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Sponges are a competitive threat to corals

By Leonard Ho - Posted May 03, 2011 02:55 PM
In a recent study published in 'Ecological Modelling,' sponges were found capable of out-competing corals to become the dominant fauna. The real estate on tropical reefs is a highly competitive environment. Studies in the past have focused on the equilibrium between corals and algae and other corals. The new findings show sponges also play a role in this balance.

As reef enthusiasts may know, sponges are generally benign; The majority also do not compete for the same space as photosynthetic corals.  However, some species - known as excavating sponges - can erode aragonite matrices, causing actual damage to corals and the reef structure itself.

Manuel González-Rivero, Laith Yakob and Peter Mumby developed a mathematical model to describe the competition between corals, seaweed, and sponges.  The model takes into account rates of growth, coral erosion, grazing of sponges and seaweed by fish, nutrient levels, physical interaction of the three groups, and habitat disturbance.

What they discovered was that given certain conditions (e.g. high nutrients, low algae competition, low sponge grazing by fishes), sponges can indeed out-compete and overtake corals as the dominant life form.  Should sponges dominate corals at the ecosystem level, recovery is unlikely.

The equilibrium between corals and algae still play the dominant role, but this study hopes to show the importance of factoring sponges into ecological models for reef ecosystems.



Author: Leonard Ho
Location: Southern California

I'm a passionate aquarist of over 30 years, a coral reef lover, and the blog editor for Advanced Aquarist. While aquarium gadgets interest me, it's really livestock (especially fish), artistry of aquariums, and "method behind the madness" processes that captivate my attention.


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