Saturday, 26 May 2012

Seething Wells Water Levels and Water Quality

Seething Wells 2009
It is understood that newly appointed consultants will resume their surveys next month. The water levels and water quality are very different from when the Filter Beds were sold (2009). The draining of the FB's (Jan, Oct, 2011) changed the site (from left) to the swan photograph below. The  pair of swans breeding at Filter Bed 7 are able to stand in the water, demonstrating the current  low water levels. Draining led to the growth of vegetation, including reeds and other plants, which have died back over the winter. As these plants have become submerged through rainfall, the increased nutrient levels in the water have led to the algal growth, which now forms dense mats over the water surface.
Filter Bed 7 May 2012 Until the water levels and  quality returns to status quo, surveys will not capture any bats foraging over the Filter Beds.








Daubenton’s bats are capable of gaffing or trawling insects directly from the water surface using their feet or interfemoral membrane.  It has been shown using fecal analysis that a quarter of the total prey caught by Daubenton’s bats are directly from the water surface and the remaining 75% from directly above. A Daubenton's bat requires one insect capture every seven seconds to energetically break even.  The draw of insects to artificial lighting has been termed the vacuum effect. This insect attraction leads to a reduction in insect density in the surrounding area, leaving light-shy bat species at a significant foraging disadvantage. If a reduction in available insects occurs, a catastrophic effect could affect population levels of this bat already declining in the London Region.


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