Effects of flow variation on recruitment in a Central Missouri fish assemblage
No Thumbnail Available
Authors
Meeting name
Sponsors
Date
Journal Title
Format
Thesis
Subject
Abstract
Flow regimes structure river and stream fish assemblages, and changes to the natural flow regime are expected to lead to changes in the biotic communities over time. The effects of flow variation are particularly strong for early life stages of fishes, as they are often unable to find refuge from uninhabitable conditions or find adequate food resources to promote growth and survival. Our objectives were to determine if the effects of extreme flows on fish recruitment are predictable based on life history traits of species, and to learn how extreme flows affect habitat characteristics and food availability for age-0 fishes. To examine this, I sampled age-0 fishes in Richland Creek and a side channel of the Lamine River in central Missouri. I also examined food resource availability by surveying the benthic invertebrate and zooplankton communities at these sites. In 2023, a year with extremely low summer flows and a late flood, opportunistic fish species predominated samples. Benthic invertebrates and zooplankton were at relatively high densities prior to the late flood and recovered quickly at the Richland Creek site. In 2024, a year with multiple, successive spring floods and more consistent streamflows, opportunistic species still predominated samples, but large-bodied periodic species such as Bigmouth Buffalo Ictiobus cyprinellus, Longnose Gar Lepisosteus osseus, and Skipjack Herring Alosa chrysochloris were also represented in the samples after not being observed in 2023. Resource availability dropped dramatically, as densities of both benthic invertebrates and zooplankton were much lower in 2024 than in 2023. As a result, age-0 fishes relied more heavily on terrestrial food sources. This suggests that the effects of increasing flow variation may influence fish recruitment in many ways depending on the timing, magnitude, and frequency of these changes.
Table of Contents
DOI
PubMed ID
Degree
M.S.