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A river draining deforested land

after rain

A forest creek after rain

Why are the forest creeks clean?

http://www.wpu.edu.ph/colleges/-aquaticscience.htm

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Why are the forest creeks clean?

The soil iscovered byleaves

Roots holdthe soil

> Rain cantwash the soileasily intothe creek

http://www.wpu.edu.ph/colleges/-aquaticscience.htm

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Why are the forest creeks clean?

Forestprovides

shadow andprotection

from directsunlight

> the waterremains cool

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0

2

46

8

10

12

14

16

0 5 10 15 20 25 30 35 40

MaximumDissolved Oxygen in Freshwater

Why are the forest creeks clean?

Forest

Open

lan

d

Cool water

can carrymoreoxygen

Biochemical

processesthat

consumeoxygen run

slower in

cool water

> Waterkeeps well

oxygenizedand healthy

C

mg / l

http://www.wpu.edu.ph/colleges/-aquaticscience.htmhttp://www.wpu.edu.ph/colleges/-aquaticscience.htmhttp://www.wpu.edu.ph/colleges/-aquaticscience.htm

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Why are the forest creeks clean?

Oxygen is

needed byall

organismsthat help

eliminatingdirt particles.

But foreststreams lack

producersthat could

supplyoxygen!

http://www.wpu.edu.ph/colleges/-aquaticscience.htm

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Why are the forest creeks clean?

Bacteria and micro fungi grow on leaf litter and otherdead organic matter> The dead organic matter decays

http://www.wpu.edu.ph/colleges/-aquaticscience.htm

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Grazers / Scrapers e.g. snails, larvae of water pennybeetles and some mayflies scrape the biofilms of

microorganisms and feed on these bacteria and microfungi

Why are the forest creeks clean?

http://www.wpu.edu.ph/colleges/-aquaticscience.htm

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Why are the forest creeks clean?

Gathererslike small

shrimpsbrush andclean theunderwatersurfaces

and featthis way onbacteria,algae and

micro fungi

http://www.wpu.edu.ph/colleges/-aquaticscience.htm

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Why are the forest creeks clean?

Detritivore gatherers e.g. scavenger water beetlesand crabs feed on dead animals and rotten plant

material

http://www.wpu.edu.ph/colleges/-aquaticscience.htm

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Shredders e.g. some stonefly larvae and somecaddisfly larvae feed on leaf litter and shred the

dead organic matter in small pieces

Why are the forest creeks clean?

http://www.wpu.edu.ph/colleges/-aquaticscience.htm

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Predators e.g. damselfly larvae,whirling beetles and water bugsfeat on other small organisms

Why are the forest creeks clean?

http://www.wpu.edu.ph/colleges/-aquaticscience.htm

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Why are the forest creeks clean?

Omnivorous smallfish feed ontheinvertebrates androtten fruits

Large

(predatory) fishfeed on the

small fish

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Why are the forest creeks clean?

The organisms ina clean stream

ecosysteminteract witheach other andcycle the matter

inputs fromoutside.

They are

specializedtherefore in theirfeeding habits:shredders,grazers /scrapers,

http://www.wpu.edu.ph/colleges/-aquaticscience.htm

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Streamorganismsarecommonlyused asbioindicatorsforevaluation of

waterquality:

e.g. SaprobicIndex

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Protect

forestcreeks!

because theyserve as ...

Clean source of

drinking water

Clean water input to

Lakes

Retreat for endemic

wildlife

Functioning divers

Ecosystem

http://www.wpu.edu.ph/colleges/-aquaticscience.htm

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Ecological Adaptation - Morphology

Stream current (rheophilic)

Reproduction

streamlining strong clawsflattening

swimming

legs

pygidial

gland

leg suckersswimming

hairs

Locomotio

n spinning gland

Water surface

(neustic)Johnston's ordouble eyes

E l i l Ad t ti

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Ecological Adaptation - RespirationGills (closed tracheal system)

Plastron / gas gill

(passive)

Anal gills PiercersAbdominal

gills

subcox

al

subabdomina

l

microplastr

on

subelytralAir reservoir (active)

macroplast

or open tracheal

system Respiratory cSnorkel

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Ecological Adaptation - Feeding habitsGathering

collectors

Shredd

ers

Filtering

collectors

PredatorsPlant

gougers

Scrapers

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