Survey or river restoration project in the Danube Delta

1. Community structure of phytoplankton,
zooplankton and macroinvertebrates in
restored and natural aquatic habitats of
Danube Delta – a preliminary
assessment
Orhan Ibram – aquatic macroinvertebrates
Liliana Török - phytoplankton
Mihaela Tudor - zooplankton
Hidrobiology Laboratory
Danube Delta National Institute

2. Channel
s
blocking

3. Babina area (satellite images)
1993 1996
1993 1996

4. -Former polder for forestry
Fortuna Lake
Danube

5. Selected natural lakes
Cuibul cu
Lebede
Isac
Uzlina
Images from GoogleEarth

6. Chaneging connectivity and lake typology
Type 2 Type 1 Type 3
River
clay sand-silt organic
OOsterberg W., Staras M., Bogdan L., Buijise A. D., Constantinescu A., Coops H., Hanganu J., Ibelings B. W., Menting G. A. M., Navodaru I.
and Torok L. (2000) “Ecological gradients in the Danube Delta; present state and man-induced changes”. RIZA the Netherlands, Danube Delta
National Institute Romania and Danube Delta Biosphere Reserve Authority Romania. RIZA rapport nr. 2000.015

7. Type 1 lakes
•Turbid lakes with high biomass
of phytoplankton and
zooplankton and a low cover of
aquatic vegetation and
filamentous algae;
•The abundance of
cyanobacteria and cladocera is
relatively high;
•These lakes tend to be deep
and large with sand-silt substrate
and a low variation in waterdepth

8. Type 2 lakes
•Clear lakes with a high abundance
of the Potamogeton trichoides
community, often with filamentous
algae;
•In these lakes phyto- and
zooplankton biomass and turbidity
are low;
•These lakes tend to have a high
seasonal variation in waterdepth
and a low cumulative residence time

9. Type 3 lakes
•Clear lakes, often with
filamentous alge;
•Phyto- and zooplankton
biomass are low;
•Shallow and small with
organic substrate;
•High cumulative residence
time

10. Evolution of phytoplankton diversity in Babina and
Fortuna areas
•The abundance of the phytoplankton found shows that diatoms constitute
a significant component of the community;
•The analyis of the saprobic status of the recorded species revealed a
predominance of meso-saprobous algae species
Analiza comparativă abundenţei numerice vs. diversitate fitoplanctonică în Analiza comparativă a abundenţei numerice relative vs. diversitate fitoplanctonică
Ostrovul Babina (2003 & 2010) în incinta Fortuna (2006 & 2010)
nr.ind./l H' (div.)
3000000 4 nr.ind./l H' (div.)
1200000 3.5
3.5
2500000
3
1000000
3
2000000 2.5
2.5 800000
2
1500000 2
600000
1.5 1.5
1000000
400000
1 1
500000
0.5 200000
0.5
0 0
B2 B4 B5 B10 B11A B12 B13 B14 B16 0 0
F - S0 F2 F8 F9 F13 F16
staţii staţii
2003 2010 H'/2003 H'/2010 2006 2010 H'/2006 H'/2010

11. Phytoplankton in natural and restored areas
-There is no significant differences between
phytoplankton development in natural lakes
compared with restored areas;
-In Isac lake high values of chl “a” are not given by
blooms of cyanobacteria which are in general
responsible for water degradation

12. Evolution of zooplankton diversity in Babina
200 186
180
160
140
nr.sp. zooplancton
120
100 87
80 71
60 46
34
40 25
19 24
20 9
0
1993 1994 …… 1997 1998 1999 2000 2001 …… 2003 …… 2010
•There is a significant increasing of the species number since the polder was flooded
(1994), more interesting in the last 4 years when the species number almost get
doubled;
• The dominant genus was Brachionus spp, represented by 6 taxa. After flooding the
polder many species that are indicators of permanent waters occurred. The constant
forms that occur every year are: Chydoridae (cladocera), Cyclopidae (copepoda) and
Brachionidae (rotifera).

13. Evolution of zooplankton diversity in Babina
16 The frecquency of rotifers families w ithin Babina Island
Philodinidae
14 Collothecidae
100%
Trichocercidae
12 90%
Testudinellidae
80%
10 Synchaetidae
nr. ind/l 70%
Lecanidae
8 60%
Habrotrochidae
50%
6 Dicranophoridae
40%
4 Notommatidae
30%
Asplachnidae
2 20%
Gastropodidae
10%
0 Lindiidae
0%
B10 B16 B2 B14 B12 B11 B5 Adinetidae B13
B4
1997 1998 1999 2000 2001
Brachionidae
Cladocera Copepoda Rotifera
• The most abundant taxonomic groups recorded until 2010 were the rotifer
species. The rotifers community across all channels, lake and outlet was
overwhelmingly dominated by Brachionus spp. (>50%). These species are found
generally in eutrophic waters (Berzins and Pejler, 1989).
• In terms of density, small herbivorous rotifers (e.g. Keratella sp. and
Aschomorpha sp.) are the most abundant in the first year after flooding, these
species being characteristic for eutrophic waters (Premazzi et al., 1992).

