Zooplankton communities in Mediterranean temporary lakes: the case of saline lakes in Cyprus

Abstract

Temporary saline lakes are diverse ecosystems mostly located in arid areas. In the Mediterranean region they are among the most remarkable, but also the most threatened habitats; thus, effective management and conservation plans need to consider their special hydrological and ecological features and requirements. They are mainly fishless systems and so zooplankton is the driver of the trophic cascade. Our aim was to determine zooplankton communities' composition and biomass in seven temporary saline lakes of Cyprus and investigate their relation with environmental variables. Salinity ranged between <2 and 300 ppt and was a key factor shaping zooplankton community. In hyposaline conditions zooplankton communities exhibited higher species diversity than in meso- and hypersaline conditions. Hyposaline lakes were dominated by Arctodiaptomus salinus (Daday, 1885), Daphnia magna Straus, 1820 and Moina brachiata (Jurine, 1820) in terms of biomass, while meso- and hypersaline lakes by anostracans Artemia salina (Linnaeus, 1758) and Phallocryptus spinosus (Milne-Edwards, 1840) or M. brachiata and D. magna highlighting competition as another factor shaping the zooplankton community. We conclude that zooplankton reflects environmental pressures, such as salinity fluctuations which are closely related to water level fluctuations, in the mostly fishless Mediterranean temporary saline lakes. Moreover, salinity fluctuations should be considered a key factor for typological considerations in quality assessments, restoration and management plans in temporary saline systems since it can reflect the hydrological variations on the communities across different years and seasons by salinity gradient even for the same water body.

Aquatic Invertebrate Community Resilience and Recovery in Response to a Supra-Seasonal Drought in an Ecologically Important Naturally Saline Lake

“…Saline lakes are also able to accumulate and recycle nutrients far better than freshwater systems, thus producing large quantities of food for fishes and Water 2021, 13, 948 2 of 18 birds [3]. These factors create a unique environment with an aquatic and semiaquatic community composition distinct from all other habitats [1,6].…”

“…Aquatic and semiaquatic biota residing in saline lakes are highly adapted to osmotic stress and, if the habitat becomes unfavorable through drying or increased salinity, are able to disperse to more favorable refuges or employ other mechanisms such as the production of resistant dormant life stages to bridge the unfavorable periods [1,35,41,42]. In general, aquatic biota of moderately saline lakes (salinity ≤ 10 g L −1 ) consists predominantly of halotolerant freshwater species, including many invertebrates with the ability to actively disperse or produce desiccation resistant life stages [6,43,44]. As salinity increases, species richness usually decreases with replacement of halotolerant species by halophilic species [1,6,43,44].…”

“…In general, aquatic biota of moderately saline lakes (salinity ≤ 10 g L −1 ) consists predominantly of halotolerant freshwater species, including many invertebrates with the ability to actively disperse or produce desiccation resistant life stages [6,43,44]. As salinity increases, species richness usually decreases with replacement of halotolerant species by halophilic species [1,6,43,44]. However, as there is a salinity threshold above which few, if any, biota are able to survive [20,45], hypersalinization is a serious threat to the biodiversity of moderately saline lakes.…”

Selection of an indicator to assess a highly modified saline ecosystem

“…The salt lakes that are exploited for the production of salt are extreme ecosystems that create particular habitats for a diversity of species (Soares et al, 2018). In this type of ecosystem, effective management and conservation plans must consider their special hydrological and ecological characteristics (Karagianni et al, 2018). In these extreme environments, organisms must adapt to stressful environmental conditions with high variations in abiotic factors (Korovessis and Lekkas, 2009).…”

“…In these extreme environments, organisms must adapt to stressful environmental conditions with high variations in abiotic factors (Korovessis and Lekkas, 2009). The trophic chain is intimately related to salinity, and salinity fluctuations should be considered a key factor for typological considerations in quality assessments, restoration and management plans in these ecosystems (Karagianni et al, 2018).…”