Modiolus modiolus

Paula Lightfoot Thanks Chris Barrett I think the hairs are definitely hairs rather than hydroids, when seen close up. Adrian Norris has just been in touch to say he reckons it's Modiolus modiolus.

Steve Wilkinson Paula I think it would still be worth opening it. It sounded quite high on the shore for Modiolus?

Paula Lightfoot Mussel 3mm x 2mm - very hairy! Found on mid-intertidal rocky shore near Whitby. We wondered if it could be Modiolus modiolus or Modiolula phaseolina...but I've just read that Mytilus edulis sometimes have hairy spat too. Looking in Paul Chambers and Hayward and Ryland for inspiration but they don't say much about the spat.

Chris Barrett Are the hairs hydroids? Could be M.edulis if so

Bernard Picton There's a great bivalve site on the National Museum of Wales web pages: http://naturalhistory.museumwales.ac.uk/britishbivalves/browserecord.php?-recid=93

Andy Pange Sharkbait Richardson Looks like Modiolus barbatus to me

Steve Wilkinson I think Modiolula phaseolina. You can separate from barbatus by whether the spines as serrated on one side or not (phaseolina is not) and be absolutely sure if you can open it and look for the little pocket of crenulations - as per the link Bernard provided.

Paula Lightfoot Thanks everyone! The actual specimen is in the (i hope) safe hands of Royal Mail on its way to our Conchological Society Recorder right now so I can't open it up. It was found quite high on the shore, attached to a blade of Ulva lactuca. Andreia Salvador, Curator of Marine Mollusca at the NHM also thinks it is Modiolula phaseolina from the photographs.

Could it be a juv Modiolus barbatus

Chris Wood Diving Mussel Beds Horse mussel (Modiolus modiolus) and Blue mussel (Mytilus edulis) beds on sediment are both priority habitats and thus target areas for Seasearch diving. Recent Seasearch dives have targeted both types. In the Isle of Man Seasearch has dived a horse mussel bed off the eastern side of the island, which is currently unprotected but thankfully remains in excellent condition. In addition to a dense covering of horse mussels, the bed also has a variety of branching sponges, especially the yellow Iophon nigricans, hydroids and mobile animals such as hermit crabs, painted topshells, urchins, starfish and young fishes. The picture shows some of the variety of life that the horse mussel bed supports. Blue mussel beds can be quite transient, and a recent Seasearch dive with Sussex Divers on the coastal chalk platform off Rottingdean found the seabed and attached plants covered in a carpet of tiny mussels. Whether they will remain in the long term is questionable, but the starfish population was already responding to the new food source with large numbers of young animals, each only about a centimetre across. A similar mussel fall was also reported from Shoreham, a few miles further west, on Seasearch dives with Brigthon BSAC. In North Norfolk a blue mussel bed has been proposed as a Reference Area (no take zone). It is a tiny area only about 500m square and a couple of kilometres offshore and we covered all of it and more in our dive as there was a current of about 2kts running which made recording callenging. The bed was patchy, with sandy areas between the clumps of mussels, but they were also providing a habitat for dahlia anemones, common starfish, sunstars, crabs and the finger bryozoan.

George Brown A couple of Geitodoris planata, enjoying some sponge, on Aequipecten opercularis. Can anyone help me with the sponge ID please? Loch Creran, 13 steps, 20m depth, nice dive.

Jade Berman Mycale macilenta maybe? Beautiful picture

Bernard Picton You've a good eye, Jade. I call this Mycale cf. macilenta because the ones on Aequipecten in Strangford Lough had some small spicule differences to the Mycale macilenta in other habitats in the Lough. It is hard to find in Strangford now as the Aequipecten seem to have gone extinct. There were plenty of big ones even after the Modiolus reefs were trashed but I suspect that the massive ecological consequences of that fishery changed things in a way that has now stopped recruitment or increased predation on juveniles.

George Brown Thank you Jade and Bernard, not just for the ID but for the background information sad though it is. I recently gave a talk to the Highland Biodiversity Forum, taking the opportunity to criticise scallop dredging, especially inshore. The forum is sponsored by the local authority, The Highland Council. This has resulted in the Council asking for more information on the effects of dredging and I've been asked for more photos/video of before/after dredging has been carried out. In an effort to maximise this opportunity do you know of any photos or video I can show our Councillors? I have nothing showing physical damage. Please be in no doubt that much of the Highland seabed has been totally devastated by bottom dredging. Thanks again for the ID.

David Kipling Hasn't Joanne Porter and colleagues got a recent paper on direct before/after effects of trawling through a Modiolus bed?

George Brown Thanks David, I'm on the case!

Becky Hitchin Yes, David Kipling, its a very good paper too

Becky Hitchin Robert Cook and colleagues in this study describe the impact of the first passage of two types of bottom-towed fishing gear on rare protected shellfishreefs formed by the horse mussel Modiolus modiolus (L.). One of the study sites was trawled and the other was scallopdredged. Divers collected HD video imagery of epifauna from quadrats at the two study sites and directed infaunal samples from one site. The total number of epifaunal organisms was significantly reduced following a single pass of a trawl (90%) or scallop dredge (59%), as was the diversity of the associated community and the total number of M. modiolus at the trawled site. At both sites declines in anthozoans, hydrozoans, bivalves, echinoderms and ascidians accounted for most of the change. A year later, no recovery was evident at the trawled site and significantly fewer infaunal taxa (polychaetes, malacostracans, bivalves and ophuroids) were recorded in the trawl track. To read more go to: http://www.plosone.org/article/fetchObject.action?uri=info%3Adoi%2F10.1371%2Fjournal.pone.0069904&representation=PDF

George Brown Thank you Becky.

Bernard Picton The critical thing to mention is the fact that the NI fisheries and environment agencies have already spent over £1 million trying to restore the habitat in Strangford Lough because the EU will start to fine them if it is not restored to a favourable status. As the habitat may have been established gradually over thousands of years and now the climate is changing it may not be possible to fix it.

Holly Latham Confirmation of the pale brittlestar... Ophiocomina nigra?

Might just be an albinos Ophiothrix fragilis

Holly Latham Hmmm... thoughts were - spines to short relative to arm width and disc is smooth. We have found Ophiocomina nigra (including in this bed)

Could be an albino nigra, certainly a fact that both species coexist in Strangford. Where there any typical black versions in the same bed

Holly Latham Yes, there was quite a mix with black and dark brown morphs...

You are probably right then given the spine diagnostic. We take these beds for granted but in world terms NE Atlantic brittle star beds are quite a unique/rare habitat

Colin Munro Spines do look very neat and even for O fragilis, much more like O nigra. Very nice.

Claire Goodwin Not sure why it's not showing up here but I think this is Ophiopholis aculeata (see album comments).

Bernard Picton Ophiopholis aculeata is a species which seems to have dramatically declined in Northern Ireland since the 1980 Northern Ireland Sublittoral Survey. It might be a very good species to monitor as a climate change indicator.

George Brown Ophiopholis aculeata is fairly common in Loch Duich but rarely caught out in the open the way Holly has photographed it.

Bernard Picton They used to be common in the open in some parts of Northern Ireland, especially in the Modiolus modiolus (Horse mussel) beds in Strangford Lough. We just don't know how much climate change has affected that habitat as it was simultaneously trashed by the Queen Scallop fishery...

Holly Latham Thank you... will now be going to take a closer look at the original image! :)