Abstract The American Fisheries Society (AFS) herein provides a list of all native freshwater mussels (families Margaritiferidae and Unionidae) in the United States and Canada. This report also provides state and provincial distributions; a comprehensive review of the conservation status of all taxa; and references on biology, conservation, and distribution of freshwater mussels. The list includes 297 native freshwater mussels, of which 213 taxa (71.7%) are considered endangered, threatened, or of special concern. Twenty-one taxa (7.1%) are listed as endangered but possibly extinct, 77 (20.6%) as endangered but extant, 43 (14.5%) as threatened, 72 (24.2%) as of special concern, 14 (4.7%) as undetermined, and only 70 (23.6%) as currently stable. The primary reasons for the decline of freshwater mussels are habitat destruction from dams, channel modification, siltation, and the introduction of nonindigenous mollusks. The high numbers of imperiled freshwater mussels in the United States and Canada, which har...

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Conservation status of the freshwater mussels of the United States and Canada

The American Fisheries Society (AFS) herein provides a list of all native freshwater mussels (families Margaritiferidae and Unionidae) in the United States and Canada. This report also provides state and provincial distributions; a comprehensive review of the conservation status of all taxa; and references on biology, conservation, and distribution of freshwater mussels. The list includes 297 native freshwater mussels, of which 213 taxa (71.7%) are considered endangered, threatened, or of special concern. Twenty-one taxa (7.1%) are listed as endangered but possibly extinct, 77 (20.6%) as endangered but extant, 43 (14.5%) as threatened, 72 (24.2%) as of special concern, 14 (4.7%) as undetermined, and only 70 (23.6%) as currently stable. The primary reasons for the decline of freshwater mussels are habitat destruction from dams, channel modification, siltation, and the introduction of nonindigenous mollusks. The high numbers of imperiled freshwater mussels in the United States and Canada, which har...

Conservation Status of Freshwater Mussels of the United States and Canada

Studies were conducted in four distinct geographic areas (biomes/sites) in northern United States to examine changes in key ecosystem parameters: benthic organic matter (BOM), transported organic matter (TOM), community production and respiration, leaf pack decomposition, and functional feeding-group composition along gradients of increasing stream size. Four stations ranging from headwaters (1st or 2nd order) to midsized rivers (5th to 7th order) were examined at each site using comparable methods. The results for each parameter are presented and discussed in light of the River Continuum Concept of Vannote et al. (1980). The postulated gradual change in a stream ecosystem's structure and function is supported by this study. However, regional and local deviations occur as a result of variations in the influence of: (1) watershed climate and geology, (2) riparian conditions, (3) tributaries, and (4) location-specific lithology and geomorphology. In partic- ular, the continuum framework must be visualized as a sliding scale which is shifted upstream or downstream depending on macroenvironmental forces (1 and 2) or reset following the application of more localized "micro"-environmental influences (3 and 4). Analysis of interactions between BOM and TOM permitted evaluation of stream retentiveness for organic matter. Headwaters generally were most retentive and downstream reaches the least. Estimates of organic matter turnover times ranged between 0.2 and 14 yr, and commonly were 1-4 yr. Both turnover times and distances were deter- mined primarily by the interaction between current velocity and stream retention. Biological processes played a secondary role. However, the streams varied considerably in their spiraling of organic matter due to differences in the interplay between retentiveness and biological activity. Differences in the relative importance of retention mechanisms along the continuum suggest that headwater stream ecosystems may be functionally more stable, at least to physical disturbances, than are their inter- mediate river counterparts.

Interbiome comparison of stream ecosystem dynamics

1.  Freshwater mussels (Order Unionoida) are the most imperiled faunal group in North America; 60% of described species are considered endangered or threatened, and 12% are presumed extinct. Widespread habitat degradation (including pollution, siltation, river channelization and impoundment) has been the primary cause of extinction during this century, but a new stress was added in the last decade by the introduction of the Eurasian zebra mussel, Dreissena polymorpha, a biofouling organism that smothers the shells of other molluscs and competes with other suspension feeders for food. Since the early 1990s, it has been spreading throughout the Mississippi River basin, which contains the largest number of endemic freshwater mussels in the world. In this report, we use an exponential decay model based on data from other invaded habitats to predict the long-term impact of D. polymorpha on mussel species richness in the basin.



2.  In North American lakes and rivers that support high densities (>3000 m−2) of D. polymorpha, native mussel populations are extirpated within 4–8 years following invasion. Significant local declines in native mussel populations in the Illinois and Ohio rivers, concomitant with the establishment of dense populations of D. polymorpha, suggest that induced mortality is occurring in the Mississippi River basin.



