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of uniformity over lake. Biomass levels lower than lower lakes, intermediate between Superior and Michigan.
Not huge difference between spring
points: Productivity between Superior and Michigan. Doesn’t have the time lag in community development of Superior, but overall productivity lower than Michigan
Species composition more similar to Superior than to Michigan
oligotrophic lakes, majority of production can occur below epilimnion. This is
because particulates in water column (i.e.
algae) sparse enough to permit light
penetration to depth, nutrients higher at
depth. Can have potential consequences
for depth distribution of zooplankton.
of heterogeneity in profiles. Unusual for upper lake.
Seems to be north/south differentiation.
in spring dominated by calanoid copepods
In summer, community biomass larger, dominated by Cladocerans (one species - D galeata mendotae), and both calanoid and cyclopoid copepods
Community extremely similar to Lake Michigan (in spite of differences in phytoplankton)
No large gradients in community composition - perhaps slight increase in biomass in the south?
communities with mean lengths above 0.8 mm
indicative of high piscivore/planktivore ratio (Mills et al). All upper lakes
above this line, lower lakes mostly below
this line. This theory has not been tested much.
that biomass higher at depth, but nutrient
status improved, which could make for better
grazing for zooplankton
by diatoms in spring - surprising percentage
of pennates. Still large percentage of
diatoms in summer, which makes it more
similar to Superior. Also, high percentage of chrysophytes. These
are ‘zooplankton friendly’ groups, but also indicative of low productivity.
Chrysophytes are classic ‘clean
lengths, most individuals are small, but most
community biomass is concentrated in larger individuals. In this graph,
cumulative biomass doesn’t quite reach
total biomass at site (41.2 mg/m3) because
to include it would have extended scale of
X axis way out to accommodate a few huge individuals.
there isn’t a strict relationship between
length and biomass (it’s species specific), some individuals in dark orange rectangle are less than 1 mm, some are more than 1mm.