L is for Lakes – that’s what L is for ...

Derwentwater from the northern shore near Keswick

I was (and am!) going to write about lakes .. but I note that Wikipedia tells me we only have one in England, and six in Scotland!  I thought we had a Lake District ... but who am I, a mere blogger, to know!

Lakes, meres (lakes that are broad in relation to their depth), waters,tarns, lochs or ponds – we all have our own terminology and understand our countries’ differences  - the word ‘lake’ comes from Middle English for lake, pond or waterway and from the Proto-Indo-European root ... to leak, drain.

Glenridding and Ullswater

Lakes – worlds doomed from their creation.  Feeder streams fill them with silt and their outlets cut every deeper drainage routes.  For plants and animals, lakes form isolated, ever-changing worlds.

Most natural lakes in the British Isles were formed by the action of the Ice Age glaciers.  Each lake is virtually a closed system – an independent world with its own shifting balance of plants and animals.

The sun ‘layers’ the still water and heats the first twenty feet or so, then there’s an intermediate layer of about ten feet of cooler water, before the unheated cold layer:

• Life in a lake depends on oxygen, which enters the surface either from the atmosphere or as a by-product of plant respiration; 

• The warming sun heats the still surface water, which floats on the denser cold water; 

• As the sun warms the top layer up, an intermediate layer forms, through which the temperature drops rapidly;  the three layers do not mix; 

• Therefore the bottom layer receives no oxygen, though it does receive a constant rain of organic debris from above; 

• Then, in winter, the surface cools and the water circulates until it is thoroughly mixed with oxygen being evenly distributed throughout, and dissolved nutrients from the bottom debris are returned to the upper levels.

The vendace (Coregonus vandesius)

is England's rarest species of fish, 

and is only found in the Lake District.

(A freshwater whitefish now

only found in Derwent Water.)

Animals vary from lake to lake, and from primitive forms of life (water fleas, phantom midge larvae) to those we more easily recognise ... mussels, worms, shrimps and water boatmen; to reed feeding animals – dragonflies and damsel flies; to fish ... brown trout, pike, perch, minnows and eels.

Lakes support local wildlife, and attract a variety of water birds ... insect feeders, divers, herons etc and migratory birds find a haven on their journey.

Sadly pollution and our demand for drinking water are causing problems in some of our lakes ... as the water levels rapidly fluctuate ... this destroys the shore vegetation upon which so much animal life depends.

There is as elsewhere in on this earth ... a web of life in a lake ... all to an extent interdependent on each aspect of the flora and fauna, which as a whole rely on their tiny self-contained ecosystem that was created millennia years ago to exist within this world of ours.

These are Lakes - that is what L is for ..    

Part of the ABC - April 2011 - A - Z Challenge - Aspects of the British Countryside

 Hilary Melton-Butcher

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