Papers by Nikos Skoulikidis
ABSTRACT Island stream ecosystems, in contrast to continental lotic systems, have been poorly stu... more ABSTRACT Island stream ecosystems, in contrast to continental lotic systems, have been poorly studied in the Mediterranean. Following the Water Framework Directive (2000/60/EC) process, we applied harmonized European methods for the ecological status assessment of the streams on Samothraki Island.
life-kriti.gr
Implementing groundwater risk assessment analysis and mapping is a widely adopted process to faci... more Implementing groundwater risk assessment analysis and mapping is a widely adopted process to facilitate management of water resources and minimize potential impacts from developmental activities. The endangered habitat of Mediterranean Temporary Ponds is located along ...
Sources, Effects and Policy Perspectives, 2011
Freshwater ecosystems play a key role in the European nitrogen (N) cycle, both as a reactive agen... more Freshwater ecosystems play a key role in the European nitrogen (N) cycle, both as a reactive agent that transfers, stores and processes • N loadings from the atmosphere and terrestrial ecosystems, and as a natural environment severely impacted by the increase of these loadings.
Geochemical Journal Journal of the Geochemical Society of Japan, Dec 1, 1997
... Sperchios, Ach. = Acheloos, Lou. = Louros. and cluster analyses have been successfully ap-pli... more ... Sperchios, Ach. = Acheloos, Lou. = Louros. and cluster analyses have been successfully ap-plied, especially for the determination of the ori-gin of hydrochemical species (eg, Hoetzl, 1982; Hoelting, 1982; Vegas-Vilarrubia and Rull, 1988; Briz-Kishore and Murali, 1992). ...
GEOCHEMICAL JOURNAL, 1997
... Sperchios, Ach. = Acheloos, Lou. = Louros. and cluster analyses have been successfully ap-pli... more ... Sperchios, Ach. = Acheloos, Lou. = Louros. and cluster analyses have been successfully ap-plied, especially for the determination of the ori-gin of hydrochemical species (eg, Hoetzl, 1982; Hoelting, 1982; Vegas-Vilarrubia and Rull, 1988; Briz-Kishore and Murali, 1992). ...
Fundamental and Applied Limnology / Archiv für Hydrobiologie, 2013
We examined the effect of spatial scale on aquatic macroinvertebrate communities in Mediterranean... more We examined the effect of spatial scale on aquatic macroinvertebrate communities in Mediterranean streams from six basins distributed across southern Europe, including Spain, France, Italy, and Greece. We classified the studied streams according to their long-term aquatic regime into the three following types: (i) permanent (P), (ii) intermittent with summer pools (I-P), and (iii) intermittent with summer dry channels (I-D). For each stream type, we analyzed taxonomic and trait diversity, as well as the composition of the macroinvertebrate community, following a spatially nested design at three spatial scales of analysis: microhabitat (substratum patches), mesohabitat (pools vs. riffles), and macrohabitat (streams). In order to assess intrinsic seasonal variability in streams from the Mediterranean region, 20 Surber samples were taken from each stream according to meso-and microhabitat frequency in the wet and the dry season during 2010. Given the need for adaptation to specific hydrological conditions and the fact that microhabitats should encompass the niche requirements of particular taxa, we hypothesized that this spatial scale would have a greater influence on macroinvertebrate taxa composition and biological traits than the other two larger spatial scales in intermittent streams. We observed that patterns in the relative importance of variance components across hierarchical spatial scales changed with time because low flow or droughts altered both mesohabitat prevalence and microhabitat composition. Our results confirm the importance of the microhabitat scale in I-P streams in the wet season but not in the dry one, when a loss of microhabitat diversity occurred. Stream-to-stream variability was more important in P and I-D streams. Our study also explored the relationships between traits and aquatic regimes. We found that aquatic macroinvertebrates inhabiting permanent streams exhibited traits related to the longer duration of life cycles in these rivers (e.g. large size of adult stages) and adaptations to flowing conditions (e.g. modes of aquatic dispersal), whereas aquatic macroinvertebrates inhabiting intermittent streams with summer pools had traits adapted to depositional conditions and ecological preferences for confined habitats (i.e. disconnected pools without flow). Finally, aquatic macroinvertebrates from intermittent streams with summer dry channels had adaptations conferring ability to survive periods with no water (e.g. modes of aerial dispersal, resistant stages). These results indicate that microhabitat conditions should not be neglected as they can play an important role in certain situations.
