Nitella opaca [Bruzelius] Agardh [Characeae] w Wielkopolsce

This paper presents historical and new localities of Nitella opaca, a rare charophyte species whose distribution in the light of published data and herbarium material was restricted to a few localities in the Wielkopolska region. The basic information on the species ecology and detailed characteristics of phytocoenotic interrelation are provided. So far, the occurrence of Nitelletum opacae in the Wielkopolska region has not been reported

Comparative study of the oospore morphology of two populations of a rare species Chara baueri A. Braun in Cedynia (Poland) and Batzlow (Germany)

Morphological features of oospores of Chara baueri A. Braun, one of the rarest charophyte species worldwide, were studied based on 100 oospores collected from a small and temporarily dried mid-field pond near Cedynia, Western Poland. This is the first Polish and fifth presently known locality of this species. For comparison 67 oospores from a German population (similar pond localized near Batzlow, Germany) were also measured. So far, data on morphology of C. baueri oospores as well as the species ecology are limited. The only more detailed study of oospores for this species was earlier performed on 15 oospores from Kazakhstan. Largest polar axis (LPA, length), largest equatorial diameter (LED, width), isopolarity index (ISI = LPA/LED × 100), number of ridges, width of fossa, distance from apical pole to LED (AND) and anisipolarity index (ANI = AND/LPA × 100) were measured. The comparative analysis revealed that the oospores from Poland are generally bigger and more prolate than the German ones. The differences for most of studied parameters were statistically significant. The finding is discussed in the context of habitat differentiation of both studied sites. Moreover, the results obtained of oospore measurements for both populations differs from most of the data known so far from the literature

Effects of overabundant nitrate and warmer temperatures on charophytes: The roles of plasticity and local adaptation

Global change effects, such as warming and increases in nitrogen loading, alter vulnerable Mediterranean aquatic systems, and charophytes can be one of the most affected groups. We addressed the possible interaction between these factors on two populations of the cosmopolitan charophytes Chara hispida and Chara vulgaris. Populations were taken from two different environments, a nitrate-poor mountain lake and a nitrate-rich Mediterranean coastal spring. The laboratory experiment had a 2 × 2 factorial design based on two nitrate levels (similar to and double the local conditions) and two temperatures. Increased temperatures favoured the growth of the four populations, but an increase in nitrate did not have any effect on their growth or architecture. Both species took up and stored more nitrogen (measured as %N in plant tissue) when more nitrate was supplied, and warming favoured this increase in %N and, consequently, in N:P ratio. The effects of both factors depended on the local conditions where the populations originated and on the species. Chara vulgaris, a pioneer species, exhibited more phenotypic plasticity than C. hispida, and its ecotype from the coastal spring was better adapted to changes in temperature and nitrate level. These differential responses to warming conditions and nitrate pollution may modify charophyte diversity, which might be reflected in ecosystem performance, a matter of concern in vulnerable Mediterranean water bodies where these species co-occur.This study was supported by the Spanish Ministry of Economy and Competitiveness for research project CGL2014-54502-C2-1-P (including EC FEDER funding). Eric Puche is the holder of a grant (UV-INV-PREDOC16F1-383810) funded by the University of Valencia.Peer Reviewe