The document discusses benthos, the community of organisms living on or near the seabed, highlighting their types, roles, and ecological importance. It categorizes benthic organisms based on various criteria such as size and location and emphasizes their role in nutrient cycling, water quality, and as a food source for various aquatic species. Additionally, it addresses the negative impacts of trawling on benthic communities, underscoring the significance of these organisms in maintaining healthy aquatic ecosystems.

1. BENTHOSANDTHEIR
ROLE IN
AQUATIC
ECOSYSTEM
Submittedby - ANURADHA NASKAR (M.F.Sc. II Sem.)
DEPARTMENT OF ZOOLOGY
AND APPLIEDAQUACULTURE
BARKATULLAH UNIVERSITY, BHOPAL
MADHYA PRADESH, 462026
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2. CONTENTS
 INTRODUCTION
 TYPES OF BENTHOS
 BY SUBSTRATUM
 BY SIZE
 BY TYPE
 BY LOCATION
 BY MOBILITY
 ADVANTAGES OF BENTHOS
 ROLES OF BENTHOS IN THE AQUATIC
ECOSYSTEM
 IMPACTS OF TRAWLING ON THE SEABED
& BENTHIC COMMUNITIES
 CONCLUSION
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3. INTRODUCTION
Benthos is the community of organisms that live on, in or near the
seabed, also known as the benthic zone. This community lives in or
near marine sedimentary environments, from tidal pools along the
foreshore, out to the continental shelf and then down to the abyssal
depths. Many organisms adapted to deep water pressure can not
survive in the upper parts of the water column. The pressure
difference can be very significant.
The term benthos is coined by Haeckel in 1891, comes
from the Greek, meaning “depths of the sea” and refers collectively
to organisms which live on, in or near the bottom of the sea. Many
organisms adapted to deep water pressure, can not survive in the
upper parts of the water column.
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4. TYPES OF BENTHOS
Benthic community is diversified from species including plants,
animals and bacteria from diverse range of food chain. Benthic
organisms can be classified on the different basis.
 By substratum :-
a. Infauna : Organisms that live in the sediment, e.g. worms,
clams etc.
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Common fire worm Giant clam

5. b. Epifauna : Organisms which either attach to the bottom or
susbstrate, e.g. sponge, oysters, mussels, starfish etc.
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Star fish Pearl oyster

6.  By size :-
a. Macrobenthos : Macrobenthos are comparatively large
organisms living on or near in the
bottom of water, e.g. Seagrass,
Echinoderms, sponges, crustaceans etc.
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Sponge Seagrass

7. b. Meiobenthos : Meiobenthos are the organisms that live in
bottom of water of both freshwater and marine
water ecosystem, e.g. Gastrotricha, Water bears
etc.
7Gastrotricha Water bear

8. c. Microbenthos : Microbenthos is the community of species
living in, on or near the bottom of water
body, e.g. Amoeba, flagella, bacteria,
diatoms etc.
8Amoeba Diatoms

9.  By type :-
a. Zoobenthos : The benthos those are animal origin called
zoobenthos, e.g. Starfish, Oysters, Mussels
etc.
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Mussels Edible oyster

10. b. Phytobenthos : Benthos those are plant origin are called
phytobenthos, e.g. Seagrass, seaweed etc.
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Seagrass Seaweed

11.  By location :-
a. Endobenthos : Endobenthos use bottom of the sediments as
their habitat, e.g. Sea pen, Sand dollar etc.
11Sea pen Sand dollar

12. b. Epibenthos : Epibenthos use top of the sediments as their
habitats, e.g. Sea cucumber, Sea snail etc.
12Sea cucumber Sea snail

13. c. Hyperbenthos : Hyperbenthos just live floating above the
sediments, e.g. Rock cod.
13Rock cod

14.  By mobility :-
a. Sessible benthos : Sessible benthos do not have any mobility,
attached or fixed with the substratum, e.g.
Benthic algae, Sea grasses, Corals etc.
14Benthic grass Coral

15. b. Vagrant benthos : Vagrant benthos are those that have
locomotory powers and either they can
move rapidly or slowly, e.g. crabs, stingray
etc.
15Crab Sting ray

16. ADVANTAGES OF BENTHOS
 Benthos are good indicators of localized conditions of water
quality due to their limited mobility.
 They are sensitive to environmental impacts from both point and
non-point source of pollution.
 They integrate the effects of short term environmental
variations.
 They serve as the primary food source for many species of
commercially and recreationally important fishes.
 When monitored together with relevant chemical/physical
parameters, benthos communities can be used to identify
sources of impairment.
 They are holistic indicators of overall water quality.
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17. ROLES OF BENTHOS IN THE
AQUATIC ECOSYSTEM
The benthic organisms are most versatile on the coastal zone
where the fish and other aquatic animals have multifaceted to a
vast array of effects. Shallow maritime biological community is
highly affected by the gathering of human and environmental
changes. Benthic invertebrates functionally play big roles in fish
production.
 Some important role of benthos is given below :-
 Essential for ecosystem : Benthos plays a big role in ecosystem
by decomposition.
 Nutrition : Benthic invertebrates release good
amount of nutrients naturally by
their feeding activities, excretion
and burrowing into sediments.
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18.  Remineralization : Benthos filter large amount of water and pump
into their bodies. By this activity sediment
and organic matters washed out that
clean the water. The unused organic matter
felled out on the bottom of the sea bed. That
is called remineralized matter.
 Food source : Many fishes feed on small to medium size
benthic organism that live on sea floor.
Vital saltwater fish community like
Haddock, catfish as well as many
freshwater fish eats benthos.
 Increase oxygen : Many of benthic animals move actively on the
bottom and mix the sediments around there
and improve the oxygen concentration which
help in higher production overall organism.
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19. IMPACTS OF TRAWLING ON THE
SEABED & BENTHIC COMMUNITIES
 Destruction or damage to structurally complex habitats
 Reduction in bioturbation
 Death and damage to infauna and epifauna
 Reduction in benthic species diversity
 Re-suspension of sediments
 Attraction of scavengers
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20. CONCLUSION
Benthos is the community of organisms that live on, in or near the
seabed. This community lives in or near sedimentary
environments, from tidal pools along the foreshore, out to the
continental shelf and then down to the abyssal depths.
Although most of the benthos are very small in size, but they play
important role in aquatic ecosystem as they act as bio-indicators,
are important as nutrient in different trophic levels of food chain
& food-web & have role in nutrient & mineral cycling as they act
as decomposers. So that they represent all the trophic levels as
producer, consumer as well as decomposers.
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21. Thank You…