Assessment of the Water and Habitat Quality of the Greek Part of StrymonasRiver (Macedonia, Hellas), in Accordance with the EU Water Framework Directive
ILIA G.*, IOANNOU A.*, PATSIA A.*, DAVIS M.**, CHATZINIKOLAOU Y.*, LAZARIDOU M.*
*Department of Zoology, School of Biology, Facylty of Sciences, AristotleUniversity of Thessaloniki, 54006
**Management Body of Kerkini Wetland, Kerkini, GR 62055, Kato Poroia,
GREECE
Abstract: -In the present study, the water quality of the greek part of Strymonas river (North Greece) was assessed using physicochemical and hydromorphological parameters and benthic macroinvertebrates. Statistical analyses (FUZZY, CCA and SIMPER analyses) were performed and the Hellenic Assessment System (HAS) was used in order to classify the sites to five levels according to the Water Framework Directive (WFD) 2000/60 E.C..None of the sampling sites appeared to be of high or bad quality according to the HAS. During the low flow season (December 2003) the sampling sites upstream the artificial lake Kerkini, had a better quality than the high flow season (May 2004) sites, while downstream the water quality was almostthe same in both seasons (high flow during December and low flow during May, due to dam regulation). For this integrated approach hydromorphological, chemical, and biological parameters were used according to the WFD 2000/60 EC.
Key-Words: Biomonitoring, Water Quality, Benthic macroinvertebrates, River Habitat Survey
1
1 Introduction
Rivers are important pathways for the flow of energy, matter and organisms. A wide range of human activities at a catchment area may lead to deterioration of the water quality.To assess pollution events the synthesis of benthic macroinvertebrate communities are particularly helpful [1].According to the ‘’Water Framework Directive’’ (2000/60) E.C. [2], all member states are obliged to establish national monitoring systems and determine the ‘ecological status’ of water quality, referring to the biological, hydromorphological and physicochemical elements. Biomonitoring is already widespread since it provides information on the water quality and ecology[3]. Biomonitoring includes both sublethal changes at the cellular or tissue leveland changes in community structure. The use of changes in community structure commonly involves benthic macroinvertebrates, since they are considered to be the most appropriate biotic indicators of water quality in EU countries, including Greece [3]. Additionally, the assessment of the river habitat quality is essential, sinceit may affect the structure andcomposition of the resident benthic communities [4]. In the present study, the water and habitat quality of Strymonas river was estimated using all the above parameters.
2 Materials and methods
2.1 Studyarea
Strymonas river is a transboundary river originating from Bulgaria and discharging, into the Stymonikos gulf (Aegean Sea, Greece). The Greek part of Strymonas river is situated in the prefecture of Serres (Macedonia) and has a length of 114 km (Fig. 1). Until 1932, intheplaceofStrymonas at the area of the Serres plain, there was the natural lake of Achinos. In order to drain the lake, in 1932 there was constructed a dam at the area Lithotopos, due to which the artificial lakeKerkini was created. Kerkinilakehasalengthof 24 km.Form the Bulgarian borders, Strymonas river runs 20 km upstream the lake and 70 km downstream. The river receives untreated domestic effluentsfrom many semi-urban settlements, treated industrial effluentsand surface run-off from agricultural land.
1
Fig. 1: Map of the study area showing Strymonas river and the sampling sites
Point sources of pollution are scattered along the whole length of the river (landfills, quarrying), whereas downstream Kerkini lake intensive agricultural activities take place.
2.2 Methodology
Samples of benthic macroinvertebrates were taken seasonally, during December 2003 and
May 2004, at nineteen sampling stations (sites) (Fig.1),of which the first 5 were situated upstream of the artificial lakeKerkini, while the rest were situated downstream.Two of the upstream sites belonged to tributaries, one was taken at the Hellenic-Bulgarian borders and two a few kilometers upstream the lakeKerkini. The first downstream sampling site was taken just after the dam at Lithotopos, whereas the rest were situated downstream Lithotopos along the river, in relation to point and non-point sources of pollution.
