In the zone

This cove has no name. It is narrow and the tide moves quickly through it. Rockweed (Ascophyllum) grows prolifically, to a height, mirrored on either side. Its habit is influenced by the environment within which it lives. Space is limited, in this intertidal zone, and organisms have evolved to tolerate water loss rather than avoid it. Seaweeds are sessile organisms and the higher they settle, the longer they will be exposed to the air as the tide recedes. Ascophyllum’s upper reach tells of some maximum amount of time that individuals may be without water during the receding tide.

Competition is the force which limits the growth of Rockweed lower down. Competition from another alga, Irish Moss (Chondrus); which you can just make out as a dark band of reddish-brown on either side of the channel and in its swirling water.

And, what lives above the band of the Rockweed? Look and you will see a thin yellow band and then a black one. It is within the former that one finds barnacles, limpets, and encrusting algae, while the latter represents countless numbers of individual blue-green algae.

All of these organisms have evolved to live and thrive at the tidal height at which they are found, balancing physiological tolerance (mostly to what is above) with the pressures of competition (from below).

The next time you look at a beautiful, seemingly barren, seaside expanse such as this and wonder where all the organisms are … think again.


8 thoughts on “In the zone

  1. Your images from Appledore remind me of our summers in Nantasket. This one conjures up memories of low-tide at Pemberton. Amazing how you capture the crisp, clarity of the water. Your posts continue to educate me. I find myself remembering to focus on smaller features which are just as important as larger ones! I’d love to jump through the screen and take a dip!

  2. There’s nothing like the excitement of leaving jetties, which is what your photo recalls for me. Part of the excitement is the acceptance of limits. No matter which course is set, some destinations are excluded. Leaving Galveston, a turn to the southeast means Florida, Cuba, or island-hopping into the Caribbean, but it also means foregoing southwestern routes to Veracruz, Ambergris Caye, and the Rio Dulce. Granted, east and west may meet eventually in Panama, or Trinidad and Tobago, but there are a lot of jetties between here and there. Decisions made at the mouth of every one shape the journey.

    • It sounds like a life lesson there! How exciting that you did all of the sailing Linda. I think I’ve told you before that I once fancied myself an ocean sailor. However, life got in the way and that never happened (not even a single open ocean experience, I am sad to say). I have a bad habit of clicking in to YouTube and watching any number of young couples who regularly post about their sailing adventures in all different corners of the world. I’d be telling a falsehood if I said that it didn’t make me sad to see those folks having the experiences I once thought I might enjoy. Looking back, however, I know that the early part of my life was filled with other wonderful experiences. No one can do it all. We make choices. It’s clear, from your comment, however that your life has certainly been full of wonderful sailing adventures. I suppose it is like anything else, you’ve got … glorious memories of many wonderful times … and some not-so-glorious memories of some not-wonderful times. Farming is certainly like that for us now that it is behind us. Anyway … that’s enough retrospection for one day. Thanks for checking in.

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