14. Evolution of zooplankton diversity in Fortuna
4,5 0,6 25
nr ind/l
4
0,5 20
3,5 20
3 0,4
nr.sp.zooplancton
15
15 14
2,5
0,3
2
10
1,5 0,2
1
0,1 5
0,5
m g/l
0 0,0
BR8 BR6 F2 F4 S0 F16 F19 F13 F12 F9 F8 F8A F10 0
2004 2005 2006 ….. 2010
nr ind/l mg/l
Zooplankton structure reveals low abunance of Cladocera and dominance
of Rotifera group with a low overall abundance;
Both species number and no of individuals/liter has decreased

15. Zooplankton in natural and restored areas
Abundance distribution of zooplanckton in natural lakes
35
30
25
no.ind/l
20
•Community structure - no difference 15
10
between natural and restored areas; 5
both types are dominated by 0
copepods; Isac Uzlina Cuibul cu Lebede
Cladocera Copepoda Rotifera
•Differences are related to the
abundance; natural lakes with higher Abundance of zooplankton in the "lake" of island Babina and
abundances than the restored ones. Fortuna polder
14
•There is an “ inside group” difference 12
in natural lakes separating Cuibul cu 10
no.ind/l
8
Lebede 6
4
2
0
Babina Fortuna
Cladocera Copepoda Rotifera

16. Evolution of aquatic macroinvertebrates diversity in
Babina (1996-2010)
• The polder waters may basically be classified in two faunistic complexes:
1. Running waters-hard bottom-lacking macrophytes;
2. Stagnating-permanent or temporary waters;
nr. specii
The hard, loamy substrate next 25
to the inlets is densely
20
populated by specimens of the
1996
snail Lithogliphus naticoides in 1997
15
association with Viviparus sp. 1998
1999
and Dikerogammarus villosus – 2000
10
freshwater shrimp-that hides 2001
2010
into the woody litter;
5
The second group is composed
mainly limnophylous species of 0
worms, snails, crustacea, water
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17. Evolution of aquatic macroinvertebrates diversity in
Babina (1996-2010)
The species composition of the Gastropoda reflects some of the most
important characteristics for the functioning of the rehabilitated wetlands of
Babina. They live on dead macrophytes and thus contribute to the
decomposition of plant biomass being also beneficial to the aerobic
conditions in the water;
The fluctuation of the specimen number between the channels and lakes is
not significant and may be neglected;
The species composition in the secondary channels is comparable to that of
the main channel

18. Evolution of aquatic macroinvertebrates diversity in
Fortuna (2006 & 2010)
18
•Most frequent species
16
are Bithynia tentaculata
14
and Valvata naticina.
12
The first one has broad
No of species
10
habitat preferences 2006
2010
inhabiting both running 8
and standing water 6
especialy in densely 4
vegetated areas. The 2
former prefers muddy or 0
fine sand sediments and
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it is found mainly in on
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Ep
the shore of the
channels with different
degree of water velocity

19. Aquatic macroinvertebrates in natural and restored
areas
Five univariate measures are calculated for each spatial category. The number of
species (S), total abundance (A), Margalef’s (d) species-richness measure, the
Shannon-Wiener (H’) diversity index (to base loge), and Pielou’s evennes (J’).
The formulae for the indices are as follows:
•Margalef’s d = (S-1)/Log (N) – where S is the number of species in the sample
and N is the number of individuals;
•Shannon-Wiener H’ = -SUM(Pi x Log (Pi)) – where Pi is the proportion of
species found in category I;
•Pielou’s evenness J’ = H’/Log (S) – derived from Shannon-Wiener to express
the observed diversity as a proportion of the maximum possible diversity.

20. Aquatic macroinvertebrates in natural and restored areas
Margalef’s d gives a basic measure of species richness that makes some
allowance for the numbers of the individuals present.
The magnitude of Shannon-Wiener may be affected by the distribution of the
data, giving underestimates of diversity particularly with small sample sizes,
and may also be affected by the number of categories.
Pielou’s J’ is used to express homogenity or relative diversity, the more
similar the proportions of all species in the sample the closer J’ tends towards
1

21. Aquatic macroinvertebrates in natural and restored
areas
25
20
A 1-way ANOVA test of
250
S (no. of species)
differences between catchments 15
showed three diversity indices 10
were significantly different. 5
200
(P<0.01) 0
Natural Restored
2.5
0.8
150
0.78 2
individuals
0.76
H' (Shannon)
1.5
Pielou's (J)
0.74
0.72 1
100
0.7
0.5
0.68
0.66 0
Natural Restored Natural Restored
195
50 4.4
4.3
190 4.2
4.1
Margalef's (d)
Abundance (N)
185
4
0 3.9
180
Isac Uzlina Cuibul 3.8
Babina Fortuna
3.7
175
3.6
170 3.5
Natural Restored Natural Restored

22. Conclusions
There is no significant differences between phytoplankton and zooplankton
development in natural lakes compared with restored areas regarding
community structure as opposed to aquatic macroinvertebrates;
Only one year of investigation is not sufficient; extending the analysis to
other type of ecosystems like channels because dominate (as a proportion)
the restored areas so the lakes are not the best representatives of these
areas
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