Ocean warming and acidification are leading to an increase in the rate of sponge biomass and bioerosion.
In order to breathe and eat, sponges filter water. Fluorescent dye shows Cliona orientalis exhales water after it was passing through its body. Orpheus Island. Credit: Max Wisshak
Combined German-Australian research, recently presented at the Ninth World Sponge Conference in Fremantle, used past, present and future climate scenarios to explore how changes are occurring.
The Australian Institute of Marine Science's Dr Christine Schönberg, based at UWA's Oceans Institute, planned and shared fieldwork and experiments with German bioerosion expert Dr Max Wisshak.
"For the past we had measured records; it was cooler and less acidic in the seas," Dr Schönberg says.
"For the future, we use models based on scientific evidence estimating what it may be like in 100 years.
"Adjusting temperature is easy—you insulate a volume of water and either cool or heat it and keep an eye on the temperature.
"With acidity, it's far more challenging. To mimic what's going on in the environment through climate change, induced by human activities, you don't simply add acid to the water.
"You have to dissolve carbon dioxide in it, which creates carbonic acid, which causes a drop in pH and thus 'ocean acidification'."
Values for bioerosion were measured from the water chemistry via alkalinity of the culture water or by weighing eroded substrates under water—a method called buoyant weight measurement. Through this, researchers found sponge bioerosion was stronger in more acidic water.
More of the review, click image