Ioannis Leonardos

Accumulation of microcystins in water and fish tissues: An estimation of risks associated with microcystins in most of the Greek Lakes

Toxin‐producing cyanobacteria in lakes and reservoirs form a threat to humans as well as various forms of aquatic life. This study is an investigation into the occurrence and distribution of Microcystins (MCYST) in 13 Greek Lakes. The distribution of MCYST in water and surface scum and toxin bioaccumulations in the omnivorous fish species Carassius gibelio were surveyed in all lakes. Considerable amounts of MCYST were found in water and scum of all lakes, irrespective of the trophic state, the type of the lake, and the reported dominant cyanobacterial species. Toxin accumulation in six tissues (liver, brain, intestine, kidney, ovary, and muscle) of C. gibelio was also analyzed. Even though the target organ for MCYST is the liver, in our study, MCYST were found also in the rest of C. gibelio tissues in the following order: liver > intestine > kidney > brain > ovaries > muscle. Risk assessments were carried out, taking into account the WHO guidelines and the tolerable daily intake (TDI) for MCYST. Our findings suggest that the amounts of MCYST found in water of Lakes Kastoria, Koronia, Pamvotis, Doirani, Mikri Prespa, Petron, and Zazari, pose adverse health risks. Also, it is likely to be unsafe to consume C. gibelio in Lakes Koronia, Kastoria, Pamvotis, and Mikri Prespa due to the high concentrations of accumulated MCYST.

Assessment of microcystin distribution and biomagnification in tissues of aquatic food web compartments from a shallow lake and evaluation of potential risks to public health

The objectives of this study were: (1) to examine the distribution and bioaccumulation of microcystins in the main components of the food web (phytoplankton, zooplankton, crayfish, shrimp, mussel, snail, fish, frog) of Lake Pamvotis (NW Greece), (2) to investigate the possibility of microcystin biomagnification and (3) to evaluate the potential threat of the contaminated aquatic organisms to human health. Significant microcystin concentrations were detected in all the aquatic organisms during two different periods, with the higher concentrations observed in phytoplankton and the lower in fish species and frogs. This is the first study reporting microcystin accumulation in the body of the freshwater shrimp Atyaephyra desmsaresti, in the brain of the fish species common carp (Cyprinus carpio) and in the skin of the frog Rana epirotica. Although there was no evidence for microcystin biomagnification, the fact that microcystins were found in lake water and in the tissues of aquatic organisms, suggests that serious risks to animal and public health are possible to occur. In addition, it is likely to be unsafe to consume aquatic species harvested in Lake Pamvotis due to the high-concentrations of accumulated microcystins.

Biological traits of rare males in the population of Carassius gibelio (Actinopterygii: Cyprinidae) from Lake Pamvotis (north-west Greece)

The gynogenetic population of Prussian carp Carassius gibelio in Lake Pamvotis (north-west Greece) included a small percentage of males (2-3%). Cytogenetic analysis revealed heterogeneity of the population at the ploidy level: all females were triploid (modal chromosome number 156-162 chromosomes) while the males were either triploid (modal number 156-158 chromosomes) or tetraploid (modal number 200-214 chromosomes). Morphometric analysis revealed significant differences in body shape among these three groups. The males were more slender than females, while the triploid males could be discriminated from the tetraploid by the morphology of their caudal peduncle. The males attained a significantly lower asymptotic standard length (L(S)) (25.04 cm) than females (29.75 cm) and had lower exponent b of the L(S) and mass relationship. Under laboratory conditions, intraspecific crossings of C. gibelio males with females could give viable all-female offspring; in comparison with goldfish Carassius auratus males, the fertility of the C. gibelio males was generally reduced but remained highly variable among individuals.