One sample of benthic macroinvertebrates was taken at each site with the 3-minute kick-sweep method [5], using a standard pond net (surface 575 cm2, mesh size 900μm, depth 27.5 cm).An effort was made to cover all the different habitats present in the sampling site proportionally. The samples were placed in plastic bottles and preserved in 4% formaldehyde. On return to the laboratory, the animals were sorted using a 0.5 mm mesh sieve. Identification of the invertebrates was made to the lowest possible taxonomic level.
Surface water samples were taken from thesame sampling stations, using polypropylene bottles. The samples were analyzed in the laboratory according to APHA methods [6]. The following parameters were examined: temperature, conductivity, total suspended solids (TSS), pH and dissolved oxygen (in situ measurements using electrode probes WTW type), biochemical oxygen demand (BOD5), nitrate, nitrite, ammonia, and phosphate.Substrate composition was also estimated visually by percentage occurrence of the following particle categories using the Wentworth scale: clay/silt (< 0.0625 mm), sand (0.0625-2 mm), gravel (2-4 mm), pebbles (4-16 mm), cobbles (16-256 mm), boulders (> 256 mm).At each site, instream vegetation cover was estimated visually by percentage occurrence.
2.3 Hellenic Assessment System
The Hellenic Assessment System [7], applied to the macroinvertebrate data, is a biotic index, which was created according to the Iberian Index BMWP(after the addition of a number of families and the reassessment of all the family scores according to the specific conditions of Hellenic rivers) and it takes into consideration the relative abundance of the taxa found.
2.4 Statistical analyses
SIMPER analysis of the PRIMER statistical package was used in order to explain which families of macroinvertebrates contribute to the similarity or dissimilarity between the upstream and downstream stations and also between the stations seasonally.
Canonical Correspondence Analysis (CCA) was performed to determine relationships between environmental variables and the respective biotic components (abundances of taxa). Monte Carlopermutationtestwasusedto test the significance of every variable contributing to the model (p>0.05). CCA is a non-linear technique used to detect relationships between species and external variables.
2.5 Habitat Quality
The recording of the physical structureof each sitewas conductedin April 2005.Therecording of the physical structure was based on the implementation of the River Habitat Survey [8] at each site on standard 500m length river stretch.It involved a systematic collection of features associated with the physical structure of its watercourse recorded at 10 spot-checks in 50 m intervals. Such features were substrate, flow, vegetation types, erosion and deposition elements in the channel, morphological and vegetation structure on the banks, and land use in the adjacent river corridor. Modifications to channel and bank structure were also recorded. Data were computerized with the help of RHS 3.2 database. The habitat quality of each site was assessed by using the Habitat Quality Assessment Score (HQA), which is based on the diversity of the physical features recorded and mentioned above. Artificial modification was estimated by a second scoring system, the Habitat Modification Score (HMS) that gives ‘penalty’ points to different types of alteration. The sites were divided in five categories according to their HMS scores (Table 1).
Table 1: Overview of the how the Habitat Modification Categories are derived from the Habitat Modification Scores.
Habitat Modification Score (HMS) / Habitat Modification Categories0…2 / Semi-natural
3…8 / Predominantly unmodified
9…20 / Obviously unmodified
21…44 / Significantly modified
45… / Severely modified
3 Results and Discussion
3.1 Physicochemical parameters
Temperature varied ranging from 5.5 oC (Station 7 in December) to 24.2 (Station 17 in May) and pH ranged between 7.55 (Station 1 in December) and 8.54 (Station 6 in May) without significant changes between the sampling points (Table 2). The highest value of conductivity was recorded at Station 2 in December (645 μs/cm) and the lowest at Station 3 in May (190μs/cm). The range of total suspended solids was from 0 mg/l (Stations 2-7, 13 in December and Stations 1, 6, 7 in May) to 36.4 mg/l (Station 18 in May).
