Comparison of physical and chemical properties of water and

Comparison of physical and chemical properties of water and

DOI: 10.2478/v10104-010-0016-x
Vol. 9
No 2-4, 183-191
2009
Comparison of physical and chemical properties of water
and floristic diversity of oxbow lakes
under different levels of human pressure:
A case study of the lower San River (Poland)
Dorota Michalska-Hejduk1, Dominik Kopeć2,
Agata Drobniewska3,4, Beata Sumorok5
1
Department of Geobotany and Plant Ecology, University of Łódź, 12/16 Banacha str.
90-237 Łódź; e-mail: [email protected]
2
Department of Nature Conservation, University of Łódź, 1/3 Banacha str.
90-237 Łódź; e-mail:[email protected]
3
Department of Applied Ecology, University of Łódź, 1/3 Banacha str. 90-237 Łódź,
4
International Institute of the PAS European Regional Centre for Ecohydrology,
3 Tylna str. 90-364 Łódź; e-mail: [email protected]
5
Research Institute of Pomology and Floriculture, 18 Pomologiczna str.,
96-100 Skierniewice; e-mail: [email protected]
Abstract
The oxbow lakes of the lower San River are the place where many valuable and
protected vascular plants such as Salvinia natans and Trapa natans can be found.
The aim of the research conducted in the San Valley in 2000 and 2004-2005 was to
ascertain the relationships between biodiversity and waterbody’s local flora but also
to examine physical and chemical water parameters and ways of micro-catchment
cultivation. The authors also attempted to measure the sensitivity of each of the
species to water deterioration. Five oxbow lakes situated in the area around the
town of Zaleszany were studied. All of the oxbow lakes came into existence at the
same time and only differ in their size and cultivation level. In the case of the San
River oxbow lakes there is no direct correlation between macrophyte distribution or
presence of threatened and protected species and environmental parametres. It is only
considerable human impact that results in macrophyte decrease (expressed as cover
index and biodiversity index). The most valuable species i.e. Salvinia natans may be
threatened by lake overgrowing and excessive eutrophication.
Key words: waterbodies, eutrophication, plant cover, protected plant species.
1. Introduction
The number of people living on Earth and
their aspirations are nowadays the main drive
for exploitation of most of the living ecosystems.
Huge economic progress means not only improved life quality but also higher human pressure
on the environment and its global degradation.
184
D. Michalska-Hejduk et al.
According to Meybeck (2003) less than 17% of
the present-day continental surface can be considered without direct human footprint. Hobbs
et al. (2006) claim that human activity is much
greater than that of the nature. That is why the
current period is called anthropocene by many
scientists (Crutzen 2002; Meybeck 2002; Meybeck, Vörösmarty 2005; Zalewski 2007).
With regard to increasing global degradation of the environment, human impact on the
ecosystems is manifested in two ways. One is
the emission of toxic substances as a result of
increasing use of energy, matter and chemical
substances and the other is the degradation of
water and bioelements circulation in the environment that determine the richness/productivity of water ecosystems. It is the latter form of
human impact that is not sufficiently recognised
by strategy managers, spatial planners, environmental technicians and most importantly those
responsible for water management.
The relations between hydrologic cycle that
drives ecological systems dynamics and biogeochemical cycles and biocenoses are extremely
complex so it is necessary to combine knowledge
from all scientific fields to develop effective protection and recultivation methods. That is why the
presented comprehensive approach to risk analysis
(Zalewski 2000), which enables the creation of a
complete program of the oxbow lakes protection,
is so important.
