Repeated flood disturbance enhances rotifer dominance and diversity in a zooplankton community of a small dammed mountain pond

Abstract

The zooplankton community in a relatively small and mountain pond was studied during the spring growing season. To investigate which factors operate in the community structure, we explored several physical conditions, such as high inflows, and the biotic dynamics of the main zooplankton groups (i.e., rotifers, cladocerans and copepods). Two extreme flood events occurred during the investigated period and caused dramatic changes in physical conditions and reduction of the planktonic community abundances. The short period between both high-flow events was enough for the recovery of microplankton, but not for the metazoan zooplankton. Our results are in agreement with the common situation in which high flood events commonly favour rotifers over crustaceans, likely due to rotifer species have great colonization ability and grow faster. However, we found that the dominance of rotifers over crustaceans in our system is evidenced by an extremely, unusual high ratio between their abundances. We observed that, at the time of the great floods, crustacean abundances as well as rotifer populations notably decreased until near zero values. Although rotifer abundance began declining before high floods, the decrease was particularly notable when the great flood happened. Our results evidenced that i) dilution rate and temperature were the main drivers which are operating in the structure of the zooplankton community; and ii) no negative biotic interactions were detected between large and small cladocerans and rotifers. Additionally, we found surprisingly that a repeated disturbance caused by high flood events does increase the species diversity of rotifers. Finally, our study also detected some cues which may indicate that diapausing egg bank is also playing an important role in the zooplankton community, favouring the dominance of rotifers; however, this phenomenon deserves further studies.

Damming interacts with the flood pulse to alter zooplankton communities in an Amazonian river

“…Rotifers respond more quickly relative to larger zooplankton owing to their short generation times (Gillooly, ), better colonising abilities (Gabaldón et al., ), and their adaptability to short‐term environmental variability (Balkić, Ternjej, & Špoljar, ). Water‐level fluctuations affect rotifers (Frutos et al., ); they are expected to dominate after a high‐water period, recolonising the water column, reaching peak densities and reproducing rapidly at the expense of other species (Dickman, ; Frutos et al., ; Gabaldón et al., ). Three testate amoebae species had their density peaks coinciding mainly with the flood period pre‐dam when, in general, the other zooplankton groups were at their lowest densities.…”

“…In unimpounded ecosystems, the natural water flow and hydrological periods of floodplains can positively influence the diversity of aquatic organisms through the interaction of several factors that act at different spatial and temporal scales (Bunn & Arthington, ). For example, the natural flooding process reduces the interaction between organisms through dilution (Angeler, Alvarez‐Cobelas, Rojo, & Sánchez‐Carrillo, ; Quintana et al., ), thereby reducing competition and consequently, increasing biodiversity (Gabaldón et al., ). Moreover, flooding of areas adjacent to the main river also provides periodic connectivity between habitats, promoting biotic and abiotic homogenisation and favouring species dispersal (Bunn & Arthington, ), which may also reduce the risk of local extinctions (Braghin et al., ; Thomaz et al., ; Ward, Tockner, & Schiemer, ).…”

“…Rotifers usually reached their greatest density and richness values in the low-water period. Rotifers respond more quickly relative to larger zooplankton owing to their short generation times (Gillooly, 2000), better colonising abilities (Gabaldón et al, 2017), and their adaptability to short-term environmental variability (Balkić, Ternjej, & Špoljar, 2018). Water-level fluctuations affect rotifers (Frutos et al, 2006); they are expected to dominate after a high-water period, recolonising the water column, reaching peak densities and reproducing rapidly at the expense of other species (Dickman, 1969;Frutos et al, 2006;Gabaldón et al, 2017).…”

“…In unimpounded ecosystems, the natural water flow and hydrological periods of floodplains can positively influence the diversity of aquatic organisms through the interaction of several factors that act at different spatial and temporal scales (Bunn & Arthington, 2002). For example, the natural flooding process reduces the interaction between organisms through dilution (Angeler, Alvarez-Cobelas, Rojo, & Sánchez-Carrillo, 2000;Quintana et al, 2006), thereby reducing competition and consequently, increasing biodiversity (Gabaldón et al, 2017).…”

Phage-centric ecological interactions in aquatic ecosystems revealed through ultra-deep metagenomics

“…Vertical profiles of the physicochemical characteristics of the water column (temperature, pH, oxygen; GRYF XBQ4, Havlíčkův Broc, CZ) and chlorophyll a (FluoroProbe TS-16-12, bbe Moldaenke, Kiel, Germany) were also taken. Site II: Jiřická pond (Czech Republic, 48.616034 N 14.676594 E) with 0.0356 km 2 , volume 6.59 x10 3 m 3 , pH 5.6-6.2, maximum depth 3.7 m, retention time ~5-7 days, dystrophic, located in the Novohradské mountains of Southern Bohemia [21]. Five samples were collected from the epilimnion (0.5m) from May 2016 to August 2017.…”