Typology, classification and management issues of Greek lakes: implication of the Water Framework Directive (2000/60/EC)

The European Water Framework Directive 2000/60/EC, requires the determination of ecological status in European waterbodies, based primarily on biological indicators, and that minimum good ecological quality is obtained by 2015. We used background morphometric, hydrologic, physico-chemical and biological data, in order to assess the typology of the main Greek lakes. Correlation analysis and multivariate analysis (Principal Component Analysis) were applied for the data statistical elaboration. Lakes were classified according to the characteristics suggested in the Directive and specified in the Annex II. Statistical analysis revealed significant correlations between the lake variables as well as the grouping of the Greek lakes according to their abiotic characteristics. Lake water uses, in most cases competed each other, were identified and management practices were also recorded. We suggest that the future conservation efforts should focus on a new holistic management philosophy taking into consideration the catchment’s management.

Biogeography of freshwater fishes of the Balkan Peninsula

Delineating biogeographical regions is a critical step towards the establishment and evaluation of conservation priorities. In the present study, we analysed the distribution patterns of the freshwater fish of an understudied European biodiversity hotspot, the Balkan Peninsula. Based on the most extensive available database of native freshwater fish species distributions, we performed a hierarchical clustering analysis to identify the major biogeographical regions of the Balkan Peninsula. We also highlighted the ‘hottest hotspots’ of freshwater fish diversity across the delimited biogeographical regions by describing the patterns of species richness, endemic and vulnerable species; indicator species were also determined. The bioregionalisation scheme consisted of eight groups of drainage basins that correspond to distinct regions of the Balkan Peninsula. Overall, the delineated biogeographical regions varied in terms of species richness, endemism, vulnerability (i.e. extinction threats) and indicator species composition. From a conservation perspective, this study emphasises the prioritisation of areas characterised by high levels of irreplaceability (endemism) and vulnerability (i.e. the Attikobeotia region, Ionian Sea and Prespa Lakes) and stresses the necessity of implementing a network of protected freshwater areas across the Balkan Peninsula.

Detection of microcystins in Pamvotis lake water and assessment of cyanobacterial bloom toxicity

Lake Pamvotis is a shallow, eutrophic Mediterranean lake with ecological significance. This paper deals with the evaluation of cyanobacterial toxicity in Lake Pamvotis. ELISA and HPLC revealed the presence of significant amounts of MCYST-LR. Danio rerio bioassay confirmed the toxic nature of the bloom. Cyanobacterial extracts had adverse toxic effects on development of D. rerio. Also, it was shown that cyanobacterial extracts containing environmentally detected concentrations of MCYST can cause reduced survival rate of fish species. The results clearly indicate that cyanobacterial blooms in Lake Pamvotis may be regarded as human and fish health hazard. Continuous monitoring of the lake is suggested, in order to prevent future possible intoxications.

Threatened fishes of the world: Phoxinellus epiroticus (Steindachner 1895) (Cyprinidae)