The nitrate-N (NO3—N) concentration ranged between 0 mg/land 1.017 mg/l. Ammonia–N(NH4+-N) fluctuated in low levels between 0 mg/l and 0.255 mg/l. Higher values of nitrite-N(NO2—N) were observed in May in all but one stations, and in all samples phosphate(PO4-3-P) concentrations were lower than 500 μg/l, which is considered as the lower limit for river waters to pose a risk of eutrophication [9]. However, the classification of macroinvertebrates communities in CCA is also due to the PO3-concentration. Organic load, as it is expressed by B.O.D5measures, presented higher values in December in most stations (Figure 2).The values of the physicochemical parameters did not exceed the limits that are suggested by the 98/83/EC Directive which concerns water for human consumption
The majority of the sites 5 to 19 (that is one site before the artificial lake Kerkini, from which point after the river was realigned, and the sites below the dam up to the sea)were characterized mostly by a substrate of fine material (silt/clay, sand) in both seasons, whereas in sites 1 to 4, where no artificial alteration has been made to the channel, the substrate is diverse, consisting mainly of coarse material (boulders, cobbles, pebbles, gravel) in both seasons, except for site 3, where in the spring the substrate was found completely changed, consisting mainly of silt/clay. The above difference is depicted in the classification of the sites according to the CCA.
3.2 Benthic macroinvertebrates
Benthic macroinvertebrates are considered to be good indicators of water quality because of their wide sensitivity variation towards contaminants and their relative immobility [3]. Point-pollution sources and diffuse loads of agricultural runoff affect macrobenthos communities and shift community composition from sensitive to tolerant taxa. In the case of Strymonas river, therecorded benthic communities and their abundance reflect human interferences. Sixteen thousandsix hundred and six (16606) animalswere sampled in the 19 sitesduring
1
Table2: Values of Dissolved Oxygen (D.O.), pH, temperature (T), conductivity (Cond.), and Total Suspended Solids (TSS) in Strymonas sites in both seasons (December 2003 and May 2004).
D.O.(mg/l) / pH / T (oC) / Cond (μS/cm) / TSS(mg/l)Dec / May / Dec / May / Dec / May / Dec / May / Dec / May
S1 / 9,7 / 9,14 / 7,55 / 8 / 12,9 / 14,2 / 394 / 323 / 0,3 / 0
S2 / 8,89 / 7,92 / 7,88 / 8,48 / 16,3 / 22,8 / 645 / 402 / 0 / 7,6
S3 / 10,97 / 10,26 / 8,09 / 7,99 / 11,3 / 14 / 436 / 190 / 0 / 11,7
S4 / 9,3 / 10,32 / 7,73 / 8,28 / 10,3 / 14,1 / 442 / 235 / 0 / 7,2
S5 / 10,8 / 10,26 / 8,13 / 8,2 / 8,3 / 20 / 440 / 268 / 0 / 7,8
S6 / 10,91 / 8,62 / 8,31 / 8,54 / 6,7 / 26 / 469 / 349 / 0 / 0
S7 / 11,1 / 4,8 / 7,89 / 7,44 / 5,5 / 22,7 / 563 / 390 / 0 / 0
S8 / 11,38 / 8,08 / 7,95 / 7,91 / 6,1 / 22,8 / 478 / 404 / 0,3 / 3,2
S9 / 10,87 / 8,62 / 7,95 / 8,14 / 6 / 22,7 / 496 / 360 / 0,1 / 2,4
S10 / 12,82 / 7,11 / 8,12 / 7,68 / 6,3 / 21,4 / 451 / 392 / 0,2 / 20,2
S11 / 12,85 / 4,92 / 7,92 / 7,7 / 6,3 / 23,2 / 448 / 449 / 0,2 / 12,5
S12 / 14,23 / 6,01 / 7,87 / 7,74 / 6,2 / 23,1 / 458 / 419 / 2,1 / 3,9
S13 / 9,92 / 6,57 / 7,79 / 8,07 / 8,4 / 21,7 / 452 / 385 / 0 / 4,2
S14 / 10,8 / 5,43 / 7,89 / 7,83 / 8,8 / 23,5 / 450 / 391 / 0,3 / 25,4
S15 / 10,88 / 6,94 / 7,795 / 7,97 / 9,1 / 22,7 / 490 / 423 / 1 / 13,5
S16 / 10,59 / 6,9 / 7,7 / 7,98 / 9,4 / 23,9 / 530 / 345 / 0,3 / 5,9
S17 / 10,5 / 6,98 / 7,57 / 7,9 / 9,5 / 24,2 / 482 / 427 / 3,6 / 24,9
S18 / 9,64 / 6,42 / 7,7 / 7,8 / 9,3 / 22,5 / 534 / 439 / 0,1 / 36,4
S19 / 10,5 / 7,58 / 7,67 / 7,96 / 9,4 / 21,5 / 554 / 458 / 0,4 / 5,6
Fig. 2: The concentration of nutrients and BOD5in the water column in both high and low flow season
1
