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Our Rocky Coast

The rock jetties are an interesting marine community to examine. The rocky shore ecosystem is a natural phenomenon in New England that has been intensely studied. Here in the Southeast, a “mini” rocky shore is found at these artificially placed rock walls. Man builds a rock sea wall in a sandy beach and tidal mud flat area, and quickly life starts to occupy it—life of the rocky coast, not the beach and mud flat.

Rocky shore communities consist of three main zones: the splash zone, above the high tide line; the intertidal zone, between the high and low tide lines; and the subtidal zone, located beneath the low tide line. Flora and fauna have different survival strategies in each of these zones. Lichen and algae will thrive in the splash zone. Periwinkle (Littorina sp.), oysters, and barnacles will be found in the intertidal areas, whereas crabs may be hiding below the rocks in the subtidal zone. Scrambling over and around the rocks you may notice inch-long cockroach-looking arthropods called sea roaches. They consume rotting flotsam that gets trapped in the rocks.

When a hard-surfaced object is placed in sea water, plants and animals almost immediately start colonizing it, called “fouling succession.” First, bacterial slime settles on the surface, and diatoms and protozoa follow within the first day. Then hydroids and bryozoa start to colonize the area on the second to third day, followed by barnacles and algae. Depending on environmental conditions and the swimming larvae that are present, you may then get a colony of oysters, or other sea life such as mussels.

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