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Mycale macilenta

(Bowerbank, 1866)


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.

Message posted on NE Atlantic Porifera on 25 Oct 2013
Jim Anderson Geitodoris planata Loch Creran, Scotland September 2012 30 mm animal atop a queen scallpop, Aequipecten opercularis, that appears to have been feeding on the encrusting sponge

Ian Smith Super picture Jim Anderson . Any idea what species of sponge David Kipling?

David Kipling Looks like an undercooked drop scone ;)

Bernard Picton This sponge is probably the same one which was common in Strangford Lough when we still had an Aequipecten opercularis population. If so it is a Mycale, similar to Mycale macilenta but in my opinion probably undescribed. Nice that you still have big Aequipecten in Loch Creran, Jim.

Jim Anderson There are thousands - they kept swimming across the view while trying to take photographs.

Message posted on NE Atlantic Nudibranchs on 11 Oct 2012
Taxonomy
Animalia (Kingdom)
  Porifera (Phylum)
    Demospongiae (Class)
      Poecilosclerida (Order)
        Mycalina (Suborder)
          Mycalidae (Family)
            Mycale (Genus)
              Mycale macilenta (Species)
Associated Species