Under Annex 1 to Council Directive 92/43/
EEC oxbow lakes are protected natural habitats
(code 3150). They are necessary to maintain river valleys biodiversity and are a habitat to many
precious, protected and disappearing species of
vascular plants such as Salvinia natans and Trapa natans. Numerous localities of Salvinia natans
have been recorded in the Sandomierz Basin (Radomski 1927; Dubiel 1973, 1989; Karczmarz, Piórecki 1977; Krzaczek, Krzaczek 1983; MichalskaHejduk, Kopeć 2002). However, the other species
i.e. Trapa natans is much more rare (Piórecki
1965, 1975). Natural eutrophication, greatly accelerated by human activity, results in rapid decrease in the number of oxbow lakes and species
localities (Dzwonko, Płazińska 1977; MacickaPawlik, Wilczyńska 1996).
Basing on the records on the occurrence
of the aforementioned species, the authors decided to undertake further studies in the San
River oxbow lakes to analyse the flora and the
impact of abiotic factors on their diversity. The
oxbow lakes analysed differ as regards shoreline
development, surrounding biotopes and extent
of pressure from human activities. The aim of
the studies was to determine which of the above
factors most greatly influences species richness
and diversity of the oxbow lakes flora, and also
to examine the relationship between biodiversity
and the presence of Salvinia natans.
2. Materials and methods
Description of the study area
and localities
Fig. 1. Locality of investigated oxbow lakes.
According to the physical geographical division of Poland (Kondracki 1994), the San River
oxbow lakes of the Zbydniów area are located in
the Northern Subcarpathian subprovince (512),
Sandomierz Basin macroregion (512.4–5) and the
Lower San Valley mesoregion (512.46).
Over the years, the lower San changed its course many times because of violent floods. What is
left behind after dynamic and repeated disastrous
floods are old river-beds called “saniska” in Polish. The so-called Stary San (“Old San” in English) is the largest of the river-beds in the lower
course of the river, with its several arms stretched
between the river-bed of today’s San and Łęg
(tributary of the Vistula) (Prarat 2009). Despite
flood embankments that helped prevent floods
which were quite frequent between the 17th and
19th century, the area is still flooded from time to
time e.g. in 2001 (Sobowiec 2005) and in 2010.
The studies were conducted in five oxbow lakes
located in the lower section of the river, near its
confluence with the Vistula River. Four out of five
oxbow lakes are connected by the Stary San River
Human pressure on water properties and flora: San River oxbow lakes
185
Table I. Physical and chemical properties, trophy and human pressure level of investigated oxbow lakes.
Oxbow lake No.
Parameter
Surface area [ha]
Number of localities
pH
temperature [ºC]
oxygen [mg·dm-3]
conductivity [S]
ammonia [g·dm-3]
P-P04[g·dm-3]
TP[g·dm-3]
N-NO3 [mg·dm-3]
WAP
MTR
1
2
3
4
6
3.25
8
7.25
21.99
2.52
423.13
40.13
66.1
120.59
0.2
5.37
32.05
3.15
8
7.37
21.06
4.21
392.13
34.03
13.24
152.94
0.1
5.71
27.84
6.30
11
7.57
19.93
3.06
390.5
62.57
51.91
188.82
1.03
5.47
23.84
1.28
5
7.59
21.22
4.89
498.6
41.65
13.82
69.61
1.12
3.65
24.60
1.78
7
7.65
18.41
1.13
666.43
137.93
111.4
429.71
0.85
7.27
18.26
(which is the right tributary of the San River). One
of the oxbow lakes is not directly connected with
the San River. The oxbow lakes are located on the
right-hand side of the Stalowa Wola–Sandomierz
road, to the north-east from Zbydniów village as
far as Berdechów (Fig. 1). Presently, the oxbow
lakes discussed are subject to protection under the
Special Protection Area Natura 2000 - Lower San
Valley (PLH180020). Individual lakes’ areas range from 1.28 up to 6.3 ha (Table I).
Sampling and analyses
Analyses were conducted during vegetation
seasons 2000 and 2004-2005. Five water bodies
differing as regards the extent of pressure from human activities and the resulting extent of modification to the flora and trophic status were selected
for analysis. Five to eleven phytosociological relevés of 4 to 16 m2 were recorded with the use of
the Braun-Blanquet method in limnetic zone and
littoral zone in each water body. The obtained floristic data was averaged for each of the oxbow lakes. A total of 39 phytosociological relevés of the
analysed area were recorded. One floristic test was
carried out in each of the oxbow lakes.
