LAKE CLASSIFICATION BASED ON ANNUAL CIRCULATION
PATTERNS
(After Hutchinson and Cole)
Amixis
Lakes that do not circulate. Typically because they have permanent ice cover
generally at latitudes greater than 80o so fairly uncommon
Holomixis
Wind-driven circulation mixes the entire lake involving the total water mass
Oligomictic Lakes
Lakes that have warm water at all depths and which remain stratified
a) low altitude equatorial lakes water always >> 4o C.
b) very large sub-alpine lakes water can ~4o C
Monomictic Lakes
Lake overturns regularly one time a year at a particular season
Cold Monomictic Lakes
Frozen during Winter and circulate after Spring thaw
Warm monomictic Lakes
Not covered by ice and circulate in the winter
usually below 40o latitude
Dimictic Lakes
Circulate two times in a year - Spring and Fall
reach 4o C. Every Winter
Polymictic lakes
Continuously circulating
Meromictic Lakes
Lakes that circulate but incompletely
Usually due to density differences caused by factors other than water temperature
Biogenic Meromixis
Usually bacterial decay products
Ectogenic Meromixis
Delivery of water from outside the lake
dilute or dense
Crenogenic Meromixis
Subsurface delivery of water
usually dense
Ecosystem and Community Ecology in Lentic Systems
I. Duration as a Factor
A. The nature of lakes
B. Temporary ponds
1. dynamics
2. models
a) random
b) life history
c) biotic interaction
II Vertebrate Predation in Lakes and Ponds
A. Introductions
B. Experimental studies
C. Top Down models of community Structure and Function
III. The Microbial Loop and its Influence on Community Structure and Function
A. The picoplanktonic community
1. scavenging
2. photosynthesis
3. redirection of products of primary production
B. Source or sink for carbon?
C. Picoplankton and Nitrogen and Phosphorus cycles
IV Zoo plankton and Nutrient cycling
V. Fish and piscivory and zooplanktivory “Top down” community control
Keough, J. R. et al. 1996 Analysis of a Lake Superior coastal food web with stable isotope
techniques. Limnol & Oceanogr. 41: 136-146.
Vanni, M. J. et al. 1997a. “Top-down” trophic interactions in Lakes. Ecol. 78: 1-20.
Vanni, M. J. et al. 1997b Nutrient recycling and herbivory as mechanisms in the “top-down”
effect in Lakes. Ecol. 78: 21-40.
Lyche, A. et al. 1996a. Mesocosm tracer studies. 1. Zooplankton as sources and sinks in the
pelagic phosphorus cycle of a mesotrophic lake. Limnol & Oceanogr. 41: 460-474.
Lyche, A. et al. 1996b. Mesocosm tracer studies 2. The fate of primary production and the role of
consumers in the pelagic carbon cycle of a mesotrophic lake. Limnol & Oceanogr. 41:
475-487.
Twiss, M. R. et al. 1996. Regeneration, recycling and trophic transfer of trace metals by
microbial food-web organisms in the pelagic surface waters of Lake Erie. Limnol. &
Oceanogr. 41: 1425-1437.
Pace, ML and J.J. Cole 1996. Regulation of bacteria by resources and predation tested in wholelake experiments. Limnol & Oceanogr. 41: 1448-1460.