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The decline of the freshwater mussel fauna of the Ohio River, U.S.A. is compared to the dates of service of the existing dams, the arrival of the exotic zebra mussel, and the presence of urban centers on the mainstem. Based upon historical records we know that most pools supported 20–50 species of mussels; today many have fewer than ten. The results presented here show a mixed effect of the dams on the mussel fauna, ranging from marked deleterious effects in Hannibal, McAlpine, and Smithland pools to comparatively little effect in pools such as Dashields, Greenup, and Markland. In nearly all cases, the most dramatic declines in mussels were associated with the arrival of zebra mussels in the Ohio River in 1991. Pools with significant urban centers often had a loss of diversity well before the construction of dams or the arrival of zebra mussels; these losses are attributed to water quality problems associated with urban centers. Mussel diversity has thus declined in the Ohio River as the result of a three-fold problem: loss of water quality, existing dams, and zebra mussels.
Leslie Hubricht (1908–2005) was one of the leading experts for the taxonomy, distribution and ecology of terrestrial gastropods of the eastern United States. He published more than 150 papers and introduced 108 new names for molluscan taxa from this area. Over six decades, he amassed a collection of 43,000 lots of eastern North American terrestrial gastropods with approximately 500,000 specimens, now housed in the Field Museum of Natural History, Chicago. Besides his work on molluscs, he also did extensive research on freshwater crustaceans (Isopoda and Amphipoda) of the eastern U. S., describing 40 new taxa in this group. This paper provides complete lists of Hubricht's publications and of his new taxa in the Mollusca and Crustacea. A brief biographical sketch of Hubricht and a list of taxa named for him are also given.
The Pupillidae form an important component of eastern North American land snail biodiversity, representing approx. 12% of the entire fauna, 25–75% of all species and individuals at regional scales, at least 30% of the species diversity, and 33% of individuals within any given site. In some regions pupillids represent 80–100% of total molluscan diversity within sites, notably in taiga, tundra, and the base-poor pine savannas and pocosins of the southeastern coastal plain. Adequate documentation of North American land snail biodiversity thus requires investigators to efficiently collect and accurately identify individuals of this group. This paper presents a set of annotated keys to the 65 species in this family known to occur in North America east of the Rocky Mountains. The distinguishing taxonomic features, updated county-scale range maps, and ecological conditions favored by each are presented in hopes of stimulating future research in this important group.
Forty-two families of terrestrial molluscs inhabit Mexico with approx. 1,178 species and subspecies. The most diverse families are the Urocoptidae (265 species), Spiraxidae (246), Bulimulidae (140), Helicinidae (72), Polygyridae (65), Xanthonychidae (58), Humboldtianidae (49), and Pupillidae (47). The 34 medium and small families comprise about 81% of the total number of families; however, their species total only 236 or 20% of the Mexican species. When looking at their distribution, we noticed that, in general, families cover large areas, but while some species are also found in the United States and Central America, the majority seems to be endemic to Mexico. However, our knowledge of the distribution of terrestrial molluscs throughout Mexico may be incomplete because of a lack of systematic collecting in many regions, particularly in the States of Aguascalientes and Tlaxcala.
Pacific land snails are among the most threatened animals on Earth, and basic information on the number of extant species is lacking for many island groups. The isolated western Pacific archipelago of Belau comprises 586 islands, most of which have suitable land snail habitat; yet little has been published on the land snail fauna. I undertook surveys throughout Belau, searching trees and emergent vegetation, leaf litter, and limestone rock. Survey results from selected, geographically representative islands are presented here. The total number of species found in these areas (117) indicates that there may be ca. 200 extant Belau land snail species. This number far exceeds previous estimates. Most species are endemic to Belau (95% in this survey), and species endemic to one or a few islands are not uncommon. Leaf litter and rock dwelling diplommatinid land snails are a large component of the snail biota: only 26 Belau diplommatinids have been described, and 81 species were collected in this survey. Although caenogastropod land snails comprise the most obvious portion of the fauna, notable pulmonates include the partulids and endodontoids, two land snail groups that have suffered extinction throughout the Pacific region. Belau has one of the most spectacularly diverse extant land snail faunas in the Pacific region, and the restricted ranges of many species highlight the need for conservation attention, particularly on the island of Babeldaob, which is undergoing increased deforestation.
In order to address the conservation status and needs of Alabama's land snail species, we examined their diversity and distribution using 11,816 museum records representing 226 land snail species. The Chao-1 statistic identified seven areas of high species richness. The areas with the highest richness contain an estimated 200 species of land snail. These seven areas are not currently well protected by state or federal lands. While taxonomic misidentification and geo-referencing quality may be inflating our results, we suggest that studies like ours provide valuable baseline diversity estimates and launching points for continued studies.