Additionally, water was sampled at the same
points. Integrated water samples were taken using
a 5 dm3 sampler from each meter of the entire water column. During the sampling water temperature,
oxygen concentration, pH and conductivity were
measured. Water for chemical analyses (dissolved
forms) was filtered through Whatman GF/F (0.45
micron) filters and then analyzed in the laboratory.
Phosphate phosphorus (P-PO4) was measured by
the ascorbic acid method (Golterman et al. 1978).
Nitrate nitrogen (N-NO3) was determined using
the cadmium reduction method (method no. 8039;
HACH 1997) and ammonia nitrogen (N-NH4) was
determined using the phenate method (Golterman
et al. 1978). Non-filtered water samples for total
phosphorus (TP) analysis were digested with the
addition of Oxisolve Merck reagent with Merck
MV 500 Microwave Digestion System and determined by the ascorbic acid method (Golterman et al.
1978). Absorbance was measured with a Miton Roy
Genesis 2 spectrophotometer. Results are given with
the accuracy of ±2 μg dm-3. Physical and chemical
properties of water were examined during the entire
vegetation period (i.e. from March until November).
Water samples were taken from each of the oxbow
lakes three times, and the results were averaged.
For each of the water bodies a number of floristic indices were calculated and then correlated
with physical and chemical parameters of water,
namely: Shannon diversity index (Odum 1982),
cover index Wp (Pawłowski 1977) and Mean
Trophic Rank (MTR) (Holmes et al. 1999). MTR
has been developed in the UK and it is one of the
methods to assess eutrophication of European river waters (Schneider 2007). In the present article
the index is used to assess water eutrophication
and to compare individual oxbow lakes.
Based on orthophotomaps from 2003 and
using ArcGIS 9.3, human modification score
(WAP) was calculated for the immediate surroundings of the oxbow lake (50-meter wide buffer
strip) (Plit 1996). Seven types of anthropization
were identified (valuation classes – from 1 for natural vegetation to 20 for totally transformed i.e.
built-up areas).
The obtained results were then analysed by
two non-parametric tests. Spearman’s rank correlation coefficient was used to determine the correlation between the values of floristic indices and
physical and chemical parameters of water. Kruskal-Wallis test and modified Tukey’s test for nonparametric analysis were used as post-hoc tests to
compare the values of individual floristic indices
and physical and chemical properties of water in
D. Michalska-Hejduk et al.
186
individual oxbow lakes. All of the statistical analyses were performed using STATISTICA 6.0
(StatSoft 2003).
3. Results
The number of macrophyte species in limnetic zone and littoral zone in individual oxbow lakes
ranges from 40 to 62. Salvinia natans and Nuphar
luteum were recorded in all water bodies, and Trapa natans was recorded in only one (oxbow lake
No. 3) (it is not certain however that the locality is
natural). It should be stressed that the oxbow lake
observed to be most abundant in species (2) was
at the same time characterized by one of the lowest values of group cover index (Wp), reflecting
macrophyte biomass and one of the lowest values
of biodiversity taken by Shannon index (H’) (Table II). The above stems from the fact that despite
Table II. Plant cover parameters of investigated oxbow lakes.
Oxbow lake No.
