Shoresearch Cornwall Blog: Stackhouse Cove

Well the weather couldn't have been better for our survey of Stackhouse Cove last Thursday. The sun was out and there wasn't a breath of wind as we walked through the gorse and bluebells from Prussia cove West till Cudden Point (the eastern boundary of the recommended Mounts bay MCZ). Abby and I were joined by a great and enthusiastic group of volunteers, Jake Meyers, Liz Barker, Rob Wells and Rob Seebold (now of Natuaral England), Jonathan Kersley, Margaret Gardener and Kathry Driscoll. We were lucky to be joined later by Angie Gall who shared her fantastic knowledge with all present, me included!

The view from the point taking in Stackhouse cove and its bizarre criss-crossing gullies, down past Perranuthnoe all the way to St Michaels Mount was breathtaking.

What a day!

We left Abby on the point with her telescope and sun cream to carry out a sea watch for cetaceans and seals while we walked down the narrow path to the cove.

Stackhouse cove was named after Victorian Naturalist John Stackhouse who was one of the first people to study the reproduction of seaweeds, from his home Acton Castle that overlooks the cove. Although at first sight the shore seemed bare a huge diversity of seaweeds and animals were found near the low water mark. The shore faces south west and is one of the most exposed parts of the MCZ. The terrible battering this coast line experienced this winter may explain the relative lack of seaweeds on all but the lowest shore and the rockpools. On a low shore flat reef Angie pointed out that a huge mass of green gut weed Ulva intestinalis was covering the rock, possibly new successional growth following the winter clear out of seaweeds. Here and there on the smooth slatey rock you would find limpet scars but there were relatively few limpets suggesting these too may have been removed by the force of the sea.

Rob and Mango shore searching

The shore is criss-crossed with spectacular deep gullies which provide their own micro climates. Within one lower shore gully Jake and Rob Seebold found a mass of sponges, hydroids and a group of sea lemons feeding and laying egg masses on this shaded but open rock surface. Prize for the best spot goes to Jake who spotted the legs of a sea spider sticking out from beneath a beadlet anemone. The spider (Nymphon gracilie), was carrying a mass of eggs below its body. They are predatory animals so I wonder what it was feeding on there? Hydroids or maybe even the anemone!

Sea spider beneath a beadlet anemone - found out of water inside a shady gully

Sea spider - note the egg mass visible beneath the body

In an open area of large flat boulders we found a huge diversity of crustaceans, Montagu's crabs, large velvet swimming crabs, edible crabs, broad clawed porcelain cabs, squat lobsters, plumed bertha sea slugs ,(Bethella plumosa) and even a tiny sea cucumber Pawsonia saxicola.

Female shanny found under a rock

In cracks facing inshore away from the prevailing swells we found encrusting star ascidians and other colonial sea squirts, being preyed upon by cowries. Beautiful bushy hydroids decorated these gullies and shannies and hairy crabs were hiding in the deepest cracks in the rock.

Male shanny gaurding his eggs in a deep crack in the baked bean seasquirt cave!

Incredible biodiversity beneath a large boulder - Photo taken by Margaret Gardener

Just to summarise how diverse this shore is Margaret sent me a photo she took of a community beneath a large boulder on the lower shore here is what you can see in this photo

1. Nice colonial ascidian (sea squirt) bright yellow Botryloides leachii,

2. bright red baked bean sea squirts Dendrodoa grossularia,

3. Large keel worms Pomatoceros lamarcki,

4. barnacles,

5. purple encrusting coralline algae,

6. black stuff – encrusting brown algae, possibly pterocelis phase of Mastocarpus Stellatus,

7. Orange encrusting bryozoan Oshurkovia littoralis,

8. an orange sponge probably Microciona fallax.

9. Some spirobid worms Spirobis rupestris.

10. Sea weeds – Bunny's ears in the bottom left Lomentaria articulata,

11. and a small piece of red seaweed possibly Rhodymenia pseudopalmata

So total species count from that one photo is 11 but there are probably many more!!

The highlight of the day was witnessing an overhanging shallow cave where every surface was covered in reddish baked bean sea squirts, sponges and beautiful Actinothoe anemones ( - the fried egg colour variety - a species rarely seen on the shore!)

Angie, Max and the baked bean cave

Baked bean seasquirts Dendrodoa grossularaia , carpeting the cave

Actinothoe sphyrodeta anemone closed up amongst the Dendrodoa

Actinothoe anemone open

The diversity of sea weed life is also notable - shallow pools were home to rainbow wrack, tuning fork weed, banded pincer weed and many other notable species and the current scoured gullies were home to species that are used to high levels of water flow such as Alaria esculenta and Laminaria digitata. There were loads of beautiful tiny new kelp plants growing on the lower shore - most likely Sacchorhiza polyschides, that tasted amazing!