we have got off pretty lightly and our visitor facilities are pretty unscathed but we are very concerned about the ecological damage. Saltwater can have a devastating impact on freshwater wildlife – not just fish but the water beetles, snails, dragonflies and other insect larvae that are important food for fish and many waterbirds - so one of the first jobs was to survey the salinity. The news is not good with the average salinity in the fen equivalent to 20% seawater – more than enough to kill the more sensitive freshwater fish and invertebrates.
In 2006 and 2007 Strumpshaw Fen experienced surge tides that had an even greater impact than last week’s. Since then we have invested in three new big sluice pipes to get salt water off the fen much more quickly and bring in freshwater to flush out the remaining salt, and we are now very glad we did. With water levels back to normal in less than 48 hours, the first part of the plan has worked well. Now we need to draw the water level down further and start bringing in freshwater to push out the remaining salt and refill the ditches and pools over the next month or two.
The flood has left us with a mystery. Compared with the 2006 and 2007 floods we have seen very few dead fish, yet the salinity is high enough in places to kill most freshwater fish. The many herons, bitterns and gulls may have mopped up the smaller dying fish but what about the big pike and bream that we know are in the Old Broad? Perhaps the regular saltwater floods have toughened them up.
The good news is that all our hides are now open to visitors, albeit along some rather muddy paths, with just the Lackford Run path still closed while it dries out.