After our surveys in northern Sonoma County yesterday, we did a little exploring in the low rocky intertidal zone. In this photo there are two species of kelp — can you see the differences? Look around at the golden-brown individuals.
One of the kelps is relatively smooth with one central mid-rib. The other kelp is puckered and has several ribs running the length of the blade.
The first species is Winged Kelp (Alaria marginata) and the second is Five-ribbed Kelp (Costaria costata). Note that these are juveniles and are quite small — only ~6 inches long or so.
Interestingly, although I haven't seen Five-ribbed Kelp on Bodega Head, there are herbarium records for it from Bodega Head in the 1960s. Has something changed? Is it just patchy? Or variable? Have you seen Five-ribbed Kelp in Sonoma County? I'd be interested in hearing about recent local records.