1
2
3
4
6
1.74
0.79
8
43
13793.75
1.67
0.78
4
62
10631.25
1.94
0.77
7
52
15609.09
1.78
0.74
3
40
15990.00
1.09
0.50
2
40
10057.14
1343.75
593.75
593.75
-
2468.75
62.50
475.00
218.75
2890.91
936.36
977.27
95.45
-
3110.00
750
-
2214.29
150.00
250.00
-
Parameter
Shannon index H'
Evenness index e
Number of plant communities
Number of species in oxbow lake
Group Wp for hydrophytes
Special care species (Wp)
Nuphar lutea (czCh)
Nymphaea alba (czCh)
Salvinia natans (V, Ch, KB)
Trapa natans (V, Ch, KB)
Utricularia vulgaris (Ch)
Dominant species (Wp)
Alopecurus geniculatus
281.3
437.5
136.4
50.0
250.0
Bidens tripartitus
62.5
781.3
409.1
52.5
250.0
Carex acutiformis
1156.3
1187.5
500.0
25.0
71.4
Carex appropinquata
62.5
62.5
45.5
50.0
535.7
Glyceria maxima
6.3
1062.5
777.3
87.5
2835.7
Hydrocharis morsus-ranae
968.8
1187.5
1731.8
412.5
321.4
Lemna minor
150.0
343.8
559.1
120.0
1235.7
Lycopus europaeus
287.5
125.0
363.6
50.0
142.9
Salix cinerea
281.3
68.8
136.4
27.5
71.4
Ceratophyllum demersum
1787.5
527.3
1050.0
392.9
Cicuta virosa
343.8
95.5
90.0
214.3
Galium palustre
62.5
187.5
250.0
321.4
Lemna trisulca
2443.8
187.5
1604.5
637.5
Lythrum salicaria
287.5
125.0
100.0
50.0
Phragmites australis
1250.0
568.8
636.4
142.9
Spirodela polyrhiza
287.5
104.5
117.5
214.3
Sium latifolium
218.8
568.8
181.8
Sparganium emersum
281.3
163.6
250.0
Sparganium erectum
281.3
545.5
25.0
Stratiotes aloides
631.3
225.0
350.0
Eleocharis palustris
468.8
90.9
Myriophyllum verticillatum
1218.8
1690.9
Explanations: czCh – partially protected, Ch – protected (Rozporzdzenia...2004), V –
vulnerable (Zarzycki, Szelg 2006), KB – protected species of the European flora
(Convention...1979)
Human pressure on water properties and flora: San River oxbow lakes
nitrate nitogen
cover index of macrophytes
1,2
18000
14000
0,8
12000
10000
0,6
8000
0,4
6000
cover index [Wp]
nitrate nitrogen [mg.dm-3]
16000
1
4000
0,2
2000
0
0
1
2
3
oxbow lake number
4
6
Fig. 2. Relationship between nitrate nitrogen and cover
index (Wp) of macrophytes.
cover inex (Wp) of macrophytes
18000
MTR
16000
35
30
14000
10000
20
8000
15
MTR
cover index [Wp]
25
12000
6000
10
4000
5
2000
0
0
1
2
3
4
6
oxbow lake number
Fig. 3. Relationship between cover index (Wp) of macrophytes and Mean Trophic Rank (MTR).
8
WAP
1200
Salvinia natans cover index
7
1000
800
WAP
5
4
600
3
400
cover index [Wp]
6
187
the oxbow lake was inhabited by a large number
of species, their abundance (expressed as cover
value) was low compared to other water bodies.
This is probably due to low nutrient concentration
(Table I) - most of all nitrogen (both as nitrates
and ammonia which would oxidize to nitrate at
high oxygen concentration (4.21 mg dm-3). Low
concentration of plant available nitrogen seems
to be confirmed by the presence of carnivorous
species of Utricularia vulgaris that was recorded
in this water body only.
Clear correlation has been demonstrated between macrophyte abundance (Wp) and the aqueous nitrate concentration (Fig. 2), yet phosphorus
concentration (both phosphates and total phosphorus) was not directly related with the abundance.
Lack of direct relation between the water body
trophic status (MTR) and macrophyte abundance
is also reflected in Fig. 3. Habitat parameters did
not affect macrophyte distribution in individual
oxbow lakes or the presence of protected species.