balwois.com
The Water Framework Directive (WFD) 2000/60/EC requires establishing ecological status classifica... more The Water Framework Directive (WFD) 2000/60/EC requires establishing ecological status classification techniques, through the use of quality elements (hydromorphological, chemicalphysicochemical and biological).The WFD dictates that the elements to be selected must be those that present sensitivity to the prevailing anthropogenic pressures. In the framework of a Life-Environment research project (2006)(2007)(2008), we undertook the task of developing and applying techniques to assess the ecological status of Evrotas River basin, using hydromorphological, physicochemical and biological (fish and macroinvertebrate fauna) quality elements. However, the research coincided with a severe drought event, which was combined with water resources overexploitation and resulted to the dessication of almost 80% of the main river course.The scope of the study was to compare data of ecological status assessment through the use of the four applied techniques. Our results indicate that the physicochemical and macroinvertebrate quality elements can provide reliable results on the pollution impacts of Evrotas River basin. In contrast, fish were found to be more sensitive to hydrological pressures and had a more lasting contribution to assessment. Finally, we assessed the overall ecological status of the basin by applying the "one out-all out" principle. Overall, the assessment techniques applied, when combined, can provide an integrated assessment of the ecological status of an artificially intermittent river. The results from this study may assist specific measures to be implemented within the Integrated River Basin Management Plan of Evrotas River Basin in order to restore environmental conditions and achieve a good ecological status for the entire drainage.
Science of the Total Environment, 2017
Published by Copernicus Publications on behalf of the European Geosciences Union.
Water Research, 2011
Olive mill wastewater (OMW) is one of the major and most challenging organic pollutants in olive ... more Olive mill wastewater (OMW) is one of the major and most challenging organic pollutants in olive oil production countries. However, the knowledge about the in-situ effects of olive mill wastewaters to lotic ecosystems and their benthic organisms is very limited. To resolve this, eight sampling sites were selected upstream and downstream the outflow of several olive mills to assess the spatial and temporal effects of OMW to stream macroinvertebrates and to ecological status of stream ecosystems. Biotic (macroinvertebrates) and abiotic (physicochemical, hydromorphological) data were monitored for two years thus following the biennial cycle of olive growth and production and hydrological variation (drought-wet years). The results of this study revealed the spatial and temporal structural deterioration of the aquatic community due to OMW pollution with consequent reduction of the river capacity for reducing the effects of polluting substances through internal mechanisms of self-purification. OMW, even highly diluted, had dramatic impacts on the aquatic fauna and to the ecological status of the receiving stream ecosystems. The organic load of the wastewater expressed as BOD(5), COD and TSS, substrate contamination (sewage bacteria) and distance from the mill outlet, were the most important factors affecting macroinvertebrate assemblages while the typology (i.e. slope, altitude) and hydrology of the stream site (i.e. mountainous-lowland) and the intensity and volume of the wastewater were the most important determinants of self-purification processes. As OMW are usually being discharged in small size streams that are not considered in the Water Framework Directive 2000/60/EC, there is a need for including such systems into monitoring and assessment schemes as they may significantly contribute to the pollution load of the river basin. Furthermore, guidelines to manage these wastes through technologies that minimise their environmental impact and lead to a sustainable use of resources are critical.
Aquatic Sciences
Water stress in Mediterranean countries is the result of both variable and changing climatic cond... more Water stress in Mediterranean countries is the result of both variable and changing climatic conditions and widespread anthropogenic pressures. Evrotas, an intermittent river located in Southern Greece, was used as a case study to assess the impacts of water stress on Mediterranean lotic ecosystems. Based on hydrological analyses, it was revealed that during prolonged drought years, such as the summers of 2007 and 2008, the vast majority of the Evrotas riverbed was completely desiccated, primarily as a result of substantial water abstraction for irrigation. The effects of desiccation on the riverine ecosystem were evaluated using fish and macroinvertebrate assemblages according to the demands of the Water Framework Directive 2000/60/EC (WFD). Faunal responses to water stress were assessed through comparisons of assemblages attributes in perennial and intermittent reaches and pre-drought versus post-drought communities. Effects of hydrological disturbance on fish species richness, density, percentage composition and size structure were more pronounced in intermittent than in perennial sites. The most obvious and immediate impact was the elimination of populations in the intermittent reaches. However, upon flow resumption, the recolonisation from upstream perennial reaches began, thereby permitting partial re-establishment of the depleted fish communities. Nevertheless, the structural integrity of fish communities remained severely impacted and recovery was markedly slow. On the contrary, post-drought macroinvertebrate assemblages were not affected by summer droughts, and the recruitment processes were rapid after flow resumption. Our findings point to the necessity of establishing a distinction between naturally and artificially driven intermittent rivers. We, therefore, propose the introduction of an “artificially intermittent Mediterranean river” condition within the context of the WFD assessment applications.