Land snail collecting methods are each designed with a particular purpose. This paper provides a brief overview of land snail collecting strategies, suggests the use of multiple methods and collection of ecological data to broaden the knowledge of land snail life habits and relationships with their environment, and indicates approaches that are most relevant to land snail conservation.
The population structure of the land snail Ventridens ligera (Say, 1821) was investigated in the Potomac River Basin (Virginia, Maryland, U.S.A.). Animals were collected from two islands and the adjacent riverbanks along an 8.8-km stretch of the river. Four landlocked populations in Illinois and Maryland were also sampled to provide a comparison to the river populations. A total of 246 individuals were genotyped with five newly designed species-specific microsatellite primers. Low pairwise FST values (<0.0477) among the Potomac River sites suggest high levels of gene flow between the populations. In contrast, the landlocked populations had high FST values (0.0738 to 0.6004) which suggest genetic structuring, most likely due to physical isolation, because FST values >0.2 indicate population structuring. Low-level isolation by distance was found among the Potomac River populations, and the low FST suggests that the river is facilitating gene flow rather than acting as a barrier.
I studied the reproduction and the population turnover of a succineid land snail living by a small lake in central Maryland. The identity of the snail, deduced from its external characteristics and the genitalia, comes closest to Oxyloma retusum (Lea, 1834). The species has a semelparous life cycle. The snails that survive the winter grow and reproduce from late March until the end of June when they reach their maximum size and die off. Their offspring (the spring generation) grow throughout the spring and the summer and reproduce briefly near the end of August. In the fall, the survivors from the spring generation and their offspring hibernate from November until the end of March. Snails mate by shell-mounting. In 89% of pairs, mating was anatomically reciprocal. During courtship, one snail climbs on the shell of a prospective mate and circles the shell to initiate mating. In mating pairs with a shell length difference of more than 1 mm, the smaller snail was always on top. This suggests that one function of shell-circling during courtship may be to help the top snail judge its potential partner's size.
Athearnia anthonyi (Redfield, 1854) is a federally endangered gastropod endemic to the Tennessee River drainage in Alabama and Tennessee. It occurs in only three small populations, the most robust in Limestone Creek, Limestone County, Alabama. In 1996, this population was restricted to the lower 14.5 km of unimpounded stream, confined to riffle and run habitats. A follow-up survey in 2006 suggested no change in range within Limestone Creek. In 1996–97, quantitative data were collected from 4 selected sites in the reach and mean A. anthonyi density was 83.9 ± 9.9 SE per m2 (N = 90). Although density did not vary among months, the proportion of individuals within four size classes differed. New recruits appeared in the population between May and July, and a significant die-off of older individuals occurred during the same period. Many individuals were suspected of having at least two breeding seasons. Increasing urbanization within the Limestone Creek watershed necessitates monitoring of A. anthonyi.
Relationships between snails, epiphyton, and macrophytes are widely studied because epiphytes decrease light for macrophytes, and snails may benefit the latter when they consume epiphytes. Thus, organic compounds released by macrophytes that attract snails could be an evolutionarily advantageous mechanism. This hypothesis was tested with three species of submerged macrophytes (natives: Egeria najas and Cabomba furcata; exotic: Hydrilla verticillata), which were maintained in microcosms in the presence of ancylid snails. However, the hypothesis of limpet attraction by macrophytes was rejected. Instead, epiphyton attached to E. najas attracted more snails than that attached to the other species. This attraction could be explained by chemical signals (organic compounds), released by certain species of algae that are detected by snails.
We examined current distributions of and influential variables on aquatic gastropods in streams and springs across the state. Our research located 37 species representing 7 families. This inventory included rare species such as Somatogyrus pennsylvanicusWalker, 1904 and several populations of the Ohio Pebblesnail Somatogyrus integra (Say, 1829). Despite targeted surveys, no collections were made of the Buffalo Pebblesnail Gillia altilis (I. Lea, 1841). We also examined the influence of rapid bio-assessment habitat measurements, reach and basin hydrological variables, and selected water chemistry variables on the freshwater snail communities of Pennsylvania. Several measures of habitat quality, drainage area, and water chemistry were among the more important variables explaining patterns in species richness. Several species appear rare and 7 species are recommended for conservation consideration. Further work is needed to better understand the diversity of freshwater gastropods in Pennsylvania.
