23 Jul 2014

Forest Fires and Fish

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Author Jesse Trushenski, Photo credit John McColgan, U.S. Forest Service

Forest fires – particularly megafires – destroy lives, land, and wildlife, but what about the fish? Think wildfires and fisheries aren’t connected?  Think again.  Here are just a few ways that wildfires can affect aquatic communities.

  1. Wildfires affecting riparian zones cause a “fire pulse,” changing in-stream productivity and increasing prey flux to the terrestrial environment.  In turn, the abundance of riparian predators may increase.  Depending on the severity of the wildlife and fire pulse, aquatic food webs can be affected for extended periods of time.  (www.nrcresearchpress.com/doi/abs/10.1139/F10-006#.U8-w0PldWzk)
  2. Both fires and fire management strategies can affect watersheds and aquatic communities, and in regions like the American West, there is conflict over how best to balance wildfire control/suppression and aquatic resource management.  Wildfire control is essential to prevent damage to property and the loss of human life; wildfires can also threaten aquatic communities, particularly isolated, remnant populations, but they can also provide nutrient and substrate subsidies to aquatic ecosystems.  (http://bioscience.oxfordjournals.org/content/60/6/460.full) (www.tandfonline.com/doi/abs/10.1577/1548-8446(1997)022%3C0006%3AWANFIO%3E2.0.CO%3B2#.U8-wdPldWzk)
  3. Wildfires heat things up, in more ways than one.  When watersheds burn, stream temperatures may rise to uncomfortable levels for aquatic life, but wildfires also have long-term effects on temperature profiles:  because of the loss of canopy cover and riparian vegetation and increased solar radiation, stream temperatures may remain seasonally elevated for years or decades after the fire.  (http://link.springer.com/article/10.1007/s10021-007-9029-8) (www.tandfonline.com/doi/abs/10.1080/02705060.2003.9663964#.U8-wevldWzk)
  4. Wildfires take, but they also give to aquatic ecosystems.  Nutrients like phosphorus and nitrogen are liberated from terrestrial systems by fires and are eventually transported into streams and rivers.  In this sense, wildfires may be an important linking factor between terrestrial and aquatic systems. (www.publish.csiro.au/paper/WF9980183)
  5. Even distant wildfires can affect aquatic systems by ash dispersal.  Ash falling into streams and other water bodies can affect nutrient levels as well as overall water chemistry profiles.  In turn, these shifts can alter the abundance and composition of prey for fishes.  (http://onlinelibrary.wiley.com/doi/10.1046/j.1365-2427.2003.01066.x/abstract;jsessionid=1AD0A0E18D04CD54051E76AC8346C629.f04t04?deniedAccessCustomisedMessage=&userIsAuthenticated=false)

Want to know more?  Contact American Fisheries Society members: Steve Midway (email: stevemidway@gmail.com) or Jesse TrushenskI (email: saluski@siu.edu).

Also, don’t miss the AFS 2014 Quebec Annual Meeting Symposia: Fire Management and Aquatic Systems: Past, Present, and Future by Rebecca Flitcroft and Jeffrey Falke!

There’s more to read: http://thefisheriesblog.com/2013/06/24/fish-fry-forest-fires-and-stream-fish