11th INTERNATIONAL CONGRESS ON THE ZOOGEOGRAPHY AND ECOLOGY OF GREECE AND ADJACENT REGIONS
A fish-based index for assessing the biotic integrity of the Evrotas River (Greece) D.
Kommatas1,
N.
Squalius keadicus
Tropidophoxinellus spartiaticus
L. Vardakas1,2,*, V. Tachos3, S. Zogaris1**, Y. Chatzinikolaou1, N. Skoulikidis1, D. Koutsoubas2 & A.N. Economou1
Koutsikos1,
1
3
Hellenic Centre of Marine Research, Institute of Inland Waters 2 University of the Aegean, Department of Marine Sciences Ministry of Rural Development and Food, General Directorate of Animal Production
Correspondence: *
[email protected] **
[email protected]
Introduction Indices of Biotic Integrity (IBI’s) are practical tools for assessing the health of aquatic ecosystems by scoring sites from degraded to un-impacted, based on the condition of biotic communities [1, 2]. Based on specific “signals” from the attributes of a standardized fish sample it should be possible to asses the relative condition of the river’s biotic integrity.
Aim of the study To develop an IBI based on fish assemblages for the Evrotas River.
Fig.3: Responses of particular metrics to site degradation. The three graphs on the left show correlations among specific fish-size metric (Y-axis) plotted against a five-scaled gradient of site degradation (1=Bad,5=High). This metric shows a positive response to specific degradation types. The fourth graph (at right) plots the sites based on their total fish-based IBI scores relative to the relative degradation of each site (anthropogenic pressure score is the summed mean value of hydrological regime alteration, habitat alteration and riparian woodland integrity alteration at each site). Sites are numbered as in the map below (Fig 5).
Study area The Evrotas River (Fig. 1) is a mid-altitude river with a catchment area of 2017 km2. Due to the overexploitation of water resources for irrigation, many river reaches have become “artificially intermittent” during the summer period.
The most acute response of ichthyological metrics was to hydrological regime alteration. The fish size-class metric was also responsive to degradation of other river features also (Fig. 3). Eight icthyological metrics were devised and integrated within the preliminary multimetric index. The index expresses the quantitative data of the fish sample results in a five-scale assessment (i.e biotic integrity assessment ranged from “high” to “bad”) (Table 1). Table 1: The preliminary fish-based IBI for the main-stem of the Evrotas River. Each metric listed on the left has proposed reference condition values under the “High” condition; these differ with respect to the three river types (A, B,C). Some metrics are not used in some river types. The proposed quantitative values at each quality status gives the score to the site’s sample (High=5, Moderate= 3, Low=1). Fig.1: Elevation model of the Evrotas River Basin in the Southeastern Peloponnese.
Ichthyological surveys were conducted using standardized electrofishing methods at 66 sites in high and low flow periods during 2007 and 2008 (for details see [3]). Remarkable seasonal flow fluctuations can be observed on an annual basis; therefore, fish-based IBI’s should be applied only during the summer period when the flow is limited and fish populations respond accutely to degraded environmental conditions.
Ecological Status
Range
High
4,2-5
Good
3,4-4,2
Moderate
2,6-3,4
Index development included the following key steps:
Poor
2,6-1,8
Classification of biotic river types (river typology) using fish-assemblage cluster analysis Establishment of type-specific reference conditions based on natural history base-lines
Bad
1-1,8
through a detailed understanding of the biota-environment relationships
Identification of appropriate metrics (ichthyological attributes that are known to respond to anthropogenic degradation) for each biotic river type Integration of type-specific metrics within a preliminary multimetric index
Results Three generic biotic river types were identified and mapped (Fig. 2) from the site-based species assemblage cluster analyses (for details see [3]). P.laconicus, S.keadicus, A.anguilla
Fig.2: Schematic diagram showing the pattern of fish assemblage distribution along a longitudinal gradient from the upland springs to the river-mouth. Three biotic river types are identified with constituent species groups. The inset map delineates the three biotic river types along the main-stem of the Evrotas. Each biotic river type has different reference conditions, as investigated here using specific attributes of the fish communities.
The application of the IBI on site-based fish surveys data in 2008 revealed widespread degradation (Fig. 4). More than half of the sites were classified as having “bad” status. These findings are attributed primarily to the over-exploitation of the hydrological regime. Other environmental assessments (chemical, hydromorphological assessments) corroborate the widespread degradation [3].
