Kevin S. Cummings

Conservation Status of Freshwater Mussels of the United States and Canada

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...

The Global Decline of Nonmarine Mollusks

Abstract Invertebrate species represent more than 99% of animal diversity; however, they receive much less publicity and attract disproportionately minor research effort relative to vertebrates. Nonmarine mollusks (i.e., terrestrial and freshwater) are one of the most diverse and imperiled groups of animals, although not many people other than a few specialists who study the group seem to be aware of their plight. Nonmarine mollusks include a number of phylogenetically disparate lineages and species-rich assemblages that represent two molluscan classes, Bivalvia (clams and mussels) and Gastropoda (snails, slugs, and limpets). In this article we provide an overview of global nonmarine molluscan biodiversity and conservation status, including several case studies documenting the diversity and global decline of nonmarine mollusks. We conclude with a discussion of the roles that mollusks and malacologists should play in conservation, including research, conservation management strategies, and education and outreach.

Freshwater mussel (Mollusca: Bivalvia: Unionoida) richness and endemism in the ecoregions of Africa and Madagascar based on comprehensive museum sampling

The objective of this study was to assess freshwater mussel (Mollusca: Bivalvia: Unionoida) species distributions among the freshwater ecoregions of Africa and Madagascar to discover areas of high richness and endemism. These are among the top criteria for identifying biodiversity hotspots and establishing conservation priorities. Distributions were determined from museum specimens in 17 collections. In total, 5,612 records for 87 unionoid species could each be assigned to one of 90 freshwater ecoregions. The majority of species (55%) are known from only one (34 spp.) or two (14) ecoregions. Only three are known from more than 20 ecoregions: Etheria elliptica (38 ecoregions), Chambardia wahlbergi (25), and Mutela rostrata (21). The most species-rich ecoregions are Lake Victoria Basin (17 spp.), Upper Nile (16), Upper Congo (14), Senegal–Gambia (13), and Sudanic Congo–Oubangi (13). Those with the most endemic species are Lake Tanganyika (8 spp.), Lake Victoria Basin (6), Bangweulu–Mweru (4), and Lake Malawi (3). Twenty-five ecoregions have no known freshwater mussels. These patterns are significantly correlated with fish and general freshwater mollusk richness. Unionoid richness also varies significantly among major habitat types. These patterns are relevant to biogeography and conservation and indicate areas in need of further research. We argue that freshwater mussels are valuable as focal species for conservation assessments, and they themselves merit management consideration for their ecosystem functions and distributions in imperiled habitats. It is recommended that field surveys be conducted to determine the current status of species in all areas of Africa and Madagascar.

Assessing sampling adequacy of mussel diversity surveys in wadeable Illinois streams

Abstract Freshwater mussels are one of the most imperiled groups of animals in North America. Effective resource management and conservation efforts require reliable estimates of species diversity and their distributions. However, sampling protocols for qualitative mussel surveys have not been well established and tested. Furthermore, the sampling effort required for a given data-quality goal (90% of species captured) often varies substantially among sites, and application of a standard effort probably would introduce bias into assemblage comparisons. We tested the sampling adequacy of time-based hand searches. We conducted 16-man-hour (mh) searches at each of 18 wadeable stream sites in Illinois that differed widely in environmental factors and historical species diversity and collected 27 to 942 individuals and 5 to 18 species per site. We accounted for imperfect species detectability by using the Chao-1 richness estimator and measured sampling adequacy as the % of the estimated number of species sampled. Four-mh searches, a frequently used effort, captured 15 to 100% of all species with an average of 61%, and yielded estimates of richness that were not significantly correlated with the estimated total richness (Pearsons r  =  0.39, p > 0.05). Ten-mh searches captured >70% of all species at >70% of sites and resulted in a significant correlation between observed and estimated richness (Pearsons r ≥ 0.78, p < 0.01). A Random Forests (RF) model based on watershed and habitat characteristics (e.g., stream size and dominant substrate types) accounted for 45% of the variance in sampling adequacy of 4-mh searches. Sampling adequacy decreased with increasing stream size and substrate size but increased with % forest in the riparian zone and logs in the stream. A 2nd RF model was developed to predict the number of man-hours required to capture 70 ± 3% of all species, and it accounted for 37% of the variance. Our findings should serve as a guide for setting standard sampling efforts for mussel surveys in Illinois and probably other midwestern states and should provide a baseline for setting site-specific efforts. Our modeling approach is of general applicability for addressing sampling-adequacy issues in studies of any assemblage.

Modeling changes in freshwater mussel diversity in an agriculturally dominated landscape

Abstract.  Freshwater mussels perform critical ecosystem functions and provide many valuable ecological services. However, anthropogenic effects have severely decreased mussel diversity and abundance at both local and regional scales. Understanding how human disturbances, particularly landuse change, and fish assemblages are related to mussel assemblages is essential for effective conservation and restoration. We used Random Forests (RF) regressions, a data-mining technique, to examine how mussel species richness, total abundance, and abundances of individual species were related to land use at different spatial scales and to fish species richness and abundance in east central Illinois, USA. Mussel richness increased with % wetlands, % open water, % grassland in the riparian zone, and total fish abundance; decreased with % urban land in the riparian zone; but responded poorly to fish species richness and fish Index of Biotic Integrity (IBI) scores. Total mussel abundance mainly increased with total fish abundance and decreased with both % urban land in the riparian zone and road density. Of 8 mussel species modeled, the abundances of 3 were strongly related to total fish abundance or fish-host abundance, 3 with both fish abundance and land use, and 2 with land use and other physical variables. These findings can help researchers and resource managers explain the spatial variation of mussel assemblages and choose abiotic and biotic variables to monitor or manipulate for maintaining or restoring overall mussel diversity or the populations of individual species.

