Lower trophic levels and alewifein Onondaga Lake 2011
Presentation for OLTAC meeting Halloween 2012
Phytoplankton in 2011
Cyclotella
Synedra
Bluegreens 2011
Biovolume 1998-2011
Phytoplankton 1998-2011
N:P ratio
Daphnia
Cyclopoid
Calanoids
Copepods
Zooplankton
Bosmina
Cladocerans
Zooplankton in 2011
Zooplankton size in 2009-11
Zooplankton average length
Alewife
Daphnia
Alewife
Cascading interactions in the food chain
Algae
Zooplankton
2010 – 60% from the 2009 year class2011 - 74% from the 2009 year class 26% from the 2010 year class 2012 28% 2009, 13% 2010, 52% 2012
Water Quality Effects
• Smaller zooplankton
• “Top-down” trophic cascades: increasing algae
Secchi 2008-20122008 2009 2010 2011 2012
Density # /m2
• Oneida 1995 – 2009: 6300 (3600 – 9400)
• Onondaga 2007 – 2011: 13000-18000
Comparison with lake-wide biomass Oneida - Onondaga
Comparison with lake-wide biomass Oneida - Onondaga
Alewife
Trophic Cascades 2008 - 2011
Algae and Water Clarity
Nutrients
Winter MortalityChamplain January 2008
Thank You