Ecological implications of the detection of freshwater bryozoan <em>Cristatella mucedo</em> (Bryozoa: Phylactolaemata) and myxozoan parasite <em>Tetracapsuloides bryosalmonae</em> (Cnidaria: Malacosporea) in southwest Montana

Tetracapsuloides bryosalmonae is a microscopic myxozoan parasite of freshwater bryozoans and salmonid fish. Infection by T. bryosalmonae under certain environmental conditions causes a deadly immune response in salmonid hosts known as proliferative kidney disease (PKD). Although T. bryosalmonae is present in rivers in southwestern Montana, its distribution, as well as that of its bryozoan hosts, is poorly understood. Environmental chemistry, environmental DNA (eDNA), and bryozoan surveys were conducted at 10 study sites on the Big Hole River and Madison River to assess the presence of the parasite and bryozoans in these areas. Tetracapsuloides bryosalmonae DNA was detectable across a wide spatial and temporal scale on both rivers. Increases in occurrence of T. bryosalmonae were correlated with seasonally driven warmer river water temperature and increased conductivity. Cristatella mucedo statoblasts were collected from the Madison River. To our knowledge, this is the first report of this species in Montana. Tetracapsuloides bryosalmonae DNA was detected in the statoblast samples, indicating that C. mucedo may contribute to the spread of T. bryosalmonae in southwest Montana.El Tetracapsuloides bryosalmonae es un parasito microscopico mixozoario, que parasita briozoos y salmonidos de agua dulce. Bajo ciertas condiciones ambientales, la infeccion de T. bryosalmonae causa una respuesta inmune mortal conocida como enfermedad renal proliferativa (PKD) en sus hospederos salmonidos. Si bien T. bryosalmonae esta presente en los rios del suroeste de Montana, se conoce poco acerca de su distribucion, asi como la de sus hospederos briozoos. Para evaluar la presencia del parasito y de sus hospederos briozoos, se realizaron muestreos de quimica y ADN ambientales (eDNA) en diez sitios de estudio en el rio Big Hole y el rio Madison. Se detecto el ADN de T. bryosalmonae en una amplia escala espacial y temporal en ambos rios. El aumento de T. bryosalmonae se correlaciono con el aumento de la temperatura del agua del rio y con un incremento de la conductividad, debido a la estacion. Se recolectaron estatoblastos de Cristatella mucedo del rio Madison. Hasta donde sabemos, este es el primer reporte de esta especie en Montana. Se detecto ADN de T. bryosalmonae en las muestras de estatoblastos, lo que indica que C. mucedo podria contribuir a la propagacion de T. bryosalmonae en el suroeste de Montana.