December 2003 and May 2004 and sixty-six (66) benthic macroinvertebrates taxa were identified during the present study. The dominant taxa were: Gammaridae (Amphipoda), Chironomidae, Simuliidae (Diptera), Lymnaeidae (Gastropoda), Baetidae, Heptageniidae, Caenidae (Ephemeroptera), Hydropsychidae (Trichoptera), Oligochaeta, and Elmidae (Coleoptera). Plecoptera, which are the most sensitive to pollution insects [1], presented low abundances at all sites. Trichoptera and Ephemeroptera were found in high percentages at the stations upstream the lake, and also at the stations 10 13, and 20, probably due to the better water quality of these stations. The latter is depicted in the classification of the upstream to the lake sites by CCA. The most tolerant taxa, such as Gammaridae, Dipteran families and Oligochaeta, were found in almost all stations, but were most abundant at the downstream stations which are classified together in CCA. Moreover, Chironomidae were found to be the most abundant family at the most impacted site (number 6, immediately after the dam). Finally, the first four sites after the dam show a low species diversity, a fact that is reversed in the next stations, probably due to the influx of a number of tributaries.
3.3 Biotic Index
Table 3 presents the classification of the sites according to the Hellenic Assessment System (HAS). Upstream the artificial lakeKerkini, the water quality was found better in December (low flow) in all stations, except for station 5, where the water quality ameliorated in May (high season). The water quality deterioration of the first four stations in spring, could be due to the increase of the agricultural run-off during that season in the area, whereas the improvement of the quality at station 5 (around 10 km) could be due to a self-purification process. Downstream the lake in May, after the closure of the dam, the situation varied: in 8 stations the quality did not change, in 4 stations it deteriorated, and in 2 stations it was ameliorated. The site with the worst water quality in both seasons was number 6, immediately after the dam, and the sites with the best water quality were the 10, 13, and 18; the two last situated immediately after the inflow of two tributaries whereas number 10 was some kilometers after a tributary. This quality in the downstream sites was related to water abstraction, quarrying, landfills, or/and many concrete bridge. However, many tributaries enriched the river (stations 10, 11, 13, 14, and 18 are situated after the influx of such tributaries and probably for that reason they had a good quality at least in the high-flow season).
1
Table 3: Values of the Hellenic Assessment System applied to Strymonas river in both seasons (December 2003 and May 2004). G: Good, M: Moderate, P: Poor
Stations / S1 / S2 / S3 / S4 / S5 / S6 / S7 / S8 / S9 / S10 / S11 / S12 / S13 / S14 / S15 / S16 / S17 / S18 / S19Dec2003 / Score / 3.5 / 4 / 3 / 3 / 3 / 2 / 3 / 2.5 / 3 / 4 / 2.5 / 3.5 / 3.5 / 3.5 / 3 / 3 / 3.5 / 3.5 / 2.5
Water quality / G / G / M / M / M / P / M / M / M / G / M / G / G / G / M / M / G / G / M
May 2004 / Score / 2.5 / 3 / 2 / 2 / 4 / 2 / 3.5 / 2 / 3 / 4 / 3.5 / 2.5 / 3.5 / 2.5 / 3 / 2.5 / 2 / 3.5 / 2.5
Water quality / M / M / P / P / G / P / G / P / M / G / G / M / G / M / M / M / P / G / M
1
3.4 Statistical analyses
According to the Simper analysis of PRIMER (the abundance data were transformed into log (x+1)), during winter, when the dam stays open, the similarity of the stations is 33%, whereas in spring, when the dam closes, the similarity decreases to 17% showing the negative impact of the dam in regard to the synthesis of the macrobenthos [10]. Moreover, the dissimilarity between the upstream and the downstream stations in both seasons washigh (66%).
