Intertidal Communities Rocky Shores  Distance from low water is correlated with variations in physical and biological stresses, resulting in distinct horizontal bands of zonation.

Intertidal Zone The area that lies between the highest high tides and the lowest low tides

Figure 10.22

Intertidal Communities Rocky Shores  The middle intertidal is more densely populated with species more troubled by competition for food and space than physical limitations of the environment.

Intertidal Communities Magnified cross-section of a lichen with algae cells (dark spots) embedded in fungal filaments. Snails and limpets grazing on sparsely distributed algae growing along the edge of a tidal pool. Rocky Shores © Wildlife Pictures/age fotostock

Intertidal Communities Rocky Shores  The upper intertidal of rocky shorelines hosts organisms that suffer with frequent desiccation and punctuated food supplies. Stunted acorn barnacles, Chthamalus, survive in the shallow depression of carved letters.

Intertidal Communities Rocky Shores The aggregate sea anemone, Anthopleura elegantissima. Exposed individuals (upper right) have retracted their tentacles to avoid dessication. © Danita Delimont/Alamy Images

Rocky Intertidal Communities Close-up view of mussels, Mytilus, attached to rocks in the middle intertidal. Algal species exposed during low tides use thickened cell walls to prevent water loss. © Carsten Medom Madsen/ShutterStock, Inc.

Rocky Intertidal Communities Tightly packed barnacles compete for space along the intertidal. Photo by Dave Cowles, Rosario Marine Invertebrates website

Rocky Intertidal Communities Sea stars, Pisaster, aggregating near the low tide line to avoid dessication. © Charles A. Blakeslee/age fotostock

Intertidal Communities Rocky Shores  The lower intertidal hosts a diversified assemblage of plants and animals that are exposed to air for only a short period of time each day. Surf grass covers rocks and helps to keep intertidal organisms moist during low tide. © Weldon Schloneger/ShutterStock, Inc.

Rocky Intertidal Communities The green anemone, Anthopleura xanthogrammica. An eolid nudibranch with long finger-like cerata projecting from its dorsal surface. © Weldon Schloneger/ShutterStock, Inc. © Kerry L. Werry/ShutterStock, Inc.

Rocky Intertidal Communities A scallop flaps its valves (shells) vigorously to jet away from a predatory sea star. © Marevision/age fotostock

MORE SPECIFICALLY Rocky Intertidal Zone Have hard rocky bottoms On shores without much sediment Found in New England and the west coast Locally here – “Montauk Bluffs” and the LI (North Shore) coastline

Rocky Intertidal Zone Problems of living in intertidal zone:  Exposure to air  Wave shock

Exposure to Air Varies along the intertidal zone  High intertidal zone is exposed longer

Exposure to Air Water Loss = Dessication Prevention:

Exposure to Air Water Loss = Dessication Prevention:  Move – tide pools  Hide – in moist areas  Close up

Figure 11.5 Seaweed Dessi- cation

Figure 11.2 Littorina

Exposure to Air Water Loss = Dessication Prevention:  Move – tide pools  Hide – in moist areas  Close up Withstand Drying out – seaweed, chitons

Exposure to Air Temperature Fluctuations  More extreme in air Solutions: tolerance or hiding

Figure 11.3

Exposure to Air Salinity Fluctuations  Fresh water from rain  High salinity in tide pools from evaporation Solutions: tolerance, close up, hide or death

Exposure to Air Restricts Feeding  Most sessile animals are filter feeders  Others are busy avoiding stress Animals in high intertidal grow slowly

Figure 11.4 (CA) Mussel

Wave Shock A problem even when the tide is high varies along coastlines

Wave Shock Adaptations to reduce the impact:  Thicker shells  Compact bodies  Flexibility

Wave Shock Many organisms must anchor themselves  Mussels- byssal threads  Seaweeds – holdfast  Barnacles – glue Others move to sheltered areas

Flexible kelp – withstands wave action

Figure 11.10

Grow taller and shorter per wave action

Figure 11.26

Sunflower Sea Star, California. Credit: © Brandon Cole/Visuals Unlimited more Intertidal Organism… Holds on!

Adaptations… Because of all of these adaptations, you see a distinct vertical ZONATION on rocky shorelines. Resultant (from competition)

Figure 11.9 Zonation in seaweeds

Rocky Intertidal Communities Vertical zonation patterns on a 3- m-high rock on the coast of Oregon.

Vertical Zonation All rocky intertidal communities are divided into distinct bands or zones Each species is only found in one specific vertical range

Vertical Zonation Results from biological and physical factors Upper limit – physical factors Lower limit – biological factors

Because of Zonation, there is Competition For Space Open space on the rock usually limits populations Food is plentiful

How to Win the Competition For Space Be the first to get there  Good dispersal Undercut or grow over your neighbors  Barnacles  “Competition example!!!”

Figure Space – newly settled barnacles (arrow); w/ 2 mussels, 2 barnacles Limpets…anemones (oh my…)

Zonation Zonation causes there to be very distinct biotic communities in a rocky intertidal zone: Upper (Intertidal) Middle (Intertidal) Lower (Intertidal)

Upper Intertidal Splash zone – above the high tide line Lichens, cyanobacteria, periwinkles (snails) Mostly land predators

Middle Intertidal May have many zones within this zone – due to tidal differences Barnacles Mussels, other barnacles and rockweed Sea stars = predators

Figure Bands/zones between organisms on rocks

Zonation in Bonaire: Limpets

Keystone Predator Sea stars can dramatically affect the community structure “Intermediate Disturbance Hypothesis” – increases diversity (will be in competition lecture too)

Local… A few pictures from your local “rocky intertidal” habitat

Long Island Sound (Bluff View)

“Rocky Intertidal” (LIS)

“Rocky” Shoreline (North Shore of LI)

<-- “Wrack Line”

“Wrack” Weed (dead)

Wrack Weed (alive) “Fucus sp.)

LONG ISLAND SOUND, LI, NY

“Gull” (Larus)

“Sandpiper” (Calidris)

Now -- Our 1 st “Main” Habitat -- part of the Rocky (hard bottom) ecosystem -- KELP FOREST (go to new lecture)