The document summarizes the marine food web. It discusses how food webs are made up of interconnected food chains and how energy flows from the sun to producers to consumers at different trophic levels. It provides examples of the different trophic levels in the marine planktonic food web, including phytoplankton as primary producers, zooplankton as primary consumers, small predators as secondary consumers, and top predators like fish and marine mammals. It also describes three types of marine food chains and how human impacts like overfishing and pollution can destabilize the marine ecosystem and food web.

1. MARINE FOOD WEB
BY,
ARABINDA PAL
MARINE BIOTECHNOLOGY
PART-I
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2. INTRODUCTION
In nature food chains are not isolated. Most
ecosystem contain several inter connected
food chains which forms a food web.
Food web is the feeding relationship in an
ecosystem.
Food chain is a linear sequence of feeding
relationship, where as food web is the
complex relation between different food chain
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3. TROPHIC LEVEL
A position in a food chain or Ecological Pyramid occupied
by a group of organisms with similar feeding mode.
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4. ENERGY FLOW
Sun is the all source of energy. Producer take light
energy from the sun and converted it into the
chemical energy. When primary consumer feed on the
producer energy transfer occur.
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5. CONNECTANCE
The complexity of food web can vary greatly & express
this complexity by a measure called connectance of
the food web.
𝑐𝑜𝑛𝑛𝑒𝑐𝑡𝑎𝑛𝑐𝑒 =
𝑎𝑐𝑡𝑢𝑎𝑙 𝑛𝑜. 𝑜𝑓 𝑖𝑛𝑡𝑒𝑟 𝑠𝑝𝑒𝑐𝑖𝑓𝑖𝑐 𝑖𝑛𝑡𝑒𝑟𝑎𝑐𝑡𝑖𝑜𝑛𝑠
𝑝𝑜𝑡𝑒𝑛𝑡𝑖𝑎𝑙 𝑛𝑜. 𝑜𝑓 𝑖𝑛𝑡𝑒𝑟𝑠𝑝𝑒𝑐𝑖𝑓𝑖𝑐 𝑖𝑛𝑡𝑒𝑟𝑎𝑛𝑡𝑖𝑜𝑛𝑠
If there is species no. is ‘n’, the potential no. of
interspecific interactions
=
𝑛 𝑛 − 1
2
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6. TYPES OF FOOD WEB
Food webs are of three types-
a.Connectedness or topological or static
food web
b.Energy flow or biogenetic food web
c.Functional or interactional food web
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7. DIFFERENT TROPHIC LEVELS OF
MARINE PLANKTONIC FOOD WEB
Producer – The primary producer are mainly
phytoplankton. They include single cell dinoflagellates,
diatoms, cyanobacteria and some algae.
They absorb the light energy from the sun and
converted into the chemical energy in the form of
carbohydrate
They account for the 95% of the oceanic productivity
and the half of the earth productivity.
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8. Zooplankton – They are primary consumer.
Phytoplankton are eaten by the primary consumer.
They include-
o single cell ciliates
o Copepods
o Shrimp
o Larvae of mollusk, etc.
Small predators - They are the secondary consumers.
They are feed on the zooplanktons. They includes-
o Krill
o Some small fish such as herring,
sardine, etc.
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9. Top Predators - They are eat both secondary predators
and zooplanktons.They includes-
o Cephalods(octopus)
o Large fish such as tuna, shark etc.
o Marine mammals such as Whales, seals,
dolphins etc.
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10. Marine planktonic Food Web
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Types of Marine Food Chain
According to John Ryther 3 types of food chain
found in marine ecosystem …
I. Oceanic type
II.Continental shelf type
III.Upwelling zone type

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Oceanic Type
Oceanic system have five-e trophic levels with a low
production of about 50 g C m-2 y-1.

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Continental Shelf Type
This type has 3 trophic levels and the primary production
is about 100 g C m-2y-1.

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Upwelling Zone Type
This type has only two trophic levels. Upwelling provided
higher and more continuous nutrient supply leading to a
primary production of about 300 g C m-2y-1.

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EFFECT OF HUMAN IN MARINE
ECOSYSTEM AND FOOD WEB
o Extreme fisheries
o Ocean pollution
o Acidification

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CONCLUSION
Marine phytoplankton produced half of the world
primary productivity. The different variation of
the marine food web shows the wide diversity of
marine ecosystem. Due to the extreme fisheries,
pollution the marine ecosystem very much
affected. Many species are extinct due to this
which destroy the equilibrium of the food web.

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ACKNOWLEDGEMENT….
T, K, Saha. Ecology and Environmental Biology
Jeffrey S. Levinton, Marine Biology
Ivan Valiela, Marine Ecological process
Wikipedia

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