George Kehayias

George Kehayias
University of Patras | UP · Department of Environmental Engineering

PhD

About

58
Publications
12,137
Reads
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752
Citations
Citations since 2017
14 Research Items
456 Citations
2017201820192020202120222023020406080100
2017201820192020202120222023020406080100
2017201820192020202120222023020406080100
2017201820192020202120222023020406080100
Additional affiliations
January 2000 - present
University of Patras
Position
  • Professor (Assistant)

Publications

Publications (58)
Article
Full-text available
This study provides elements on the spatial and temporal mesozooplankton variability during a three-year study, encompassing vertical hauls from 50 m deep to the surface from four coastal locations of Cyprus. The total mesozooplankton abundance fluctuated between 190.4 and 882.5 individuals m-3. A total of 90 holoplanktonic and meroplanktonic taxa...
Article
Economidichthys trichonis is the smallest teleostean of Europe and is inhabited Lake Trichonis (Greece). Previous investigation concerning the feeding of the dominant fish of this lake (Atherina boyeri) revealed that the use of fishing lights in the purse seine fishery of this species may result to its increased preda­tion upon the larvae of E. tri...
Article
Full-text available
A reliable and comparative fungicide index (FI) was assessed to describe the fungicide use in the agricultural land of Europe during the first 20 years of the twenty-first century (from 2000 to 2018). FI is not uniform across EU27. The highest mean value (1.34 kg ha⁻¹) of FI was observed in Southern Europe compared to the other sub-regions of the E...
Article
Full-text available
Fishing ensures necessary food for humans and is inextricably linked with the environment because coastal communities developed special fishing procedures to achieve better exploitation of the aquatic resources. Lake Trichonis, Greece’s largest natural lake, is a freshwater ecosystem in which a marine species ( Atherina boyeri ) has entered and dom...
Article
Full-text available
Fishing with light is an old and common practice yielding a substantial catch volume globally. Despite the popularity of the method and the efforts to improve it, there is a lack of field studies on the effects of light on the feeding preferences of the attracted fishes. A previous report suggested that purse seine fishing lights can differentiate...
Article
Fishing with light is an old and common practice yielding a substantial catch volume globally. Despite the popularity of the method and the efforts to improve it, there is a lack of field studies on the effects of light on the feeding preferences of the attracted fishes. A previous report suggested that purse seine fishing lights can differentiate...
Article
Full-text available
Within the ecosystem services framework, cultural ecosystem services (CES) have rarely been applied in state-wide surveys of protected area networks. Through a review of available data and online research, we present 22 potential proxy indicators of non-material benefits people may obtain from nature in Natura sites in Greece. Despite the limitatio...
Article
Full-text available
Industrial wind farms are being developed within many protected areas, such as in EU Natura 2000 sites; this includes proposals on small Mediterranean islands, such as Samothraki in Greece. Scarce wild land areas on islands may be particularly vulnerable to landscape-scale degradation; this may have serious negative societal impacts. Samothraki's r...
Article
Full-text available
We introduce a field survey method to assess the conservation condition of landscapes. Using a popular rapid assessment format, this study defines observable "stressed states" identified through the use of general metrics to gauge landscape degradation. Fifteen metrics within six thematic categories were selected through a literature review and ext...
Article
Full-text available
The publication includes contributions by: M. Aybeke (1-10), B. Biel & Kit Tan (11-22), C. Cattaneo & M. Grano (23-27), K. Giannopolous, Kit Tan & G. Vold (28-102), G. Kunev (103-107), A. Petrova (108-119), K. Polymenakos & Kit Tan (120-123), A. Strid (124-148), L. Tsounis, Kit Tan & G. Kehayias (149), V. Vladimirov (150-154), V. Vladimirov & Z. Sz...
Poster
Scardinius acarnanicus Economidis, 1991 (Photo 1) is an endemic fish species in lakes and rivers of the western Greece, among which is Lake Trichonis (Map 1). In the only previous study on its feeding conducted nearly 40 years ago in the lakes Trichonis and Lysimachia, its diet consisted solely of aquatic vegetation and phytoplankton (Iliadou 1991)...
Article
Background. Purse seining with the use of light is among the most common fishing practices around the world, but there is lack of studies on the effect of light on the feeding of the target species in this kind of fishery and the possible consequences for other prey species. The presently reported investigation intended to provide indications on th...
Article
