Transcript Zooplankton Production - Ohio State University

Zooplankton Production
Wetzel, Chapter 16
Pages 468-482
Zooplankton Production, General
Concepts
• Net Productivity – sum of the growth
increments of all specimens of the
populations
• P = C – F – U – R – G; where P =
production, F = egestion, U = excretion, R =
respiration, and G = gametes
• NOTE: this is Net Production, not Gross
Production
Zooplankton Production, General Concepts, continued
• To measure Production we need:
– Distribution of organisms
– Stages of development and ages
– Development times
• These ALL vary among species, seasons, changing
environmental conditions
• Frequency of sampling MUST be shorter than
generation times of organisms
• Consequently, Production is easy to measure in
organisms with long lives and short reproductive
bursts but difficult to measure in organisms with
short lives and continuous reproductive bursts
P/B Ratios
• This measure is the ratio of Production to
Biomass
• B = measure of biomass of population
– Units – mass per unit area (or volume)
– Represents a “storage” of mass or energy
• P = measure of production of a population
– Units – mass or energy per area per time
– Represents a “flux” or “flow” of energy or mass
P/B Ratios continued
• Therefore, P/B = mass/area/time divided by
mass/area = 1/time = Turnover Rate
• This Turnover Rate is an estimate of the
replacement of a population and is used for
comparisons among species and different
environmental conditions
• 1/P/B = B/P = time = Turnover Time
• Turnover Time = average duration of the
life of a species
P mass / area / time
1


 TurnoverRa te
B
mass / area
time
Turnover Times
• Times vary for
different classes of
organisms in different
lakes under varying
environmental
conditions
• Wetzel Table 16-18
Factors Contributing to ZP Productivity
• Temperature
• Food Resources
– Primary Productivity
– Bacteria
– Detritus
• Body Size
• Algal Productivity itself may not be sustainable
for all ZP productivity
– Productivity supplemented by bacterial and detritus
web
• Major loss of organic matter to decomposition
without consumption
Factors continued
• Wetzel emphasizes the non-predatory, detrital food-webs
and how productivity is lost to these other webs
• Wetzel Fig 16-41; notice productivity estimates by trophic
status
Productivity in Ecosystems
• Varying conditions
influence changes in
productivity
– Temperature, food
quality, etc.
– Spring biomass max.
follows algal bloom
– Productivity lags
behind biomass
• Wetzel Fig 16-43
Productivity in Ecosystems cont.
• Rotifers contribute
significantly to
productivity (energy
cycling)
– Small size but quick
turnover times
• Wetzel Table 16-22
Productivity in Ecosystems cont.
• Productivity can also
demonstrate the structure
of inter-specific
competition
• Position of species’ niches
distributed in time and
space but also in relation
to food, predators
• Allows coexistence of
limnetic zooplankton
• Wetzel Fig 16-44
Productivity in Ecosystems cont.
• Transfer Efficiency – ability to pass energy up trophic web
• 10% of Production of lower trophic level is passed up to
the next higher level
• Wetzel Table 16-25; NOTE rows Production and
Decomposition Losses
Conclusion
• Differences and similarities between
biomass & production
• How zooplankton production is dependent
on features of the ecosystem
• Interaction among zooplankton and both
lower and higher trophic levels