Upload
stone-greenleaf
View
231
Download
3
Tags:
Embed Size (px)
Citation preview
Rocky Shore 2
The Intertidal The intertidal zone
is the area between the highest high and the lowest low tide
Organisms that live in this area undergo the greatest variations in environmental conditions
Rocky Shore 3
Tidal Forces Gravitational pull on the earth by
the sun and moon combined with centrifugal force generated by the earth-moon-system
Semidiurnal tides Diurnal tides
Rocky Shore 5
Rocky Intertidal Community
Rocky coasts usually occur on steep coasts that lack sediment
Fort Fisher is one of the only naturally occurring rocky outcrops in the S.E. U.S. Epifauna Sessile
Rocky Shore 7
Abiotic Factors
Desiccation Extreme changes in temperature Changes in salinity Turbulence
Rocky Shore 8
Water Loss For survival the
duration of exposure to air is critical
Sessile animals have structural adaptations
Rocky Shore 9
Dessication Algae - can
withstand 70 - 90% of water loss in tissues and survive
Littorina sp. (Periwinkle) reduce area in contact with the substrate and have a light colored shell to deal with extreme heats
Algae mat at low tide
Rocky Shore 10
Changes in Temperature Due to its high heat capacity water shows a
minimum change in temperature when compared with the air
If extreme temperature does not kill an organism it may severely weaken it and cause it to die of secondary causes
Extreme temperatures may hasten desiccation
Adaptations
Rocky Shore 11
Drastic Fluctuations in Salinity
Salinity may change due to severe rainfall If severe enough at
low tide the entire community may experience high mortality
Rocky Shore 12
Wave Action
Waves act to smash and tear organisms from the substrate
Sessile animals use cement (barnacles), holdfasts (seaweeds) and, byssal threads (mussels)
Mobile animals have appendages for clinging and snails have an enlarged foot used for attachment
Wave action also effects the intertidal by disturbing the substrate
Rocky Shore 14
Modes of Feeding Due to the lack of
sediment there are no deposit feeders!
Almost all of the sessile animals are filter or suspension feeders
Heavy wave action also effects feeding
Suspension
Feeding
Barnacles
Rocky Shore 15
Vertical Zonation Species settle in specific vertical bands
based on their ability to withstand exposure to air
The rocky intertidal provides many microhabitats (Numerous niches)
High species diversity Distinct banding which progress from the low tide
line to the high tide line Zonation occurs due to a both physical and
biological interactions
Rocky Shore 16
Rocky Shore Zonation
Organisms are found in a given area by their ability to compete and deal with physical factors. Most animals in the intertidal live near the upper end of their lethal limitsLower distribution is determined by competition and predation
Rocky Shore 18
Biotic Factors Competition
Due to the limited amount of area, competition for space is acute
Succession – natural progression of communities The creation of open spaces results in quick
colonization by opportunistic species. Soon replaced by slower growing competitively
dominant spp.
Keystone Predators Keystone species: a single species,
which has a controlling effect on the community in which it lives