There are numerous of different trophic classes, e.g. 3 oligotrophic, mesotrophic or eutrophic. However, you can even find more defined classifications using a smaller resolution. However, if I am searching for how these classes were quantified I can not find a multiple repeated studies quantifying these classes showing similar results. What is often quantified is a regime shift, clear lakes to turbid lake. If we could regarded this as biological recognized classes then we would have two trophic classes: oligotrophic and eutrophic (and perhaps some gray area). I understand that it is perhaps easier to talk in this way about an ecosystem, but It can also create issues if species then start to be classified as having preferences for certain trophic states. Is someone aware of any studies trying to quantify trophic states based on responses of biota (algae, macrophytes, fish, macro-invertebrates, zooplankton, etc)?
@ Wim, the number of trophic levels in an ecosystem are limited and are not more than 3-4. Because the amount of energy flow decreases with successive trophic level, as only 10% of energy is transferred from one trophic level to the next trophic level.
Hello Wim; I follow the systematic literature about ants. Characterizing the species concept resembles your question. My impression is that there is no clean answer. Mr. Tarafdar above has a helpful point of view. Energy flow through a piece of habitat can be analogized to a braided stream across a leaky bed. Producers are at the upstream end and decomposers are at the end. Volume of flow, path of flow and the like are what the nomenclature is trying to corral. But the braided stream keeps changing. A clean numenclature is not likely.
Best regards, Jim Des Lauriers
Well,
17 chapters search in the ecology of freshwater can be found in the attached pdf.
Regards
An interesting question and am keenly following because i do not know also
J. C. Tarafdar, how does the (plus minus)10% comes in? The loss of energy/biomass to the next trophic state? For example starting at 100 - 10 - 1 - 0.1 - 0.01. But, why is 3-4 than the maximum? Make sure that you do not mistake the trophic level in a food web/chain with the trophic state of an ecosystem, of which I am speaking of.
I added a figure to what I would expect to find in literature. I would expect to find something representing the red line which show changes along an increasing univariate/multivariate gradient. The trophic levels are here expressed as the total biomass/energy/production rate in a system. We can observe a regime shift from a clear lake full of plants to a turbid phytoplankton dominated lake. However, this does not mean the amount of biomass/energy in that system changed. We can plot the amount of chlorophyll along a gradient of total phosphorus. Both log~log transforming the data results in a linear relation, which would represent the green line. It seems we just created classes based on more subjective observable patterns.
Three trophic levels are Surface dweller, Column dweller and bottom dweller. According to feeding habit fish choose their trophic level in fresh water as well as in marine water.
In minamata disease famous incidence for fish mortality due to Hg pollution near Nublear station.
So according to trophic level no. of fish may vary.
Hi Wim,
I am currently working on deep-sea benthic systems in different trophic regimes (eutrophic, mesotrophic, oligotrophic) and I was wondering the same thing, even though oceans are quite different from lakes :)
I feel that these classifications are currently given based on comparison among known systems: the system with the highest input is called eutrophic, the system with the lowest input is called oligotrophic. However, lets imagine that the food input will be reduced globally, so that the eutrophic site receives as much input as the oligotrophic site before the global reduction, and the oligotrophic site is reduced beyond levels seen formely, how would you classify them?
- If you use the relative comparison, the eutrophic site after global reduction would still be called eutrophic even though the quantitative food input is similar to the former oligotrophic site.
- If you use a hard food input threshold based on the state before reduction, all new regimes would be diffferent 'shades' of oligotrophic.
- Or, as you suggest, you could perhaps classify based on the response of the benthic community, or perhaps some other ecological characteristic, which I think is a really smart idea!
Not sure if there is any literature on it, but I haven't done a focussed search.
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