George Catsadorakis

Bio: George Catsadorakis is an academic researcher. The author has contributed to research in topics: Endemism & Introduced species. The author has an hindex of 3, co-authored 3 publications receiving 96 citations.

The establishment and impact of Pseudorasbora parva, an exotic fish species introduced into Lake Mikri Prespa (north-western Greece)

Abstract: 1. The topmouth gudgeon Pseudorasbora parva Schlegel, 1842, a south-east asian cyprinid, was introduced accidentally in the Danube Delta in Romania in the 1960s and has now achieved a pan-Danubian distribution. P. parva has been introduced into other countries, such as Greece, usually inadvertently included with other species imported for fish farming. In 1984–85, during a study of the fish populations of Lake Mikri Prespa (north-west Greece), several topmouth gudgeon were caught. Our aim was to study the changes in the population size of P. parva over nearly 10 years, to study its life history traits and to assess its potential impacts on native fish species. 2. The catch per unit effort (CPUE) in spring increased significantly between 1984 and 1992. We found evidence that P. parva has established a breeding population in the lake. P. parva combines many characteristics likely to favour a successful colonization (resistance to harsh climatic conditions, early sexual maturity, extended breeding season, broad dietary spectrum). Growth in Lake Prespa, where the oldest individuals captured were 3 years old, is very similar to that observed within its native range. 3. There is evidence for dietary overlap between P. parva and three endemic species: Paraphoxinus epiroticus prespensis, Cobitis meridionalis and Alburnoides bipunctatus ohridanus. No decline in the populations of these three species has yet been demonstrated. Other possible impacts are discussed. The successful colonization by P. parva was certainly favoured by the absence of a true piscivorous fish in the lake and by the isolation and high level of endemism of fish communities. 4. The conservation of the many endemic species in the lake should be a priority and the introduction of exotic species should be banned.

Lake Prespa, Northwestern Greece

Abstract: Lake Mikri Prespa is 47 km2 in area, with a maximum depth of 8.4 m and a normal water level at around 850 m above sea level. It collects water from a granitic and karstic catchment of 189 km2 which includes snowy mountains rising to over 2000 m. The main flat land is the sedimentary plain to the east and the sandy isthmus that separates Mikri Prespa from the much larger Megali Prespa into which the former normally drains. Rainfall averages around 750 mm because the 600 mm to 700 mm falling on the plains is augmented by heavier falls including much snow on the mountains. There is rainfall each month with an autumnal maximum. River inputs to the lake and the lake level itself peak in the spring with the snowmelt. Mikri Prespa normally rises by about a metre to flood the surrounding wet meadows landward of the reed fringe. The annual cycle of water level fluctuation is superimposed on infrequent upward surges in the level of Mikri and Megali Prespa because of particularly wet and snowy winters and, in recent years, the steady decline of the level of Megali Prespa because of tectonic activity. There has been considerable human modification of the hydrology of the area with the diversion of the Agios Germanos torrent from Mikri to Megali Prespa, the creation of a canal in Albania which can input or withdraw water from the lake, the culverting of the canal linking Mikri and Megali Prespa, and the creation of an irrigation scheme taking water directly from Mikri Prespa and from the Agios Germanos stream. The lake water is base rich because of the limestone in the catchment. Whilst concern has been expressed at the eutrophication of the lake, recent studies have proved that there has been no significant change in nutrient status this century and the lake is not eutrophic. There has been a significant increase in turbidity but this may be the result of sediment disturbance by an introduced fish species. The lake and its supporting hydrological system will need careful monitoring if it is to be effectively managed. A particularly high priority is the development and implementation of a water level management plan for the lake.

Lake Prespa, north-western Greece : a unique Balkan wetland

Abstract: The physical basis of the Lake Mikri Prespa systems - geology, climate, hydrology and water quality, G.E. Hollis and A.C. Stevenson the soils, C.S. Kosmas, et al the flora of Prespa National Park with emphasis on species of conservation interest, G. Pavlides aquatic and terrestrial vegetation of the Prespa Area, G. Pavlides species composition and seasonal cycles of phytoplankton with special reference to the nanoplankton of Lake Mikri Prespa, E. Tryphon and M. Moustaka-Gouni the zooplankton of Lake Mikri Prespa, E. Michaloudi, et al the benthic fauna of Lake Mikri Prespa, D. Petridis and A. Sinis fish and fisheries in the Prespa Lakes, A.J. Crivelli, et al. The distribution and habitat preferences of the amphibians of Prespa National Park, D. Bousbouras and Y. Ioannidis the space utilization by reptiles in Prespa National Park, Y. Ioannidis and D. Bousbouras breeding birds from marshes to alpine meadows, G. Catsadorakis the importance of Prespa National Park for breeding and wintering birds, G. Catsadorakis conservation and management issues of Prespa National Park, G. Catsadorakis and M. Malakou.