Freshwater mussels (Mollusca: Bivalvia: Unionoida) of Angola, with description of a new species, Mutela wistarmorrisi

ABSTRACT The aquatic fauna of the Angola region in southwestern Africa, including the Cuanza (= Kwanza), Cunene, Okavango, upper Zambezi, Cassai (= Kasai) and lower Congo basins, is poorly known. The freshwater mussels (Mollusca: Unionoida) of the region have received little attention, and then usually as fringes to the Congo and Zambezi-Okavango systems. All available freshwater mussel specimens from thirteen major mollusk collections were examined and, along with a literature review, form the basis for this checklist. Twenty-three species in three families (Etheriidae, Iridinidae and Unionidae) are recognized from the Angola region, eight of which are newly recognized in the region or had not been treated as valid in recent revisions (Mandahl-Barth, 1988; Daget, 1998). One of these species, Mutela wistarmorrisi, is new to science and described herein. Chambardia welwitschi (Morelet), a widely recognized subspecies, is elevated to species-level status, and four more names are resurrected to valid status from synonymy: Mutela langi Pilsbry & Bequaert, Chambardia moutai (Dartevelle), Coelatura stagnorum (Dautzenberg) and C. rotula Pilsbry & Bequaert. Mutela legumen (Rochebrune) is recognized as the senior synonym for the species formerly referred to as Mutela carrei (Putzeys), and the known range of Aspatharia subreniformis (Sowerby) is expanded to include the Cunene, Okavango and Zambezi basins. Figures of each species are provided, and known distributions and persistent taxonomic issues are discussed. An appendix lists geocodes for localities associated with specimen records.

Chapter 11 – Mollusca: Bivalvia

Publisher Summary This chapter introduces general biology, morphology, ecology, physiology, life histories, evolution, and classification of bivalve molluscs found in freshwaters of North America. The freshwater bivalves of North America are represented by two native groups, the freshwater mussels (Unionoidea) and the pill, fingernail, and pea clams (Sphaeriidae), as well as two widely publicized invasive genera, Corbicula and Dreissena. The North American fauna of freshwater bivalves is the richest in the world, with about 350 species of mussels and clams, nine or so of which are exotic. The latter includes Asian clams and zebra mussels. Molluscs, are major deposit and suspension feeders within permanent lakes, streams, and large rivers, where they are often the largest invertebrates in body mass. Freshwater mussels are considered to be part of a guild of freshwater, sedentary filter feeders. These molluscs have interesting and important ecological interactions with their environments. Given the processes they perform and their high biomass in rivers where they are abundant, freshwater mussels have the potential to have strong effects by modifying the habitat and controlling the availability of resources to other organisms.

Actual and Alleged Freshwater Mussels (Mollusca: Bivalvia: Unionoida) from Madagascar and the Mascarenes, with Description of a New Genus, Germainaia

ABSTRACT. Madagascar is widely recognized as a biodiversity hotspot, but the freshwater bivalves have received only limited recent attention. Based upon examination of records from 15 major museums and a literature review, at least nine species of freshwater mussels (Mollusca: Bivalvia: Unionoida) have been reported from either Madagascar or the Mascarene Islands (specifically, Reunion or Mauritius) in the Indian Ocean, east of Africa. The quality of the data, however, is generally poor. Seven of those species records are regarded as either erroneous reports of taxa known from other regions or as nomina dubia. No records from the Mascarenes are considered to be valid. The two remaining species, Etheria elliptica Lamarck 1807 and Unio geayi Germain 1911 (= Coelatura geayi) are both from Madagascar, and the latter is discussed in the context of two alternative hypotheses for the origin of the family Unionidae, nicknamed “Out of Africa” and “Into Africa.” Germainaia gen. nov. is introduced for Unio geayi to emphasize the distinction of that species from other Afrotropical freshwater mussel lineages. The possibility that Germainaia may represent the Hyriidae in Madagascar is discussed, but the new genus is left incertae sedis at the family-level in the absence of complete data. New taxon: Germainaia Graf and Cummings

Newly recognized distribution records for two pleurocerids (Gastropoda) in Kansas

Aquatic snails (Gastropoda) are a vital component of stream ecosystems. Not only do they act as biological indicators of stream integrity (Lydeard et al. 2004), but they also occupy a pivotal position in stream food web dynamics by grazing on periphyton and serving as a food source for many predators (Stewart 2006). However, freshwater mollusks, including gastropods, are one of the most imperiled groups of animals in North America, primarily as the result of habitat destruction (Lydeard et al. 2004). Despite sufficient evidence that aquatic snails are ecologically important, scientists have a poor understanding of the geographic distribution, environmental requirements, and even systematic classification of these imperiled species (Graf 2001; Stewart 2006).

Timed Search Technique Used to Evlauate Freshwater Mussel (Bivalvia: Unionidae) Species Richness in Headwater Streams: Is a Single One-Hour Visit Enough?

ABSTRACT Freshwater mussels were sampled in the upper Mackinaw River basin, Illinois, for five years to determine if a single, one-hour visit was enough to adequately characterize the species richness at a headwater stream site when using the timed search technique. Eight sites were each handpicked for one person-hour every year, and species richness was calculated to determine if it varied by year for five years. During 39 person-hours, 2,692 live individuals of 14 species were collected. Species accumulation curves and Spearmans correlation analysis suggested that a single, one-hour visit was not adequate when using the timed search technique to determine species richness in headwater streams of the Mackinaw River basin and might not be sufficient in other basins.