Comparisons of zooplankton and phytoplankton in created shallow water habitats of the lower Missouri River: implications for native fish

Abstract

Shallow water habitat (SWH) is important for riverine fish and their invertebrate prey, yet the availability of SWH has declined in many systems due to human impacts. We evaluated the potential ecological benefits of restoring SWH by comparing zooplankton and phytoplankton from created backwaters (a floodplain feature connected to the river on the downstream end but disconnected at the upstream end) and chutes (a side channel of the river that diverts flow from the main channel through the chute and back into the main channel) on the lower Missouri River. We tested the hypothesis that backwaters support higher abundances of zooplankton and phytoplankton than chutes using data that were collected during the summer of 2010. As predicted, backwaters had more diverse cladoceran communities and greater abundances of rotifers, copepod nauplii, adult copepods, and cladocerans than chutes. Total algal biovolume was the same in chutes and backwaters; however, phytoplankton taxa richness was higher in backwaters, and there was a greater biovolume of green algae (Chlorophyta), Crypotophyta, cyanobacteria, and Euglenophyta in backwaters than in chutes. Differences in zooplankton and phytoplankton between backwaters and chutes appeared to be related to slower current velocities, longer retention times, and lower levels of turbidity and total suspended solids in backwaters. While chutes have the potential to provide greater habitat diversity than the mainstem, there were no differences in water quality or phytoplankton abundance, community structure, or diversity between these two habitats. Combined, our results suggest that created backwaters initially provide a greater potential food resource for native fishes. However, additional research is needed to determine whether chutes can also develop beneficial shallow water features over a longer period of time.

Assessment of Missouri River floodplain invertebrates during historic inundation: implications for river restoration

“…Thus, high densities of rotifers were sampled during the first month of high water at all three floodplain sites. Mean rotifer densities sampled during the first month of floodplain sampling often exceeded those sampled from other lower Missouri River habitats including created backwater (<35 rotifers•L −1 ) and SWH chute sites (<10 rotifers•L −1 ) (Dzialowski et al, 2013) and the mainstem of the Missouri River near Dalbey (<100 rotifers•L −1 , USACE unpublished data); in contrast, mean densities from mainstem samples near Baltimore were as high as 290 rotifers• L −1 (USACE unpublished data) demonstrating that rotifer densities in the mainstem are capable of exceeding floodplain densities. Additionally, taxa richness, evenness and diversity peaked early at Baltimore and Dalbey (excluding trip 6 because of the lentic conditions discussed above).…”

Environmental requirements and heterogeneity of rheophilic fish nursery habitats in European lowland rivers: Current insights and future challenges

“…With relatively low water temperatures in European temperate lowland rivers, shallow habitats with a gentle bank slope warm up relatively fast in spring and summer. They often contain broad temperature gradients, which is beneficial for zooplankton production (Dzialowski et al, 2013; Górski et al., 2016) and for the metabolic processes in small fishes (Schiemer et al, 2002). The way in which both YOY fish and their prey respond to the interplay of river discharge, flow patterns and temperature, plays a major role in the population success of river fish (Humphries et al., 2013).…”

Lethal Thermal Maxima for Age‐0 Pallid and Shovelnose Sturgeon: Implications for Shallow Water Habitat Restoration

“…Shallow depths combined with slow‐moving water are prone to daily and seasonal temperature fluctuations that can influence the growth of age‐0 Scaphirhynchus spp. (Dzialowski et al ., ). Based on empirical SWH data from the Missouri River, we found that water temperature rarely exceeded 30 °C, a temperature that would not directly imperil sturgeon during a typical growing season.…”