Cultural landscapes are poorly inventoried and evaluated in protected natural areas. This study presents a novel procedure to assess cultural landscape features and their cultural values in protected areas. After identifying a set of culturally modified land cover types and habitat types the GIS-based survey of the entire Natura 2000 protected area...
Article
This paper describes the construction of a novel lamp raft for the purse seine fishery and its evaluation in real conditions for 14 days during a six-month period in a freshwater ecosystem (Lake Trichonis, Greece). A simple, but durable and inexpensive design was constructed comprising a LED lamp producing green light, powered by a 12 V battery whi...
Article
Full-text available
A 12-month zooplankton survey (September 2008 to August 2009) in the hypoxic, stratified and seasonally eutrophic Amvrakikos Gulf (western Greece) revealed the presence of larvae of the Cephalochordate Branchiostoma lanceolatum. The larvae were found at almost all sampling occasions, except September and February, and presented their peak of abunda...
Article
Full-text available
The main objective of this study was the production of biotechnological oil/biodiesel from a filamentous cyanobacterium Limnothrix sp. with simultaneous treatment of a model wastewater. A novel attached-growth photobioreactor was designed to facilitate the harvesting of cyanobacterial biomass and to maximize biomass and lipid production compared to...
Article
This study investigated the temporal and spatial variation of the zooplankton community of a hypoxic coastal embayment (Amvrakikos Gulf, Western Greece) in relation to hydrological characteristics during an annual cycle. The main hydrological feature was the prolonged water stratification, which determined hypoxic conditions in the deeper layers th...
Article
The potentiality of offshore wind energy development in the western coast of Greece in relation to all the protected areas in this region was investigated. Major factors like minimum distances from constraining the offshore wind farms installations, ports and Natura sites were analyzed as environmental constraints in the region. The results indicat...
Article
Full-text available
The trophic state of a freshwater ecosystem reflects its environmental quality. This is why several trophic indicators have been developed for such water bodies based on chemical, physical and biological parameters. Apart from that, there are several biotic elements which can be used in accessing the environmental condition of a freshwater ecosyste...
Book
Zooplankton organisms comprise very important elements of the structure and function of marine and freshwater ecosystems, not only as consumers of primary production, but also as food items for juvenile stages of several fish species. Moreover, its sensitivity to both man-made and natural changes makes zooplankton quite suitable for assessing alter...
Chapter
Full-text available
Zooplankton is an important element of the structure and function of freshwater lake ecosystems, while the study of changes in abundance, species diversity and composition in zooplankton communities can provide important indications of long term environmental changes. The present study provides elements on the community structure, the spatial and s...
Article
A one-year investigation of the zooplankton community composition and dynamics in Lake Οzeros (western Greece) revealed 25 invertebrate species (16 rotifers, three copepods, five cladocerans and one mollusc larva). The mean zooplankton abundance fluctuated between 59.4 to 818 ind l-1, with maximum values in spring. The species composition and seaso...
Article
Full-text available
Etoliko, an anoxic semi-enclosed basin, is part of a complex wetland in Western Greece extremely rich in biodiversity. It covers an area of 1,700 ha with an atypical orientation that has been formed tectonically. In order to identify the main factors influencing the bacterial profile at the Etoliko basin, 48 samples were collected, representing sea...
Article
Full-text available
The study of physicochemical and biological parameters can assess the trend of a lake’s trophic state. A trophic state index (TSI) was used to assess eutrophication of Lake Amvrakia. Total phosphorus and chlorophyll concentrations that recorded were generally at the same level with those recorded in previous years, a fact which indicates that lake’...
Article
The present study investigates the zooplankton community dynamics and the abiotic environment in the eutrophic Lake Lysimachia (western Greece). The lake is considered to be recovering from eutrophication after the termination of an urban sewage inflow in 2000, and its waters are replenished constantly from the nearby oligotrophic Lake Trichonis. T...
Article
The variation of the smaller size fraction of zooplankton was investigated during a two-year period in a brackish deep and anoxic coastal lake of western Greece (Aitoliko), along with the specific environmental characteristics of this ecosystem. The zooplanktonic community comprised a relatively small number of taxa and it was dominated by brackish...
Article
Full-text available
The variation of the smaller size fraction of zooplankton was investigated during a two-year period in a brackish deep and anoxic coastal lake of western Greece (Aitoliko), along with the specific environmental characteristics of this ecosystem. The zooplanktonic community comprised a relatively small number of taxa and it was dominated by brackish...
