Community assembly of rotifers based on morphological traits

Abstract

Trait patterns can give insights into how communities assemble under a functional perspective. We constructed a rotifer trait matrix related to food acquisition and predator defence and calculated Rao's quadratic entropy (Q) as an index of functional diversity to investigate trait patterns in different layers (0-2, 5-35, 0-35 m) for a 5-year dataset of Lake Tovel, Italy. Trait patterns were determined by comparing Q observed to Q from random communities. While trait patterns can be determined by species traits, richness, and abundance, in most samples, irrespective of layer, trait patterns could be solely attributed to traits indicating their importance for community assembly. Trait convergence dominated in the upper layer, while trait divergence dominated in the lower layer. Using logistic regression, we related trait patterns to environmental parameters. In the lower layer, trait divergence was linked to competition for food while trait convergence was linked to copepod predation. However, in the upper layer neither competitors nor predators influenced trait patterns, and we suggest that ultraviolet radiation and temperature were the main drivers of trait convergence. Our study indicated that environmental filtering drove rotifer trait patterns in the upper layer, whereas species interactions drove trait patterns in the lower layer.

Plankton dynamics across the freshwater, transitional and marine research sites of the LTER-Italy Network. Patterns, fluctuations, drivers

“…rotifers. Furthermore, rotifer vertical distribution and trait patterns are related to ultraviolet radiation and competition for food (Obertegger and Flaim, 2015;Obertegger et al, 2008). In lakes Santo and Scuro mesozooplankton…”

Comparative analysis of the spatio-temporal dynamics of rotifer community structure based on taxonomic indices and functional groups in two subtropical lakes

“…Functional diversity has been widely investigated and applied to studies of various types of aquatic biology, such as phytoplankton 20 , crustaceans 18 , 21 , and copepods 22 . As has been suggested by previous studies 23 , 24 , the trait-based indices of GR and GR′ have also been applied in rotifer community ecology, based on the feeding strategies and diets of the rotifer communities 24 – 27 . The functional diversity of crustacean zooplankton communities in 18 lakes in Canada experienced a linear decline over a TP gradient (as an index of trophic status), while species richness exhibited a unimodal relationship along the same gradient 18 .…”

Is the Cyanobacterial Bloom Composition Shifting Due to Climate Forcing or Nutrient Changes? Example of a Shallow Eutrophic Reservoir

“…At the same time, in the lower basin the zooplanktonic community switched from a dominance of Polyarthra and Bosmina during 2018 to a dominance of Keratella, Pompholyx and Daphnia in 2019, which could have been provoked by decreasing cyanobacteria in the phytoplankton community. Some zooplankton taxa such as the raptorial rotifer Polyarthra , or to a lesser extent the cladocerans Bosmina , are highly selective feeders avoiding cyanobacteria compared to filter feeders like Daphnia that thrive better in the absence of cyanobacteria [ 37 , 38 , 39 , 40 ]. A zooplankton community can also be top-down controlled by zooplanktivorous fish preferring large zooplankton such as Daphnia [ 41 ].…”