Two laboratory trials were conducted to determine the required host fish for the Carolina heelsplitter (Lasmigona decorata (Lea, 1852)), an endangered freshwater mussel (Unionidae). The first trial used glochidia from a female collected from the Yadkin-Pee Dee River basin, and the second trial used the glochidia of an adult collected from the Catawba River basin. Two different techniques were utilized for glochidia extraction: flushing and serotonin-induced release. The first female tested (Yadkin-Pee Dee) packaged most of its glochidia attached to unfertilized eggs, and extraction of glochidia by flushing the marsupia with a syringe yielded few glochidia and caused extensive tearing of the gill tissue. In the second trial (Catawba) the female was immersed in 500 mg/L serotonin creatinine sulfate, and the glochidia were readily released without injury to the adult. Several species of minnows (Cyprinidae) from both basins served as hosts. Some sunfish species (Centrarchidae) supported transformation of a few juveniles, but differences in transformation success were observed between the two basins on these species.
Chilinidae is a family endemic to South America, ranging from the Tropic of Capricorn to Cape Horn and the Falkland Islands, and includes 32 species. However, there are few population studies on the Chilinidae. We study aspects of the ecology of an endemic species, Chilina megastoma Hylton Scott, 1958, from the Arrechea Falls in the Iguazú National Park, Argentina, such as density and individual annual growth trends. Nine samplings were carried out between December 2003 and December 2005, using two transects that crossed the waterfall. Individual annual growth rate was analyzed according to length, following von Bertalanffy's model. Six cohorts were identified, some in the same climatic season but successive years (two in winter and two in summer). The winter and autumn cohorts reached 85% of their last whorl length in the first year. Compared to other families of gastropods from subtropical climates, these populations have several recruitment events per year, but never in winter.
On low intertidal and shallow subtidal shores on the west coast of Okinawa, Japan, we investigated the trophic associations of sacoglossan opisthobranchs associated with Bryopsidalean green algae. During 11 short research visits (55 days total) from 2002 to 2008, we recorded almost 500 specimens of 11 species. These sacoglossans include a new record for Japan (Caliphylla A. Costa, 1867), a recent record for Japan (Placida daguilarensis Jensen, 1990), two undescribed species (Placida Trinchese, 1876 and Elysia Risso, 1818), one unnamed (but well-described) species (Placida sp. sensuBaba 1986), and six other Indo-Pacific species. Not only did we record more sacoglossan species but also we found higher slug abundances than other colleagues in Okinawa or the Indo-Pacific region. Quantitative population attributes and feeding preferences are described for these sacoglossans. In contrast to temperate geographic regions, several of these Japanese sacoglossans specialized on a single algal genus rather than two or more genera in different families. This specificity is consistent with narrower host-plant associations in high-diversity communities; yet monophagy has not yet been demonstrated in this guild of Okinawan sacoglossans. Given the broad geographic ranges, restricted host ranges, often predictable populations, and high frequency of life cycles with planktotrophic larvae, western Pacific subtropical sacoglossans should be considered “predictably rare” (sensuRabinowitz 1981) rather than at “special risk” (sensuClark 1994).
Bivalves are good candidates for tag and recapture studies because the accrual of shell material provides a stable record of growth. Obtaining measurements for tagged individuals over time relies on the resilience of markings or tagging devices to environmental stress as well as the readability of identifying markings upon capture. Tagging devices should also be easy and quick to apply in order to minimize potential stress to the animal during extirpation from the water. A variety of methods to attach devices to the inside and outside of bivalve shells have been used in tagging studies. This paper describes a low cost, commercially available, self-adhesive numbered tag for application to clams and other bivalves. Tests of the tag demonstrate its resilience to severe conditions over a short time scale with a ninety-five percent recovery of individuals with tags remaining intact. Ninety-four percent recovery of individuals with tags intact was also achieved in long-term studies. No problems with legibility of tags recovered occurred in any of the tests.
We document the first occurrence of a live red abalone, Haliotis rufescens Swainson, 1822, found on the central coast of British Columbia. The initial identification was based on morphological characteristics. Previously, the northern or “pinto” abalone Haliotis kamtschatkana kamtschatkana Jonas, 1845 has been the only abalone species considered to naturally occur in the coastal waters of British Columbia. Since hybridization of H. kamtschatkana with H. rufescens was known to occur, genetic analysis of tissue samples was undertaken to confirm the morphological identification as a purebred red abalone.
The American Malacological Union (now Society), founded in 1931 as a national organization of collectors, students, professionals, and others interested in the holistic study of molluscs, is now an international society mainly of professionals. Although diminished in size, it continues to attract and fund students, publish a respected peer-reviewed journal, and host annual meetings featuring world-class symposia. In recognition of the society's 75th annual meeting in 2009, I provide a detailed account of the founding, meetings, membership, publications, governance, and societal identity of AMS, gleaned from meeting programs, newsletters, scrapbooks, correspondence, and the memories of Past Presidents and other members.
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