In situ experiments on predatory regulation of a bivalve mollusc (Dreissena polymorpha) in the Mississippi and Ohio Rivers

Abstract

1. In situ exclosure experiments in the Mississippi and Ohio Rivers determined the importance of fish predation in regulating zebra mussels (Dreissena polymorpha), an increasingly important constituent of the benthic invertebrate assemblages in both rivers. 2. We evaluated the effects of predatory fish on the density, biomass and size distribution of zebra mussels in a floodplain reach of the upper Mississippi River and in a naturally constrained reach of the Ohio River. Fifty, six‐sided, predator‐exclusion cages and fifty ‘partial’ cages (mesh at the upstream end only) were deployed, with half the cages containing willow snags and half clay tiles suspended 12–16 cm above the bottom. A single snag or tile sample unit was removed from each cage at approximately monthly intervals from July to October 1994. Types and relative abundances of molluscivorous fish were evaluated by electrofishing near the cages in both rivers. Actual and potential recruitment of young zebra mussels on to the substrata were measured using benthic samples in both rivers and estimated (Ohio River only) from counts of planktonic veligers. 3. Zebra mussels were consumed by at least three fish species in the upper Mississippi River (mostly carp, Cyprinus carpio, and redhorse suckers, Moxostoma sp.) and five species in the Ohio River (primarily smallmouth buffalo, Ictiobus bubalus, and channel catfish, Ictalurus punctatus), but potential recruitment seemed adequate to replace consumed mussels, at least in the Ohio River. The number of juvenile benthic mussels showed no apparent link with the density of veligers soon after initiation of reproduction. Recruitment of juveniles on snags and tiles was not affected by cage type (thus eliminating a potentially confounding ‘cage effect’). 4. Fish significantly influenced mussel populations, but the impact was often greatest among low density populations in the upper Mississippi. Density and biomass differed in both rivers for cage type (higher inside cages), substratum (greater on tiles), and date (increased over time). Presumed size‐selective predation was present in the Mississippi (greater on larger size classes) but was not evident in the Ohio. We hypothesize that fish in the Mississippi can more easily select larger prey from the low density populations; whereas size‐selective predation on tightly packed zebra mussels in the Ohio would be difficult. 5. Although fish can reduce numbers of Dreissena polymorpha in the two rivers, current levels of fish predation seem insufficient to regulate zebra mussel densities because of its great reproductive capacity. The recent invasion of zebra mussels, however, could lead to larger fish populations while promoting greater carbon retention and overall ecosystem secondary production.

Round goby predation onDreissenain coastal areas of eastern Lake Michigan

“…Similarly, previous investigations on fish predation in areas without the round goby showed negative effects on Dreissena density (Thorp et al 1998;Bartsch et al 2005). In our experiment, round goby growth rates were negatively associated with initial stocking biomass in enclosures (Figure 2), suggesting that food was a limiting resource in cages.…”

“…There are several fishes in Muskegon Lake Bhagat and Ruetz 2011) that have been known to eat Dreissena such as the freshwater drum (Aplodinotus grunniens), pumpkinseed (Lepomis gibbosus), redhorse suckers (Moxostoma spp. ), and common carp (Cyprinus carpio) (Tucker et al 1996;Thorp et al 1998;Magoulick and Lewis 2002;Andraso 2005;Bartsch et al 2005). Large-bodied molluscivorous fishes were implicated in limiting Dreissena densities in a Lake Erie costal wetland (Bowers and de Szalay 2007) and in the Upper Mississippi River (Bartsch et al 2005), although there was spatial variation in the magnitude of the effect in the Upper Mississippi River.…”

Predation and physical environment structure the density and population size structure of zebra mussels

“…Physicochemical properties of the recipient environment, such as surface area, depth, substrate, Ca concentration, pH, temperature, and trophic status, have been suggested as main factors constraining density, growth, and invasion success of zebra mussels at regional (among-lake) scales (Ramcharan et al 1992b, Mellina and Rasmussen 1994, Sprung 1995, Naddafi 2007, Whittier et al 2008, whereas biotic factors, such as fish predation, have been suggested as secondary factors (Thorp et al 1998). McMahon (1991) proposed fishes as the most active predators of settled zebra mussels, but only a handful of studies have indicated the potential of fish predation to control invasion success and density of exotic mussels (Eggleton et al 2004, Bartsch et al 2005, Watzin et al 2008.…”

Modelling the predation effects of invasive crayfish,Procambarus clarkii(Girard, 1852), on invasive zebra mussel,Dreissena polymorpha(Pallas, 1771), under laboratory conditions

“…McMahon (1996 proposed fishes as the most active predators of settled zebra mussels, but only a handful of studies have indicated the potential of fish predation to control the invasion success and density of exotic mussels (Eggleton et al 2004;Bartsch et al 2005;Watzin et al 2008). The results of Magoulick and Lewis (2002) indicate that predation could potentially suppress initial zebra mussel colonization and recolonization of adult zebra mussels following temperature-dependent mortality, and the relative susceptibility of zebra mussels to predation can be influenced for several biological and ecological factors (Thorp et al 1998). Perry et al (2000) and Naddaffi et al (2010) also suggested the potential impacts of predation on recruitment or on the early life history stages of zebra mussels, because during the early stages of an invasion the average zebra mussel size is small and these individuals are therefore more vulnerable.…”