Zooplankton Collections for EEGLE

Zooplankton were collected at each station with a 50 cm, 153-um mesh net equipped 
with a calibrated flowmeter and hauled from approximately 2 m off the lake bottom to 
the surface.  Two replicate samples were collected at each station. 


Zooplankton Abundance

In the laboratory, two or more subsamples were taken with a Stempel pipette for each 
sample collected until at least 600 animals were identified.  All adult copepods and 
cladocerans in each subsample were identified to sex and species.  Immature copepodites 
were identified to genus, while nauplii were combined into one group.  The mean abundance 
of the two replicates is presented as the number of organisms per cubic meter.  


Zooplankton Biomass

Lengths were determined for those animals that contributed to at least 5% of the total 
number of animals in the sample to estimate dry biomass from length-weight regression 
equations from the literature.  Mean lengths were averaged from 10 individuals of both 
adult male and female copepods and 25 individuals for nauplii, copepodites, and cladocerans.  
Default weights from the literature were used for rare taxa that were not measured.  Mean 
dry biomass is presented as milligrams per cubic meter.


Note

Zooplankton samples were collected with a 64-um mesh net in addition to the  153-um mesh 
net, which does not efficiently sample small nauplii.  There may be additional data in the 
future for nauplii abundance and biomass estimates from the smaller sized net.  Mysis 
relicta numbers are not reliable because they must be sampled at night using a special net. 


Contact Information

Megan Agy or Henry Vanderploeg
NOAA/Great Lakes Environmental Research Laboratory
2205 Commonwealth Blvd.  Ann Arbor, Michigan  48105.  
Phone number: (734) 741-2284
E-mail: henry.vanderploeg@noaa.gov