Charophytes (Charophyceae, Charales) of South Kazakhstan: Diversity, Distribution, and Tentative Red List

Abstract

The presented research was conducted during 2019–2022 in south and southeast Kazakhstan to document the species richness, distribution, and ecology of charophytes (Characeae) as a first step towards to estimate the need for species protection. Across the 54 sites, we found ten species and one variety. Chara vulgaris Linnaeus and C. contraria A.Braun ex Kützing were the most common species, followed by C. canescens Loiseleur, C. kirghisorum C.F.Lessing, C. tomentosa Linnaeus, C. dominii J.Vilhelm, C. globata W.Migula, Nitellopsis obtusa (Desvaux) J. Groves, and Nitella hyalina (De Candolle) C. Agardh. The list of localities for each species was compiled. The distribution of each taxon was mapped in relations to the ecoregions studied. The two most frequent species were found in a wide spectrum of ecoregions, whereas all other species occurred in only a few regions in Kazakhstan. The Kaskelen River Valley had the most sampled sites with the highest number of co-occurring species (up to five together). Statistical maps were plotted in attempt to outline key environmental variables explaining the distribution of each species. A comparison of species and environmental variables distribution maps lets us assume that C. vulgaris prefers low altitude habitats with higher water temperatures, organic enrichments, and color, but low oxygen and pH. Other species prefer clear, alkaline, organically unpolluted, and well-oxygenated waters in lowland habitats. The redundancy detrended analysis (RDA) defined pH and altitude as negative factors for Nitellopsis obtusa whereas an increase in water temperature was positive. Altitude and water temperatures affected Chara contraria positively while altitude negatively influenced the rare species: Chara tomentosa, C. kirghisorum, and C. dominii. The matK sequences were obtained for C. contraria and C. vulgaris to confirm their identity according to morphological traits and to compare populations of C. gymnophylla and C. vulgaris from an arid region in Israel. Our data allowed for the preparation of a tentative red list from the study region. One species was recognized as endangered, four species and one variety as vulnerable, and two species as least concern. There was insufficient data to determine the status of two species and one variety.

The Charophytes (Charophyceae, Characeae) from Dagestan Aquatic Habitats, North Caucasus: Biogeographical and Barcoding Perspectives

“…Chara globata is mainly a Central Asian species with several localities in Southeast Europe, North Africa, the Middle East, and China [26,35,49,75,101,124]. Its distribution area extends north of the Caucasus to the arid regions of Volga and Don Interfluve [75,107].…”

“…Chara globata is mainly a Central Asian species with several localities in Southeast Europe, North Africa, the Middle East, and China [26,35,49,75,101,124]. Its distribution area extends north of the Caucasus to the arid regions of Volga and Don Interfluve [75,107]. It is known from a few localities in the Caucasus, although its remarkable habit and size nearly exclude its undersampling during targeted searches for charophytes and allow it to be used as a flagship species for biogeographical studies [26].…”

Biodiversity, Ecology and Distribution of Mediterranean Charophytes in Southern Italy

“…Indeed, despite several species showing a preference for certain elevation ranges, with the highest community biodiversity at the lowest end, they are likely more sensitive to other environmental factors that vary with elevation, such as temperature, dissolved oxygen, and dissolved organic matter, than to the elevation itself [9]. The variations in environmental factors with elevation would therefore explain the importance of this repeatedly documented variable [65], with a clear example provided by C. vulgaris in south Kazakhstan, preferring low altitude habitats with higher water temperatures and organic compounds, as well as lower oxygen and pH [6].…”

“…Characeae (Charophyceae, Charales), hereafter referred to as charophytes, are a worldwide distributed group of macrophytes that comprise several species colonizing different Mediterranean aquatic habitats [1]. They derived their common name of "stoneworts" [2] from the stony external texture that several species acquire as a result of encrustation of their surface, mainly with calcium carbonate [3], and they are included in a number of red lists [4][5][6], since they represent the most endangered group of macrophytes [3,7,8] and one of the most threatened groups of organisms in Europe [1,9,10]. Many of the habitats dominated by charophytes are also of community interest [7] according to the Habitats Directive 92/43/EEC [11], and their conservation is thus considered under the Water Framework Directive 2000/60/EC [12].…”

“…Moreover, by counteracting resuspension of sediment particles [3,29,32], by acting as nutrient sinks [21,29,33], and by hampering phytoplankton biomass growth [4,10], charophytes participate in the establishment and maintenance of clear-water states [3,29]. As a consequence, charophytes characterize the pattern of ecological successions (in which they often represent pioneer species [6]) and the community structure of several types of water bodies [3,29]. Their conservation and the promotion of the establishment of charophyte meadows can thus prove pivotal in ensuring freshwater ecosystem functioning and dynamics [18,21].…”