Efpraxia Mavromati

This study contributes to the knowledge of freshwater Oligochaeta from Greece by providing the first annotated checklist, with emphasis on species distribution and newly recorded taxa. The checklist is based on a comprehensive review of published literature combined with original data derived from field sampling conducted in the profundal and sublittoral zones of 18 Greek lakes. It includes all aquatic families except the Enchytraeidae. In total, 52 species are currently recognized from Greek inland waters, representing a substantial increase compared to the 26 species previously listed in the Global Biodiversity Information Facility (GBIF) database. The family Naididae is the most species-rich group (including 21 Tubificinae, 17 Naidinae, 5 Pristininae and 2 Rhyacodrilinae species), followed by Lumbriculidae with three species, while Haplotaxidae, Criodrilidae, Lumbricidae and Propappidae are each represented by a single species. Six species are newly recorded for Greece: Dero dorsalis Ferronière, 1899; Nais pardalis Piguet, 1906; Nais stolci Hrabě, 1981; Paranais frici Hrabě, 1941; Potamothrix vejdovskyi (Hrabě, 1941) and Lophochaeta ignota Štolc, 1886. Despite these additions, the known freshwater oligochaete fauna of Greece remains comparatively less diverse than that of several neighboring Balkan countries. Faunal similarity analysis indicates the closest affinity with Bosnia and Herzegovina and North Macedonia, and the lowest similarity with Kosovo. Rarefaction analysis suggests that sampling effort in lake habitats is approaching completeness; however, significant gaps persist, particularly in lotic systems, springs, ponds, and specialized microhabitats. Further systematic surveys are expected to considerably expand the known diversity and may reveal additional endemic taxa.

Until now, little information was available regarding phytoplankton communities of Greek lakes. In this study, we present the first comprehensive analysis of phytoplankton composition and biovolume, as well as their inter-annual variations, across 15 natural lakes in Greece from 2016 to 2021. The ecological status and trends of these lakes were assessed using HeLPhy, a phytoplankton index of the Water Framework Directive (WFD). Additionally, this study examined potential similarities among lakes based on the number of phytoplankton taxa identified, the composition of phytoplankton communities, and the ecological classification. A total of 462 phytoplankton taxa from 10 taxonomic groups were recorded in 287 phytoplankton samples collected between 2016 and 2021. The phytoplankton communities in all lakes were dominated mainly by Cyanobacteria, Bacillariophyta, and Chlorophyta. The highest number of phytoplankton taxa was recorded in Chlorophyta and Cyanobacteria taxonomic groups. Based on the HeLPhy index, the lakes were classified into four ecological status classes: high, good, moderate, and poor. Inter-annual variations in ecological classification were observed. Eight of the 15 lakes were classified as having good or better ecological status according to WFD criteria, with deep lakes generally exhibiting a better status than shallow lakes. Bacillariophyta were more prevalent in lakes with high and good ecological status, while Cyanobacteria were more abundant in poor status lakes and dominated in bad status lake-years. Lakes in moderate and poor status exhibited higher total phytoplankton and Cyanobacteria biovolume values. This research improves our understanding of the status and temporal variations of phytoplankton communities in Greek lakes.

The objective of this study was to investigate the effects of substrate type in macroinvertebrate assemblages in Mediterranean lakes. Samplings have taken place in the littoral zone of 21 lakes in Greece, between 2015 and 2018. We compared benthic macroinvertebrate assemblages among three substrate types of their littoral zones; sandy, covered with macrophytes and stony substrate. Benthic macroinvertebrate assemblages at sites with extended macrophyte cover differed only slightly in composition and abundance from the ones found in stony and sandy substrates. Coenagrionidae were indicative of sites covered with macrophytes and Oligochaeta and Erpobdellidae were representative of stony substrates. The type of substrate proved to be a statistically significant factor influencing the number of benthic macroinvertebrate taxa, the relative abundance of Oligochaeta and the relative abundance of Odonata. In the context of designing site-adapted management measures, priority could be given to the conservation and restoration of aquatic vegetation in lake littoral zones, which host rich macroinvertebrate assemblages with abundant taxa of Odonata.

A new multimetric index (HeLLBI) based on littoral benthic macroinvertebrates is presented in this paper for classification of Greek natural lakes, in compliance with the requirements of Water Framework Directive (WFD). The method was developed based on the collection of littoral benthic invertebrate fauna and environmental data from 109 sampling sites in 21 natural lakes of the Greek National Water Monitoring Network. We focused the analysis on the effects of shore morphological alterations and eutrophication to the littoral invertebrate fauna, identified to family level, except oligochaetes, which were identified as a class, and more particularly to taxonomic composition and abundance, to taxa sensitivity, and to richness/diversity. Three metrics were included in the multimeric index: the relative abundance of Odonata classes, the Average Score per Taxon, and the Simpson’s diversity index. The metrics were converted to ecological quality ratios and ecological class boundaries were defined. The final multimetric index HeLLBI is expressed as an arithmetic average of normalized ecological quality ratios of the above metrics and a final score was assigned to each lake. Pressure-response relationships of HeLLBI scores were statistically tested for morphological alterations, expressed as percentage of artificial shoreline, and eutrophication, expressed as total phosphorus. The HeLLBI scores correspond to ecological classes, according to WFD, and sampling sites with different ecological status contained distinct biological communities; those at high status where more diverse and with sensitive taxa and as the water quality deteriorated, macroinvertebrate assemblages consisted of fewer and more tolerant to degradation taxa. The HeLLBI method gave a reliable assessment of littoral benthic invertebrate fauna of Greek natural lakes and could be a useful tool for the classification of ecological status of other Mediterranean lakes.