Environmental Toxicology, 2010
The toxicity and the biochemical effects of olive mill wastewater and citrus processing wastewate... more The toxicity and the biochemical effects of olive mill wastewater and citrus processing wastewater were evaluated using acute toxicity bioassays (Gammarus pulex and Hydropsyche peristerica) and biochemical biomarkers (acetylcholinesterase [AChE] and glutathione S-transferase [GST]). The bioassays indicated toxic properties of olive mill and citrus processing wastewaters. The 24 h LC50 values of olive mill wastewater ranged from 2.64% to 3.36% for G. pulex and 3.62% to 3.88% for H. peristerica, while the LC50 of citrus processing wastewater was 25.26% for G. pulex and 17.16% for H. peristerica. Based on a five-class hazard classification system applied for wastewaters discharged into the aquatic environment, olive mill wastewater and citrus processing wastewater were classified as highly toxic and toxic, respectively. Results of the biochemical biomarkers showed that both agroindustrial effluents at increasing sublethal wastewater concentrations could cause inhibition of the AChE and induction of the GST activities. These first results showed that both species as well as their AChE and GST activities have the potential to be used as indicators and biomarkers for assessing olive mill and citrus processing wastewaters quality. © 2010 Wiley Periodicals, Inc. Environ Toxicol, 2011.
Journal of Hydrology, 2009
ABSTRACT Hydrological pathways, speciation, and in-stream spatio-temporal variations (including i... more ABSTRACT Hydrological pathways, speciation, and in-stream spatio-temporal variations (including initial flood pulses), along with soil/sediment characteristics, pointed out to the most probable factors and processes driving the origin, levels and dynamics of nutrients in a minimally disturbed Greek temporal river. Nitrogen and phosphorus were predominately found in the organic form and, despite the high suspended sediment transport, in the dissolved phase. Forest soil leaching and erosion fuelled the river with organic nutrients both in the dissolved and particulate phase, especially at the upstream portion of the basin. This part of the basin exhibited “pristine” dissolved nutrient levels (e.g. 30 μg/l DIN, 1.04 μg/l P–PO4), despite substantial transport through precipitation and subsurface flow, suggesting that certain biogeochemical processes acting in the watershed and in-stream effectively reduce riverine dissolved nutrient concentrations. Intense erosion caused a significant downstream increase of suspended sediments and associated nutrient concentrations. Flushing processes, that were detected even in a monthly base in particular river stretches, enhanced dissolved and particulate nutrient concentrations. Initial flood pulses created “hot moments” chiefly for suspended sediments (RMF during initial flood events reached up to 7) and associated nutrients (e.g. RMF of POC during initial flood events reached up to 32), although flood event sediments presented lower nutrient portions compared to usual sediment transport. Flush peaks of ammonia (max 19 mg/l NH4) and nitrite (max 42 μg/l NO2), that surpassed aquatic quality standards, were attributed to rapid mineralization of organic matter upon rewetting and subsequent nitrification. River bed sediments were characterized by organic carbon and nitrogen losses, due to leaching and mineralization processes, and phosphorus retention, thus affecting nutrient ratios and hence photosynthesis in receiving waters.
