Crassostrea and TBT – a very thick shell

Posted on August 21, 2017 by winderjssc

I been looking out some specimens of oyster shells that I collected from modern oyster beds on the south coast of England in the early 1980s. Way back in the early to mid 20th century, the hulls of boats were often coated with anti-fouling paint containing Tri-butyl tin (TBT). It was discovered that seawater contaminated with this chemical had an affect on some marine invertebrates. One of the noticeable phenomena was the way its presence caused the shell layers and chambers of the imported Pacific oyster (Crassosrea gigas) to wildly proliferate. Shells do in fact thicken naturally with age anyway – but in shells affected by TBT the rate of thickening is abnormal. Ultimately this unusual thickening prevented the oyster from opening up its two shell valves to feed and thus caused death of the organism.

A lot of research has been done regarding the affects of TBT on oysters. Laws have been introduced banning the substance in anti-fouling paints. The specimen illustrated in this post (with the images showing the same shell from various perspectives) is probably a rare survivor from the era when such abnormalities were fairly common. Nowadays, proliferation in shell growth of this type is more likely to be caused naturally and not chemically induced.

Natural Curiosities 1

Posted on May 31, 2017 by winderjssc

A collection of natural objects displayed on my mantelpiece at the moment, along with a postcard of a watercolour painting The Pelicans by the artist Angela Gladwell (angelagladwell.co.uk).

Click once on the image to find out what the objects are.

Click twice or three times to see the details of the objects.

Studland Beach Finds

Posted on May 29, 2017 by winderjssc

Wire Weed floating in clear shallow water

Red seaweed washed ashore on a sandy beach

Sea, sand, and blue sky at Studland Bay in Dorset.

Green Sea Lettuce seaweed washed up on a sandy beach

Some of the things that caught my eye as I walked along the beach at Studland in Dorset, England, included interesting beach stones; stranded clumps of red, green, and brown seaweeds; an empty shell of a clam just eaten by a bird; and tubes of Sand Mason Worms.

Molluscs in Archaeology – new book announcement

Posted on May 24, 2017 by winderjssc

I am delighted to announce the forthcoming publication of a brilliant new book called Molluscs in Archaeology – methods, approaches and applications edited by Michael J. Allen and published as part of the Studying Scientific Archaeology Series (3) by Oxbow Books. I have myself contributed a chapter on Oysters in Archaeology to this book, summarising my past research and suggesting new ways forward using latest technologies. It is available at a pre-publication discounted price for a limited period. See the details below. You can also download a list of the contents and a copy of the application form as pdf files.

Seashells & Shingle at Whitstable

Posted on May 20, 2017 by winderjssc

Wild yellow flowers growing on a shingle beach of flints andpebbles with many small holes made by marine organisms

Empty seashells on flints and pebbles against a wooden breakwater at the beach

Oyster shells on the beach at Whitstable

Oyster shells washed ashore at Whitstable

Oyster shells on a shingle strandline between breakwaters

Flints and beach stones with holes on a shingle shore

Oyster shells on a shingle strandline at the seashore

Wild flowers growing on a shingle beach by an unturned dinghy

Rust-stained wooden upright post in a seashore groyne

Seashells, flints, and pebbles on the seashore

Yellow flowers growing on a shingle beach by a wooden breakwater

Oyster shells on a shingle strandline on the seashore

Yellow lichen growing on top of an upright wooden post on the seashore

Wooden breakwaters or groynes on the beach are a major coastal defence structures against flooding

Wild flowers growing on the stabilised shingle of the upper beach at Whitstable

Oyster and other shells on the strandline of a shingle beach

Wild flowers growing on a shingle beach by a blue tarpaulin

Oyster and other shells on a shingle beach

Empty oyster shells on flints and pebbles at the beach

Seashells, flints, and pebbles against a wooden breakwater on the shore

Pink and white wild flowers growing on the beach between overwintering boats

Wooden breakwaters or groynes at Whitstable

The shingle shore at Whitstable in Kent is protected by massive wooden groynes or breakwaters. At the time of my visit, the tide was high and the flint and other mostly worm-holed pebbles were steeply banked. The flat top of the beach was stabilised by vegetation with pink and white valerian and yellow ragwort the most colourful flowers. Pale bands of white empty oyster shells (mostly the rock oyster Crassostrea gigas) were high, dry, and dull on the shingle between the groynes; while lower down splashed by waves or heaped up against the wooden sea defence structures was a great variety of other empty shells including winkles, cockles, mussels, limpets, slipper limpets, whelks, netted whelks, Manila clams, and sting winkles. These were jumbled up with wet and dry seaweed, horn wrack, small pieces of driftwood, and flotsam. There was a marked contrast in the appearance of the shells and stones between the water’s edge where the wet shells were brighter and more colourful and the upper shore where everything was dry.

A Modern Oyster Shell Midden

Posted on May 14, 2017 by winderjssc

I have spent a large part of my life studying oyster shells that have been excavated on archaeological excavations of sites in the British Isles dating from the last two thousand years. The shells have been found in a variety of contexts including middens which are heaps of kitchen waste including oyster and other marine mollusc shells. Strangely, I had never seen a modern equivalent until this week when I visited Whitstable on the north Kent coast. I had read all about the famous Whitstable Oyster Fishery but somehow had never got around to visiting the place.

I did not choose a very good day to see Whitstable for the first time. It was very cold, dull, and windy with the choppy sea high up the shingle beach and salt spray continuously misting my camera lens. Nonetheless, I had a great time and made some interesting discoveries – not least of which was my desire to go back ago and explore some more.

Almost the first thing I saw when I hit the shore after a coffee at the Horsebridge Gallery, was the building of the historic Royal Native Oyster Stores belonging to the Whitstable Oyster Company. It included a seafood restaurant closed at the time, and outside were two substantial heaps of empty oyster shells – middens – one against a wall and the other on the shore. A casual observer might wonder why mounds of empty shells had been left lying around and not properly disposed of. There is a good and logical reason.

The shells are being kept for cultch. The youngest form of an oyster is a free-swimming larval stage which needs to find somewhere suitable to settle down and grow. It is very particular about the type of object on which it will land and attach its embryonic shell. It has a limited time, maybe just a couple of weeks if the temperature is optimum, to find just the right place. It likes all sorts of hard substrates but it likes oyster shells best – sometimes empty ones and sometimes live ones.. Traditionally, this preference is catered for by the oyster fishermen who put down quantities of empty oyster shell as cultch on the seabed to encourage the settlement of young spat oysters. They also string old shells together to act as suspended spat catchers in the water. It is interesting to see these historic practices still in operation in an age when many oysters are bred in laboratories before being grown on in metal mesh bags on trestles covered by the tides. They use both old and new methods here.

The pictures in this post show more than one type of oyster shell. The Native British Oyster, also known as the European Flat Oyster (Ostrea edulis) is the type for which Whitstable is most famous. They also use the Pacific or Rock Oyster (Crassostrea gigas) which grows faster and is therefore a good commercial proposition, especially when in recent times the numbers of our native species have reduced.