No interactions present.
The main plants in this image are not Carpobrotus edulis, although they do appear at the back of the image. Crithmum maritimum is also present as you say but the plant that comprises the main part of the photo is another succulent-maybe Mesembryanthemum or Delosperma, not sure which one as not a succulent expert but there are several established alien succulents at the Lizard.
David J Trevan
Thanks David for this helpful explanation - I found it quite hard to find an identification for any of these.
Tis hard to tell from a photograph especially ones without flowers but the smaller leafed ice-plant may be a Disphyma possibly crassifolium. David is correct that the much larger leafed ice-plant to the rear is a Carpobrotus. However, as Carpobrotus hybridise readily between themselves and with Disphyma taxa, it would be very difficult to identify any clones or populations. At least two Carpobrotus species are naturalised in the UK.
Lat/Lng: 49.9585, -5.2075
OS grid ref: SW700114
Growing prolifically on rocks close to sea near SW coastal path at the Lizard, Cornwall.