Intertidal Zones

Intertidal zones

littoral zones, emersion and immersion cycles, lots of water movement, tides, waves, soft or hard substrate

Litoral zone

area that is from high tide zone to low tide zone

Abiotic gradients in intertidal zones (littoral zones)

temperature, moisture, light, oxygen, salinity, wave exposure

Zonation in intertidal zones

spray zone, middle intertidal, lower intertidal, sublittoral zone

Rocky shores

hard, rocky substrate, physical wave impact, variable topography, microsites, high diversity

Sandy shores

soft, sandy/murky substrate, churning of sediment, fewer microsites, lower diversity than that of rocky shores

Rocky intertidal organisms

sessile or mobile epifauna, algal growth, lots of grazers, sessile filter-feeders, mobile predators, scavengers

Challenged in rocky intertidal zones

desiccation, temperature extremes, salinity extremes, wave shock, feeding restrictions, space limitations

Challenges in rocky spray zone

sea spray, exposed to air, direct sun exposure, high evaporation, salt residues accumulate

Spray zone

“periwinkle zone”, organisms have adaptations to desiccation, primary producers are lichens and cyanobacteria, tolerant grazers and mobile detritivores

Organisms adaptations against desiccation in rocky spray zone

closeable shells, moist/shaded microsites (sessile vs mobile creatures, tidepools, crevices, bore holes), tolerate water loss

Challenges of rocky intertidal zones

wave exposure, extreme changes, lots of light, nutrients, hot, dry periods, ephemeral (short lasting) tide pools

Mobile grazers

nerita snails, limpets, sea urchins,

Nerita snails

mobile grazer in splash zone and upper intertidal, snails and eggs in splash zone and upper intertidal zone, phylum mollusca, class gastropoda

Limpets

mobile grazers , feed when immersed, seals shell when emersed, bioeroder, phylum mollusca, class gastropoda

Sea urchins

mobile grazers and bioeroders to create shelter in tide pools in intertidal zone, phylum echinodermata, class echinoidea

Mid-intertidal filter feeders

barnacles and anemones, decorator anemone and thatchroof barnacle

Mid intertidal filter feeder adaptions to heat

ridged shells, light color, “covering reactions”, high tolerance of thermal stress (extreme cold can be a problem)

Lower intertidal zone

lower emersion times, mostly marine, lots of water movement, permanent tide pools

Adaptions to wave shock in lower intertidal zones

adhesive base (if sessile), suction and no swim bladders (is mobile), enter protected microsites (ex: crabs), bore/burrow intro substrate (ex: urchins), low profile body shape, retractable body parts

Sandy intertidal zones

gradual slopes with accumulated sediments, soft, unsable substrates, gradients in moisture, temperature, salinity, oxygen, relatively uniform habitat, detritus-based food chain

Sandy intertidal organisms

mostly infauna, lower diversity, detritivores, deposit feeders and scavengers, mobile predators

Splash/spray zone

salt tolerant plants (help stabilize the shore and provide shade for nocturnal hermit crabs)

Upper intertidal zone: crabs

air breathing scavengers, ‘wrack’ (OM, algae, seeds, on high tide line)

Mid-lower intertidal zone

ingauna, meiofauna, mobile detritivores

Infauna

burrow into soft, unstable substrate, important food for shorebirds, gills, suspension feeders and deposit feeders

Meiofauna

burrow into soft, unstable substrate, microscopic intersitial organisms