Rocky Shore Ecology

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Rocky Shore Ecology

• YSCN0024
• 6th April 2007

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Semi-diurnal Tides of HK
High Tide
Low Tide
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Rocky Shore Substratum

• Hard shore non-penetrating, rocky boulders or
  bedrock.
• Complex topography
• Steeper slopes
• Stronger wave action

Chiton (Acanthopleura)
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Sessile Organisms

• Permanently attached onto rock surface for their
  adult life (larvae are planktonic)

Tetraclita japonica
Acorn barnacles (crustaceans)
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Mussels
Stalked barnacles
Acorn barnacles

• Sessile organisms attached to a rock surface
  evenly distributed or clumped distribution?

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Vertical Zonation
Low shore
Mid shore
High shore

• Vertical zonation is compressed over a much
  shorter distance than on sandy shores.

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• Macroalgae, or seaweed, are non-vascular plants
  (non-flowering).
• Only thrive in winter in HK, die back in summer.

Sargassum
Brown seaweed
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Corallina

• Coralline algae are red algae that deposit
  calcium carbonate (white) ? looks pink in colour.
• Die back in summer to leave a pink paint on the
  rocks, or as white scars.

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Mobile Epifauna

• Although mobile, these organisms may be
  stationary for most of the time unless foraging
  in awash period, e.g. limpets.

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• Limpets (Cellana toreuma) graze on biofilm of
  algae and cyanobacteria.

• Mussels (Septifer) filter feed at high tide on
  plankton

Mobile
Sessile
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Procedure

• Investigate the vertical zonation on a rocky
  shore in Starfish Bay.
• Compare the species composition and species
  diversity between the high shore, mid shore and
  low shore.