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Mangrove Estuary
Mangrove Estuary Swamp
Investigation
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Aim: To compare the biotic and abiotic
factors in two distinct mangrove swamp
communities.
Abiotic Factors
In this lab, you will identify and measure the
abiotic factors on the rocky shore.
- some of the factors that you will investigate
are:
Salinity, substrate, exposure to light,
temperature, turbidity and more…
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Abiotic Factors in the
Mangrove Estuary Swamp
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SUBSTRATE surface material
The muddy substrate is composed of
detritus, and fine inorganic particles.
Some organisms burrow under the mud
and live there. (we will not disturb them in
our study).
The mangrove roots go deep into the
muddy substrate.
Different species have specific root
forms; many have aerial or buttress roots.
Abiotic Factors on the Shore
• TEMPERATURE
• Immersion in water buffers against temperature change.
Abiotic Factors on the Shore
LIGHT
 Needed for photosynthesis.
 Water will filter off some of the wavelengths of
light and reduce the intensity.
 Small algae, e.g. some of the red algae, will
photosynthesise with very little light and occur
under other larger algae.
 Mangrove trees provide shade for species
underneath.
Some Abiotic Factors in the
Mangrove Estuary Swamp
TURBIDITY is the
cloudiness of the water.
Large amounts of
plankton, detritus, or
sewage pollution can
increase the turbidity.
This restricts the light
reaching the algae on
the rocks.
Using Quadrats for sampling
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We cannot count all of the organisms in the
two mangrove swamp communities.
Instead we can take samples.
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We will imagine quadrats which are small
square areas (usually 1m x 1m--ours are
approx. 0.5m x 0.5m), and counting all of
the organisms of each kind inside of these
quadrats.
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We will do this at each of the stations in our
mangrove ecosystems.
Identification and Abundance of
Organisms
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As you observe the organisms of the estuary, you will
count the individuals and record their abundance.
The number of each species will be recorded as…
A=abundant, C=common, F=frequent,
O=occasional, R=rare, N=absent.
(Known as the “ACFOR(N) Scale”)
There are scales that will help guide you in
determining the abundance for various types of
organisms.
Organisms to look for in the
estuary swamp…
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Mangroves: These interesting trees dominate
the mangrove ecosystem. There are several
species in Thailand, two of which we will see
easily, with a few others scattered about.
Watch for differences in tree morphology, leaf
structure, seed pods, and the root systems.
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Lichens: The symbiotic algae-fungi
organisms grow on many surfaces.
Organisms that you might find in the
estuary swamp…
• Mudskippers – These fish are
able to survive out of the water
for short bouts of time by
storing water inside of their gill
chambers and breathing through
their wet skin. They can be seen
near the roots of the mangrove
trees.
• Blue crabs -- These crustaceans
may be seen on the mangrove
roots or near burrows. If lucky,
you will see them foraging!
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Snails: You will see a number of snails in the mangroves.