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Nathan A Johnson

Freshwater mussels (Unionidae) are among the most imperiled groups of organisms in the world. Unionids are plagued with a lack of basic information regarding species distributions, life history characteristics, and ecological and biological requirements. We assessed the influence of hydrologic factors on the occurrence of the Suwannee Moccasinshell, Medionidus walkeri, a federally threatened freshwater mussel species endemic to the Suwannee River basin in Georgia and Florida. We also assessed the influence of survey effort on detection of M. walkeri during field surveys. All current (2013-2016) mussel survey records in the Suwannee River Basin were compiled, and cumulative discharge contributed by upstream springs...
Here we present the data collected during a mark-recapture study on freshwater mussels in Bruce Creek, Walton County, Florida. These data were used to evaluate the non-lethal impacts of a gill sampling protocol to assess gravidity of freshwater mussels. Data were collected every four weeks, or as weather permitted, to be able to monitor the reproductive status of each mussel every month of the year. The dataset includes unique tag numbers to identify specific female mussels captured and recaptured during this study. Genus and species were identified, and the gravidity status was evaluated for each individual mussel.
An important physiological constraint influencing distributions of coastal freshwater organisms is their tolerance for saline conditions. We experimentally evaluated salinity tolerance for three freshwater mussel species (Utterbackia imbecillis, Elliptio jayensis, and Glebula rotundata). Mussels were transferred abruptly from well water to one of five treatments (0 [control], 6, 12, 18 or 24 parts per thousand [ppt]) with no acclimation. Utterbackia imbecillis survived on average about 2 days at treatments ≥ 6 ppt, while Elliptio jayensis survived slightly longer (about 4 days). Glebula rotundata was most tolerant to salinity, surviving as well at 6 and 12 ppt as it did in the control. Additionally, G. rotundata...
Here we provide public access to six DNA sequence alignments and details on all specimens utilized in Smith and Johnson (2020).
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