Tuesday, February 16, 2016

Seashore Safaris with Judith Oakley

Last night (15 Feb 2016), marine biologist Judith Oakley gave an illustrated talk to the Society about Seashore Safaris, focusing on the intertidal life of the rocky shores around The Gower in South Wales.

Judith is the author of the book ‘Seashore Safaris’ (Graffeg) and, through her work with Oakley Intertidal, organises educational Seashore Safaris for all ages to visit the intertidal zones at low tide. The programme for Summer 2016 (and further information about the initiative) can be found on the Oakley Intertidal Facebook page, the website http://www.oakleyintertidal.co.uk/ and at the bottom of this post.

In her presentation, Judith started by presenting ‘The Seashore Code’. Best practice, for example, is not to use nets at all, place overturned boulders and rocks back where you fund them, to place only one creature at a time in a bucket or tray for observation, and to always put it back before the water in that bucket or tray becomes too warm or oxygen-depleted.

At low tide, a number of zones on the shore can be identified in terms of their different plants and animals, with biodiversity increasing the closer you get to the low water mark (where organisms have the lowest exposure to the air).

A range of micro-habitats occur on rocky shores. We explored three of them through Judith’s photographs: rockpools, overhangs, and under boulders.

In rockpools, we were introduced to creatures such as the common starfish that feed on mussels by prising their shell apart with their suckers and everting their stomach through their mouth into the shell to digest their prey. Chameleon prawns were shown to change colour to match different backgrounds; while grey sea slug has evolved immunity to the stings of sea anemone, and after consuming them it utilises those stings to defend itself. Another sea slug (noted generally as being far more interesting than their terrestrial counterparts) was shown tucking into a breadcrumb sponge. The beautiful stalked jellyfish (red, about 1.5cm across) is rare around The Gower, and one of the species that you can report to help improve knowledge of seashore biodiversity, for example, through the Marine Life Information Network (MarLIN) – see the sealife survey page at http://www.marlin.ac.uk/

Under overhangs at low tide, a range of exotic-looking creatures can be found. Here the humidity can remain high and the bigger overhangs are almost like mini-caves (so a torch could be handy). Here Judith introduced us to the soft coral known as dead man’s fingers – each finger being a colony of the soft coral made up of myriad tiny animals called polyps. Sea anemones, sponges, barnacles, sea firs, and other organisms are also attached to this unique micro-habitat; where you may also find the UK’s largest sea slug, and creatures such as long-legged spider crabs, sea cucumbers, and baked-bean sea squirts.

It is always fun to look under boulders (but remember to carefully put them back as they were afterwards) to find the creatures underneath. Judith showed us photos of some of the rich biodiversity that can be encountered, such as cowries, squat lobster, pipefish (with their male brood pouches), urchins and various crabs.

We will all be looking more closely next time we find ourselves on a rocky shore.

The Summer 2016 programme of Seashore Safaris led by Judith Oakley:

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