NOBANIS -Invasive Alien Species Fact Sheet

Abstract: Scientific names: Acer negundo L., Aceraceae. Synonyms: Negundo aceroides Moench (1794), Negundo fraxinifolium (Nutt.) DC. (1824). Common names: Box-elder, ash-leaved maple, manitoba maple (GB and US), Eschen-Ahorn (DE), askbladet lon (DK), saarvaher (EE), Saarnivaahtera (FI), askhlynur (IS), uosialapis klevas (LT), Oslapu kļava (LV), Vederesdoorn (NL), asklonn (NO), klon jesionolistny, jesioklon (PL), asklonn (SE).

Pan-continental invasion of Pseudorasbora parva: towards a better understanding of freshwater fish invasions

Abstract: In recent years, policy-makers have sought the development of appropriate tools to prevent and manage introductions of invasive species. However, these tools are not well suited for introductions of non-target species that are unknowingly released alongside intentionally-introduced species. The most compelling example of such invasion is arguably the topmouth gudgeon Pseudorasbora parva, a small cyprinid species originating from East Asia. A combination of sociological, economical and biological factors has fuelled their rapid invasion since the 1960s; 32 countries (from Central Asia to North Africa) have been invaded in less than 50 years. Based on a combination of monitoring surveys (2535 populations sampled) and literature reviews, this paper aims to quantify and characterise important invasion parameters, such as pathways of introduction, time between introduction and detection, lag phase and plasticity of life history traits. Every decade, five new countries have reported P. parva introduction, mainly resulting from the movement of Chinese carps for fish farming. The mean detection period after first introduction was 4 years, a duration insufficient to prevent their pan-continental invasion. High phenotypic plasticity in fitness related traits such as growth, early maturity, fecundity, reproductive behaviour and the ability to cope with novel pathogens has predisposed P. parva to being a strong invader. The Pseudorasbora parva invasion has provided quantitative data for the development of 1) early warning systems across different spatial scales; 2) rapid eradication programmes prior to natural spread in open systems and 3) sound risk assessments with emphasis on plasticity of life history traits.

Fish habitat: essential fish habitat and rehabilitation

Abstract: —With the passage of the Sustainable Fisheries Act in the fall of 1996, significant new opportunities and challenges exist in the United States to protect and conserve the habitat of marine, estuarine, and anadromous finfish as well as key populations of mollusks and crustaceans. As of October 1998, all federal fishery management councils (the Councils) were required to amend their fishery management plans (covering over 700 stocks) to identify, for each species, the essential fish habitat, which is “those waters and substrate necessary to fish for spawning, feeding or growth to maturity.” Threats to habitat and steps necessary to ameliorate those threats also had to be identified. Information from fisheries scientists and managers throughout the country will be needed to accurately identify essential fish habitat and habitat threats and to monitor the effectiveness of protective measures that come into force once habitat has been identified as essential. My vision, which is also that of the National Oceanic and Atmospheric Administration, is no further loss of habitat quantity and quality as well as the preservation and restoration of habitat biodiversity by the year 2004. The essential fish habitat provisions of the Magnuson-Stevens Act provide an outstanding opportunity for the National Marine Fisheries Service, the Councils, and our numerous partners from every sector of society to develop new ecosystem approaches to fishery management addressing cumulative impacts to habitats in a comprehensive, effective, and efficient manner.

Can life‐history traits predict the fate of introduced species? A case study on two cyprinid fish in southern France

Abstract: 1. The ecological and economic costs of introduced species can be high. Ecologists try to predict the probability of success and potential risk of the establishment of recently introduced species, given their biological characteristics. 2. In 1990 gudgeon, Gobio gobio, were released in a drainage canal of the Rhone delta of southern France. The Asian topmouth gudgeon, Pseudorasbora parva, was found for the first time in the same canal in 1993. Those introductions offered a unique opportunity to compare in situ the fate of two closely related fish in the same habitat. 3. Our major aims were to assess whether G. gobio was able to establish in what seemed an unlikely environment, to compare populations trends and life-history traits of both species and to assess whether we could explain or could have predicted our results, by considering their life-history strategies. 4. Data show that both species have established in the canal and have spread. Catches of P. parva have increased strongly and are now higher than those of G. gobio. 5. The two cyprinids have the same breeding season and comparable traits (such as short generation time, small body, high reproductive effort), so both could be classified as opportunists. The observed difference in their success (in terms of population growth and colonization rate) could be explained by the wider ecological and physiological tolerance of P. parva. 6. In conclusion, our field study seems to suggest that invasive vigour also results from the ability to tolerate environmental changes through phenotypic plasticity, rather than from particular life-history features pre-adapted to invasion. It thus remains difficult to define a good invader simply on the basis of its life-history features.