Download Adaptations of Organisms to Lotic Habitats

Adaptations of Organisms to
Lotic Habitats
By:
Victoria Lewis
Natalie Jackson
Nancy Jones
Ruth Starr-Keddle
Introduction

In lotic systems, the velocity of flowing water
is a major influence on:
 substrate type, with boulders deposited in fast-flow and fine
sediments in slow-flow areas,
 transport of particles, either as a food source for filterfeeders or, during peak flows, as scouring agents,
 maintenance of high levels of dissolved oxygen.

A stream or river contains heterogeneous
micro-habitats interspersed with;
riffles,
deeper natural pools,
erosion of banks,
sediments deposited,
areas of unstable, shifting sandy substrates.
Adaptations Of Aquatic Plants
To Lotic Habitats

Leaves & stems within, or floating on Water.

Upper leaves or shoots able to grow above the water,
lower ones able to grow submerged.
 Tall monocotyledons- Grasses, sedges & rushes
 Short dicotyledons-the fringing herbs-typically found fringing the
sides of small brooks
 Short monocotyledons, mainly grasses, again frequently at the sides
of brooks
 A very few tall dicotyledons

Bank plants growing above normal water level,
flooded after heavy rain.
Adaptations of Insects to Lotic
Habitats

Morphological Adaptations
Dorsoventral Flattening
Case Construction
Suckers
Silk Nets
Size

Behavioural Adaptations
Use of Drift
Burrowing
Morphological Adaptations

Dorsoventral Flattening
Allows the organism to stay close to the
substrate where there is a layer of still
water. An example of this is the Water
Penny.

Case Construction
A variety of case shapes made by caddis
fly larvae assist in streamlining and act as
a ballast.
Morphological Adaptations

Suckers
Allows the insect to stick to quite smooth
exposed surfaces such as rock faces or in
waterfalls, some Diptera larvae use this.

Silk Nets
Used to maintain position in flow. Blackfly
larvae attach their claws to a silk pad
attached to a rock.
Morphological Adaptations

Size
Beneficial to be smaller and have flexible
bodies, allowing them to live in the bed
(benthos) of the stream between the
boulders, stones and pebbles.
Behavioural Adaptations

Drift
A drifting stategy can be used to move
from an unsuitable location. Some insects
such as Baetis follow a diurnal periodic
pattern of drift. ‘Catastrophic Drift’ is used
by some as a response to physical
disturbance.
Behavioural Adaptations

Burrowing
Insects will burrow deep into the substrate
(the hyporheic zone) where they can avoid
fluctuations in the environment.
Adaptations of Vertebrates to Lotic
Habitats



All 5 phyla possess species adapted to life in
lotic habitats;fish, amphibians, reptiles, birds,
and mammals.
Streamlined body shapes to reduce friction in
water.
Some more specialised adaptations in life
history, physiology and morphology.
Adaptations of Fish


8,500 freshwater species.
Salmonoids & Lampreys; DIAROMOUS
Lampreys larval stage; AMOCOETE
Salmonoids can vary their growth rates


CATADROMOUS, e.g. eels
DIADROMOUS GLOBOID; larval stage at sea.
Adaptations of Amphibians




2 common families; URODELA (salamanders
& newts), ANURA (frogs & toads).
Eggs laid in freshwater.
Larval stage possess gills, but also use skin
for gaseous exchange.
Adults possess lungs but still use their skin as
well for gaseous exchange.
Adaptations of Reptiles


Some species of snake and turtle are found in
lotic habitats.
Crocodiles;
Eyes, nostrils & ears on top of head.
NICTITATING membrane to cover eyes.
Valves to close ears & nostrils.
Long thin body with short legs good for sinuous
swimming movements.
Adaptations of Birds

Dippers;
Dense, waterproof feathers.
Nasal flaps.
Wings used like flippers when in water.
NICTITATING membrane.

Ducks;
Few species are confined to a lotic habitat.
Harlequin duck, truly lotic.
Adaptations of Mammals


Few aquatic species exclusively reside in lotic
habitats.
Otters; lutra (genus)
Streamlined body shape.
Broad flat tail involved in sinuous swimming
movements.
Short dense fur impermeable to water.
Large lung capacity allowing long dives.
Partially webbed feet for swimming.

Platypus;
Webbed feet, short fur, Lacks external ears.
Feeds on bethic invertebrates.
Bill covered with soft skin possessing many
electrosensors.
Broad flat tail used as rudder when diving &
surfacing

River Dolphin;
only mammal confined to lotic habitats.
Poor vision.
Narrow, very sensitive sonic beam for location of
food & obstacles.
Smaller body size than marine dolphin.
Conclusion

Some plants and invertebrates have specific
adaptations to the lotic environment, and
vertebrates tend to be suited to an aquatic
environment.

All are linked together in the lotic
environment, ie. Submerged plants provide
egg-laying sites for invertebrates and fish,
and lurking sites for predators.