Geology topics

Isaac Standish

Publications and source records attributed to Isaac Standish.

3 recordsLinked to original sources

USGS2024

Freshwater mussel viromes increase rapidly in diversity and abundance when hosts are released from captivity into the wild

Freshwater mussels create habitat, filter water, and enhance food webs, but they are also among the world’s most imperiled taxa. Conservation efforts largely rely on captive propagation in which mussels are grown in protected aquaculture environments (hatcheries) for later release. Recent evidence has highlighted the importance of pathogens in population losses of freshwater mussels. In response to ongoing mass mortality events of freshwater mussels in the Upper Tennessee River Basin in Virginia and Tennessee, USA, we conducted a multi-year study to document viruses across multiple restoration sites and compare them to viruses in mussels from the hatchery. Viral communities changed greatly after mussels were released. Of the 681 viruses of the 27 families we documented, only 20 viruses were found exclusively in hatchery mussels, compared to 451 viruses found only in mussels stocked to the wild. After release, mussels rapidly acquired new viruses, and the number of viruses increased steadily over time. These findings have implications for how mussel introduction programs might be managed for greater success, for example, by incorporating acclimatization periods prior to full release.

Tennessee, Virgnia↗

USGS2023

A bacteriological comparison of the hemolymph from healthy and moribund unionid mussel populations in the upper Midwestern U.S.A. prompts the development of diagnostic assays to detect Yokenella regensburgei

Recent bacteriological investigations of freshwater mussel mortality events in the southeastern United States have identified a variety of bacteria and differences in bacterial communities between sick and healthy mussels. In particular, Yokenella regensburgei and Aeromonas spp. have been shown to be associated with moribund mussels, although it remains unclear whether these bacteria are causes or consequences of disease. To further understand the role of bacteria in mussel epizootics, we investigated mortality events that occurred in the upper Midwest in the Embarrass River (Wisconsin) and the Huron River (Michigan). For comparison, we also studied mussels from an unaffected population in the St. Croix River (Wisconsin). Diverse bacterial genera were identified from these sites, including Y. regensburgei from moribund mussels in the Embarrass River (Wisconsin). This bacterium has also been consistently isolated during ongoing mortality events in the Clinch River (Virginia). Subsequently, we developed and validated molecular assays for the detection of Yokenella to use in future investigations of mussel mortality events and to identify environmental reservoirs of this bacterium.

Michigan, Minnesota, Wisconsin↗

USGS2023

Efficacy of florfenicol and oxytetracycline administered in feed to control cisco mortality associated with Aeromonas salmonicida infections

Two medications (one with florfenicol and one with oxytetracycline) that are approved in the United States to control mortality due to furunculosis associated with Aeromonas salmonicida were assessed to determine their efficacy in medicated feeds to treat A. salmonicida -infected Cisco (also known as Lake Herring) Coregonus artedi . Cisco were subjected to static infection baths containing A. salmonicida or a sham control and then were distributed to replicate test tanks within four treatment groups: (1) fish infected with A. salmonicida and treated with 15 mg florfenicol·kg body weight (BW) −1 ·d −1 , (2) fish infected with A. salmonicida and treated with 83 mg oxytetracycline·kg BW −1 ·d −1 , (3) fish infected with A. salmonicida and treated with a nonmedicated control feed, and (4) uninfected fish treated with a nonmedicated control feed. Medicated and comparative nonmedicated feed rations were administered at 2% BW/d for 10 consecutive days in accordance with the U.S. Food and Drug Administration-approved drug label, followed by a 7-d postdosing observation period using only nonmedicated feed. Cisco that were infected with A. salmonicida and treated with florfenicol (79% survival) and oxytetracycline (85% survival) had significantly higher survival than A. salmonicida -infected fish that received no medicated treatment (3% survival). No statistical difference in Cisco survival between the two medicated feed types was found. Aeromonas salmonicida was not detected in the kidney tissue of any surviving fish treated with medicated feeds at 7 d postdosing using quantitative PCR analysis. Overall, this study demonstrated that florfenicol- and oxytetracycline-medicated feeds were effective A. salmonicida treatments for Cisco. Outcomes may inform ongoing propagation efforts for Cisco restoration within the Great Lakes basin.

North American Journal of Aquaculture↗