Science of The Total Environment, 2009
Fifteen major Balkan rivers with over 80% of the inflows in Eastern Mediterranean were examined f... more Fifteen major Balkan rivers with over 80% of the inflows in Eastern Mediterranean were examined for their environmental state within the DPSIR framework. Physicogeographic and hydrochemical conditions differ substantially among river basins, which may be roughly classified into three main zones. Despite strong fragmentation, most of the rivers are liable to flash floods and have low summer flow. Decreasing precipitation and (mis)management caused a dramatic discharge reduction over the last decades. Wars, political instability, economical crises over the past decades, combined with administrative and structural constraints, poor environmental planning and inspection and, frequently, a lack of environmental awareness imposed significant pressures on rivers. Large wetland areas were drained in favour of widespread intensive agriculture. The treatment of municipal wastewaters is barely adequate in Greece and insufficient elsewhere, while management and treatment of mining and industrial wastewaters is overall poor. In general, lowland river sections are hydro-morphologically modified and are at the greatest pollution risk, while upstream areas mostly retain their natural conditions. Nutrient concentrations in a number of central and eastern Balkan rivers often exceed quality standards, whereas pesticides and heavy metals, partly of geochemical origin, occasionally exceed quality standards. Reservoirs retain vast masses of sediments, thus adversely affecting delta evolution, while dam operation disturbs the seasonal hydrological and hydrochemical regimes. Almost all Balkan countries face daunting water resource challenges because of urgently needed investments in water supply, sanitation, irrigation, and hydroelectricity. International treaties and designations and European Union Directives have mobilized pollution mitigation and conservation efforts. However, the application of environmental legislation has proved in a number of cases inadequate. Constraints arise from long-standing topdown planning traditions, inadequate planning of national environmental policies, poor administrative capacities, and heavy investment requirements, often combined with a lack of environmental awareness.
Environmental Modeling & Assessment, 2009
Ecological (biological and hydrochemical assessment) and hydrogeological (vulnerability and pollu... more Ecological (biological and hydrochemical assessment) and hydrogeological (vulnerability and pollution risk mapping) tools have been combined to assess the ecological quality and hydrogeological vulnerability of an agricultural river basin. In addition, the applicability of the recently developed vulnerability assessment approach (COP method) in the particular environmental conditions was tested by comparing its results with hydroecological assessment tools (i.e., pollution metrics). Five sampling sites were selected and sampled for benthic macroinvertebrates and physicochemical variables during summer and spring. Overall, sites ranged from moderate to poor ecological quality. The results illustrated that 26% of the study area was of moderate pollution risk, while 65% was classified as of low and very low risk zones. However, the higher elevation zones where calcareous rock formations are encountered presented moderate to high pollution risk that was accredited by the ecological quality assessment. Pollution metrics facilitated from hydrochemical analysis indicated a significant association with groundwater vulnerability, thus validating vulnerability and risk estimations. This study indicated that the particular groundwater pollution risk mapping methodology and the water quality assessment indices can be well combined to provide an integrated evaluation tool at a catchment scale.
Ecological Modelling, 2009
Nutrients Axios River watershed Impacts Coastal zone modelling a b s t r a c t The estimation of ... more Nutrients Axios River watershed Impacts Coastal zone modelling a b s t r a c t The estimation of nutrient fluxes, the determination of spatial and temporal response and the understanding of biogeochemical changes in the past, present and future in the Axios River catchment, in Greece, as well as the impacts to the coastal zone of Thermaikos Gulf were accomplished by the use of harmonized watershed and coastal zone models. The mathematical model MONERIS was the watershed management model that was used to model the export loads of nutrients in Axios River. MONERIS was developed to estimate the nutrient inputs into river basins by point sources and various diffuse pathways. Watershed hydrologic and water quality data were collected and synthesized to develop input data sets for the simulation of Axios River catchment. The model was modified to better assess organic nitrogen export loads in Mediterranean watersheds. The results showed the importance of agricultural and livestock activities, concerning their nutrients emissions in the River. MONERIS was integrated with the coastal zone model WASP 6.0 to assess the impacts of the nutrient loads to the eutrophication status of the coastal zone. Several management scenarios were assessed. Management scenarios included measures for reduction in the emissions from the fertilizer plant of Veles, removal of phosphorous from the detergents in FYROM, treatment of urban wastes to EU Standards, reduction in N-fertilizer input, reduction in erosion and the green scenario that represented the maximum reduction scenario of all the measures together. The model simulations indicated that the coastal zone of Axios mouth will be eutrophic for nitrate (2.69-3.34 M) and phosphate (0.2-0.68 M)
Limnologica, 2009
A central aspect of the Water Framework Directive 2000/60/EC addressed to Member Countries is to ... more A central aspect of the Water Framework Directive 2000/60/EC addressed to Member Countries is to proceed to type-specific ecological assessment and classification by establishing typology systems. Sixty-four permanent stream sites distributed throughout mainland Greece and islands were assessed with macroinvertebrate indicators to evaluate their ecological quality. Local and catchment scale parameters were determined and recorded to obtain an integrated assessment of the main factors affecting stream integrity and macroinvertebrate communities. Twenty-three sites were classified as reference or good status in terms of biological, chemical and hydromorphological quality with the use of various metrics. Multivariate statistical techniques were performed (MDS, BIOENV, correlation analysis and PCA) to investigate the main environmental factors structuring benthic macroinvertebrate communities and to select candidate environmental variables for establishing a biotic typology for Hellenic rivers. The results revealed relatively distinct macroinvertebrate communities within defined abiotic zones of the country. Assemblages of macroinvertebrate fauna were most strongly associated to differences in geographical position, altitude, slope, catchment area, current velocity, conductivity and water temperature. In view of the lack of sufficient data at the country level on the three last variables and after considering cause-effect relationships between large scale variables and the latter, it has been demonstrated that a number of catchment scale variables could be used as robust surrogates.
