The mechanisms by which invasive species negatively affect native species include competition, predation, and the introduction of novel pathogens. Moreover, if an invasive species is a competent disease reservoir, it may facilitate the longterm maintenance and spread of pathogens in ecological assemblages and drive the extinction of less tolerant or less resistant species. Disease-driven loss of biodiversity is exemplified by the amphibian-chytrid fungus system. The disease chytridiomycosis is caused by the aquatic chytrid fungus Batrachochytrium dendrobatidis (Bd) in anurans and is associated with worldwide amphibian population declines and extinctions. For amphibian species that metamorphose and leave infected aquatic habitats, the

Coursework that is dependent on experiential learning, such as that offered in the laboratory-based sciences, can present barriers for a variety of students. These barriers can be magnified for students who experience disabilities that impact their access to the full depth of the course content and materials. Our unique perspective was formed primarily by supporting two blind students at two institution types across multiple biological science departments. In this paper, we explain the barriers we find are currently impacting blind and visually impaired (VI) students’ access to STEM as well as some tools to navigate creating more equitable and accessible spaces to support blind/VI students in STEM. More specifically, we provide general recommendations for working with blind/VI students using a student-centered approach to planning and daily interactions, followed by tips and tools for preparing accessible materials and a case study on how to use learning outcomes to modify course activities to be more useful for blind/VI students, and lastly we provide recommendations for important collaborations.

Losses in biodiversity can alter disease risk through changes in host species composition. Host species vary in pathogen susceptibility and competence, yet how changes in diversity alter host-pathogen dynamics remains unclear in many systems, particularly with respect to generalist pathogens. Amphibians are experiencing worldwide population declines linked to generalist pathogens, such as ranavirus, and thus represent an ideal group to investigate how host species composition affects disease risk. We conducted experiments in which amphibian larvae of three native species (Pacific tree frogs, Pseudacris regilla;Cascades frogs, Rana cascadae; and Western toads, Anaxyrus boreas) were exposed to ranavirus individually (in the laboratory) or as assemblages (in outdoor mesocosms). In a laboratory experiment, we observed low survival and high viral loads in P. regilla compared to the other species, suggesting that this species was highly susceptible to the pathogen. In the mesocosm experiment, we observed 41% A. boreas mortality when alone and 98% mortality when maintained with P. regilla and R. cascadae. Our results suggest that the presence of highly susceptible species can alter disease dynamics across multiple species, potentially increasing infection risk and mortality in co-occurring species.

Pathogens can alter species composition and ecosystem function by causing direct and indirect effects on communities. Zoospores of the chytrid fungus Batrachochytrium dendrobatidis (hereafter, Bd), a pathogen implicated in worldwide amphibian declines, can be consumed by filter-feeding zooplankton and can damage mouthparts of infected amphibian larvae. Consequently, we hypothesized that this pathogen would affect the abundance of zooplankton and survival and feeding abilities of larval amphibian hosts. In turn, this could affect the algal food resources of zooplankton and tadpoles, which can include phytoplankton and periphyton. We tested these hypotheses by manipulating the presence of western toad (Anaxyrus boreas) larvae and Bd in outdoor mesocosms and quantifying the densities of amphibians, zooplankton, phytoplankton, and periphyton. Bd infections reduced amphibian larval densities, but this only weakly benefitted periphyton (a density-mediated indirect effect). After controlling for larval densities, mesocosms with Bd-exposed larvae had significantly more periphyton biomass than mesocosms with larvae but no Bd, consistent with infection-induced mouthpart damage reducing larval feeding rates on attached algae (a trait-mediated indirect effect). In fact, the estimated trait-mediated effect of Bd on periphyton biomass was larger than the densitymediated effect. However, we did not find evidence that Bd exposure triggered a switch to filter-feeding phytoplankton. The presence of Bd was associated with increased copepod abundance, consistent with zooplankton consuming chytrid zoospores. These results suggest that Bd has the potential to cause both trait-and density-mediated indirect effects that can alter community composition and perhaps the primary productivity of freshwater ecosystems.