Community structure of phytoplankton, zooplankton and macroinvertebrates in restored and natural aquatic habitats of
Danube Delta – a preliminary assessment
Orhan Ibram – aquatic macroinvertebratesLiliana Török - phytoplanktonMihaela Tudor - zooplankton
Hidrobiology LaboratoryDanube Delta National Institute
Channels blocking
Babina area (satellite images)
1993 1996
1993 1996
Fortuna Lake
Danube
--Former polder for forestryFormer polder for forestry
Selected natural lakes
Isac
Uzlina
Cuibul cu Lebede
Images from GoogleEarth
Chaneging connectivity and lake typology
Type 2 Type 1 Type 3
clay sand-silt organic
River
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
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
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
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
Evolution of phytoplankton diversity in Babina and Fortuna areas
Analiza comparativă abundenţei numerice vs. diversitate fitoplanctonică în Ostrovul Babina (2003 & 2010)
0
500000
1000000
1500000
2000000
2500000
3000000
B2 B4 B5 B10 B11A B12 B13 B14 B16
staţi i
nr.ind./l
0
0.5
1
1.5
2
2.5
3
3.5
4H' (div.)
2003 2010 H'/2003 H'/2010
•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 a abundenţei numerice relative vs. diversitate fitoplanctonică în incinta Fortuna (2006 & 2010)
0
200000
400000
600000
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1000000
1200000
F - S0 F2 F8 F9 F13 F16staţi i
nr.ind./l
0
0.5
1
1.5
2
2.5
3
3.5
H' (div.)
2006 2010 H'/2006 H'/2010
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
Evolution of zooplankton diversity in Babina
•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).
919 24
46
71
186
25
87
34
0
20
40
60
80
100
120
140
160
180
200
1993 1994 …… 1997 1998 1999 2000 2001 …… 2003 …… 2010
nr.s
p. z
oopl
anct
on
Evolution of zooplankton diversity in BabinaThe frecquency of rotifers families w ithin Babina Island
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
1997 1998 1999 2000 2001
Philodinidae
Collothecidae
Trichocercidae
Testudinellidae
Synchaetidae
Lecanidae
Habrotrochidae
Dicranophoridae
Notommatidae
Asplachnidae
Gastropodidae
Lindiidae
Adinetidae
Brachionidae
• 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).
0
2
4
6
8
10
12
14
16
B10 B16 B2 B14 B12 B11 B5 B4 B13
nr. i
nd/l
Cladocera Copepoda Rotifera
Evolution of zooplankton diversity in Fortuna
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
20
1415
0
5
10
15
20
25
2004 2005 2006 ….. 2010
nr.s
p.zo
opla
ncto
n
0
0,5
1
1,5
2
2,5
3
3,5
4
4,5
BR8 BR6 F2 F4 S0 F16 F19 F13 F12 F9 F8 F8A F10
nr ind/l
0,0
0,1
0,2
0,3
0,4
0,5
0,6
mg/l
nr ind/l mg/l
Zooplankton in natural and restored areasAbundance distribution of zooplanckton in natural lakes
0
5
10
15
20
25
30
35
Isac Uzlina Cuibul cu Lebede
no.in
d/l
Cladocera Copepoda Rotifera
Abundance of zooplankton in the "lake" of island Babina and Fortuna polder
0246
8101214
Babina Fortuna
no.in
d/l
Cladocera Copepoda Rotifera
•Community structure - no difference between natural and restored areas; both types are dominated by copepods;
•Differences are related to the abundance; natural lakes with higher abundances than the restored ones.
•There is an “ inside group” difference in natural lakes separating Cuibul cu Lebede
Evolution of aquatic macroinvertebrates diversity in Babina (1996-2010)
0
5
10
15
20
25
Hirudin
eeGas
tropo
deCrus
tacee
Efemeropter
e
Odona
teHeterop
tere
Trihopte
reLe
pidop
tere
Coleopte
re
nr. specii
1996199719981999200020012010
• The polder waters may basically be classified in two faunistic complexes:1. Running waters-hard bottom-lacking macrophytes;2. Stagnating-permanent or temporary waters;
The hard, loamy substrate next to the inlets is densely populated by specimens of the snail Lithogliphus naticoides in association with Viviparus sp. and Dikerogammarus villosus – freshwater shrimp-that hides into the woody litter;
The second group is composed mainly limnophylous species of worms, snails, crustacea, water mites and aquatic insects.
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
Evolution of aquatic macroinvertebrates diversity in Fortuna (2006 & 2010)
0
2
4
6
8
10
12
14
16
18
Gastro
poda
Hirudin
eaHeterop
tera
Odona
taTric
hopte
raEph
emerop
tera
Coleopte
ra
Crustac
ea
No o
f spe
cies
20062010
•Most frequent species are Bithynia tentaculata and Valvata naticina. The first one has broad habitat preferences inhabiting both running and standing water especialy in densely vegetated areas. The former prefers muddy or fine sand sediments and it is found mainly in on the shore of the channels with different degree of water velocity
Aquatic macroinvertebrates in natural and restored areasFive 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.
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
Aquatic macroinvertebrates in natural and restored areas
A 1-way ANOVA test of differences between catchments showed three diversity indices were significantly different. (P<0.01) 0
5
10
15
20
25
Natural Restored
S (n
o. o
f spe
cies
)
0
0.5
1
1.5
2
2.5
Natural Restored
H' (
Shan
non)
3.5
3.6
3.7
3.8
3.9
4
4.1
4.2
4.3
4.4
Natural Restored
Mar
gale
f's (d
)
0.66
0.68
0.7
0.72
0.74
0.76
0.78
0.8
Natural Restored
Piel
ou's
(J)
170
175
180
185
190
195
Natural Restored
Abun
danc
e (N
)
0
50
100
150
200
250
Isac Uzlina Cuibul Babina Fortuna
indi
vidu
als
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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