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Community Ecology Freshwater Communities Changing Through Time (Ch 8)

Community Ecology Freshwater Communities Changing Through Time (Ch 8). Time Scales that affect FW communities Hours Diel Vertical Migration, protist cell division Days algal cell division, rotifer reproduction Weeks zooplankton reproduction Months

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Community Ecology Freshwater Communities Changing Through Time (Ch 8)

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  1. Community EcologyFreshwater Communities Changing Through Time (Ch 8)

  2. Time Scales that affect FW communities • Hours • Diel Vertical Migration, protist cell division • Days • algal cell division, rotifer reproduction • Weeks • zooplankton reproduction • Months • seasonal succession of phytoplankton and zooplankton, fish reproduction • Years • Invasions • Decades • Eutrophication, climate change • Centuries to Millennia (climate change, evolution)

  3. Zooplankton move towards bottom at dawn and towards surface at night • Larger-bodied species have greater tendency to migrate because they are more susceptible to fish predation • Juvenile fish and large invertebrate predators may migrate to follow their prey and also escape predation • DVM is cued by predator chemical signals HoursDVM (diel vertical migration)

  4. Days:Algae and Zooplankton reproduction Example of Algae Bioreactor Mostly rotifers Initial Lake Culture (mixed species) Chlorella only 4 days 1.5 weeks

  5. Weeks and Months:Seasonal succession of phytoplankton populations

  6. Annual Phytoplankton Growth Cycle

  7. Annual Phytoplankton Growth Cycle Zooplankton “Clearwater phase”

  8. Years: Invasions From: Mills et al. 1993

  9. More invasions

  10. Steps of an Invasion Species is endemic somewhere on Earth Founder population appears far from its native habitat Species persists in the new location; this is an exotic species Species spreads from original founder location; the species is now Invasive

  11. Nuisance vs. Neutral Invaders

  12. Decades:Eutrophication, Extinctions and Climate Change Eutrophication in Lake Erie

  13. Endemic Cisco Species X X X

  14. Climate Change Warmer, drier climate Reduced duration of winter ice cover, increased evaporation Lower lake water levels

  15. Centuries to Millennia New endemic species may evolve over the course of thousands of years Great Lakes Ciscos African Cichlids Long-term changes in Lakes are best studied using Paleolimnological methods

  16. Paleolimnology • See presentation at http://post.queensu.ca/~low/Intro%20to%20Paleolimnology%20page.html By Dr. Jon Smol, founder of Journal of Paleolimnology

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