Effects of reservoir management on abundance, condition, parasitism and reproductive traits of downstream mussels

Abstract

The large-scale impoundment of rivers has led to global declines in freshwater mussel populations. It is important to understand the mechanisms underlying these declines to initiate an effective recovery strategy. We examined population traits of three Quadrula species (Quadrula pustulosa, Q. cylindrica and Q. quadrula) at three locations that were exposed to two different reservoir management regimes: releases that mimicked natural flow patterns and releases that were higher and colder in summer months than the natural system. We found lower mussel density, higher hermaphroditism and parasitism rates, and reduced body condition downstream of the dam with unnatural flow regimes. Sex ratios varied on a species and site basis. We found more Quadrula cylindrica females than males averaged across all three sampling sites while Q. pustulosa was male biased across all sites and at site 1. We observed approximately equal sex ratios in Quadrula quadrula. Population disturbances downstream of the more naturally-regulated dam were not as severe. Our data indicate that dam operation can have effects on a variety of mussel life history characteristics that may ultimately reduce population viability.

A Tale of Two Rivers: Implications of Water Management Practices for Mussel Biodiversity Outcomes During Droughts

“…Such releases need to be planned carefully based on the dynamics of specific rivers and species life history and habitat needs. For example, hypolimnetic water releases that lead to higher water levels and cooler temperatures during summer months can affect mussel gamete development, parasitism rates, and body condition (Galbraith and Vaughn 2009;Galbraith and Vaughn 2011), and even inhibit mussel reproduction (Layzer et al 1993;Peterson et al 2011).…”

“…The influence of stream flows on mussels is pervasive, making them a model study system to investigate the environmental effects of hydrological alterations. Mussels rely on predictable stream flows for reproduction (Galbraith and Vaughn 2011), the maintenance of tolerable temperatures (Gagnon et al 2004;Spooner and Vaughn 2008;Gough et al 2012) and stable habitats (Allen and Vaughn 2010), as well as the abundance of host fish required for juvenile mussel recruitment (Roy et al 2005;Vaughn 2012). Changes in hydrology due to dam construction and river channelization is considered to be the primary cause of mussel declines in the US (Vaughn and Taylor 1999;Strayer et al 2004), and effects of climate change and water withdrawals are predicted to accelerate mussel declines in the future (Spooner et al 2011).…”

Temperature effects on burrowing behaviors and performance in a freshwater mussel

“…Anthropogenic causes such as industrial outflows, damming, and management of water can have substantial effects on their thermal regimes and, in turn, on metabolic and vital rates of the organisms in them (Poff and Hart 2002). Some of these practices already have documented effects on downstream mussel fauna (Galbraith and Vaughn 2011). Alterations of thermal regimes, due to either natural or anthropogenic reasons, are likely to be exacerbated by mechanisms such as mussel burrowing patterns (Caissie 2006).…”

The process domains concept as a framework for fish and mussel habitat in a coastal plain river of southeastern North America

“…We observed similar effects in the upper reach where coarse substrates and channel incision were prominent. Such geomorphic effects of dams on downstream channels may lead to burying, displacement, and mortality of mussels leading to reduced mussel abundance and extirpation of sensitive species (Galbraith and Vaughn, 2011). Vaughn and Taylor (1999) reported significant dam effects on mussel species richness on a similar-sized river also located in the southeastern United States.…”

“…Additionally, mussel life history traits often vary among populations and the life history classifications of populations described by Haag [ 2 _ T D $ D I F F ] (2012) might deviate from the proper classifications of species in our study system. Thus, further investigation of these and other functional traits (e.g., burrowing behavior) as well as measurement of individual and populationlevel performance metrics (e.g., Galbraith and Vaughn, 2011) in the upper Neches River will elucidate mechanisms driving community variation among reaches. The overall weak variation in trait composition among reaches suggests that environmental filtering of other traits such as burrowing behavior may be important (Allen and Vaughn, 2009).…”