MBE 230-Chapter 26: Rocky Intertidal

Rocky Intertidal SLIDE 1:

- There are hard substrates --> often associated with strong currents that are able to carry sediment away

- They are mostly intertidal and shallow subtidal zones

- They are also comprised of ice rafted rocks and spreading ridges:

- Human structures such as piers and ships

- In the tropics, there is a small tidal range; semidiurnal (it experiences two high and two low tides of approximately equal size every lunar day)

- In the polar, there is a large tidal range and it is diurnal (with one high and one low tide per day)

Environmental challenges of intertidal zones:

- Desiccation

- Immersion time --> amount of O2, feeding

- Temperature

- Freezing and ice scours (A narrow ditch on a seabed caused by the movement of pack ice)

- Freshwater

- Wave action

- The intertidal zone is populated by marine organisms and NOT terrestrial organisms

Rocky Intertidal SLIDE 2:

- Generally: physical factors set the upper boundary and biological factors set the lower boundary (predation, competition)

- There is strong seasonality on the polar and continental coasts

- It is more persistent along maritime coasts

- They have a high biomass in the temperate waters

- They have ice scours in the polar

- They have extreme temperature and desiccation (dried out) in the tropics

Intertidal vs Subtidal:

The intertidal is composed of:

- Individuals

- Sexual reproduction

- Long living larvae (weeks)

- Risk of catastrophe

The subtidal is composed of:

- Clonal colonies

- Asexual reproduction

- Clonal budding expansion

- There is a competition for space

- Sessile animals have planktonic larvae that colonize other areas:

- Long living larvae colonize distant areas of habitats that are subject to much disturbance

- More spawning during spring tide

- Settling larvae are able to orient themselves by:

- Light

- Gravity

- Chemoreception

- Many larvae settle but not many are able to survive