Slight changes of WAP do not result in variations
in the presence of Salvinia natans. It is considerable anthropization (human modification score WAP)
that leads to decreased abundance of macrophyte
(Fig. 4 and Fig. 5) and biodiversity, which is clearly
visible in the case of oxbow lake No. 6 (Fig. 4).
The correlation between oxbow lake surrounding area use (WAP) and nutrient concentration is clearly visible, mostly as regards ammonia concentration (Fig. 6). When it comes to the
correlation between floristic indices and habitat
parameters, the only significant (negative) correlation observed is that between water pH and its
conductivity and trophic status (MTR) (Table III,
Fig. 7, 8, 9).
2
200
1
0
1
2
3
4
6
oxbow lake number
Fig. 4. Relationship between human modification score
(WAP) and Salvinia natas cover index.
cover index (Wp) of macrophytes
18000
WAP
Results of chemical analyses show that all
analyzed oxbow lakes waters of conductivity ranging from 390 to 666 μS can be classified as ion
8
8
7
7
6
6
0,12
5
5
0,1
4
0,08
3
3
0,06
2
2
0,04
2000
1
1
0,02
0
0
0
0,16
WAP
0,14
10000
4
8000
6000
4000
1
2
3
4
6
oxbow lake number
Fig. 5. Relationship between human modification score
(WAP) and cover index (Wp) of macrophytes.
WAP
12000
WAP
ammonia nitrogen
14000
ammonia nitrogen [mg.dm-3 ]
16000
cover index [Wp]
5. Discussion
0
0
1
2
3
4
6
oxbow lake number
Fig. 6. Relationship between human modification score
(WAP) and ammonia nitrogen.
D. Michalska-Hejduk et al.
188
Table III. Sperman’s rang correlation and confidence level (grey - significant corelation, p-value<0.05).
MTR Shannon evenness number
Index
index
of species
pH
temp.
oxygen
conductivity
MTR
1.00
0.47
0.53
0.45
-0.40
0.28
-0.02
-0.42
Shannon Index
0.47
1.00
0.82
0.96
-0.07
0.11
0.13
-0.26
evenness index
0.53
0.82
1.00
0.69
-0.10
0.14
0.14
-0.30
number of species
0.45
0.96
0.69
1.00
-0.04
0.09
0.11
-0.21
pH
-0.40
-0.07
-0.10
-0.04
1.00
-0.09
0.25
0.15
temperature
0.28
0.11
0.14
0.09
-0.09
1.00
0.61
0.01
oxygen
-0.02
0.13
0.14
0.11
0.25
0.61
1.00
-0.09
conductivity
-0.42
-0.26
-0.30
-0.21
0.15
0.01
-0.09
1.00
Fig. 7. Comparison of water conductivity in investigated oxbow lakes.
rich. Analyses of total phosphorus concentration
which is termed the main eutrophication factor
by many researchers (Wojciechowski, Zykubek
1999; Chełmicki 2002), demonstrate that the analyzed water bodies, with the exception of oxbow
lake No. 4, are hypertrophic (Kajak 1979). Similar
results, both as regards conductivity and total phosphorus were obtained in the Bug River oxbow
lakes (Urban, Wójciak 2006). Such comparison
cannot be made with respect to nitrogen concentration due to methodology differences (in the San
River oxbow lakes ammonia nitrogen and nitrate
nitrogen were tested, while in the Bug River oxbow lakes it was total nitrogen). In the analysed
oxbow lakes the presence of Salvinia natans is
not related to water contamination level. A similar lack of correlation between the presence of this
species or communities with the species present
(Spirodelo-Salvinietum) and chemical properties
of water (mostly nitrogen, ammonia and phosphorus concentration) was also observed in other parts
of Europe (Kočič et al. 2008).
River and lake ecosystems occupy the lowest parts of the landscape. Therefore any human
activities in the river basin/catchment and the re-
Fig. 8. Comparison of Mean Trophic Rank (MTR) in
investigated oxbow lakes.
