Olga Petriki

DNA barcoding analysis of fish species diversity in four north Greek lakes

Materials and methods: The present study is the first to apply DNA barcoding on identifying 37 freshwater fish species from the rich Balkan ichthyofauna. Results: The results are highly successful since in most cases barcodes cluster according to species, in agreement with morphological taxonomic studies. This is also evident based on mean conspecific and congeneric Kimura two-parameter distance values. The 5.6-fold difference between these values is lower than previous barcoding studies, possibly due to the restricted samplings and the recent taxonomy reevaluation for several species. A number of species were identified, where future work is needed: For the species Scardinius erythrophthalmus, Perca fluviatilis, and Rutilus rutilus, the divergence values found among conspecific populations could warrant their placement into different species; for Barbus and Rhodeus populations, the reported interspecific distances found were lower than expected; and for Cobitis species, the application of barcoding seems problematic, due to their complicated reproduction. Conclusion: The extension of this work to other Greek or even Balkan freshwater systems should clarify the situation.

Food web modelling on the structure and functioning of a Mediterranean lentic system

AbstractΤhe ecosystem structure of a Mediterranean lentic system (Lake Volvi, Northern Greece) was assessed and quantified for the first time, using the Ecopath with Ecosim model. Biological and fisheries-related data were collected during 2014–2015 from field surveys; moreover, operational and other data concerning fisheries exploitation were assessed by interviews. The model will (a) describe the ecological structure of the lake in terms of trophic flows (b) disaggregate the impacts imposed by fishing and other factors on the food web and (c) investigate the ecosystem’s functional changes by testing the introduction of a new fish species. Lake Volvi constitutes a mature system whose food web is characterized by “bottom-up” processes, exhibiting a “good” systemic resistance to unexpected perturbations and a rather low intensity of fisheries exploitation. Simulations from 2015 to 2025 revealed that an increase in fishing effort and/or stocking with the new species will have negligible impact on the food web and will not affect negatively the fisheries resources and top megafauna. The model presented provides key ecosystem information that is lacking for most European freshwaters systems, which can be useful in assessing their ecosystem structure and in simulating the pressure of fisheries exploitation on their food web.

Range expansion of Pachychilon macedonicum (Actinopterygii: Cypriniformes: Cyprinidae) in Northern Greece

The cyprinid freshwater fish, Pachychilon macedonicum (Steindachner, 1892), is an endemic species in the Balkan Peninsula and has a restricted distribution in Greece. Here, we report new records of the species out of its known natural range, namely at the Mpogdanas Stream (drainage area of lakes Koronia-Volvi, northern Greece), which now constitute a new eastern limit for the distribution of the species in southern Balkans. It appears that the new record is related to a human-mediated translocation.