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ROCKY INTERTIDAL ZONE

Western US rocky intertidal zones –less seasonal changes.The greatest limiting factor is space.

Eastern US soft-bottomed intertidal zones - temperature changes cause seasonal population changes. The greatest limiting factor is climate.

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Rocky coasts are characterized by:

- abundant food supply with good light

- tides produce hours of flooding in cool water followed by desiccation (drying out) and high temperatures

- tidal pools are created and emptied- temperature and salinity fluctuate

- very distinct zonation worldwide

- wave shock http://www.youtube.com/watch?v=6pZ0PZBNgU4

- competition for space fierce (limiting factor)

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COPING STRATEGIES / ADAPTATIONS:

- WATER LOSS:- run & hide, clam up, tolerate- allow drying out- find tide pools- http://www.youtube.com/watch?v=6QaMA5S1E1E - http://www.youtube.com/watch?v=IyNEG-PvZmM

- TEMPERATURE- tolerate- move to moist areas- light color

- SALINITY- clam up- tolerate

- RESTRICTED FEEDING (MOST ARE FILTER FEEDERS)- only feed when tide is high- tide height determines where they can live

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COPING STRATEGIES / ADAPTATIONS:

- WAVE SHOCK:- attach (holdfasts, byssal threads, glue)- cling (suction cups)- fish lack swim bladders- find shelter- thicker shells- compact shape- low profile- go with the flow / flexible

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Wave action cuts rocks into sea caves, cliffs and sea stacks that provide shelter. Competition for these limited living spaces is high.

Inhabitants must find a place to attach or hide or be crushed between waves and rocks.

Methods of attachment include cement, byssal threads, holdfasts, muscular and tube feet, and boring.

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Adaptations also include symbiosis and reproductive strategies, like hermaphrodites and organisms that change sex.

The rocky coastal communities’ succession has a predictable pattern that is often controlled by sea urchins. Grazing urchins remove algae from rocks.

NOAA

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New communities can then begin because one group doesn’t over populate the area.

Pioneer stage - bacteria and algae

Juvenile - protozoa and worms

Mature - barnacles, rockweed, mussels, seastars and sea urchins

Collectively these animals became known as fouling communities because of their harmful effects on ship’s hulls, docks, pilings, and the smell they create at low tide.

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THE BATTLE FOR SPACE

- AVAILIBILITY OF SPACE LIMITS

POPULATIONS IN INTERTIDAL- COMPETITION FOR SPACE DOMINANT BIOLOGICAL FACTOR

- HOW TO COMPETE- be first to get to open space- effective dispersal

- reproduce rapidly

- take over

- grow over

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VERTICAL ZONATION

- UPPER, MIDDLE & LOWER ZONES

- UPPER LIMIT SET BY PHYSICAL FACTORS

- LOWER LIMIT SET BY BIOLOGICAL FACTORS (predation & competition)