Conference Proceedings - IAD

39th IAD Conference, August 2012, Szentendre, Hungary
Figure 5.Dendogram of macrozoobenthos species composition coincidence inJDS,
JDS2 and JDDS
2,9
2,7
2,5
2,3
2,1
1,9
1,7
1,5
0 , % S im ila rity 5 0 1 0 0
st. 1
st. 2
Zelinka-Marvan
index
st. 3
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st. 8
Figure 6. Ecological conditions classification: white – II-Good, gray – III-Moderate, black
– IV–Poor
Quantitative development indexes have not been investigated in the context of
the JDS. In the JDS2 and the JDDS, the structure of main taxonomic groups had
certain differences in terms of quantity: in the Lower Danube, Amphipoda,
Gastropoda, Bivalvia and Oligochaeta were dominant (JDS2 2007); according to
JDDS results the sequence of dominating groups in the mouth area was
different: Oligochaeta, Gastropoda, Amphipoda and Chironomidae. Bivalvia,
though prolific in the JDS2 samples were rather rare in 2011: Сorbicula fluminea
was registered at two stations only and did not form mass colonies; with regard
to Dreissena only isolated specimens were detected.
Mollusks (Gastropoda and Bivalvia) accounted for the largest share in biomass.
In comparison to the JDS2 results, Bivalvia accounted for over 80% of the total
208
st. 9
st. 10
st. 11
st. 12
st. 13
J D D S
J D S
J D S 2
JDS2 JDDS
st. 14
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st. 16