Searching our shores: Calshot and Lepe 2019

Our shore searching season has kicked off with two intertidal surveys in the western Solent - Jenny Mallinson shares what we found.

We began this year’s intertidal surveys on the last spring tide weekend before the start of British Summer Time, which will give us more evening daylight to work with. This was also the lowest spring tide of the year – as such, more of the beach was exposed than we usually get to see, revealing a variety of crabs, starfish and sponges as well as the usual selection of molluscs and even the odd fish!

At Calshot, we had eight surveying stalwarts attending, and shared the beach with the Maritime Archaeology Trust, who were investigating Roman and Bronze Age wooden structures uncovered by the very low tide. The extent of this low tide also uncovered concrete and metal debris that we rarely get to see, and we found live native oysters (Ostrea edulis) there. This species is severely depleted and therefore no longer easy to find in the Solent, so we took GPS-tagged photos for submission to Natural England.

Inside an old drainage pipe we found an anemone, although the only way to see the detail needed to identify it was to stuff a camera in and hope for the best! From my photo you can just see the stripes on the column, making it Sagartiogeton undatus (no common name). If anyone from the survey has a better photo showing lines on the tentacles this will help to confirm the identification, so please let us know.

Another new find was a forked sponge known as mermaid’s glove (Haliclona oculata) hanging under one of the large boulders. We often find it detached and washed up on the shore, but I have not seen it actually growing at this site before.

The seasonal sea slugs didn’t disappoint either: first we found their eggs on a piece of seaweed and then their 'mum', a dark red sea hare (Aplysia punctata). Nearby was a large yellow sea slug – a sea lemon, previously known as Archidoris pseudoargus and now called Doris pseudoargus. This is an example of how taxonomists reclassify species as they learn more about them, hence the change in the Latin names.

Calshot is my ‘Adopt a Beach’ site, so my partner Ken and I visit it throughout the year, building up a long list of species to monitor, and this survey made an excellent start. We will be going again and not so many people live round that side of the estuary, so if anyone would like to join us please do get in touch. Another beachcomber slightly to the west of our site found a live cockle with spines - probably the intertidal rough cockle Acanthocardia tuberculosa - so that’s something to look out for in our patch!

The next day we were at Lepe Country Park for the annual intertidal training course and survey. We had nearly 30 people on the beach practicing some new Wildlife Trust surveying techniques which will be fully launched later in the year. Our search was concentrated in a 20m corridor from the top of the beach to the water, which we split into three different zones according to the prevalence of green, brown, and red algae.

Intertidal survey at Lepe Country Park © HIWWT

Intertidal survey at Lepe Country Park © HIWWT

As at Calshot, the extreme low tide allowed us to see features we would not have had access to otherwise – in this case patches of growing seagrass we weren’t previously aware of. Bird enthusiasts Chris Marshall and Sue Hyam also spotted several waders at the water’s edge (beyond the capabilities of my eyesight!) including curlews, plovers and turnstones, which I’ve added to the species list for this site.

The find of the day at Lepe was an introduced non-native species: the Asian date mussel (Arcuatula senhousia). It looks similar to our familiar edible mussel (Mytilus edulis) but the shell flares out beyond the end where the hinge is. This species was only discovered in the UK last year, when it was spotted at Weston Shore. We can now track the progress of its ‘invasion’ as we did with the Pacific oyster a decade ago. Congratulations to Sam Hatherly, who found it halfway down the beach, for being so attentive on the training course and observant out on the shore!

Nearer the low water line we found another impressive furry sea slug – we have found the closely related Aeolidiella alderi at Lepe before, but this one was bigger and with a pinkish tinge so I think it is a grey sea slug (Aeolidia papillosa). This species has Y-shaped white lines on its head - if anyone from the survey has a good photo showing that then please get in touch. We also saw an Acanthodoris pilosa, a little white sea slug (sorry, again no common name).

Grey sea slug © Jenny Mallinson

Grey sea slug © Jenny Mallinson

In total at Lepe we found 54 of the 81 species recorded since 2017 - that's more than half and in just one day. That is an excellent result and there is plenty more of the year left to look for the rest! If you are interested in seeing the full list of species for these sites, or have anything to add (ideally with a photo) then please get in touch.

The intertidal surveys and training session form part of the Trust's marine project, Secrets of the Solent. There are lots of ways to get involved in the project, so do give it a look. I hope to see lots more sharp-eyed spotters at the upcoming intertidal surveys!