The functional role of burrowing bivalves in freshwater ecosystems

Abstract

1. Freshwater systems are losing biodiversity at a rapid rate, yet we know little about the functional role of most of this biodiversity. The ecosystem roles of freshwater burrowing bivalves have been particularly understudied. Here we summarize what is known about the functional role of burrowing bivalves in the orders Unionoida and Veneroida in lakes and streams globally. 2. Bivalves filter phytoplankton, bacteria and particulate organic matter from the water column. Corbicula and sphaeriids also remove organic matter from the sediment by deposit feeding, as may some unionids. Filtration rate varies with bivalve species and size, temperature, particle size and concentration, and flow regime. 3. Bivalves affect nutrient dynamics in freshwater systems, through excretion as well as biodeposition of faeces and pseudofaeces. Excretion rates are both size and species dependent, are influenced by reproductive stage, and vary greatly with temperature and food availability. 4. Bioturbation of sediments through bivalve movements increases sediment water and oxygen content and releases nutrients from the sediment to the water column. The physical presence of bivalve shells creates habitat for epiphytic and epizoic organisms, and stabilizes sediment and provides refugia for benthic fauna. Biodeposition of faeces and pseudofaeces can alter the composition of benthic communities. 5. There is conflicting evidence concerning the role of resource limitation in structuring bivalve communities. Control by bivalves of primary production is most likely when their biomass is large relative to the water volume and where hydrologic residence time is long. Future studies should consider exactly what bivalves feed upon, whether feeding varies seasonally and with habitat, and whether significant overlap in diet occurs. In particular, we need a clearer picture of the importance of suspension versus deposit feeding and the potential advantages and tradeoffs between these two feeding modes. 6. In North America, native burrowing bivalves (Unionidae) are declining at a catastrophic rate. This significant loss of benthic biomass, coupled with the invasion of an exotic burrowing bivalve (Corbicula), may result in large alterations of ecosystem processes and functions.

Making sense of policy implementation: The construction and uses of expertise and evidence in managing freshwater environments

“…Population declines have been caused by factors such as pearlfishing, pollution, acidification, organic enrichment, siltation, river engineering, declining salmonid stocks and changing flood frequency and magnitude . It is important to protect and support freshwater pearl mussel populations because a decline could have a negative impact on riverine ecosystem processes (Vaughn and Hakenkamp, 2001). …”

Ecology of the invasive Asian clam Corbicula fluminea (Müller, 1774) in aquatic ecosystems: an overview

“…The principal problem of the recent freshwater bivalve species invasions, such as C. fluminea, resides in the potential change in the ecological conditions of the invaded ecosystems. Corbicula species potentially affect native bivalve fauna in several ways: burrowing and bioturbation activity, principally at high abundances, may displace and/or reduce available habitats for juvenile unionids and sphaeriids (Vaughn & Hakenkamp 2001); suspension and deposit feeding by Corbicula may negatively impact unionid juvenile recruitment (Yeager et al 1994, Hakenkamp & Palmer 1999; dense populations of Corbicula may ingest large numbers of unionids sperm, glochidia and newly metamorphosed juveniles (Strayer 1999); Corbicula may advantageously compete for food resources with sphaeriids and juvenile unionids since they have larger filtration rates, on a per biomass basis, than sphaeriids and unionids and consequently have the potential to limit planktonic food available to native bivalves (McMahon 1991). However, the reasons behind these negative impacts in the native fauna remain speculative and further manipulative research is needed to clarify these ecological interactions and impacts.…”

“…Displace and/or reduce available habitat for other species (Vaughn & Hakenkamp 2001); Suspension and deposit feeding by C. fluminea may negatively impact the recruitment of other species (e.g. juvenile unionids, sphaeriids) (Yeager et al 1994, Hakenkamp & Palmer 1999;…”

Transcriptomic responses of the endangered freshwater mussel Margaritifera margaritifera to trace metal contamination in the Dronne River, France

“…Despite their role in particle processing, nutrient release, and sediment mixing (Vaughn and Hakenkamp 2001), our knowledge about the complex biology of freshwater bivalves (order Unionoida) is still scarce (Lopes-Lima et al 2014). Freshwater mussels form a species-rich group of bivalves, with about 900 species present on all continents except Antarctica (Carella et al 2016).…”