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

Abstract

Climate change is predicted to increase drought occurrence and severity in small continental watercourses. Here, we studied the structure and the functional diversity of benthic diatom assemblages in lowland intermittent and permanent watercourses of the Carpathian Basin. We assumed that the community structure of intermittent and permanent watercourses would be markedly diff erent, and the functional diversity in both would be strongly influenced by autumn drought. We found that intermittent streams were primarily characterized by small-sized generalists and aerophilic taxa, while permanent watercourses were inhabited by large-sized planktic or fast moving groups. The functional richness was significantly lower in intermittent than in permanent streams. This decrease in the functional richness of benthic algal communities may negatively aff ect the functioning of lotic algal communities. We conclude that diatom assemblages in lowland intermittent watercourses are sensitive indicators of changes in ecosystem properties, and should be considered in appropriate evaluation and management of extreme climatic events on aquatic ecosystems.

Trait‐based diatom functional diversity as an appropriate tool for understanding the effects of environmental changes in soda pans

“…The status of soda pans is dependent upon the maintenance of their natural hydrological cycle (Stenger‐Kovács et al, ). Drying out is a natural and required feature of the pans (Gavrilović et al, ), and this, in turn, can radically reduce functional diversity (B.‐Béres et al, ). Under pristine ecological status, not only small species numbers and species‐based diversity (Stenger‐Kovács et al, ), but also restricted trait variations can be found in the present study: Motile, small, elongated diatom species are characteristic (e.g., Nitzschia austriaca Hustedt, Nitzschia aurariae Cholnoky , Craticula elkab (O. Muller ex O. Muller) Lange‐Bertalot, Kusber & Cocquyt), indicating the harsh (high conductivity and turbidity, temporary drying out) environment (Stenger‐Kovács et al, ).…”

“…The application of functional traits and diversity indices as indicators of stressors of aquatic organisms is scarce (Ding et al, ). Only a few studies connecting structural patterns to the primary production are to be found (Niyogi, Lewis, & McKnight, ; Rowe, Sánchez‐España, Hallberg, & Johnson, ), and especially in the case of phytoplankton (Abonyi et al, ; Török et al, ) and benthic algal communities (B.‐Béres et al, ; Cibils, Principe, Márquez, Gari, & Albariño, ). However, diatoms are one of the most understudied groups of biota from this point of view (Alahuta et al, ), despite the possibility that diatom trait diversity (e.g., thickness of the valves, size, morphology or life strategies, and linking ability) may have a crucial role in environmental processes such as the ocean carbon pump (Tréguer et al, ).…”

“…In other words, these extreme ecosystems impose highly stressful conditions on the biota, making this a selection force for species, and consequently a strong driver of the selection of suitable traitsTeittinen, Weckström, & Soininen, 2018). Only functionally similar species can survive, causing low functional diversity not only in these saline and extreme ecosystems, but also in intermittent streams, where droughts (extreme events) also have negative effects on the functional diatom diversity (B.-Béres et al, 2019). As in terrestrial plant communities, low functional diversity is also characteristic in mountains with specific environmental conditions(Schneider et al, 2017).Of the factors examined, region, status, and watercolor type were found to have a considerable effect on the functional diversity of soda pans.…”

Groups of small lakes maintain larger microalgal diversity than large ones

“…They can provide detailed information about the ecosystem functioning and ensure a deep knowledge about ecosystem vitality. Thus, they have a remarkable role in conservation and environmental management (Padisák et al, 2006;Borics et al, 2007;B-Béres et al, 2019). In phytoplankton ecology, the functional group concept, proposed by Reynolds et al (2002), has become the most widely used classification system (Salmaso et al, 2015).…”

Long-Term Changes of Species Composition and Functional Traits of Epiphytic Diatoms in the Szigetköz Region (Hungary) of the Danube River

“…Oxygen requirement of the species present and the ratio of temporally aerophilic taxa are good indicators of trends related to change in water discharge. Studies of transient small water courses revealed that the proportion of aerophilic species in drying out sites was higher than in sites with constant water coverage [58,59]. During rehabilitation, increased water velocity associated with increased water discharge transported better mixed, oxygen-rich water into the tributary system, also indicated by the increase in the proportion of species with higher oxygen requirement.…”