Dams threaten salmonids by triggering temperature-dependent proliferative kidney disease

Area of Science:

• Ecology
• Environmental Science
• Aquatic Health

Background:

• Dams alter river ecosystems by changing flow and temperature.
• Brown trout (Salmo trutta) are popular game fish affected by environmental changes.
• Proliferative kidney disease (PKD) is an emerging salmonid disorder.

Purpose of the Study:

• To investigate the impact of small river impoundments on brown trout health.
• To identify novel threats posed by reservoirs to aquatic ecosystems.
• To assess the role of dams in parasite spread and disease prevalence.

Main Methods:

• Monitoring downstream water temperatures in areas with small river impoundments.
• Assessing the prevalence and abundance of the parasite Tetracapsuloides bryosalmonae.
• Evaluating the impact of elevated temperatures on brown trout and PKD outbreaks.

Main Results:

• Small impoundments elevate downstream summer water temperatures.
• Increased temperatures correlate with higher prevalence and abundance of T. bryosalmonae.
• Reservoirs act as hotspots for this parasite, increasing PKD risk in brown trout.

Conclusions:

• Dams, specifically reservoirs, can exacerbate parasite-driven diseases in fish like brown trout.
• Disease risks should be integrated into dam assessment and management decisions.
• Downstream areas of reservoirs serve as crucial monitoring sites for climate change impacts on rivers.