17 May 2014

Kelp beds...

With the usual apologies for the recent radio silence, but full time jobs and family life do cheerfully get in the way of naturalizing. However, this sunny morning we made it to the beach. Low tide, just off spring tides and a lot of normally invisible kelp beds were exposed:
Given that most of the kelp thrown up on the beach is Laminaria digitata I had assumed that the kelp beds close inshore would be the source of the washed up seaweed, and would be L. digitata. They aren't. A good look this morning tells us it's this stuff, photographed exposed at low tide today:


Laminaria hypoborea. The holdfast (the bit that grips the rock substrate) is smaller in L. hypoborea than L. digitata yet a lot more L. digitata is torn from the seabed and thrown onto the beach; the stipe (stalk) is much longer and thicker in L. digitata (comparison photo to come) and the fronds smaller. The section of the Bay where L. hypoborea thrives is one of the most energetic bits of the Bay; it's where the biggest waves come ashore yet these seaweeds with comparatively puny stipes and holdfasts and with big fronds survive very well. A proper scientist needs to look at the hydrodynamics of this.

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