Macroinvertebrate and fish communities in the watershed of a re-constructed Mediterranean water body: link to the ecological potential.

The role of benthic macroinvertebrate and fish communities for assessing the ecological quality of an artificial re-constructed, after 50 years of dryness, Mediterranean water body (Karla Reservoir, Greece) is presented. Moreover, we provide knowledge on the structure of the biological communities and their functioning role, for inspiring feature actions that will contribute to biodiversity protection and ecosystem services. Water (physicochemical parameters), benthic macroinvertebrates, and fish were monitored during a 2-year survey (2013-2015) in Karla and Kalamaki reservoirs and the inflowing ditches. A clear temporal pattern was evident for all sampling stations studied, differentiating the low- and high-flow period samples as to their physicochemical parameters. Redundancy analysis (RDA) revealed NO3-N, total nitrogen and total dissolved phosphorous as the most significant environmental parameters in explaining benthic invertebrate variance in ditches. Generally, tolerant to organic pollution macroinvertebrate taxa were abundant in ditches and reservoirs, while the fish fauna in Karla was composed almost exclusively of planktivorous and invertivorous species. Macroinvertebrate (GLBiI) and fish (GLFI) indices classified the ecological quality of Karla Reservoir as "poor" while ditches were classified as "bad" according to HESY-2. The anthropogenic pressures applied in the catchment and the benefits of improving water quality are discussed in the context of the implementation of Water Framework Directive 2000/60/EC for introducing sustainable management plans, taking into account some ecological restoration principles.

Artificially-born "killer" lake: phytoplankton based water quality and microcystin affected fish in a reconstructed lake.

Lake Karla (Greece) is an example of a lake ecosystem which was dried in 1960's and now is restored, facing various anthropogenic pressures, whereas it is also listed in the network of Greek protected areas in terms of its conservation value. The objective of the present study was to determine the presence of microcystins (MCYST) in the lake water and their accumulation in tissues of the commercial fish species Cyprinus carpio, along with the highlighting of phytoplankton community and general limnological features of Lake Karla, a newly reconstructed lake, the first year of its refilling. MCYST concentrations in water and fish tissues were determined by an enzyme-linked immunosorbent assay (ELISA). Results suggest that Lake Karla has undergone a progressive cultural eutrophication with frequent cyanobacterial blooms. The most dominant species in lake's phytoplankton were Anabaenopsis elenkinii, Sphaerospermopsis and Planktothrix agardhii. MCYST concentrations were detected in water samples comparable to those reported for other eutrophicated Mediterranean lakes while considerable amounts of MCYST were detected in the tissues of the species C. carpio in the following order: liver>kidney>brain>intestine>muscles. The presence of prominent cyanobacterial blooms dominated by toxic species highlights the need to undertake eutrophication control measures so as to avoid further toxicological problems.

Long term changes in the eutrophication process in a shallow Mediterranean lake ecosystem of W. Greece: response after the reduction of external load.

Lake Pamvotis is a shallow Mediterranean lake located in Western Greece near the city of Ioannina. The lake has been recognized as an internationally important conservation site under European Community legislation due to its rich biodiversity. However, during the last three decades the trophic status of the lake has changed as a result of anthropogenic activity (among others irrigation and domestic sewage discharge), resulting in serious problems. Here we present data about the long-term development in eutrophication of Lake Pamvotis. Water samples were collected and analyzed (water temperature, pH, dissolved oxygen, nutrients, chlorophyll-a) during three monitoring periods: 1985-1989, 1998-1999, 2004-2005. The high nutrient concentrations in the lake water during the three monitoring periods, as well as its eutrophic to hypertrophic status reflect the degree of impact anthropogenic activity has had on the lake. Commencement of a restoration plan in 1995-1996, involving sewage diversion, led to a reduction in external nutrient load and consequently to lower in-lake nutrients and Chlorophyll-a concentrations. Orthophosphate concentration decreased by about 87%, nitrates fell below 1.20mg/l, whilst the total reduction of inorganic N compounds showed a weaker downward trend, fluctuating between 0.39 and 1.24mg N/l with an average value of 0.76mg N/l. However, after a short-term recovery the eutrophic status of the lake remains eight years later (2004-2005), suggesting the importance of the internal loading process and the absence of the top-down effect of fish. This study provides evidence for the need of greater restoration efforts utilized in Mediterranean shallow lakes.

