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.


Comments

Post a Comment

Please share your thoughts

Most viewed

Heritage Trees part 2: street trees.

Image
  Oaks and maples Cambridge Gardens 2019   Street trees can often be the most beautiful objects in our streets. They are important to their communities as well as having environmental benefits. They are a living history in our landscape and can have particular connections. They may be fragments of a previous landscape incorporated into a modern street scene, such as the oaks at Cambridge Gardens once  part of the Duke of Cambridge's estate.  A great read with information on how to research street trees is a  History of Street Trees by Dr. M. Johnston.  London plane trees CRE 1976 Beech tree, Chesterton Terrace 1976 Studies show that the difference in local tree cover can reflect the various socio-economic groups. In Victorian times middle class areas were planted with many street trees or had higher quality front gardens than working class districts; now referred to as 'green equity'. It can be demonstrated by looking at old photos of the seven...
Read more

Fishing the Hogsmill

Image
Fly-fishing the Hogsmill   It is interesting to see the river from a different perspective: the Hogsmill is popular with anglers at this time of year; although it is unusual to see someone fly- fishing. A chub has just been caught on bread and it looks a good size. Trout are sometimes seen in the Hogsmill and can sit in the weir notch by the school. Our own Richard Jefferies in his book 'Nature Near London'  remarked on the Hogsmill trout as far up as Tolworth Hall Bridge (now the A240). chub    This fish was carefully unhooked and orientated in the swim where it soon finds it way - probably to the next father and son - sitting further upstream. These anglers have caught the 'ghost' koi within the last two weeks and appear to be the second successful pair to catch the pond-escapee in the last few days. Ghost koi are a British invention. They were produced by accident in the early 80’s when a farmer allowed a mirror carp and a koi to spawn together. The offspri...
Read more

Seething Wells: they've done it again

Image
The last day of May, I went to see if I could find the black redstart that had been widely reported, no luck but it will turn up again on one of the old buildings. The lush vegetation was looking beautiful between the Filter Beds at Seething Wells. I made a note of the breeding birds: goldfinches twinkling away, blue tits gathering food, sand martins flying over the FB's (only two this year unfortunately) moorhens and some scruffy little coot chicks entangled in the algal blooms.   Proud parents were showing off their four Canada chicks; they can cover a lot of ground in a short space of time they were soon feeding on water pepper and bistort gleaned from  the ziggerat-sided basins. A song thrush sang from the wharf alongside greenfinches as well as the seasonal chiff chaff; although this year all numbers are down, reflecting not only the topsy-turvy Spring but also the continued tumble in insect numbers (even seed eating birds are dependent on insects to feed their youn...
Read more