Ch. 11 Between the Tides

BasicsIntertidal zone

Between tidesLittoral zoneBest studied areas

Emersion vs. ImmersionFew marine places open

to airMust give up advantages

HabitatThe tides/community

rely on type of bottom

http://www.youtube.com/watch?v=qfhNjpu_IU4

Basics cont.Habitat

Community-all the different pop. in an area

Bottom-the material which organisms live on Substrate/substratum Different bottoms

define habitat

Low Tide ExposureProblems

Harsher environmentHigher up more time

out of water The highest is never

submergedWater Loss

Desiccation Must tolerate, or

prevent it Two main ways, hiding

or “clamming up”

Low Tide ExposureWater Loss

Hiding Go run and hide to

somewhere wet Tide pools Sessile organisms only

spawn in wet areas“Clam up”

Some protective covering Holds water, and they go

in to their covering Some clamp themselves

to rocks

http://www.youtube.com/watch?v=FeUilWF-MoI

Rocky Bottom CommunitiesBasics

Formed by Active coasts uplifting Ice scraping and

weighing Waves carry

away/erodeOrganisms

Most are epifaunal Many are sessile Both cause stress

Low Tide ExposureWater Loss

“Clam up” Some close off their

operculumNot caring

Chitons and rockweeds just don’t care

Temperature and SalinityHeat capacity

allows for moderate water temp

Low Tide ExposureTemperature and

SalinityAir temp. is more

extreme Most are eurythermal Some hide in the shade Some colors are lighter

Salinity also affects organisms Some clam up Some burrow (more

common in soft)

Low Tide ExposureRestriction of feeding

Deposit uncommon (rocky)

Filter common among sessile Only underwater

Others eat detritus or seaweed Predatory problems at low

tideNot being able to eat at

higher up in the habitat Slower development

The Power of the SeaWaves

The distribution of wave action is varied Refraction not perfect Bays less action, headlands

moreWave impact intensity

(wave shock) is variedCoping with Wave Shock

Some only live sheltered Deal with sediment more

The Power of the SeaCoping with Wave Shock

Some anchor themselves to rocks Seaweed-holdfasts Mussels-byssal threads

Move slowly Suction cups

No swim bladder Anchoring can

disadvantageousThicker shellsThis causes greater

diversity among locations

http://www.youtube.com/watch?v=r1KfBg56UVc

The Battle for SpaceSpace limitation

Plenty of foodLimiting resource is

mainly open spaceWays to compete

First one there Quick dispersal

Forcing out others Growing over others

Vertical Zonation of Rocky ShoresBasics

Community divided into bands One organism won’t exist

throughout Vertical zonation

General rule Upper limit physical Lower limit biological Not perfect Fuzzy

Split into Upper, middle, lower Not universal

Vertical Zonation of Rocky ShoresUpper intertidal

Highly exposed to air Above high tide line Affected by splash “splash zone”

Farther on exposed coasts

Organisms Lichens Cyanobacteria Algae Periwinkles

Littorina zone Limpets

Vertical Zonation of Rocky ShoresMiddle intertidal

Parts are submerged more than others Causes greater diversity

Top almost always has barnacles Due to larva, predation, and

desiccation tolerance Bottom limit from

predation/competition Have to stop from drying out

Other parts are determined by the specific site

Vertical Zonation of Rocky ShoresMiddle intertidal

The middle of the middle is dominated by Mussels, barnacles, and

brown seaweeds Seaweed forms algal turf Mussels killed by sea stars,

or spiny lobsters Keystone predator

Ecological succession Final climax community

Not always typicalDiversity increases with

competitive exclusion

Vertical Zonation of Rocky ShoresLower intertidal

Immersed mostlyMany predatorsMany seaweeds

Light and space limited

Self sustaining tide pools

http://www.youtube.com/watch?v=g7Rlh5sA8WE

Soft Bottom Intertidal CommunitiesBasics

Any bottom composed of sediment Can be confusing

For book is burrowable

Dominate east Cape Cod and the Gulf

The shifting sedimentsUnstable ground

Less seaweed, more seagrass

Soft Bottom Intertidal CommunitiesThe shifting sediments

Most organisms are infaunal Protection from physical

and predatorsMost sediment is a mix

Calmer=finer Rougher=larger

Living in the sedimentOxygen availability

Detritus main source of food

Deposit feeders

Soft Bottom Intertidal CommunitiesLiving in the sediment

Oxygen availability Oxygen and detritus is

dependent on sediment size Coarser=more

This is due to the porosity of the sediment

In muddy bottoms, the organic matter uses the little bit of oxygen Interstitial water Anoxic bacteria thrive Others bioturbate Others have special

hemoglobin And others are lazy

Soft Bottom Intertidal CommunitiesLiving in the

sedimentGetting around

To move around Clams use muscular

foot Worms open a path

with their pharynx Crustacean dig

Some eat while moving through the sediment

Meiofauna live in between the grains and are worm-shaped

http://www.youtube.com/watch?v=vNqEQjGaDVk

Soft Bottom Intertidal CommunitiesLiving in the sediment

Feeding Plankton and diatoms are

major primary producers Suspension feeders lay out

a net to catch detritusZonation

Not as obvious Burrowing

Higher up the sand is drier Crustaceans

Really hard to tell on mud flats where the tide line is fuzzy due to low slope