Grafham Treasures

Grafham reservoir between Kimbolton and St Neots is a good meeting point for walks, picnics, sailing and obviously exploring.

Last Sunday along with three other explorers I walked the 10 mile circuit around the reservoir , this is mainly flat with a few mini hills and parcels of woods as you travel round.

The water level is low after a long hot summer and the shore line is very interesting. There are whole banks of shells of fresh water molluscs and fossils to be found.

There have been lots of these blue sky days this November and the trees continue to shine as their leaves slowly drift from them.

The berries are burdening trees with their weight. These spindle berries added a different colour to the normal reds and oranges.

These two explorers were taking in the view half way round , little did we know then that the tea room was actually closed and all we had was a packet of Tangtastics to sustain us !

Finds from the shore:-a tiny scoop of shore sand ……..absolutely full of shells !

Fresh water molluscs galore, easily sorted to start with into gastropod , those with a twist or spiral and bivalve, those with flat shells.

The sand is mainly broken shell fragments some shells are perfect and tiny.

Using a 5p for scale

One of the shells, a bivalve that there were a lot of were zebra mussels these are an invasive species which threatens the native fresh water mussels.

An article below explains the threat.

Millions of invading zebra mussels are playing havoc with England’s drinking water supplies. 

The zebra mussel is a species that arrived 200 years ago in the UK from the Caspian Sea and is now thriving as a result of the cleanliness of our water systems. 

They can spread easily as their larvae move through canals and rivers like cars on a motorway network. The invading mussels also kill British native freshwater mussels. 

If the zebra mussels get into water treatment works, they can block up the whole system.

Inside Out’s David Whiteley visits Grafham Water in Cambridgeshire where millions of this invasive species are in danger of taking over. But what can be done to stop the spread of these foreign invaders? 

David also travels to Rutland Water where £1.5 million has been spent on a trap to stop the zebra mussels clogging up water pipes.

There are six species of freshwater mussels in Britain, they are very important to the ecology of a river or lake. The aptly named depressed mussel is under threat. One reason for this is the management techniques for rivers that often includes dredging which destroys the mussel beds.

It is surprising that there are so many types of freshwater mussel native to Britain , 5 in the lowland rivers and the pearl mussel in upland waterways.

The Gastropods in this sand are very small , using the key the flat spiral species in the photo with the 5p is a rams horn snail , maybe Gyralus crista it is very small so difficult to identify.

The taller spirals

Those with left hand spiral – Physella acuta

Those with right hand spiral – Lymnaea bathica.

Looking through the tiny specimens there may be one more – Bithynia leachii.

It’s amazing what you scrunch under foot walking along the shore, making more sand .

A good walk with lots to see.

Address: Grafham Water Visitor Centre, Marlow Park, Grafham, Huntingdon, Cambs, PE28 0BH.

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