Scale‐dependent patterns of metacommunity structuring in aquatic organisms across floodplain systems

Abstract

Aim Evaluating how groups of organisms vary in dispersal capability and how environmental, spatial and temporal signals vary across multiple scales is critical to elucidating metacommunity theory. We examined whether the relative contributions of environmental, spatial and hydrological factors have different effects on organismal groups with different dispersal abilities at three spatial scales, and how this knowledge contributes to our understanding of metacommunity dynamics. Location Four major Brazilian floodplains, with the largest distance among them of 2,300 Km. Taxon 10 aquatic organismal groups, ranging from bacterioplankton to fish. Methods We sampled lakes connected to the main river in the low‐ and high‐water periods of each floodplain between 2011 and 2012. Different biological groups were analysed across three hierarchical spatial scales (fine, intermediate and subcontinental) within and between floodplain systems. We applied a series of partial redundancy analyses to estimate the relative contributions of environmental factors, spatial factors and hydrological period for each biological group. Results At the fine spatial scale, predominantly environmental factors and hydrological period structure metacommunities, although less so for microorganisms than for micro‐invertebrates and macro‐organisms. The relative importance of environmental factors increased at the intermediate spatial scale. At the subcontinental scale, the relative importance of spatial factors increased for all biological groups, but environmental factors remained the primary regulators of microorganisms even at the largest scale. Main conclusions This study design allowed us to make more robust inferences about the mechanisms responsible for regulating community structure of distinct biological groups at different spatial scales. Our results suggest that biological groups displaying distinct body size likely determine the spatial extent at which environmental, spatial and hydrological processes prevail as the primary regulators of community structure. These findings are important in guiding the conservation and management of floodplain biodiversity because these systems are naturally highly heterogeneous in space and time.

Model‐based decomposition of environmental, spatial and species‐interaction effects on the community structure of common fish species in 772 European lakes

“…Among those, a significant contribution of spatial effects was found for 12 river basins, suggesting that dispersal primarily within larger and lake‐rich river basins contributed to the similarity of lake fish communities. This result confirms similar studies showing that dispersal within river basins homogenizes the species composition at fine spatial scales (Beisner et al., 2006; De Bie et al., 2012; Lansac‐Tôha et al., 2021). In contrast, > 80% of all river basins listed in the CCM2 database contained fewer than five lakes, and 57% ( n = 119) of the river basins had only one lake for which we obtained the fish community data.…”

“…Selection represents deterministic differences in fitness among species, drift represents stochastic changes in species abundance, speciation creates new species, and dispersal is the movement of organisms across space. The effects of speciation and drift on local communities can be inferred only from following community composition over time, whereas information on the effects of selection and dispersal can be obtained from comparisons of community composition across large spatial and environmental gradients (e.g., Boulangeat et al., 2012; Cazelles et al., 2016; Lansac‐Tôha et al., 2021). The metacommunity model of dispersal assumes a network of small local communities linked by dispersal among them (Holyoak et al., 2005).…”

“…Freshwater lakes are good model systems for exploring the relative effects of dispersal, abiotic conditions and species interactions on community assembly, because lakes can be considered as relatively discrete ecosystems within the terrestrial landscape, potentially with a hydraulic connection to other similar ecosystems (Heino et al., 2021; Jackson et al., 2001; Tonn et al., 1990). The metacommunity structure of several organism groups in freshwater lakes has been demonstrated empirically (Beisner et al., 2006; De Bie et al., 2012; Heino et al., 2015; Lansac‐Tôha et al., 2021), with differences in the dispersal intensities of organisms determining the spatial extent at which environmental, spatial and hydrological processes structure aquatic communities. For example, in Brazilian floodplain lakes, environmental factors interact with hydrological period to structure communities of micro‐ and macro‐organisms at the smallest (within floodplain) spatial scales, whereas species distributions are not dispersal limited.…”

“…For example, in Brazilian floodplain lakes, environmental factors interact with hydrological period to structure communities of micro‐ and macro‐organisms at the smallest (within floodplain) spatial scales, whereas species distributions are not dispersal limited. Between floodplains, the relative importance of environmental factors increases, whereas spatial factors become most important at the subcontinental scale, especially for poor dispersers (Lansac‐Tôha et al., 2021). Other studies on freshwater invertebrates across large spatial scales suggest that, in addition to spatial factors, climatic gradients (e.g., temperature, precipitation) and ecosystem size are dominant predictors of species richness, community composition and average organismal size in lakes (Hayden et al., 2019; Meerhoff et al, 2012).…”

Editorial: Spatio-Temporal Dynamics of Metacommunities - Implications for Conservation and Management

“…According to metacommunity theory (Leibold et al, 2004), the structure of local communities results from the interplay between local factors (e.g., environmental filtering, species interactions) and regional factors (e.g., dispersal rates, landscape configuration). The relative importance of these factors is highly dependent on the organisms' biological traits, landscape connectivity, and the spatial and temporal scales considered (Heino et al, 2015;Tonkin et al, 2018;Viana and Chase, 2019;Almeida-Gomes et al, 2020;Cañedo-Argüelles et al, 2020;Lansac-Tôha et al, 2021). However, the differences in metacommunity assembly mechanisms found among studies are far from being fully understood.…”