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Flashcards in Test 2 Part 2 Deck (20)
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The _ coastal waters provide lots of _ and _.
How (2)?

shallow; light; nutrients
Vigorous plant growth produces abundant food; high tide bathes the intertidal in plankton rich water
; waves and tides bring in more food of drifting seaweed and detritus


Competition for space - the ability to outcompete depends on two factors

1. effective means of dispersal (first to occupy new patches of open space must get their offspring there)
2. ability to hold on to it (the ability to rapidly reproduce and disperse the young to the next opening


Some organisms do not colonize open patches. They take over space already occupied.
Owl limpets?
Other intertidal organisms?

Undercut their neighbors (loosening them from the rock);
keep a territory for themselves by bulldozing out intruders;
Grow over their competitors, making them vulnerable to waves, smothering them and blocking out precious sunlight


Vertical zonation

the upper limit at which a species occurs is usually determined by physical factors,
and the lower limit is usually determined by biological factors
especially predation and competition.


Tests to explore Zonation

Transplantation, removal, and caging



Organisms are moved from one place to another:
mussels grown on panels, transplanted to different heights on pier piling
barnacles soon died if placed higher than they normally lived.
physical: body fluids showed desiccation


Why don't organisms live lower in the intertidal?

Competitors or predators set the lower boundary


Removal experiment

one species is removed from an area, which is compared to an untouched control area


Caging experiment

some sort of barrier stops animals from getting into study area (can be wire cages; anything that keeps the animal out)


Why aren't removal experiments practical?

Not enough time to remove all the predators or competitors
They move back into an area too fast after removal



When a patch of space is cleared
new organisms often move into the patch and get replaced by others in a regular sequence.


Ecological succession

refers to such a regular pattern of regrowth.


Planktonic settlement and metamorphosis

Planktonic larvae select a particular environment on which to settle and undergo metamorphosis.
Metamorphosis may be triggered by specific
& biological factors


Soft-bottom intertidal communities

Sediment; organisms are able to burrow in easily
East coast south of Cape Cod, almost all of the Gulf coast, rocky west coast


The type of sediment depends on three factors

How much water motion there is
Where the sediment comes from
The slope of the land


Soft bottoms are _ and _ _ in response to _, _, and _.

unstable; constantly changing; waves; tides; currents


Advantage of living in the sediment?
Main food?

Bottom stays wet when tide goes out, desiccation not as critical as rocky shore.
Degree of desiccation depends on grain size
sand dries out quickly
partially responsible for coarse sand beaches having relatively little animal life.


Infauna depend on the _ _ _through the _ to _ the _ _.

circulation of water; sediments; replenish; oxygen supply



water circulation through fine sediment is greatly restricted


Factors of Muddy Bottoms

a lot of organic matter to decay
reduced water flow into sediment
Below the upper few centimeters of mud
the interstitial water is deficient of oxygen
below this depth, sediments have no oxygen = anoxic.
Many organisms overcome this oxygen shortage by
pumping oxygen-rich water from the sediment surface with siphons
or through their burrows.