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ABSTRACT Wild populations face unprecedented pressure from an assortment of anthropogenic environmental changes and parasites. We sought to understand how host–parasite interactions are affected by the interactive effects of multiple environmental stressors and subsequent parasite infection.We focused on American bullfrog tadpoles (Lithobates catesbeianus) that can become infected by several parasite species (e.g., trematodes in the family Echinostomatidae genus Echinstoma, andBatrachochytrium dendrobatidis; “Bd”) and are affected by abiotic stressors including road salt and variable temperatures attributed to climate change. In a multi‐phase laboratory experiment, we exposed tadpoles to one of two salt treatments (0 and 1.5 g L−1added NaCl sublethal salt) and one of two temperature treatments (constant 23°C and fluctuating between 20°C and 25°C). Next, we exposed these tadpoles to one of four parasite treatments (parasite absent,Bdonly, trematodes only, andBd& trematodes together) at a constant temperature (23°C) without added salt. We then recorded morphological measurements (length, mass, developmental stage) and quantified infection intensity.Tadpoles exposed toBdwere larger in mass than the other parasite treatments, and the effects of trematode exposure on length varied by temperature. We did not detect any effect of our treatments on developmental stage. We found an interaction between the salinity and temperature treatments where tadpoles exposed toBdonly or to fluctuating temperatures andBdand trematodes together had higherBdinfection in the no salt added treatment compared to the sublethal salt treatment. Tadpoles in stable temperatures and no salt treatments had lower subsequentBdinfection loads than those in stable temperatures and elevated salt. With trematode infection, we found that when no salt was added, tadpoles exposed to trematodes only had higher parasite abundance compared to the other treatments (i.e., a salinity by parasite interaction).Our results suggest that the interaction of temperatures and salt pollution in freshwater can increase subsequentBdinfection and that the parasites (Bd& echinostome trematodes) can interact with each other, altering infection levels.
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This content will become publicly available on November 20, 2026
Spatio-temporal patterns of Perkinsus marinus infections are driven by a changing environment in the Chesapeake Bay
Shellfish fisheries and aquaculture within the Chesapeake Bay (hereafter 'the Bay') and its tributaries have been historically impacted by disease and climate events. Climate-driven shifts in temperature and salinity can alter host-parasite dynamics, influencing outbreaks. Here, we explore the relationship between temperature, salinity and parasite distribution and abundance in the eastern oysterCrassostrea virginica-Perkinsus marinussystem. We use long-term (30 yr) environmental data andP. marinussurveys in the Bay to identify (1) how climate affectsP. marinusprevalence and intensity, (2) seasonal and climate-driven infection patterns, and (3) regional environmental influences on disease. We found significant relationships betweenP. marinusinfection intensity, prevalence, increasing temperature and decreasing salinity. Our results indicated that there is an overall decreased abundance ofP. marinusprevalence and intensity throughout the Bay driven by decreases in salinity over time, most prominently from 2003-2020. However, these temporal trends in prevalence and intensity vary largely by region, with some regions still experiencing high disease burden. Examining monthly environmental parameters reinforced the dominant role of salinity in driving disease patterns. Salinity had significant relationships with prevalence and intensity year-round, with the largest effects in late spring/early summer. Monthly temperatures had fewer significant relationships to prevalence and intensity, but the largest significant effects were seen in late winter/early spring. Notably, this study is the first to document that winter salinity influences fall parasite prevalence, sometimes exerting a greater effect than temperature. Continued and expanded monitoring of marine disease is crucial to understand how the changing climate is impacting disease.
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- Award ID(s):
- 2222310
- PAR ID:
- 10648671
- Publisher / Repository:
- Diseases of Aquatic Organisms
- Date Published:
- Journal Name:
- Diseases of Aquatic Organisms
- Volume:
- 164
- ISSN:
- 0177-5103
- Page Range / eLocation ID:
- 111 to 127
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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