Mike Holdsworth Jackie Anderson Zooplankton Mike Holdsworth Jackie Anderson

Importance of Zooplankton Food Web Trophic link Indicator Ecosystem Contaminants Biological processes Nutrient cycling Biocontrol Algal blooms

Parameters studied Species abundance Community dominance Whole lake interactions Differences between lakes

Lakes Studied Oneida Lake Arbutus Lake Deer Lake Rich Lake Onondaga Lake Green Lake

Sampling Methods Shindler trap Net tow Distinctive depths Lake zones Net tow Whole water column (excluding Green Lake) Samples anesthetized with Seltzer Preserved in ethanol

Lab Methods Concentrated sample Diluted to known volume Examined known subvolume Identification of individuals from subvolumes 100 specimens of same species Data

Data Manipulation; Net Tows Took net tow averages from each lake Calculated relative percentages of taxa present in samples Graphical representations

Data Manipulation; Schindler Traps Relative percentages of taxa by lake zones for each lake Table of most concentrated Schindler depth and deepest point sampled depth

Whole Water Column; Net tows Calenoid copepods dominant in all lakes but Onondaga 85% Arbutus Lake 47% Oneida Daphnia dominated in Onondaga Fewer total zooplankton

Specific Depths; Schindler Trap Oneida lake Cyclopoid dominate epilimnion Calonoid dominate hypolimnion

Arbutus Lake Rotifers at depth Possible explanations

Green lakes 100% calanoid dominance in monimolimnion Why? Dominant in all layers but epilimnion

Daphnia dominated Rich Lake Epilimnion Hypolimnion Differs from net tow data

Schindler Summary Lake Depth of most zoops (m) Deepest depth sampled (m) Oneida 1 8 Deer 3 Arbutus 7 Green 11 to 15 35 Rich 11 Onondaga 14

Conclusions Net tow data and Schindler trap data did not always correspond Patchiness Net tow may not reach bottom Net tow mixes layers Copepods were important to all communities Communities could be very different between lake layers

Sources of Errer Identification difficulties Subsample stirring Recounting Lake patchiness