Interannual and Spatial Variability of Cyanotoxins in the Prespa Lake Area, Greece

Abstract

The Prespa Lakes area in Greece—comprised partly of lake Great and lake Lesser Prespa and the Vromolimni pond—has a global importance for biodiversity. Although the waters show regular cyanobacteria blooms, assessments of water quality threats are limited. Samples collected in 2012 revealed scattered and low microcystin (MC) concentrations in Great Prespa (<0.2 μg MC L−1) whereas considerable spatial heterogeneity in both total chlorophyll (2.4–93 µg L−1) and MC concentrations (0.04–52.4 µg MC L−1) was detected in Lesser Prespa. In 2013, there was far less spatial variability of MC concentrations in Lesser Prespa (0.4–1.53 µg L−1), however in 2014, increased concentrations were detected near the lakeshore (25–861 µg MC L−1). In Vromolimni pond the MC concentrations were on average 26.6 (±6.4) µg MC L−1 in 2012, 2.1 (±0.3) µg MC L−1 in 2013 and 12.7 (±12.5) µg MC L−1 in 2014. In 2013, no anatoxins, saxitoxins, nor cylindrospermopsins were detected in Lesser Prespa and Vromolimni waters. Tissue samples from carps, an otter and Dalmatian Pelicans contained 0.4–1.9 µg MC g−1 dry weight. These results indicate that cyanotoxins could be a threat to the ecosystem functions of particularly Lesser Prespa and Vromolimni.

Four Decades of Surface Temperature, Precipitation, and Wind Speed Trends over Lakes of Greece

“…For instance, lake warming may explain the increase in the occurrence of toxic cyanobacteria blooms that has been already reported for several lakes in Greece [56][57][58][59][60]. Rising temperature may enhance the cyanobacteria growth rate but also may increase the duration of the lake stratification which favors the buoyant cyanobacteria [61].…”

Drone-based water sampling and characterization of three freshwater harmful algal blooms in the United States

“…Concentrations of MC in Lesser Prespa ranged from 25 to 861 ug/L (ppb) in 2014. In addition to the spatial heterogeneity observed in MC toxin concentrations in Lake Lesser Prespa, a high variability was observed in the surface accumulation of cyanobacteria in 2012 (Maliaka et al, 2021). The cyanotoxin levels found in Lake Anna were much lower than the other lakes and were below the dog RUV level (Figure 4).…”

“…This variability of MC concentration within a distance of only 100 m highlights the importance of testing multiple water samples across space and time. Another example of spatial variability of MC toxins was observed in the Prespa Lakes, Greece during 2012-2014 (Maliaka et al, 2021). Concentrations of MC in Lesser Prespa ranged from 25 to 861 ug/L (ppb) in 2014.…”

“…Nutrient runoff from agricultural and industrial sites that has been linked to the overall health of aquatic environments (Fraterrigo and Downing, 2008;Anderson, 2012). An increase in phosphorus content could push a population of cyanobacteria to be nitrogen-limited and shift toxin production from one congener of microcystin to another (MC-RR to MC-LR) (Maliaka et al, 2021). MC-LR is ten-fold more toxic than MC-RR (Zurawell et al, 2005).…”

Harmful Blooms of Cyanobacteria: Adding Complexity to a Well-Studied Topic

“…In our Special Issue, we have assembled several case studies and three more general articles. The variability of cyanotoxins was examined in the Lakes Prespa system, which has received limited relevant studies despite its global importance for biodiversity [4]. The classic pattern of increasing cyanobacterial biomass and toxin concentration in response to an increasing lake trophy was confirmed, and cyanobacterial toxins were also retrieved from carp and pelicans.…”