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Comparing the Health of Two RiversAs macro-invertebrates do not
move much, they make excellent indicators for pollution effects
inrivers. Both the number of species and the actual types of
species can be used to indicate how
polluted an area is. We will use two different measuresof
diversity to compare our sampling areas.
TASK: We will collect data on the invertebrates from the river
at HaBinh !"ietnamese name #$ng B%&i'. We will then use two
differentmeasures to assess the health of this river !attached' to
decide if this riveris in a near natural state, damaged by human
activity, highly polluted etc.(ou will need to compareand
evaluatethe result from each measure ofriver health and use these
to come up with your own !scientific' opinionon the state of this
river
Sampling areas:
)deal sites have a flow of *.+ *. ms !try dropping a stick in /
timing'. 0he surface is slowmoving and slightly broken. 0he bottom
is fairly stable, ideally cobbles or small rocks. 0he depthsare
1*-+*cm !at times of low flow'.
Methods of sampling:
All methods of sampling involve moving the substrate !what is on
the bottom of the river' andcatching the dislodged invertebrates
with a net placed on the downstream side of the sampling area.
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#ur two sampling $ndices:%&' Simpson(s )iversit! $nde*
Yep, our old friend again!
='1!
'1!
nn
NND
5 6 0otal 5umber of organisms
n 6 5umber of individuals of each species
%+' ,ollution Tolerance $nde* %or ,T$'
)n this system, each macro-invertebrate is given a points value.
0he higher the points the betterthe water must be for the organism
to live there.
0he number of types of organisms found for each organism group
!can be genus or family 7ustuse the table and diagrams below' is
multiplied by their points value. 0he sum of these numbers
is the 80) value for the area sampled.
Table Two: Points value for using the PTI macro-invertebrate
index
Group I Group II Group III Group IV(4 points each
species)(3 points each
species)(2 points each
species)(1 point each species)
Intolerant ofPollution
Moderatel !olerant ofPollution
"airl !olerant ofPollution
!olerant of Pollution
Mayfy
Stonefy
Gill snail
Caddisfy
#i$e %eetle
&o%son'
(aterpenn
)lder' )mphipod
&amsel'
&ra*on'
+ow%u*
+cud
,rane'
,lam/mussel
,ra-sh /lo%ster
eeches
Mid*e
"latworms
Black flylarvae
Water mite
ristle worms
#oundworms
Ma**ot
!u%erfe0
Pouch +nails
loodworm
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Ta.le /our: Some common benthic macro-invertebrates found in
river
Alderfl! larvae
Amphipod%or scud'
0lac1fl! 2arva
0ristleworm
Caddisfl! 2arva
@ay be brown, green or have sand, sticks, stonescemented to
itself
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)o.son fl! larvae
)ragonfl! 3!mph
/latworm
2eech
Ma!fl! 3!mph
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Sow.ug
Stonefl! 3!mph
ater penn!
@odified from
httpwww.riverwatch.ab.cahowtomonitorinvertidentifying-ident.cfmCmayfly
http://www.riverwatch.ab.ca/how_to_monitor/invert_identifying-ident.cfm#mayflyhttp://www.riverwatch.ab.ca/how_to_monitor/invert_identifying-ident.cfm#mayfly
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