No interactions present.
It's rare to see such good channelling and such a lack of papillae.
See mine http://www.ispotnature.org/node/748161
THREE MARINE PROJECTS
appear in the spring - this post is February - and these fronds have yet to mature. The papillae, which are cystocarps, appear later, mature in July and August and spore discharge seems to continue until December.
As others have commented elsewhere, this is a variable species both in frond size, frond division and in overall appearance between early and mature fronds. That's what make seaweed ID fun.
Lat/Lng: 51.1634, -4.6571
OS grid ref: SS143438