Common name: Tsima. Conservation status: This species is listed as data deficient in IUCN, World Conservation Monitoring Centre (Baillie & Groombridge 1996). Identification: Body laterally compressed; dark green back, fading gradually to silver or white in the abdomen; a dark single wide stripe on each side of the body. Caudal peduncle relatively thin; pelvic fins narrow and relatively long; the mouth is terminal. The first rays of the dorsal and anal fins are relatively short reaching to the half of each second ray. Scales tiny cycloid, thin and deeply inserted in the skin; lateral line is incomplete, extends maximally up to the height of the ventral fins. Vertebrae 31, D III, 6-7, P I, 14-15, A III, 6-7, V II, 7, principal caudal rays 22 (19-23), pored LL 15-22, pharyngeal teeth 5-5. Gillrakers 11 rather dense, long and thin. P. epiroticus is short-lived, longevity is about 2–3 years, with rapid growth during the first year of life, attaining 5–6 cm TL. Maximum size 10 cm TL, rarely exceeding 7 cm (Prassa et al. 2003). Distribution: P. epiroticus is endemic in Lake Pamvotis of Epirus, NWGreece (Stephanidis 1974). Abundance: Until the end of the 1980s, P. epiroticus was very abundant but heavily exploited. It is now considered critically endangered. Habitat and ecology: P. epiroticus is a schooling fish often found in association with spring outflows and adjacent to aquatic macrophytes. They feed on a wide range of small aquatic invertebrates especially crustaceans, algae, larvae of winged insects, small insects and worms. Reproduction: Sexual maturity is reached during the first year of life. Spawning occurs from middle of March to end of April. Spawning sites are near springs and inflows of water. Eggs are yellowish, adhesive and deposited mainly on aquatic plants. Threats: P. epiroticus is nearly extinct due to the cumulative impacts of habitat degradation and fragmentation by ecologically unsustainable agricultural development. This includes excessive water abstraction, eutrophication, changes in the physicochemical parameters of the water, water level fluctuations during spring and the absence of submerged macrophytes (due to the increased turbidity and alien fish species (e.g. Ctenopharyngodon idellus) nutritional preferences). Its current status may also be attributed to the presence of indigenous predatory species such Silurus aristotelis but in particular European eels (Anguilla anguilla). The numbers of eels have increased recently due to management of the population by local fishermen. Alien cyprinid species have also been introduced (Economidis 1991) which compete with P. epiroticus for feeding and/or spawning grounds. Furthermore, the species is subject to predation from water snakes and several aquatic birds, especially great cormorants (Phalacrocorax carbo) which have increased in numbers during the last decade (Perdikaris et al. 2003). The above threats in combination with the intensive fishing pressure, practiced by local fishermen, have significantly decreased the P. epiroticus population. Conservation action: P. epiroticus is included in the Annex II of the European Council Directive 92/43 ‘‘The Conservation of Natural Habitats, Wildlife and Flora’’. Conservation recommendation: Provisions should be made to protect the species and its habitat in order to ensure its survival. The long-term key remains effective habitat conservation and rehabilitation, including prevention of the further spread of invasive alien fishes, the education and co-operation of fishermen. A detailed study of current distribution, population status and the biology and ecology of species is required. Spawning protocols must be established in order to increase the size of the population. Moreover, it is absolutely necessary to list this species as critically endangered.

The reproductive behavior of Economidichthys pygmaeus: secondary loss of sound production within the sand goby group?

In this study, the reproductive behavior of Economidichthys pygmaeus was investigated under laboratory conditions with simultaneous video and acoustic recordings. Males of the freshwater goby E. pygmaeus do not produce sounds either during the courtship/spawning phase or during aggressive interactions. A detailed analysis of the behavioral sequences revealed the absence of any digging and nest-building activities, whereas the other behavioral components of courtship and spawning are similar to those described for other goby species, showing also a similar function. Results were discussed in terms of secondary loss of sound production within the sand gobies, a group of highly soniferous fishes in the family Gobiidae.

Life History Traits of Ylikiensis Roach (Rutilus ylikiensis) in Two Greek Lakes of Different Trophic State

ABSTRACT The possible influence of trophic state on the life traits of a Greek endemic cyprinid fish (Rutilus ylikiensis) was investigated in two contrasting lakes. Lysimachia Lake is a eutrophic and very polluted shallow lake, while Trichonis Lake is an oligotrophic to mesotrophic, clearer, and deeper lake. Significant differences between the lakes were found in relation to the life history traits of the fish. In the eutrophic lake, fish achieved higher age and spawned more but smaller eggs than in the oligotrophic lake. In the eutrophic lake, females achieved higher age than males and the overall sex ratio of males: females was 1:3.42. The extrapolated mortality rate for females was significantly lower than that for males. Females were significantly heavier than males of the same length. In contrast to the above, no such differences between sexes were found in the oligotrophic lake.

LENGTH-WEIGHT RELATIONS OF 22 FISH SPECIES FROM THE LITTORAL ZONE OF THE EASTERN IONIAN SEA, GREECE

Length-weight relations are presented for 22 fish species caught in the littoral zone of the eastern Ionian Sea. Mean values of b ranged from 2.58 to 3.43. For Greek waters no information regarding the LWR existed for 2 of the recorded species. This is the first study on the LWR for species of the littoral zone of the east - ern Ionian Sea which may be helpful in future fisheries studies in this area.