Phytoplankton dynamics and structure, and ecological status estimation by the Q assemblage index: a comparative analysis in two shallow Mediterranean lakes

Abstract

IntroductionShallow lakes in Mediterranean climates, which are generally situated in lowland areas, due to their high evaporation/precipitation ratios, low geographic relief, and dense human population have long water residence times and are becoming more eutrophic (Allan et al., 1980;Borics et al., 2013). Moreover, elevated release of phosphorus from sediments or greater loads from the catchment area and destruction of submerged vegetation may trigger an increase of phytoplankton density and a related decrease in water clarity (Moss et al., 2009;Dokulil and Teubner, 2011). The increased biomass of phytoplankton and frequently occurring toxic algal blooms triggered the reassessment of lake management strategies (Borics et al., 2013). The Water Framework Directive was deigned to assess the ecological quality of surface waters through the analysis of various characteristics of aquatic flora and fauna, and to declare management plans in European countries (EC, 2009). Investigation of the functional traits of phytoplankton of shallow lakes was found to be important to estimate ecological quality and to understand the operation of these systems (Borics et al., 2012).Many attempts have been made to categorize traits and functions of phytoplankton (Reynolds et al., 2002;Borics et al., 2007;Padisák et al., 2009). At present, 40 phytoplankton functional groups (FGs) have been described, identified by numeric character codes (codons) (Padisák et al., 2009). Padisák et al. ( 2006) developed an index (Q index) using FGs to estimate the ecological status of lakes. The index combines the relative weight of FGs in the total biomass and considers a factor number for each assemblage for each type of water body. It was tested on water bodies significantly differentiated by origin, altitude, salinity, mixing, and stratification in the world (e.g., Crossetti and Bicudo, 2008;Pasztaleniec and Poniewozik, 2010) and in Turkey (e.g., Demir et al., 2014;Çelik and Sevindik, 2015).Lake morphometry and hydrology are criteria for the composition of lake biota (Murray and Pullar, 1910), and may favor distinct life strategies. Nevertheless, even taking into account the hydromorphology, substantial differences are recognizable when considering the effects of latitude and climate on phytoplankton composition and abundance (Pollingher, 1990). Moreover, lakes that are located in the same geographic region and have similar hydromorphologies could be composed of diverse phytoplankton assemblages as a result of different nutrient content and light availability (Scheffer, 1998;Naselli-Flores, 2000). In addition, Borics et al. (2014) found

The Role of External Factors in the Variability of the Structure of the Zooplankton Community of Small Lakes (South-East Kazakhstan)

“…The minimum values of the abundance and biomass of communities were recorded in Lake Altynkol (abundance 8.5 × 10 7 cells/m 3 , biomass 0.52 g/m 3 ). These results were close to the values established for the most polluted water bodies of Argentina (abundance 6 × 10 6 to 8.30 × 10 6 cells/m 3 , biomass from 0.02 g/m 3 to 0.3 g/m 3 ) and Turkey (biomass 0.001 g/m 3 -0.05 g/m 3 ) [64,66]. The highest abundance of phytoplankton established in some lakes at a lower altitude was comparable to the quantitative variables of microalgae in wastewater reservoirs in South-East Kazakhstan (from 5.8917 × 10 9 to 6.2876 × 10 9 cells/m 3 and 4.77-5.62 g/m 3 ) [67].…”

“…Shannon phytolankton diversity varied from 0.46 to 3.69, but more often, it was at a moderate level-from 1.34 to 2.70 in the surveyed lakes. Similar Shannon diversities were found in water bodies of Turkey and Denmark with organic pollution [64,72]. Shannon's diversity index was very low (around 0.44-0.70) in wastewater reservoirs of South-East Kazakhstan, with the extreme level of pollution [67].…”

“…In summer of 2019, the phytoplankton of the surveyed lakes was represented by 74 taxa. A similar number of taxa were found in the phytoplankton of shallow water bodies in other regions of Kazakhstan (Northern Kazakhstan), Turkey, and Poland [63][64][65]. According to the network analysis results, phytoplankton species composition in the lakes at higher altitude differed from the composition of phytoplankton species in the lakes at lower altitudes.…”

“…Cyanobacteria dominated in abundance almost all surveyed water bodies, except for the Middle Kolsay, Ali, and Pervomayka. Cyanobacteria prevail mainly in water bodies with organic pollution [64,68]. The variability of hydrochemical parameters, especially phosphate concentration increase, led to cyanobacteria dominance in water bodies [68].…”

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“…Studies on the effects of environmental variables on distribution on algae started in the 80s (Altuner, 1984;Gönülol & Aykulu, 1984). and a huge amount of data on algal communities of various water resources was published so far (Akçaalan et al, 2014;OngunSevindik, 2010;Çelik & Ongun-Sevindik, 2015;Ongun-Sevindik et al, 2017). However, although the subject gained attention of many researchers, the dams in Thrace region was neglected except Kadıköy Reservoir on which a single study was performed so far (Öterler, 2013).…”