Multitrophic richness enhances ecosystem multifunctionality of tropical shallow lakes

Abstract

The role of multitrophic diversity in sustaining multiple functions simultaneously (multifunctionality) is still poorly understood in natural communities, especially in highly diverse aquatic ecosystems. Existing studies have focused on the effect of single trophic group on ecosystem function and on individual ecosystem functions, neglecting the fact that multiple trophic groups are needed to maintain ecosystem multifunctionality. Here, using a 16‐year database from tropical shallow lakes, we combined species richness of nine single trophic group into a unique measurement of multitrophic richness. We then investigated the influence of the richness within separate single trophic group and in a multitrophic context on ecosystem multifunctionality. We also investigated how removal of any single trophic group influence the effect of the multitrophic richness on multifunctionality; and how the interactions among multiple single trophic group affect multifunctionality. We showed that the multitrophic richness had a stronger positive effect on multifunctionality than the richness of single trophic group. The removal of each single trophic group decreased the effect of the multitrophic richness on multifunctionality. The larger predatory vertebrates and primary producers had stronger positive effects on multifunctionality, but the richness of basal trophic groups fuelled the large‐sized predators, thus indirectly contributing to increase multifunctionality. Our study highlights the need for preserving multiple trophic groups to sustain multifunctionality in highly diverse aquatic ecosystems; thus, trophic degradation of the ecosystems should strongly impair their functioning. A free Plain Language Summary can be found within the Supporting Information of this article.

Pervasive decline of subtropical aquatic insects over 20 years driven by water transparency, non-native fish and stoichiometric imbalance

“…The main drivers of the declines detected here were a combination of decreased turbidity and increased invasions of non-native insectivorous fish and changes in N : P stoichiometry over time. All these drivers exemplify human impacts caused by reservoir construction [12,24,25].…”

“…Decreased turbidity, which translates to increased water transparency, is closely related to sediment and nutrient deposition upstream, trapped by reservoir cascades built in the Upper Paraná basin [12]. In concert with increasing water transparency, the upper Paraná River floodplain underwent massive fish invasion caused by a hydroelectric power plant built downstream, which removed their natural geographical barrier (a set of waterfalls) separating the Lower from the Upper Paraná River [16,24,25]. The increase in non-native predators and water transparency likely strengthened the top-down control of insect prey which, bearing a dark integument, had reduced ability to camouflage.…”

“…Recent studies have reported a decrease in native fish diversity associated with accelerated invasions of non-native fish over time [24,25]. We sampled these non-native, insectivorous fish in each aquatic environment using two gear types: seines and gillnets.…”

Regime shifts in a shallow lake over 12 years: Consequences for taxonomic and functional diversities, and ecosystem multifunctionality

“…Furthermore, the clear state often supports a great diversity of organismal traits that underlie ecosystem functioning. For example, large‐sized apex predators and filter feeders control multiple ecosystem functions such as fluxes of nutrients, primary production and standing biomass (Moi, Romero, Antiqueira, Mormul, et al., 2021). The great diversity of traits related to feeding modes and habitat use during the clear state may enhance the overall resource utilization by communities, in turn increasing their ability to maintain ecosystem multifunctionality (Gross et al., 2017).…”

“…We then quantified an ecosystem multifunctionality index using a set of five ecosystem variables, including nutrient concentrations (in situ measurements of in situ measurements of total N and total P available in the water), algae production (biomass of edible algae), underwater light availability and standing animal biomass (biomass of fish community). Together, these variables provide proxies for primary production, photosynthetically active radiation, nutrient availability and standing biomass, which are important determinants of ecosystem functioning in shallow lakes (Austin et al., 2021; Moi, Romero, Antiqueira, Mormul, et al., 2021). We predicted that (a) the taxonomic diversity and FD of fish and zooplankton would be lower in the shaded and turbid states than in the clear state and that (b) ecosystem multifunctionality would be lower in the shaded and turbid states despite differences between single ecosystem functions (Hilt et al., 2017).…”