Conclusions & Discussion
Type A
Springs
The biotic environment of this river is unique and severely threatened. Of the six freshwater fish in the basin, Squalius keadicus is exclusively endemic to the river, while Pelasgus laconicus and Tropidophoxinellus spartiaticus are endemic to the southern Peloponnese. The study confirms that even endemic fish are effective indicators for assessing anthropogenic impacts.
Type B P.laconicus, S.keadicus, T.spartiaticus, A.anguilla
Type C P.laconicus, S.keadicus, T.spartiaticus A.anguilla, S.fluviatillis, G.holbrooki
Mouth
Reference conditions were determined by using data from near-reference sites in combination with historical data and expert judgments based on what the natural expression of the particular ichthyological attributes would be under presumed “natural” conditions at each river type.
Fig. 5: Summer congregation of smallsized fish, primarily Tropidophoxinellus spartiaticus at Site 15 (Sparti Bridge). The relative scarcity of large sized Squalius keadicus (>10 cm) is an attribute that shows that this site is relatively degraded. The site is assessed as having “Moderate” biotic integrity relative to the proposed reference baselines. within this river type (mid EvrotasType B).
The recommendations of Annex V of the Water Framework Directive 2000/60/EC (WFD) The dominant anthropogenic pressures in the study area The responsiveness of metrics to anthropogenic degradation, as shown when the sampled sites were “pre-classified” with respect to specific anthropogenic degradation (without using the fish sampling results) References
Acknowledgments
[1] KARR, J.R & E.W .CHU. 2000. Sustaining living rivers. Hydrobiologia, 422 / 423: 1-14
Special thanks to our colleagues for logistics assistance and support in research: S.Giakoumi, I.Karaouzas, E.Kalogianni, K. Gritzalis, E.Colombari, E.Dimitriou, K.Ntemiri, E. Economou, G. Kapakos and D. Tragaki. This study was funded by a European Life Project entitled “Environmental Technologies for Rural Development (LIFE05ENV/GR/000245EC)”.
[3] SKOULIKIDIS N., ECONOMOU A.N., KARAOUZAS I., VARDAKAS L., GRITZALIS K., ZOGARIS S., DIMITRIOU E., & V. TACHOS. 2008. Hydrological and biogeochemical monitoring in Evrotas Basin. Final Technical Report 1. Institute of Inland Waters, H.C.M.R. Life-Environment: LIFE 05 Final Report (LIFE05ENV/GR/000245EC).. [4] ANGERMEIER P.L & G. DAVIDEANU. 2004. Using fish communities to assess streams in Romania: initial development of an IBI of biotic integrity. Hydrobiologia, 511: 65-78.
Fig.4: Map of the biotic status of the main-stem river segments of the Evrotas based on the preliminary Fish-based IBI. The colours reflect relative level of degradation as in Table 2. (Site 19 is not correctly assessed, see [3]).
Ecological quality assessments based on multimetric indices must necessarily be based on in-depth natural history knowledge the best available monitoring data [4]; in this case our data-set is severely limited and available sampling sites are few due to the river’s small size. This index can be improved by monitoring fish communities and better relating anthropogenic pressures with community and species attributes. Although the index is not yet validated it does assess coarse trends. A refined fish-based IBI should contribute to River Basin Management Planning for preserving and restoring water bodies within this distinctive river basin.
The list of metrics and their quantitative values were derived with respect to the following:
[2] ECONOMOU, A.N., ZOGARIS, S., CHATZINIKOLAOU, Y., TACHOS, V.,GIAKOUMI, S., KOMMATAS, D., KOUTSIKOS, N., VARDAKAS, L., BLASEL, K. & U. DUSSLING. 2007. Development of an ichthyological multimetric index for ecological status assessment of Greek mountain streams and rivers. Technical Report. Hellenic Center for Marine Research – Institute of Inland Waters / Hellenic Ministry for Development. Main Document: 166 pp. Appendices: 189 pp. (In Greek).
Table 2. The ranges of the metric scores when integrated into a single index. The EU’s WFD ecological quality colours are charted in the following map (Fig. 4).
The Fish-based Index is being developed at the Institute of Inland Waters, HCMR, Athens.
