Diatom composition of the rheoplankton in a rhithral river system

Abstract

-Diatom composition of the rheoplankton (phytoplankton) in the Sajó-Hernád river system (Slovakia and Hungary) was studied. Forty two sample sites were designated on the watershed from source to mouth of the two rivers and their tributaries. Samples were taken in July 2012. Altogether, 258 diatom taxa were identifi ed. The microfl ora was dominated by tychoplanktonic elements. According to the relative abundance of the occurring taxa, four groups could be distinguished. Differentiation of these groups was confi rmed by differences in the habitat characteristics, viz. altitude, width of watercourse, macrophyte coverage and river bed material. Diversity of diatom taxa in the phytoplankton was also studied. A positive relationship was found between the macrophyte coverage and the Simpson and the Shannon indices. In contrast, a negative relationship was shown between the macrophyte coverage and Berger-Parker diversity, in which metric the role of the dominant taxa is emphasized. Although the phytoplankton in rhithral rivers is infl uenced by stochastic events, our results reveal that geographical and hydromorphological characteristics of the rivers and coverage of macrophytes can also play role in shaping the composition and diversity of the phytoplankton.

Autumn drought drives functional diversity of benthic diatom assemblages of continental intermittent streams

“…Finally, the presence of planktic taxa was another characteristic of diatom assemblages in our perennial streams, which may indicate a water velocity reduction (B-Béres et al, 2017;Rimet and Bouchez, 2012). This characteristic is also a typical example of source-sink dynamic (Leibold and Chase, 2018), and can be frequently observed in small streams with lakes or reservoirs in their upstream sections (Bolgovics et al, 2015;.…”

Phytoplankton of rhithral rivers: Its origin, diversity and possible use for quality-assessment

“…Being the basis of the food chain, this group received considerable scientific interest since the early ages of oceanographic and limnological research. Although there is wealth of scientific information about phytoplankton assemblages of lakes, our knowledge about riverine phytoplankton is still limited (Szemes, 1967;Uherkovich, 1969;Schmidt, 1994;Kiss, 1995;Dokulil, 2013Dokulil, , 2014Bolgovics et al, 2015). Partly because the basis of the food chain is allochthonous material, and partly because respiration is greater than in-stream primary productivity, rivers are basically considered as heterotrophic systems (Welker and Walz, 1999), where autotrophic production is only of secondary importance.…”

“…The aim of this study was to investigate the phytoplankton and benthic algal communities in a relatively unaltered rhithral river system, focusing on the questions of how euplanktonic elements entrain into the riverine phytoplankton; (ii) how diversity of the phytoplankton changes at both site and catchment levels; and (iii) how riverine phytoplankton can be used in water quality assessment. In order to avoid terminological misunderstandings, we use the term rhithroplankton (Bolgovics et al, 2015) for the plankton of rhithral rivers in this study.…”

How length of light exposure shapes the development of riverine algal biomass in temperate rivers?

“…benthic taxa that entrained to the plankton after detached from the substrates (Bolgovics et al, 2015(Bolgovics et al, , 2017. Thus, phytoplankton of rhithral rivers strongly depends on the composition and biomass of the benthic algae living in the various habitats of the river bed and the current velocity has to be sufficient to keep benthic organisms in suspension.…”

“…In upper river segments, where WRT is not sufficient for the development of phytoplankton (Lucas et al, 2009), planktic assemblages consist primarily of suspended benthic elements (mostly pennate diatoms) entrained from various surfaces of the river-bed (Abonyi et al, 2012;Bolgovics et al, 2015Bolgovics et al, , 2017Várbíró et. al., 2007).…”