Hydrobiologia, 2008
Vegoritis is a large, deep, mesotrophic, karstic lake in NW Greece, located in Ptolemais basin. D... more Vegoritis is a large, deep, mesotrophic, karstic lake in NW Greece, located in Ptolemais basin. Dramatic lowering of the lake’s level has occurred during the last half century due to human pressures. The Ptolemais Basin and the lake itself are subjected to serious human pressures. Pollutants are carried into the lake through both, the atmosphere and surface runoff. In order to identify the levels, and assess the origin of heavy metals in surface lake sediments, 24 samples were collected and analyzed for their grain size, as well as for their mineral, organic matter, major element and heavy metal content. The origin of heavy metals has been attributed to specific geogenic and anthropogenic sources. Despite the anthropogenic disturbance, the levels of micropollutants were low, possibly due to the low retention time of lake water and the recent increase of sedimentation rates. Only Cr, Ni, Co As, and Ba were present in relatively high concentrations. Ba is derived from the erosion of acid silicate rocks, Cr primarily from mafic rocks and secondarily from pollution, whereas for Ni and Co the opposite is true, while As is primarily attributed to fly ash deposition. The lowering of the lakes’ water level exposes sediments, which are then being oxidized. Mobilization of As and Cr could impair humans’ and ecosystems’ health.
Hydrological Sciences Journal-journal Des Sciences Hydrologiques, 2008
Seven catchments of diverse size in Mediterranean Europe were investigated in order to understand... more Seven catchments of diverse size in Mediterranean Europe were investigated in order to understand the main aspects of their hydrological functioning. The methods included the analysis of daily and monthly precipitation, monthly potential evapotranspiration rates, flow duration curves, rainfall-runoff relationships and catchment internal data for the smaller and more instrumented catchments. The results showed that the catchments were less "dry" than initially considered. Only one of them was really semi-arid throughout the year. All the remaining catchments showed wet seasons when precipitation exceeded potential evapotranspiration, allowing aquifer recharge, "wet" runoff generation mechanisms and relevant baseflow contribution. Nevertheless, local infiltration excess (Hortonian) overland flow was inferred during summer storms in some catchments and urban overland flow in some others. The roles of karstic groundwater, human disturbance and low winter temperatures were identified as having an important impact on the hydrological regime in some of the catchments.
Environmental Science & Technology, 2007
A reach at the estuary of Krathis River in Greece was used to assess how in-stream processes alte... more A reach at the estuary of Krathis River in Greece was used to assess how in-stream processes alter its hydrologic and biogeochemical regime. Krathis River exhibited high annual flow variability and its transmission losses become significant, especially during the dry months. These transmission losses are enhanced in chemistry due to release of nutrients from river sediments. These fluxes are significant because they correspond to 11% of the dissolved inorganic nitrogen flux of the river. Release of nitrogen species was influenced by temperature, while release of phosphate was not because phosphate levels were below the equilibrium concentration. There is a significant amount of sediments with fine composition that create "hot spot" areas in the river reach. These sediments are mobilized during the first flush events in the fall carrying with them a significant load of nutrient and suspended matter to the coastal zone. The nutrient organic content of sediments was also significant and it was studied in terms of its mineralization capacity. The capacity for mineralization was influenced by soil moisture, exhibiting significant capacity even at moisture levels of 40%. Temporary rivers are sensitive ecosystems, vulnerable to climate changes. Instream processes play a significant role in altering the hydrology and biogeochemistry of the water and its impacts to the coastal zone.
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Papers by Nikos Skoulikidis