Some Ecology Considerations

April 26, 2015

We woke up at 6:30 AM to a beautiful, cloudless sky with moderate W winds, 75 degrees. The weather report called for more severe storms in the afternoon. Of course that didn’t happen – so much for weather forecasts.

I weighed anchor and we motored north on the Amelia River toward Fernandina. When I got the anchor aboard it had a sprig of red alga (sea weed) hanging on. Red algae, phylum Rhodophyta, contain certain pigments that impart distinctive red color. While looking the sprig over I noticed that attached to the thalli (stems) were hundreds of tiny copepods (arthropods) about 1 -2 millimeters long. I suspect that if I shook all these little creatures off the sprig there may have been an ounce by weight total. If this particular red alga species is a ubiquitous as I suppose it to be (I have brought it up on anchor before many times) and assuming this particular copepod species is associated, there must be hundreds, maybe thousands of tons (probably more) of these creatures in the waters along the ICW in this country. This one example illustrates the tremendous productivity of these marine ecosystems - the tremendous amount of energy sequestered in living organisms. And I’m just talking about one species.

These little guys, who graze on even smaller organisms on the surface of the sea weed, are food for small crabs and other arthropods and fish, which are food for larger fish, which are food for even larger fish, which are food for yet larger predaceous fish and marine mammals including of course the dolphins, our daily companions.

What a remarkable thing to think about – a food chain – and what effect breaking that chain by somehow eliminating a particular link – what effect that can have on all the organisms in the chain. And think of all the food chains in nature!

I had a great ecology professor in college who started his course with the proposition that ecology was pretty simple. Every living thing needs a place to live, air to breathe and something to eat. Everything else is just detail.

We crossed Cumberland Sound and the St. Mary’s River, the boundary between Florida and Georgia, with a strong NW wind on the nose. Headed north on St Mary’s past King’s Bay Naval Base, a major US Navy nuclear submarine installation. We passed through the Cumberland Dividings on the Cumberland River, crossed Jekyll Sound to Jekyll Creek, and passed Jekyll Island to the east, crossed St. Simonds Sound and St Simonds Island to the east, up the Mackay River to finally anchor on Wally’s Leg at mile 665 ICW after a sixty-one mile run. We sailed for a bit in Jekyll Sound, but as usual the wind was forward and contrary.

All this talk of sounds. The sounds we crossed were either wide or narrow channels spilling out into the Atlantic. Sounds are bodies of water formed by the coming together of two rivers or creeks and are the final, defined “water” that feed a sea or ocean. For us, basically they are places to look out to the ocean and wonder what it would be like “out there”.

Sweet Dreams