How can we use our knowledge of trophic cascades to our benefit?
The removal of a top predator has cascading
effects on the environment. The cascade effect often leaves ecosystems barren
of vegetation. I wanted to look at some ways we can use the knowledge of the
trophic cascade mechanism to restore ecosystems. In my previous post, Monbiot
(2013) introduces rewilding. But today, I want to present a new method of
utilising trophic cascades to re-establish ecosystems to their previous health.
Biomanipulation is the process of ‘manipulating’ the ‘biology’ of an ecosystem (Carpenter 2014).
The aim of Biomanipulation is to eliminate or reduce the presence of harmful
phytoplankton (microscopic plants). The presence of harmful phytoplankton such
as blue-green algae is most commonly caused by excess nutrients (eutrophication).
Eutrophication is the process of the build-up of nutrients in aquatic systems (Carpenter 2014).
Although eutrophication occurs naturally, humans accelerate the process,
resulting in more damage. Eutrophication has negative impacts on aquatic
systems because the excessive nutrients disturb the ecosystem dynamics (Riedel-Lehrke 1997). Excess
nutrients decrease the population of large fish causing a cascade
that finally results in an abundance of algae (image 1).
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| Image 1: Trophic cascade in an aquatic ecosystem caused by eutrophication (Missouri Department of Natural Resources 2005) |
Too much algae reduces the level of dissolved oxygen in water systems. Obviously this is not good for fish or other organisms relying on the aquatic ecosystem (image 2).
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Image 2 Fish die due to lack of oxygen in water (Archer
2013)
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To restore these ecosystems back to their previous health,
trophic cascades can be used. By introducing more fish to the ecosystem, or
protecting the current fish populations the balance between trophic levels can
be restored (Riedel-Lehrke 1997). This use of biomanipulation in aquatic ecosystems also effect the
abundance of aquatic vegetation, which effects sediment stability and indeed
nutrient cycling.
It is important to study and understand natural processes
such as trophic cascades that might be used to maintain the dynamics in
ecosystem. With this knowledge we can find ways to restore ecosystems damaged
by human interference.
Image sources
Missouri
Department of Natural Resources 2005, US Environmental Protection
Agency, Missouri, viewed 30 April 2014, <http://www.lmvp.org/>
Archer 2013, University of Michigan, viewed 30 April 2014, <http://sustainability.umich.edu/>
Other sources
Carpenter, S 2014, Encyclopaedia
of Britannica, viewed 25 April 2014, <http://www.britannica.com/EBchecked/topic/1669736/trophic-cascade/288348/Biomanipulation-in-lakes>
Riedel-Lehrke, M 1997, ‘Biomanipulation:
food web management of lake ecosystems’, Student Online Journal, vol. 2, no. 2,
pp. 1-4.
This is also a very interesting idea. Are there examples of biomanipulation in terrestrial environments? You mention that a possible solution could be to introduce more fish to the ecosystem. Would you potentially advocate the introduction of an invasive fish species (if it could be closely controlled) to curtail algae in over-burdened aquatic ecosystems?
ReplyDeleteHey Tasmin, I cannot seem to find any information on biomanipulation in terrestrial environments. I think it might be pretty specific to eutrophication. Rewilding would be a similar alternative for terrestrial ecosystems. The introduction of invasive species could be effective but, manipulating the abundance of local species would be my personal preference.
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