Copper and zinc in four freshwater fish species from Lake Pamvotis (Greece).

Lake ecosystems are vulnerable to heavy-metal pollution. Fish samples are considered as one of the most indicative factors, in freshwater systems, for the estimation of trace metals pollution potential. Lake Pamvotis (NW Greece) is a typical Mediterranean ecosystem of great importance in regard to biodiversity and to aesthetic value. The fish species found most commonly in the lake are Cyprinus carpio, Silurus aristotelis, Rutilus ylikiensis, and Carassius gibelio. The aim of the present study is to evaluate the level of contamination of two essential heavy metals (copper and zinc) appearing at high concentrations in lake water in the above four fish species. Metal concentrations were measured by atomic absorption spectroscopy in three different tissues (muscle, liver, gonads) in order to assess the fish contamination. A two-factor analysis of variance, based on the procedure of general linear models, was employed in which fish species (four levels) and fish tissue (three levels) were examined for potential influence on Cu and Zn concentrations. Differences between level means per factor were treated using Tukey's multiple comparisons of means. The study showed that C. carpio and R. ylikiensis presented the highest metal content. Tissues analysis revealed that liver and gonads accumulated the highest levels of Cu and Zn. Metal concentration in the edible part of the examined fish (muscle) were in the safety-permissible levels for human consumption.

Induction of gynogenesis and androgenesis in goldfish Carassius auratus (var. oranda).

Chromosome engineering was used to develop lines that expressed the stable phenotypic characteristics of goldfish, Carassius auratus (var. oranda). To obtain androgenetic individuals, carp eggs were irradiated and fertilized with sperm from goldfish bearing telescopic eyes. The fertilized eggs were divided into four groups and three of them were subjected to heat-shock treatment at 42 degrees C for 2.0 min at 34, 37 and 40 min after fertilization. All groups exhibited low viability of embryos and after hatching the embryos were severely deformed on the head, yolk sac and tail and exhibited 100% mortality, within 2 days after hatching. To obtain gynogenetic individuals, a thin layer of carp milt was subjected to ultraviolet irradiation for 26 min to neutralize its genetic material and used to fertilize a mixture of eggs derived from three different variations of C. auratus individuals with characteristics such as round fat body, triple tail, red and black colour and telescopic eyes. The fertilized eggs were divided into six groups and five of them were subjected to heat-shock treatment at 39.5 degrees C for 2.5 min at 15 (group 2), 20 (group 3), 30 (group 5) and 45 (group 6) min after fertilization. The percentage of fertilized eggs that survived ranged from 20 to 50% and the percentage of larval survival in groups 2-5 was 22-28% with lower levels in groups 1 and 6, ranging from 10-12%. However, 40-60% of the larvae exhibited severe deformities on the head, yolk sac and tail, whereas the rest developed normally. Fish with the typical oranda phenotype were observed in all the groups and about 1% of the fish were characterized by a triple tail but there was no fish with telescopic eyes. The results indicate that gynogenetic individual goldfish can be produced but that the induction of androgenesis requires further improvement of the techniques.

Distribution of Clostridium perfringens in different aquatic environments in Greece.

Clostridium perfringens and especially its spores, which are more tolerant to various physiochemical effects than the other fecal indicator bacteria, could serve as a useful indicator in ecosystems with stress factors. In order to determine the numbers of Clostridium perfringens in waters of rural North-West Greece, we utilised a new medium, lactose-sulfite (LS) broth, suggested for rapid enumeration and identification of Clostridium perfringens without the necessity for further confirmatory tests. Membrane filtration equipment was used on site. All samples were alternatively passed through two membrane filters, one (20-25 microns pore size) was used for retention of the abundant phytoplankton and the other (porosity 0.45 micron) for Clostridium perfringens. Membranes were placed into the first tube of 10-fold dilutions from 10(1) to 10(4) and incubated aerobically in a water-bath at 46 degrees C for 24 h. The numbers of Clostridium perfringens revealed fluctuations depending on the sampling site. It was significantly more common in the vicinity of industrial or domestic activities. LS broth not only allows the detection of small numbers of Clostridium perfringens but also permits rapid detection within 24 h. We propose the medium and the procedures described in this paper as a reliable technique for estimation of Clostridium perfringens as indicator of fecal contamination in waters.