Sponges Major Players In Acidification: Some Can Leach 20Kg/M2 From Reefs Each Year
EDIT
Bioerosion is the erosion of hard materials caused by living organisms (such as microbes, sponges, sea urchins, fish, snails, bivalves and worms), which have specific ways to attack a variety of materials.
Some weaken materials by rasping or removing particles, which is mechanic bioerosion, Dr Schönberg says. But whats important in the context of climate change and ocean acidification is the so-called chemical bioerosion, an etching process often involving acid that dissolves the materials attacked.
If the water becomes more acidic, the bioeroders spend less energy to work against a chemical gradient and need to produce less acid to create the same effect.
Dr Schönberg says sponges are often the most important bioeroders in warm waters and can be dominant on coral reefs, especially if the reefs are stressed. Very active sponge species can remove as much as 20kg calcium carbonate rock per square metre each yearrock that was slowly created by corals is now reduced to fine sediments by the sponges.
EDIT
http://www.sciencewa.net.au/topics/fisheries-a-water/item/2585-sponges-erode-coral-reef-under-acidification-scenarios.html