3.  A comparison of species loss at various sites before and after invasion indicates that D. polymorpha has accelerated regional extinction rates of North American freshwater mussels by 10-fold. If this trend persists, the regional extinction rate for Mississippi basin species will be 12% per decade. Over 60 endemic mussels in the Mississippi River basin are threatened with global extinction by the combined impacts of the D. polymorpha invasion and environmental degradation.

https://www.jstor.org/stable/pdfplus/2647282.pdf

Impending extinctions of North American freshwater mussels (Unionoida) following the zebra mussel (Dreissena polymorpha) invasion

The widespread recent decline in the species diversity and population density of freshwater mussels in North America may be partly related to chronic, low-level exposure to toxic metals. As benthic filter-feeding organisms, freshwater mussels are exposed to metals that are dissolved in water, associated with suspended particles and deposited in bottom sediments. Thus, freshwater mussels can bioaccumulate certain metals to concentrations that greatly exceed those dissolved in water. In adult mussels, the most common site of metal uptake is the gill, followed by the mantle and the kidney. The toxic effects of metals on freshwater mussels have been examined in a few acute toxicity tests, but the sublethal effects of long-term exposure to low environmental concentrations are little understood. Sublethal exposure to metals can alter growth, filtration efficiency, enzyme activity and behaviour. Sublethal effects are frequently observed at concentrations that are only half the lethal concentrations. However, few toxicity tests have used environmentally realistic exposure concentrations. Total concentrations of Cd, Cu, Hg and Zn in many oxic surface waters are in the ngl(-1) range, yet many toxicity studies have exposed mussels to concentrations in the μgl(-1) or even the mgl(-1) range. An understanding of the processes by which metals affect freshwater mussels would provide insights on the ecotoxicological significance of metal contamination to natural mussel populations and aid in the development of water-quality criteria that adequately protect mussels.

A review of the effects of heavy metals on freshwater mussels.

There have been a number of mussel surveys (Smith, 1889; Coker, 1914; Grier and Mueller, 1922-23; Grier, 1922, 1926) in the Mississippi River to determine the relative value of these animals as a source of pearl button material. Other studies (Cooper, 1834; Galtsoff, 1924; Wiebe, 1927; Ellis, 1931) were concerned more with general biological problems involving ecology, limnology and fisheries. Several valuable lists (Pratt, 1876; Call, 1885; Grant, 1885; Baker, 1903, 1905; Shimek, 1921; Dawley, 1947) furnish good records of species from various parts of this river. However, there has not been a single published report which gives an account of the distribution of these animals throughout the productive area of the main stream. A comprehensive survey made by Max M. Ellis and his staff during the summers of 1930 and 1931 now makes possible a report on those collections. These records are the only inclusive source of information concerning this unusually rich assemblage of naiades in our largest river.

The Mussels of the Mississippi River

A Revision of the Mollusca of Indiana

Nembutal as a Relaxing Agent for Mollusks

In 1925, Dr. A. E. Ortmann published in this journal the results of his investigations of the fresh-water mussels in the Tennessee drainage below Walden Gorge. That study constitutes the only source of basic information available for this group of animals in the entire lower Tennessee River. Recently, considerable additional material regarding the mussels inhabiting the main portion of the river from Walden Gorge to its mouth at Paducah has been made available for study. The collections upon which this research is based were largely accumulated by Dr. M. M. Ellis of the U. S. Bureau of Fisheries, who with the aid of a staff of field assistants surveyed the lower Tennessee in July and August of 1931. The information resulting from this survey has been supplemented by records available in the collections of the University of Michigan Museum of Zoology, and by reference to citations in the literature.

Additional Notes on the Naiades (Fresh-Water Mussels) of the Lower Tennessee River

In view of the decided changes which have occurred in the Naiad fauna of the St. Joseph River drainage due to domestic sewage, industrial wastes, water-power development, and the depletion of the fauna as a result of excessive clamming operations, it seems advisable to summarize the data contributed by other workers, notably Call (1900), Wenninger (1921), and Dolley (1933), and to add data available from my own records. It is unfortunate that no careful survey was made of the fauna before the drainage was subjected to so many detrimental influences. However, though much valuable data will of necessity be lacking, we may still piece together the available information in an attempt to formulate a better knowledge of the fauna.

https://www.jstor.org/stable/pdfplus/2419976.pdf

Henry van der Schalie

Papers

The Mussels of the Mississippi River

A Revision of the Mollusca of Indiana

Nembutal as a Relaxing Agent for Mollusks

Additional Notes on the Naiades (Fresh-Water Mussels) of the Lower Tennessee River

The Naiad Fauna of the St.Joseph River Drainage in Southwestern Michigan