Distribution, abundance, and roles of freshwater clams (Bivalvia, Unionidae) in the freshwater tidal Hudson River

Abstract

SUMMARY 1. An extensive series of PONAR grabs was used to determine the distribution and abundance of unionid clams in the freshwater tidal Hudson River. 2. The five species of unionids collected were distributed very unevenly within the river. Mean river‐wide density and biomass of unionids were 8.0m−2 and 6.2 g DM m−2 (shell‐free)., respectively. 3. The environmental variables that we measured (water depth, distance from shore, sediment granulometry and organic content, presence or absence of macrophytes, and the chlorophyll a and particulate organic matter content of the water) explained little of the variation in abundance of unionids. 4. The distributions of the various species of clams did not differ significantly with respect to the environmental variables measured. 5. We estimate that unionids filter a significant amount of water (0.14m3 m−2 day−1, on average) in the Hudson River estuary, roughly equivalent in magnitude to downstream flushing. 6. We project that unionids will serve as a major substratum for the settlement of the zebra mussel (Dreissena polymorpha), which is now invading the estuary. We emphasize that unionids may play important non‐trophic roles in large river ecosystems.

The role of geomorphology in substratum patch selection by freshwater mussels in the Hawkesbury–Nepean River (New South Wales) Australia

“…The relationships between freshwater mussel distribution and macrohabitat variables such as land use (Arbuckle and Downing, 2002;McRae et al, 2004), riparian vegetation (Morris and Corkum, 1999;Poole and Downing, 2004) and impoundments (Blalock and Sickel, 1996;Layzer and Scott, 2006;Haag and Warren, 2007) have been used to predict mussel diversity and abundance in large river systems (Strayer, 1993;Strayer et al, 1994;Di Maio and Corkum, 1995;Hastie et al, 2003). In smaller drainages, microhabitat factors such as current velocity, channel depth and sediment size are thought to be important for predicting mussel distribution (Neves and Widluk, 1987;Layzer and Madison, 1995;Johnson and Brown, 2000).…”

Bivalve diets in a midwestern U.S. stream: A stable isotope enrichment study

“…Deposit feeding is the consumption of particles from the sediment. Descriptions of unionid behavior and the role of unionids in aquatic ecosystems emphasize the suspension mode of feeding (e.g., McMahon 1991; Strayer et al 1994Strayer et al , 1999Box and Mossa 1999).…”

Unionid clams and the zebra mussels on their shells (Bivalvia: Unionidae, Dreissenidae) as hosts for trematodes in lakes of the Polish lowland

“…The unionids are important players in the functioning of freshwater ecosystems (dillon 2000, VAughn & hAkenkAMP 2001. They constitute a significant benthos biomass (ÖklAnd 1963, PieChoCki 1999 and filter large volumes of water (lewAndowski & StańczykowSka 1975, strAyer et al 1994, thus contributing to purification of aquatic systems (PusCh et al 2001). They are a source of food for other organisms (zAhnerMeike & hAnson 2001) and may also provide a habitat for various free-living and parasitic symbionts (PieChoCki & dyduCh-FAlniowskA 1993).…”