Article
This study investigates the adaptation of certain feeding strategies by a population of Atherina boyeri inhabiting a freshwater ecosystem (Lake Trichonis, Greece) and links feeding habits with ecosystem interactions, using stomach content analysis and food availability. The use of Ivlev's electivity index (E) revealed the selection of different pre...
Article
Full-text available
Temporal and spatial distribution of physico-chemical and water quality parameters and their correlation with meteorological and hydrological data, was investigated for anoxic lagoons, in Greece. Monthly variations of parameters like temperature, salinity, dissolved oxygen, chlorophyll-a, total phosphorus etc., along the Aitoliko lagoon water colum...
Article
Full-text available
The balance between physicochemical processes, influencing vertical and temporal distributions of metal compounds in one relatively isolated anoxic environment, constitutes the objective of the present work. Ion activity product (IAP) was calculated for manganese and iron sulfides, in order to define the metal sulfide forms that control Fe and Mn s...
Article
Full-text available
The objective of the present work was to determine the bioaccumulation of arsenic (As), cadmium (Cd), copper (Cu), lead (Pb), mercury (Hg), uranium (U) and selenium (Se) in gill, liver, and muscle tissues of the fresh water fish Salmo trutta macrostigma (Duméril, 1858) in Munzur Stream, Tunceli, Turkey. The highest concentrations of U (1.83 μg kg−1...
Article
Recent molecular studies on dreissenid species in southern Europe found that Dreissena blanci (Westerlund, 1890) resides in several lakes where previous studies identified it as Dreissena polymorpha (Pallas, 1771). Because D. blanci seems to constitute a “new record” in the Balkans, the present study provides novel information on the biology and ec...
Article
The balance between physicochemical processes, influencing vertical and temporal distributions of metal compounds in one relatively isolated anoxic environment, constitutes the objective of the present work. Ion activity product (IAP) was calculated for manganese and iron sulfides, in order to define the metal sulfide forms that control Fe and Mn s...
Article
Full-text available
Zooplankton species composition and abundance variation was studied in Lake Amvrakia, which is a deep, temperate, gypsum karst lake situated in the western Greece. The two year survey of zooplankton revealed 33 species (23 rotifers, five cladocerans, four copepods and one mollusc larva). The mean integrated abundance of the total zooplankton ranged...
Chapter
Molecular genetics studies on the biogeography of dreissenid species in southern Europe revealed that Dreissena blanci (Westerlund, 1890) is one of the two distinct sister taxa of Dreissena in the Balkans. This is in contrast to earlier reports about the presence of D. polymorpha in this region, which includes also several aquatic ecosystems of Gre...
Article
he present study investigates the vertical distribution of the copepods found in a deep and anoxic Mediterranean coastal lake during a two-year period. The numerically most important adult copepods were the calanoids Paracartia latisetosa (66.9 %) and Calanipeda aquaedulcis (27.4 %), while the harpacticoids Euterpina acutifrons, Harpacticus gracili...
Article
Full-text available
The present study aimed to determine and compare the bioaccumulation of heavy metals in two freshwater species of mussels Unio elongatulus eucirrus (Bourguignat, 1860) and Dreissena polymorpha (Pallas, 1771) in Keban Dam Lake, Turkey. The amount of Arsenic (As), Cadmium (Cd), Copper (Cu), Lead (Pb) and Uranium (U) were detected. Heavy metals concen...
Article
Anoxia constitutes an important environmental problem, affecting coastal systems around the world. The physicochemical alterations on the water column of anoxic basins, caused by morphological modifications, were studied.Deepening on the connecting sill between the permanent anoxic Aitoliko lagoon and Messolonghi lagoon was accomplished on May 2006...
Conference Paper
Zooplankton organisms and especially copepods comprise very important elements in the productivity and energy transfer of lagoonal ecosystems. Aitoliko is a deep lagoon situated in the western Greece being part of the productive Messolonghi-Aitoliko lagoonal complex. Aitoliko lagoon has particular hydrological characteristics, such as the persisten...
Article
Full-text available
The investigation of the vertical distribution of the zooplankton community in the temperate Lake Trichonis during four seasons in 2005, showed the existence of vertical segregation among species, ontogenetic stages and sexes within and between the major groups. In each season, the two or three more abundant rotifer species distributed at separate...
Article
Full-text available
This study investigates the diel vertical distribution and the diet of the most important chaetognath species found in the 0–50 m surface layer of a coastal area in the eastern Mediterranean during a 24-hour period in July 2004. Among the recorded chaetognaths, Sagitta enflata was the most abundant species (41.6%), followed by S. minima (32.5%) and...
