1. Marine Shores: Life Between the Tides
Toni Christopher

2. Overview Geography Structure Physical Conditions Chemical Conditions
Biology
Human Influences

3. Geography Intertidal Zones
Area covered and uncovered by the tides
Tide pools, salt spray, and sweet smelling kelp
Thousands of kilometers(.6 miles/km) worth worldwide
Can be either exposed(rocky) or sheltered(sandy/muddy) shores

4. Structure

5. Physical Conditions: Light and Temperature
Varies with the tide
High tide, water turbulence = less light
Low tide = full sun
Temperature
Every changing; varies with tide and location
Low tide= below freezing at high latitudes when exposed to air; above 40C(104F) in tropics and subtropics
High tide = temperature is that of water, 17C(62.6F)

6. Physical Conditions: Water Movement: Tides and Waves
Vary in strength and frequency
Semidiurnal or diurnal
Can vary from few cm to 15m in Canada’s Bay of Fundy
Affected by alignment of both sun and moon
At full and new moons, sun, moon, and Earth align; stronger tides; called Spring
At ¼ and ¾ moons, sun and moon at right angle, opposing one another; weakest tides; called Neap
Size and location of bay, sea, coastline, etc determine if sun and moon effect amplified or dampened
Waves
Vary greatly from area to area; affect distribution of life
Headlands vs. Coves and Bays

7. Chemical Conditions: Salinity and Oxygen
Varies more on the shores than in the oceans
Desert shores: higher from evaporation
Rainy shores and tropics in wet season: much lower
Oxygen
Amount typically not a limitation factor
Species exposed to air at low tides
Water is mixed and well oxygenated
Exceptions are sandy/muddy shores of sheltered bays, etc that don’t have good water circulation

8. Biology Life adapted to a marine/terrestrial existence
Covered and uncovered by tides periodically
Zonation of species
Species live where best adapted
Habitats include tide pools, the different zones, salty streams, sandy/muddy shores, and rocky shores

9. Human Influence Some species devastated by humans
Mussels, oysters, clams, etc
Exploitation for food, education, and research
Oil spills pollute and ruin habitats
Introduction of non-native species on bottoms of ship hulls

10. Resources
Molles, Manuel C Jr. Ecology, Concepts and Applications. Fifth Ed., 2010.
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