Intertidal Zone

California Aquatic Biome

Intertidal Pool

The area where the land meets the sea, it is The area where the land meets the sea, it is alternatively submerged and exposed by the alternatively submerged and exposed by the daily cycle of tides. The resident organisms daily cycle of tides. The resident organisms are subject to huge daily variation in are subject to huge daily variation in temperature, light intensity, and availability of temperature, light intensity, and availability of seawater, which makes life difficult.seawater, which makes life difficult.

Intertidal Zonation

Four Main ZonesFour Main Zones

Splash Zones : The splash zone is never covered by water and is Splash Zones : The splash zone is never covered by water and is only sprayed with saltwater during high tides.only sprayed with saltwater during high tides.

High Intertidal Zone: The high tide zone is covered with saltwater High Intertidal Zone: The high tide zone is covered with saltwater only during high tidesonly during high tides

Middle Intertidal Zone: The mid tide zone is covered and Middle Intertidal Zone: The mid tide zone is covered and uncovered twice a day by the tidesuncovered twice a day by the tides

Low Intertidal Zone: The low tide zone is only uncovered during Low Intertidal Zone: The low tide zone is only uncovered during the lowest of tidesthe lowest of tides

Intertidal Zones in California

What Causes the Tide?

Tides are created by the gravitational pull of the Tides are created by the gravitational pull of the moon and, to a lesser extent the sun, upon the moon and, to a lesser extent the sun, upon the Earth's oceans. The sun has about half the effect Earth's oceans. The sun has about half the effect that the moon has on the Earth's tides.that the moon has on the Earth's tides.

In most areas, typically two high tides and two low In most areas, typically two high tides and two low tides occur within a 24 hour and 50-minute lunar tides occur within a 24 hour and 50-minute lunar day. (A lunar day is 50 minutes longer than a solar day. (A lunar day is 50 minutes longer than a solar day.) The time between each high and low tide (or day.) The time between each high and low tide (or low and high tide) is 6 hours and 12.5 minutes.low and high tide) is 6 hours and 12.5 minutes.

Abiotic Factors

TemperatureTemperature

The temperature of tide pools is affected by air temperature and The temperature of tide pools is affected by air temperature and direct sunlight on the pool.direct sunlight on the pool.

SalinitySalinity

The sun and wind evaporate water from the surface of pools. In The sun and wind evaporate water from the surface of pools. In isolated tide pools, this caused an increase in salinity (salt isolated tide pools, this caused an increase in salinity (salt concentration).concentration).

Abiotic Factors

WindWind

It increases heat loss by evaporation and convection. It also contributes to water loss It increases heat loss by evaporation and convection. It also contributes to water loss in organisms by increasing the rate of evaporation in animals and transpiration in in organisms by increasing the rate of evaporation in animals and transpiration in plants.plants.

LightLight

Most aquatic plants and algae are limited to a fairy narrow zone close to Most aquatic plants and algae are limited to a fairy narrow zone close to the surface , where light is sufficient to allow photosynthesis the surface , where light is sufficient to allow photosynthesis

MoistureMoisture

Without moisture there can be no life. Water acts as a solvent for Without moisture there can be no life. Water acts as a solvent for chemical reactions, takes part in the reactions of hydrolysis. chemical reactions, takes part in the reactions of hydrolysis.

Abiotic Factors

RocksRocks

SandSand

Biotic Factors

Zone 1: “Splash Zone”Zone 1: “Splash Zone”

Above the high tide, and is reached only by the Above the high tide, and is reached only by the splash of the wavessplash of the waves

Adapted to prolonged period exposure to air.Adapted to prolonged period exposure to air.

Reproduce independently of water.Reproduce independently of water.

Zone 1: “Splash Zone”

Zone 2: High Tide Zone

Flooded during high tide only.Flooded during high tide only.

High saline environment.High saline environment.

Water is not high enough to sustain large Water is not high enough to sustain large amounts of vegetation, but higher compared amounts of vegetation, but higher compared to the “splash zone.”to the “splash zone.”