Article
Full-text available
The investigation of the zooplankton community in the upstream part of Stratos reservoir during a 24 months survey (September 2004–August 2006) revealed 26 invertebrate species (14 rotifers, 6 cladocerans, 5 copepods and one mollusk larva). The mean abundance of the total zooplankton was higher in the first sampling period (2004–2005) and ranged be...
Article
Plankton nets equipped with chemical light showed increased abilities in capturing zooplankton and ichthyoplankton and proved effective for the collection of rare organisms not usually caught in nets.
Article
The investigation of the zooplankton community in Lake Trichonis during a two‐year survey (September 2003–August 2005) revealed 37 invertebrate species (26 rotifers, three copepods, seven cladocerans and one mollusc larva). The seasonal distribution followed a biacmic pattern in the first year and a monoacmic in the second. Copepoda prevailed, with...
Article
The present study presents data on the abundance, vertical distribution and feeding of chaetognaths found in the 0–50 m column in a neritic area of the eastern Aegean Sea during July 2004. The abundance of total chaetognaths ranged between 7.76 and 35.92 ind m. The highest values were recorded in the uppermost 20 m and values decreased with depth....
Article
Full-text available
Mediterranean Temporary Ponds (MTPs) are priority habitats (Natura 2000) of great importance according to the European Legislation (Habitats Directive 92/43/EEC). They are being destroyed mostly because of public ignorance of their significant value. Today, MTPs are subject to high pressures from several human activities (agriculture, livestock, to...
Article
Full-text available
In order to sample the larvae of Atherina boyeri in the large and deep lake (Lake Trichonis), we devised a simple Plexiglas™ light trap in which the light was produced by five colors of Cyalume™ light sticks. In trials during July 2006, 957 larvae were caught, with greater numbers of larvae recovered from the traps with the green and blue light sti...
Article
Various types of light traps have been used in aquatic ecosystems to attract fish larvae, zooplankton, and benthic invertebrates. However, most of these devices have been cumbersome and expensive. I devised a simple and inexpensive light trap using a modified Ruttner water sampler and green Cyalume® light sticks. Repeated trials in Kastraki Lake (G...
Article
Full-text available
The feeding of the most important chaetognath species (Sagittaenflata, Sagittaminima, Sagittasetosa and Sagittaserratodentata) found in a grid of 35 stations in the north Aegean Sea (Strymonikos and Ierissos Gulfs) was investigated through gut content analysis during five sampling periods from June 1997 to May 1998. Sagittaenflata and S.minima were...
Article
Full-text available
In Lake Trichonis 9 crustacea species and the molluscan larvae of Dreissena polymorpha were recorded during four seasonal samplings from summer 2002 to spring 2003. Mean integrated values of crustacea abundance ranged from 4.5 to 12.9 ind/L and were mainly dominated by the calanoida Eudiaptomus drieschi. The abundance values recorded, as well as th...
Article
Full-text available
The abundance distribution of chaetognaths in pelagic waters (0–300 m) of the eastern Mediterranean Sea was investigated during autumn 1991 and spring 1992. The sampling stations were situated in four areas: the Ionian, the Cretan, the Rhodes Seas, and the Cretan Passage. The abundance of chaetognaths showed a clear geographical heterogeneity in bo...
Article
The diet of all chaetognath species found in a broad pelagic area of the eastern Mediterranean was investigated through gut content analysis. Eight chaetognath species were recovered from four depth intervals between 0 to 300 m in the Ionian, Cretan and Rhodes Seas and in the Cretan Passage. The mean food containing ratio (FCR) value for all chaeto...
Article
A single maturity classification key applied to five common chaetognath species of the eastern Mediterranean is presented. The efficiency of the key was tested using biometrical data: body length (BL), ovary length (OL) and seminal vesicle width (SVW). For each species the key proved easy to use and efficient in the distinction of the maturity stag...
Article
The chaetognaths Sagitta enflata, S. serratodentata atlantica and S. bipunctata were caught in six sampling periods from September 1988 until July 1989 during both day and night in Kisamos Gulf (Cretan Sea, Eastern Mediterranean) in the upper layers (0–50 m). Gut content analysis showed that copepods were the predominant food organisms in the diet...
Article
The vertical distribution of chaetognaths and their developmental stages were investigated in the pelagic waters (0 to 500 m) of the Eastern Mediterranean Sea. Twenty vertical hauls were taken during autumn 1991 in the Ionian, Cretan, Levantine and Rhodes Seas. The chaetognaths Sagitta bipunctata and S. enflata had the same median depth distributio...

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