0000000000367749
AUTHOR
Sean C. Godwin
Increasing temperatures accentuate negative fitness consequences of a marine parasite
AbstractInfectious diseases are key drivers of wildlife populations and agriculture production, but whether and how climate change will influence disease impacts remains controversial. One of the critical knowledge gaps that prevents resolution of this controversy is a lack of high-quality experimental data, especially in marine systems of significant ecological and economic consequence. Here, we performed a manipulative experiment in which we tested the temperature-dependent effects on Atlantic salmon (Salmo salar) of sea lice (Lepeophtheirus salmonis)—a parasite that can depress the productivity of wild-salmon populations and the profits of the salmon-farming industry. We explored sea-lou…
Warming temperatures and ectoparasitic sea lice impair internal organs in juvenile Atlantic salmon
As a consequence of climate change and open net-pen salmon farming, wild Atlantic salmon Salmo salar are increasingly likely to encounter elevated temperatures and parasite abundances during their early marine migration. Such stressors can compromise fitness by diminishing liver energy stores and impairing cardiac muscle. To assess whether temperature and infestation by salmon lice Lepeophtheirus salmonis are important correlates of liver energy stores and cardiac muscle performance in juvenile salmon, we experimentally infested fish at 3 abundances of louse infestation (zero, low, and high) and 5 temperatures (10, 13, 16, 19, and 22°C). At the end of the experiment (i.e. when sea lice reac…
Salmon lice in the Pacific Ocean show evidence of evolved resistance to parasiticide treatment
AbstractParasitic salmon lice (Lepeophtheirus salmonis) threaten the economic and ecological sustainability of salmon farming, and their evolved resistance to treatment with emamectin benzoate (EMB) has been a major problem for salmon farming in the Atlantic Ocean. In contrast, the Pacific Ocean, where wild salmon are far more abundant, has not seen widespread evolution of EMB-resistant lice. Here, we use EMB bioassays and counts of lice on farms from the Broughton Archipelago, Canada—a core region of salmon farming in the Pacific—to show that EMB sensitivity has dramatically decreased since 2010, concurrent with marked decrease in the field efficacy of EMB treatments. Notably, these bioass…