Suspended material availability and filtration–biodeposition processes performed by a native and invasive bivalve species in streams

Abstract

Unionid mussels are among the most threatened group of freshwater organisms globally. They are known for their ability to filter food particles from flowing and standing waters. However, invasive bivalve species, such as the Asian clam (Corbicula fluminea) in North America, have the potential to overlap in feeding and potentially out-compete the native species. Yet, the feeding preferences of unionid mussels and C. fluminea are incompletely understood. We hypothesized that Elliptio crassidens (native) and C. fluminea (invasive) would select for specific organic components present within seston. We examined changes in seston (dry mass and ash-free dry mass) resulting from bivalve feeding activity for three size classes of material that were isolated using gravimetric filtration. The treatments were also sub-sampled for flow cytometry (FC) which separated the suspended materials in the stream water into five categories: detritus, heterotrophic bacteria, picoautotrophs, nanoautotrophs, and heterotrophic nanoeukaryotes. Our results indicated that both species of bivalve showed preferences for organic and living materials. E. crassidens preferentially filtered nanoeukaryotes, whose decreases were associated with an increase in Present Address: bacteria. In contrast, C. fluminea preferred smaller materials through selective filtration of picoautotrophs. In addition, both species increased the concentration of large materials toward the end of the experiment because of the suspension of their pseudofeces biodeposits. To our knowledge, this study is the first to examine grazing by bivalve species on natural stream particulate matter using FC. Our results suggest that native and non-native mussels have different functional roles, which has important implications for organic matter processing and food webs in streams.

Does size matter? Particle size vs. quality in bivalve suspension feeding

“…They were maintained for up to six weeks on 0.17 mL of concentrated, preserved microalgae (Shellfish Diet and Nanno 3600; Reed Mariculture Inc, CA) that was added to the flow‐through water daily (10 3 cells/L within the chamber; McNichols et al., ; vanden Byllaardt & Ackerman, ; Tremblay, Morris, & Ackerman, ). Prior to experiments mussels were maintained without food for three days to reduce incidents of non‐feeding (Atkinson, First, Covich, Opsahl, & Golladay, ; Beck & Neves, ; Silverman et al., ). No animals were harmed during this study, and the mussels were returned to their collection sites at the end of the experiments.…”

The invasive Asian clam (Corbicula fluminea) increases sediment denitrification and ammonium flux in 2 streams in the midwestern USA

“…Their high density, excretion rates, and burrowing activity enable C. fluminea to affect stream ecosystem function (Atkinson et al 2011, Zhang et al 2011. Additional studies are needed to measure the fate of N in biodeposits and clam biomass over longer time scales, their effect on N fluxes relative to native mussels and other invasive bivalves, and seasonality in C. fluminea-mediated N fluxes.…”

Long-Term Acclimation to Different Thermal Regimes Affects Molecular Responses to Heat Stress in a Freshwater Clam Corbicula Fluminea

“…C. fluminea is a nuisance species that colonizes the pipes of water treatment systems and power stations altering flow and increasing sedimentation rates. Established C. fluminea populations also affect the water quality and sediment mixing through active filtration and burrowing behavior1314. Due to their broad distribution, important role in freshwater ecosystems and common occurrence in the CWD areas of the power plants, C. fluminea are useful organisms to study the acclimation capacity to long-term warming.…”