An amazing amount of Giant Kelp (Macrocystis pyrifera) washed up on local beaches during the last two days. Although abundant in the Monterey area, Giant Kelp is less common in Bodega Bay. I don't think I've ever seen this much Macrocystis on beaches in Bodega Bay (during the last 12 years).
The photo above shows the rippled or corrugated blades of Giant Kelp.
Below, note its relatively loose and sprawling holdfast (the portion of the kelp that attaches to the substrate):
(Why is the holdfast purple? Maybe someone out there can provide some ideas?)
There was some large Bull Kelp (Nereocystis luetkeana) mixed in with the Giant Kelp. Bull Kelp is the more common large kelp in our area. In the photo below, the Bull Kelp is tangled up with the Giant Kelp, but you'll recognize Bull Kelp's very large float (pneumatocyst) and the smooth and shiny blades (the Bull Kelp blades also lighter in color than the Giant Kelp blades):
Here's a photo comparing the holdfasts of the two species:
The Giant Kelp holdfast is on the left and the Bull Kelp holdfast is on the right.
I had wondered if this kelp might have been ripped out by the powerful 20-21 January storm, but upon closer inspection, I noticed quite a few pelagic barnacles (Lepas sp.) attached to the kelp, indicating it had been at sea for quite some time. [There's a lot going on in this photo, so I've highlighted a good example of a pelagic barnacle with a circle.]
Based on the amount of kelp, its age, and strong recent currents from the south, I'm still guessing that this Giant Kelp originated from sites to our south. But I'm not sure why so much has arrived on our beaches! (Let me know if you have some ideas!)