The wonderful world of zooplankton The wonderful world of zooplankton (and what it means to us)

What did we sample? Daphnia nauplii Calanoid copepods Also: Cyclopoid copepods Bosmina Rotifers Other zooplanton

Why should we study these tiny organisms?  Food Web Dynamics  Productivity Indicator  Chemistry Indicator

Where did we go? (a little memory jog)  Onieda Lake  Deer Lake  Arbutus Lake  Green Lake  Rich Lake  Onondaga Lake syracuseh20.tripod.com

How did we collect the data? aslo.orgplanktonweb.ifas.ufl.edu Schindler TrapNet Tows

The details are in the methods… Schindler Trap Allowed us to sample at specific depths, usually at epi, meta, and hypolimnion Allowed us to sample at specific depths, usually at epi, meta, and hypolimnion Emptying whole trap on lap was a hazard Emptying whole trap on lap was a hazard Net Tows Allowed sampling for zooplankton throughout entire water column Allowed sampling for zooplankton throughout entire water column Got as close to lake bottom without actually touching it and disturbing sediments Got as close to lake bottom without actually touching it and disturbing sediments

Data Manipulations  Pooled data Combined all types of “zoops” for each lake to compare abundance within each zone and each lake Combined all types of “zoops” for each lake to compare abundance within each zone and each lake  Cross Lake Comparison Population structure of zooplankton taxa within each lake separately Population structure of zooplankton taxa within each lake separately

Zooplankton Depth Trends Diel Migration – movement out of epilimnion during day to escape predation by vertebrate predators (fish), move up to epilimnion at night to feed - Zoops in Arbutus, Deer, and Rich Lakes followed the pattern - Green Lake showed pattern; high zoop abundance at chemocline due to purple sulfur bacteria food source - Oneida Lake zoops did not follow the pattern Why??? 1 )Possible that sampling could have been affected by very windy conditions; lake is completely mixed (shallow) 2)Missing data for metalimnion zooplankton density….. ……maybe we would have seen the pattern if we had this data

Why so many zoops in Deer Lake?  We conclude: INCONCLUSIVE RESULTS  No phosphorous data available for this Lake  Nothing extraordinary shown in other YSI parameters  Possible allochthonous food source (forested watershed)  Perhaps few predators of zoops in Deer Lake (would need to sample the fish population)  Perhaps few predators of zoops in Deer Lake (would need to sample the fish population)* *Anyone in the fisheries class??

Cross Lake Zoop Comparison OnondagaOneidaDeer Arbutus Green Rich

What does the cross-lake comparison tell us?  Calanoids comprise >40% of the zoop pop. in every lake except Onondaga (Daphnia dominate)  Also highest diversity of zoop taxa in Onondaga Lake (six different taxa) Why?  Chlorophyll – extremely high abundance of chlorophyll in Onondaga Lake, much of which is chlorophyta (green algae)….remember Daphnia feeding ecology….  We see small percentages of Daphnia when chlorophyta levels are low (Oneida & Arbutus)

Tying it all together…  Population of zoops is fairly low  Oneida Lake – Population of zoops is fairly low - eutrophic, but fairly low chlorophyll (zebra mussels?) - eutrophic, but fairly low chlorophyll (zebra mussels?) - has abundant fisheries; top-down food web effects - has abundant fisheries; top-down food web effects  Fewest number of zoops in epilimnion  Green Lake – Fewest number of zoops in epilimnion - very oligotrophic; clear - very oligotrophic; clear - limited by chlorophyll amounts, except in chemocline - limited by chlorophyll amounts, except in chemocline - water clarity of lake leads to abundance of specialized red calanoid copepods - water clarity of lake leads to abundance of specialized red calanoid copepods

 Only lake with high percentage of Daphnia, also highest diversity  Onondaga Lake – Only lake with high percentage of Daphnia, also highest diversity - highly eutrophied, lots of chlorophyll (chlorophyta) - highly eutrophied, lots of chlorophyll (chlorophyta) - high conductivity, would expect to see lower diversity of zoops - high conductivity, would expect to see lower diversity of zoops - no data on depth trends - no data on depth trends   Deer Lake – Most zoop in net tows - data shows moderate pH, chlorophyll, and Oxygen levels, no data for phosphorous - lack of predators?

  Arbutus Lake – High abundance of rotifers (344) - skewed hypolimnion abundance, but not reflected in net tow percentages…hmmmm - perhaps data were recorded wrong (other values were 2.08 each for calanoids, cyclopoids and nauplii)   Rich Lake – Did not exhibit any extreme measurements - fairly low chlorophyll levels - fairly low chlorophyll levels - would not expect to see a large population of zoops (fits expectations) - would not expect to see a large population of zoops (fits expectations)

Further Measurements  Resample all lakes for greater replication  Sample at night to observe vertical diel migration patterns through the water column

Sources of Error  Schindler trap vs. net tow values for Arbutus Lake – very high zoop abundance in trap; much lower in net  Missing Data  Wind on day we sampled Oneida Lake - net was “nearly horizontal in water column,” so Schindler trap could have been compromised also - net was “nearly horizontal in water column,” so Schindler trap could have been compromised also

Questions or Input?