Seasonal shifts in the assembly dynamics of benthic macroinvertebrate and diatom communities in a subtropical river

Abstract

Identifying seasonal shifts in community assembly for multiple biological groups is important to help enhance our understanding of their ecological dynamics. However, such knowledge on lotic assemblages is still limited. In this study, we used biological traits and functional diversity indices in association with null model analyses to detect seasonal shifts in the community assembly mechanisms of lotic macroinvertebrates and diatoms in an unregulated subtropical river in China. We found that functional composition and functional diversity (FRic, FEve, FDis, MNN, and SDNN) showed seasonal variation for macroinvertebrate and diatom assemblages. Null models suggested that environmental filtering, competitive exclusion, and neutral process were all important community assembly mechanisms for both biological groups. However, environmental filtering had a stronger effect on spring macroinvertebrate assemblages than autumn assemblages, but the effect on diatom assemblages was the same in both seasons. Moreover, macroinvertebrate and diatom assemblages were shaped by different environmental factors. Macroinvertebrates were filtered mainly by substrate types, velocity, and COD Mn , while diatoms were mainly shaped by altitude, substrate types, and water quality. Therefore, our study showed (a) that different biological assemblages in a river system presented similarities and differences in community assembly mechanisms, (b) that multiple processes play important roles in maintaining benthic community structure, and (c) that these patterns and underlying mechanisms are seasonally variable. Thus, we highlight the importance of exploring the community assembly mechanisms of multiple biological groups, especially in different seasons, as this is crucial to improve the understanding of river community changes and their responses to environmental degradation. K E Y W O R D SChishui River, functional diversity, functional traits, lotic assemblages, null model | 693 WANG et Al.

Harmonizing and Searching Macroinvertebrate Trait Information in Alpine Streams: Method and Application–A Case Study in the Three Parallel Rivers Region, China

“…And the number of traits to be included in the initial trait matrix for functional diversity calculation to adequately reflect the relationship between organisms and their environment is still unresolved (Maasri, 2019). Some studies used approximately a dozen traits (Statzner et al, 2005;Wang et al, 2020), while others used more than sixty (Feld et al, 2014). This significantly hinders relevant comparative studies and meta-analyses.…”

“…(2) There are still many studies on macroinvertebrate traits in China and the world using the binary method (Krynak and Yates, 2018;McKie et al, 2018;Wang et al, 2020). ( 3) The advantage of this approach is that it simplifies functional and even phylogenetic analyses, thus allowing an exploration of the dominant relationships between traits and macroinvertebrate taxa (Poff et al, 2006).…”

Differences in diversity and community assembly processes between planktonic and benthic diatoms in the upper reach of the Jinsha River, China

“…The relative importance of environmental and spatial processes on algal communities also may vary among seasons (Zhang et al, 2019;Wang et al, 2020). Seasonal variation in river flow tends to change hydrological characteristics and trophic status in the water bodies, and affects biotic community patterns, too (Biggs & Smith, 2002;Thomaz et al, 2007).…”

Stochasticity overrides deterministic processes in structuring macroinvertebrate communities in a plateau aquatic system

“…Generally, previous studies on community assembly mainly focused on the taxonomic dimension, while investigations on other dimensions of beta diversity emerged only recently. Moreover, existing studies have mainly been carried out in lowland rivers, streams, lakes, or ponds (Rocha et al 2018, Garcia‐Giron et al 2019, Hill et al 2019, Lindholm et al 2020, Wang et al 2020). However, studies conducted in high‐elevation plateau aquatic ecosystems are still largely lacking and centered on examining taxonomic diversity (Li et al 2019 a , b ).…”