intertidal ecology. what is the intertidal zone? zone between highest and lowest tide lines immersed...
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Intertidal Ecology
What is the Intertidal Zone?
• Zone between highest and lowest tide lines
• Immersed and Emersed
• Rocky and soft intertidal zones
Review: TidesReview: Tides
• What causes tidal movements?• What does it mean to be:
• Diurnal• Semidiurnal• Mixed
• How do tidal movements vary by area?
• What causes tidal movements?• What does it mean to be:
• Diurnal• Semidiurnal• Mixed
• How do tidal movements vary by area?
Pattern: Vertical Zonation
Processes: What causes the pattern?
Upper limit determined by physical factorsExposureWave shock
Lower limit determined by biological factorsCompetitionPredationRecruitment
Varies by location and often not totally clear cut
Exposure
Problems due to emersion: Physical:
DessicationTemperature and salinity fluctuationO2 availabilityUV radiationWave shock
Biological:Feeding restrictionsInability to hide from predators
Dessication
Water loss to the airStrategies:
“Run and Hide” - crevices, tide pools, moist algae, subtidal, burrowing (soft only)
“Clam up” - protective cover seals in moisture (mussels, periwinkles, barnacles)
Allow drying out - massive water loss until next tide (seaweed, limpets)
Temperature Variation
Air vs. Water Adaptations:
Higher tolerance Seek shade and
moisture Morphology Clumping (ex.
Mussels)
Other Issues
Salinity variation due to rain, evaporation
Respiration Gills reduced and/or protected to reduce
drying Organisms slow down metabolism
Feeding Active when tide is high (reduces risk of
exposure)
Wave ActionVaries based
on shorelineF=ma (Where
does the force go?)
Wave shock and shearing
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Dealing with Wave Action
Shelter Permanent
anchorage Holding on Morphology
Compact and streamlined
Hardened bodies Flexibility
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Competition - The Battle for Space
Open space quickly colonized
Strategies: Fast dispersal
and settlement Evict competitors Grow on or over
competitors
Connell experiment
Very little difference at settlement Chthamalus range reduced by competition Transplant/Exclusion experiment results:
Balanus high = dies Chthamalus low = thrives
Eating and Not Being Eaten
How are limits set?
How are limits set?
Rocky Upper Intertidal
“Splash zone” Lichens,
cyanobacteria, and some algae
Periwinkles and limpets
Terrestrial predators
Rocky Mid-Intertidal
Upper areas - gray and rock barnacles Lower limit set by competition and
predationLower areas - mussels and brown algae
Lower limit set by predation from sea stars and spiny lobsters
Ecological Succession
Ecological Succession
Rocky Lower Intertidal
Mostly immersedDominated by seaweeds
Food for grazers, protection from predators
Compete with each otherSea urchins, stars, anemones,
nudibranchs, fishes
Soft-Bottom Intertidal
Sediment accumulationUnstable bottom - what kinds
of organisms cannot live here?
Sediment composition based on wave mixing
Gravel, sand, mud
Importance of Grain Size
Burrowing (Infauna) or living between grains (Meiofauna)
Water circulationLess dessicationNeeded for O2 (no photosynth)
Amount and type of detritus (coarser has less)
Dual problem with mud: Less water + more detritus to decay = less O2
Feeding
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