Zone 2: High Tide Zone

Zone 3: Middle Tide Zone

The approximate limits of this zone may be The approximate limits of this zone may be recognized by the development of mussel recognized by the development of mussel beds at the upper level and the patches of the beds at the upper level and the patches of the surf grass at its lower level.surf grass at its lower level.

More favorable for many species, and the More favorable for many species, and the major biological factor at work is the major biological factor at work is the competition for space.competition for space.

Increased submergence time.Increased submergence time.

Zone 3: Middle Zone

Zone 4: Low Tide ZoneMostly submerged in water.Mostly submerged in water.

More marine vegetation.More marine vegetation.

Organism in this area are not well adopted to periods of Organism in this area are not well adopted to periods of dryness and temperature extremes.dryness and temperature extremes.

Creatures in this area can grow larger sizes because there Creatures in this area can grow larger sizes because there is more available energy available..is more available energy available..

Water is shallow enough to allow plenty of light to allow Water is shallow enough to allow plenty of light to allow substantial photosynthesis.substantial photosynthesis.

The area is also protected from large predators such as The area is also protected from large predators such as large fish because of the wave action and water being large fish because of the wave action and water being shallow.shallow.

Zone 4: Low Tide Zone

Intertidal Zone Ecology

Advantages

There are a number of advantages to living in a tide pool There are a number of advantages to living in a tide pool ecosystem.ecosystem.

• • Algae and other intertidal plants grow in the abundant Algae and other intertidal plants grow in the abundant sunlight and support an entire food chain of animals.sunlight and support an entire food chain of animals.

• • Constant wave action supplies the tide pool with Constant wave action supplies the tide pool with nutrients and oxygen.nutrients and oxygen.

• • Food is abundant. Food is abundant.

• • A varied substrate provides hiding places and A varied substrate provides hiding places and surfaces to cling to.surfaces to cling to.

Challenges to Living in the Intertidal Zone

The rapidly changing conditions of a tide pool The rapidly changing conditions of a tide pool make survival a challenge. Exposure to surf and make survival a challenge. Exposure to surf and sun varies considerably.sun varies considerably.

• • Plentiful sunlight, which helps intertidal plant life Plentiful sunlight, which helps intertidal plant life grow quickly, can also rapidly dry up precious grow quickly, can also rapidly dry up precious moisture and increase the water temperature.moisture and increase the water temperature.

• • As the tides rise and fall, the As the tides rise and fall, the salinitysalinity (salt (salt concentration) constantly changes. Animals living concentration) constantly changes. Animals living in the intertidal zone must be able to tolerate wide in the intertidal zone must be able to tolerate wide salinity variations. salinity variations.

Challenges to Living in the Intertidal Zone

• • If sufficient nutrients are available, intertidal If sufficient nutrients are available, intertidal animals reproduce rapidly, so they constantly animals reproduce rapidly, so they constantly compete for space, light, and food.compete for space, light, and food.

• • Animals are also exposed to predators while Animals are also exposed to predators while the tide is out.the tide is out.

• • Waves that bring in much-needed nutrients Waves that bring in much-needed nutrients and moisture can also carry unprotected and moisture can also carry unprotected animals out to sea.animals out to sea.

Adaptations

Small animals that live in the splash zone can avoid desiccation Small animals that live in the splash zone can avoid desiccation by closing their shells tightly to seal in moisture.by closing their shells tightly to seal in moisture.

The strong pounding of waves caused a major problem. Some, The strong pounding of waves caused a major problem. Some, like sea stars, cling fast to the rocky surfaces; others find shelter like sea stars, cling fast to the rocky surfaces; others find shelter in crevices or hide under thick mats of seaweed when the tide is in crevices or hide under thick mats of seaweed when the tide is out.out.

Some species may eviscerate.Some species may eviscerate.

Some animals secrete a glue-like mucus to stick to the rock's Some animals secrete a glue-like mucus to stick to the rock's surface.surface.

Many fishes that inhabit tide pools, such a sculpin and young Many fishes that inhabit tide pools, such a sculpin and young opaleyes, can breathe air at the surfaceopaleyes, can breathe air at the surface