The Great Escallop

Last week we bade farewell to our current group of brilliant V Factor volunteers. They have worked extremely hard to record data from our scallop shell collection. They have successfully photographed and identified bryozoan colonies. Their photos will be used to a make a key which will help future groups of volunteers with ID work.

Thank You Group 2!

We celebrared their achievements with Certificates and Scallop shaped macaroons!

Our Scallops

Unlike the biscuits our real scallops were not just destined to be eaten. Our real life shells originally came from a Scottish sea food restaurant; they were then used by PhD student Rob Cook for his research into the best substrate for re-establishing horse mussel beds. His project is now over, but instead of chucking out 300 buckets of shells they are being re-used again to obtain data on the distribution of bryozoan species around the UK. Once the shells have been processed they will be reused yet again in our ‘Biota in a Box’ educational boxes which families can borrow for free through this website.
 

Our real scallops!

Scallop biology

Our Scallop shells are all King Scallops (Pecten maximus). They can swim away from predators, like starfish, by ‘clapping’ their shells together, letting water in between the shells and then forcing it out to propel themselves (although not particularly gracefully). Like bryozoans they are filter feeders, feeding on algae and diatoms. Although you wouldn’t know it from looking at ‘dead’ scallop shells the entire curved edge of the scallop shell is lined with sensory tentacles and up to 35  green-blue eye spots (very simple light sensing organs).

                   

Live King Scallop, Pecten maximus (image taken from: http://perth-bsac.co.uk/scuba-diving-in-scotland/isle-of-skye-day-2_2009...)

Their upper shell is always flat, and the bottom curved/cupped. They often excavate ‘craters’ in the seafloor for themselves, sitting with their flat upper shell just at the surface, a bit like a trap door.

Did you know? Like trees, Scallops (and other shells) have growth rings which are indicators of their age. Scallops up to a year old are called ‘spats’.

Scallops and humans

As well as being an important part of our underwater ecosystems Scallops are considered a delicacy often gracing the menus of tops restaurants.  In 2013 48.7 thousand tonnes of scallops were landed in the UK by UK based fisheries, at an estimated value of £62.5 million.1
Unfortunately our taste for scallops is in some cases harming the marine environment. Scallops are often caught using a method called dredging. Which involves boats dragging a net with a comb like bar attached to the base, effectively raking the sea bed for scallops (see diagram below).  This method is considered one of the most damaging fishing techniques, because it seriously decreases seafloor biodiversity.2


Diagram showing construction of scaollop dredging  gear which would be towed behind a boat harvesting scallops (image taken from: http://www.fao.org/wairdocs/tan/x5923e/x5923e01.htm)

According to the Marine conservation society the best way to harvest scallops is by hand, but this method is more expensive and time consuming, increasing the cost to the consumer.

Interestingly although bryozoans appear to love to colonise our empty scallop shells, they are far less keen to make their homes on living Scallops. Possible due to competition from other organisms like sponges.3

Thankfully Marine Protected Areas offer a safe haven from dredging for our wildlife, including bryozoans!

Links

Ever seen a scallop swim? https://www.youtube.com/watch?v=4jA84EFrI34

Want to know more about King Scallops http://eol.org/pages/449733/overview

References:
1 Marine Management Organisation (2014) ‘UK Sea Fisheries Annual Statistics Report’ [Online] . Available from: 2013’ https://www.gov.uk/government/statistical-data-sets/uk-sea-fisheries-ann... (accessed:14/03/2015)
2Howarth, L. M. & Stewart, B. D. (2014) The dredge fishery for scallops in the United Kingdom (UK): effects on marine ecosystems and proposals for future management. Report to the Sustainable Inshore Fisheries Trust [Online]. Marine Ecosystem Management Report no. 5, University of York, 54 pp. Available from: http://www.sift-uk.org/media/file/Howarth%20and%20Stewart%20%282014%29%2... (accessed:14/03/2015)
3 Ward, M. A., Thorpe, J. P., (1991) ‘Distribution of encrusting bryozoans and other epifauna on the subtidal bivalve Chlamys opercularis’ [Online] Available from: DOI: 10.1007/BF01313711 (accessed:14/03/2015)

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Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith