Fig. 2
From: Sponge bioerosion accelerated by ocean acidification across species and latitudes?
Set-up of the experimental system situated in a constant temperature room at the Helgoland Alfred Wegener Institute. Individual sealed bioreactors (five replicates per treatment level), carrying 3–5 sponge-bearing oyster shells, and one bioreactor with seawater only for monitoring purposes, all placed into a larger 15 °C buffer tank to maintain ambient temperature. The moderately and strongly elevated pCO2 levels were adjusted by perturbation with specifically mixed gases; for present-day pCO2, compressed air was used