While navigating the rocky shoreline at Cattle Point last Tuesday, I was brought back to my early childhood of beach combing in Puget Sound. I distinctly remember walking around with a thallus of Fucus and popping the pneumatocysts as I went. It was like free bubble wrap at the beach! I had no idea what it was and my dad used to tell me it was kelp (now I know better)!
Now, looking at the brown algae Fucus gardneri in the context of intertidal ecology, I feel like I have almost come full circle. I have wanted to be a “marine biologist” since I was very young, but didn’t always understand what it meant exactly. Now I feel like I’m almost there! I now know that the structures I was popping are called pneumatocysts. Formed by internal gas secretions, they exist to provide buoyancy so that the thallus can stay upright when submerged.
Look at those pneumatocysts!
Also, the gametangia are located in “receptacles” on the end of the thallus. This is where haploid gametes are formed through meiosis and released. Fucus has a fairly simple reproductive cycle. It has a single morphological phase and when oogonia (female-associated gamete) and antheridia (male gamete) meet in the water, the zygote settles and forms the same origional morphological structure. This is different from other algae species which often go through different morphologies throughout their life cycle.
Of course, all of the other intertidal species we encountered were just as intriguing. Emily pointed out a good-sized aggregation of Codium, one of my favorite algae. The nitrogen-loving Prasiola meridionalis was very interesting as well. According to Emily, the genus Prasiola occurs in both marine and terrestrial habitats. The Irish study that found occurrences outside of pubs was pretty funny.
Cattle point was a great place to observe intertidal zonation in action! There was enough of a vertical slope in the rocky shoreline so that the horizontal zone changes were easily visible. False bay on the other hand…
As the sun came up, and we started to perk up a little bit, the view of the entrance to San Juan channel and the Straits of Juan de Fuca materialized before our eyes.