10 Oct 2008

Seaweed zonation on Runswick beach

This is extreme low water at a spring tide - feet and cameras rarely get here. We're into the Laminaria digitata beds that are usually below the low tide mark.

View of the Laminara beds at low tide. The smaller seaweed is Fucus serratus, saw wrack.

Mid-beach, the saw wrack shares the beach with the green Ulva lactuca (sea lettuce) and Cladophera rupestris, a green algae which looks reddish brown here.

Around the high water mark amost every other species is displaced by bladder wrack, Fucus vesiculosus.

At high water, no algae can establish themselves on this rock:

2 comments:

Kevin Zelnio said...

Wow, that is some tidal outflow there! How deep is the area under high tide?

Peter McGrath said...

Kevin, I shall make it my job to find out exactly. The max springs tidal range is 5.2 metres ish. 2.4 at neaps. I shall consult my chart of the bay and let you know.