SARGASSUM

I hadn't wanted to write about seaweed so soon after introducing you to red algae last week, so this week on the beach I studiously avoided looking too hard at heaped-up seaweed. But then there atop a stretch of naked sand as if someone had dropped the thing there just to make sure I couldn't pass it by, there lay a hand-sized sprig of seaweed so curious looking that I had to investigate it.

It was structured like a cluster of grapes in that the entire thing was composed of smaller clusters. Each of those two-inch-long smaller clusters bore strap-shaped, greenish-brown leaves about half an inch long, mingled with spherical, greenish-tan bladders ranging in size from BB size to as large as small peas. These clustered bladders further made the whole structure remind me of a cluster of grapes.

Poking the discovery into my pocket I headed to Hotel Reef's computer room and Google's image-search feature. Searching on the keywords "algae, bladders, Gulf of Mexico," soon I spotted the picture shown at http://www.jaxshells.org/922uu.htm.

As that page says, I had found a sprig of Sargassum, SARGASSUM NUTANS.

Sargassum!

In-lander that I am, I'd had no idea that Sargassum might be found here. All my life I've read about the great Sargasso Sea, that body of water in the mid Atlantic two-thirds the size of the US, where Sargassum floats in peace because ocean currents flow in a circle around the sea's center, and the sea resides at the latitude known as The Doldrums where trade winds blow neither here nor there.

Sargassum floats in perpetual circles in the North Atlantic's center, in the process providing to untold numbers and kinds of organisms food and protection, just like trees in a forest. The Sargasso Sea is one of the most productive and diverse ecosystems on Earth, a real "floating jungle."

With my handlens I could see that even this little washed-up sprig drying on the sand still bore its share of other organisms. Something like tiny, empty, waferlike combs from a beehive grew over parts of the sprig like a crustose lichen on a rock (I'm guessing it was a bryozoan). Something else was like a thread from which arose hundreds of interlocking Ys, each arm of each Y ending in roundish buds. On some bladders (The bladders keep the plant afloat) were almost microscopic things like barnacles, and here and there were white filaments like fungal hyphae. Yes, just like a tree in a forest, this sprig of Sargassum was home to an enormously diverse community of interrelating organisms!

Water currents at the Sargasso Sea's edges split off from the spinning sea carrying Sargassum far beyond the Sargasso Sea, and winds blow Sargassum in our direction. In fact, the Gulf of Mexico harbors more Sargassum than any other place on Earth, save the Sargasso Sea itself.

The word Sargassum comes from a Portuguese word meaning grapes. Two Sargassum species are abundant in the Sargasso Sea. The one I had found bore thicker, more densely leaved branches than the other. As last week we had a red alga of the Rhodophyta, Sargassum is a brown alga of the Phaeophyta.

Somehow it just does me a world of good to think of the continent-sized Sargasso Sea out in the middle of the North Atlantic nurturingly circling, circling, just taking care of business photosynthesizing and sharing its wealth with all the community, sometimes spewing off arms of itself into the Gulf of Mexico and elsewhere, and all the time not paying any attention at all to me, you, George Bush or the Pope.

You can read more about Sargassum at http://www.crystalbeach.com/weed.htm.