Charophyte variation in sensitivity to eutrophication affects their potential for the trophic and ecological status indication

Abstract

Charophytes (stoneworts) form a group of macrophytes that are considered sensitive to eutrophication. The high indicator value of charophytes toward eutrophication results in their wide use in the bioassessment systems. I explored the variability of stonewort communities' requirements for trophic conditions in lowland temperate lakes and attempted to determine the role of individual syntaxa in assessing the ecological status of lakes in Poland. The position of charophyte communities' niches along the trophic gradient was analysed using the Outlying Mean Index approach. A few stonewort communities, i.e., Nitelletum opacae, N. mucronatae, N. flexilis and Charetum filiformis appeared to be specialised concerning water quality and may be considered indicators of habitats less eutrophic than the “mean” trophic conditions in the study domain. Most stonewort communities were relatively common in European waters. Four of them, i.e., Charetum tomentosae, C. asperae, C. contrariae and Nitellopsidetum obtusae, can be classified as ‘generalists’ with low marginality and broad ecological tolerance. Most stonewort communities appeared in a broad range of ecological status classes. In the case of 15 communities, 6 to 25% of occurrences were observed in lakes representing a less than good status, and they cannot be considered indicative of good ecological conditions. However, the high taxonomic diversity and extensive phytolittoral zone were most likely to occur when the phytocoenoses of stoneworts were present. In lowland naturally eutrophic lakes inhabited by eurytopic species, the extraordinary role of charophytes in the assessment of the ecological status can be interpreted through their significant contribution to the development of the littoral.

Minor effect of wind exposure and littoral slope on macrophyte characteristics in non-impacted lowland lakes of Poland

“…Water fertility, however, is only one of an array of factors that determine the habitat niche occupied by a species. The communities of Nitellopsis obtusae and Chara tomentosa were shown to occupy similar habitats concerning trophic conditions ( Kolada, 2021 ), whereas in this study we found they are indicative of different littoral slopes. The preferences of submerged plants to occupy different parts of the littoral zones results also from their tolerance to mechanical stress caused by water movements, hence, is determined, to a high degree, by growth-form ( Puijalon et al., 2011 ; Bertrin et al., 2018 ; He et al., 2019 ).…”

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

“…Chara contraria, C. globularis, and C. vulgaris are widely distributed species. They are generalists in many temperate regions [121]. Chara gymnophylla is the second most frequently found species in the area studied.…”

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

“…Other evidence for evaluation of Red List Category: This is one of the most common, generalist species in many temperate regions [ 42 ].…”

“…Other evidence for evaluation of Red List Category: The most common species in Central Asia is able to grow in a wide spectrum of habitats including newly created and maintained for millennia for irrigation in the region studied [ 63 ]. This is one of the common, generalist species from many temperate regions [ 42 ].…”

“…Recent studies have shown that water quality variables, such as temperature, pH, salinity, electrical conductivity, total dissolved solids, and nutrient saturation, affect charophyte spatial distribution, diversity, and ecology [ 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 ]. Nevertheless, the research on the effects of water quality on spatial distribution is yet to be undertaken in south and southeast Kazakhstan because these environmental relations might not be the same in different ecoregions, especially in the large arid regions from this study.…”