Population assessment and potential functional roles of native mussels in the Upper Mississippi River

TLDR

Native mussel ecology in large rivers is understudied, limiting restoration efforts. The authors conducted large-scale systematic surveys across three reaches of the Upper Mississippi River, documenting 16–23 mussel species per reach with densities of 2.9–4.5 individuals per square meter and high recruitment. The mussels had mean tissue biomass of 2.1–3.1 g C m⁻², production of 0.4–0.6 g C m⁻² yr⁻¹, filtered 0.05–0.07 m³ m⁻² d⁻¹ totaling 53.1 million m³ day⁻¹, and accounted for 0.5–12.2 % of river discharge depending on flow, indicating a significant role in sequestering suspended materials. Published in 2011 by John Wiley and Sons, Ltd.

Abstract

Abstract Despite a heightened global concern for native mussels, fundamental research on mussel ecology in large rivers is lacking. These gaps in knowledge about where mussels occur, and why, are limiting habitat restoration activities. Large‐scale systematic surveys for native mussels in three reaches of the Upper Mississippi River documented mussel communities composed of 16–23 species and ranging from 2.9–4.5 live mussels m −2 that were actively recruiting new cohorts into their populations (87–100% of the species were found as juveniles ⩽5 years old). Estimates of mean tissue biomass and production in these reaches ranged from 2.1–3.1 g C m −2 and 0.4–0.6 g C m −2 year −1 , respectively. Mussels filtered a significant amount of water (range, 0.05–0.07 m 3 m −2 d −1 ) over a 480 km reach of the Upper Mississippi River – amounting to a filtration rate of 53.1 million m 3 day −1 . The filtration rate of mussels as a percentage of river discharge ranged from 0.5–1.4% at high flows (5% exceedance), from 1.5–4.4% at moderate flows (50% exceedance) and from 4.4–12.2% during low flows (95% exceedance). Collectively, these data suggest that native mussels play an integral role in this ecosystem by sequestering suspended materials that can be used by other benthic organisms. Published in 2011 by John Wiley and Sons, Ltd.