Canonical Correspondence analysis showed that the ordination of the stations was due mainly to the substrate (gravel and mud) (axis I) and the chemical quality (phosphates) (axis II) (Figure 3).
Fig.3:The output of the CCA analysis (CANOCO) between the environmental variables and the benthic macroinvertebrates
3.5 River Habitat Survey
The vegetation structure of the riparian zone was of high complexity consisted of broadleaved and mixed woodland. Sites 5, 6, and 15, had the highest HMS values (Table 4). Reinforcements, embankments and bridge construction were the principal modifying factors while in site 6 the basic
feature of artificial influence was the dam of artificial Kerkini lake.
The Habitat Quality Score was ranged from 14 to 52 with site 5 having the lowest score due to disruption of the riparian zone because of the presence of a bridge. Generally, the HQA scores imply that the diversity of physical features are due to high quality channel and bank vegetation.
However, in order to more accurately assess the overall habitats quality of Strymonas river it would be necessary to conduct a more extensive survey at a least 33% of the total river length.
1
Table 4: Habitat Quality Assessment (HQA) and Habitat Modification (HMS) scores at the 19 sites of Strymonas river
Site / S1 / S2 / S3 / S4 / S5 / S6 / S7 / S8 / S9 / S10 / S11 / S12 / S13 / S14 / S15 / S16 / S17 / S18 / S19HMS / 0 / 2 / 4 / 20 / 23 / 45 / 2 / 10 / 1 / 3 / 1 / 9 / 1 / 2 / 23 / 12 / 13 / 2 / 12
HQA / 31 / 52 / 42 / 43 / 14 / 34 / 41 / 49 / 40 / 36 / 35 / 46 / 40 / 43 / 43 / 37 / 40 / 33 / 38
1
References:
[1] Hynes, H.B.N., The Ecology of Running waters, University Press,Liverpool 1970.
[2] Directive 2000/60 ECof the European Parliament and of the Council of 23 October 2000establishing a framework for Community action in the field of water policy. Official Journal L327, 22 Dec 2000
[3] Karr, J. R., Chu, E. W. Restoring life in running Waters: Better Biological Monitoring, Island press, Washington, D.C., 1999.
[4] Maddock, I., The importance of physical habitat assessment for evaluating river health,Freshwater Biology, Vol. 41, 1999, pp373-391.
[5] Armitage, P.D., Moss, J.F., Wright, J.F., Furse, M.T., The performance of a new biological water quality score system based on macroinvertebrates over a wide range of unpolluted running water sites,Water Research 17, 1983, pp 333-347.
[6] APHA: Standard Methods for the Examination of Water and Wastewater, 16th Edition, American Public Health Association, New York, 1985.
[7] Artemiadou V, Lazaridou M. (in press). Evaluation Score and Interpretation index for the ecological quality of running waters in Central and Northern Hellas. Environmental Monitoring and Assessment.
[8] Raven, P.J., Fox, P., Everard, M., Holmes, N.T.H., Dawson, F.H., River Habitat Survey: a new system for classifying rivers according to their habitat quality,in: Boon, P. J., Howell, D. L (Eds.):Freshwater quality: Defining the Indefinable?The Stationery Office, Edinburgh, 1997, pp 215-234.
[9] Mourkidis, G., Papadopoulou, E., Katsanos, A., Kakanis, P. Elemental analysis of water and sediments, Part 4: Aliakmon river,Greece, Chemistry and Ecology,4, 1990, pp. 65-83.
[10] Giller, P.S., Malmqvist, B., The Biology of Streams and Rivers, OxfordUniversity Press, 2000
1