Fig. 9. Comparison of water temperature in investigated oxbow lakes.
sulting gravitational transport of material and pollution with water affect aquatic ecosystems and
organisms living there through hydrologic cycle
(Kucharski et al. 2004).
Each of the presented oxbow lakes of the San
River has been transformed by human activities to
a different degree. Physical and chemical analyses
Human pressure on water properties and flora: San River oxbow lakes
provide reliable information about water pollution. Moreover, they provide the background for
the interpretation of biological and biochemical
processes in aquatic ecosystems. At the same time
they reflect the method of micro-catchment use.
According to Yunus and Nakagoshi (2004) catchments with less human activity have less sources of organic and inorganic pollutants from both
point and non-point pollution sources. The results
obtained show that the highest concentration of
nutrients (P-PO4 and N-NH4) was recorded in
samples obtained from oxbow lake No. 6 which is
characterized by the highest human modification
score (WAP). As mineral nitrogen is more water
soluble than phosphorus (Kajak 2001) in total nutrient load in oxbow lake No. 6, it may be assumed
that nitrogen dominates in non-point sources (e.g.
farm-field runoff), and phosphorus in point sources (e.g. illegal waste discharge). Relatively low
concentration of the above nutrients was recorded
in oxbow lake No. 4 whose WAP is the lowest.
Dissolved Oxygen (DO) is an important component of surface water for self-purification processes and the maintenance of aquatic organisms. This
parameter is more reactive and variable in the shortterm than most chemical constituents of water.
Mean oxygen concentration is the lowest in
oxbow lake No. 6, which is probably due to input of sewage that is rich in organic matter. The
highest DO was observed in oxbow lake No. 4.
The effect of micro-catchment use on the
quality of surface water can also be considered by
comparing oxbow lakes No. 1 and 3 whose WAP
scores are similar, whereas water physical and chemical properties are different. A better developed
ecotone around the oxbow lake may be the reason
why the concentration of nitrate nitrogen, ammonia nitrate and total phosphorus in oxbow lake No.
3 is higher despite the fact that the area is bigger.
Biocoenoses and in particular plants are an important stabilizing factor as regards water amount and
quality as well as dynamics of biogeochemical
cycling (Baird, Wilby 1999; Zalewski et al. 2003).
Plants are the first level in ecosystem structure and
therefore they control the flow of energy and nutrients circulation in the environment (RodriguezIturbe 2000). Farming fields, arable land and phyocoenoses must therefore be created in such a way
that nutrient flows from agricultural catchments to
aquatic ecosystems are limited.
According to Ryszkowski (1992) proper
agrotechnical measures, development of mosaic catchments and buffer zones can help to limit transfer of nutrients to waters by several or
even several tens times. The amount of nutrients
that can be absorbed and accumulated by plants
depends mostly on plant species, its biology and
abiotic and biotic factors (Ozimek, Renman 1996).
It is important because analyses of oxbow lakes
maps demonstrate that oxbow lakes are surroun-
189
ded by many farming fields which are a potential
source of nutrients. According to HELCOM Report (HELCOM 2007) 60% of phosporus load is
emitted from non-point source pollution and 25%
is emitted from point sources. The above value
compared to nature value (15% total phosphorus
load P) shows that it is necessary to undertake
actions aimed at reducing non-point source pollution. According to data and calculations presented
by Sapek (2008) 5 kg P ha-1 are accumulated in the
soil every year, which means that the soil is enriched by over 100 kg P ha-1 over one generation.
Such a huge amount of phosphorus means that
what we face is a potential “ecological bomb” as
water resources may be spoiled by uncontrollable
eutrophication.
Conclusions
• Oxbow lake area use affects water nutrient concentration.
• There is no direct correlation between macrophyte distribution or presence of threatened
and protected species and environmental parameters.
• It is only considerable human impact that results in macrophyte decrease (expressed as cover index and biodiversity index).
• There is a significant (negative) correlation between habitat parameters such as water pH and
conductivity and MTR (its value decreases proportionally to the habitat abundance).
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