Benthic Foraminifera in a large Indo-Pacific coral reef aquarium

Live (rose Bengal-stained) benthic foraminifera were studied from one of the largest coral reef aquaria in the world (Burgers' Ocean, Arnhem, the Netherlands). Benthic foraminifera were unintentionally transported to the aquarium with live rock (i.e., natural reef substratum) from Java and Bali (Indonesia) during initial setup in 2000. After eight years and stabilization of the water chemistry, the foraminifera were found to have successfully colonized this artificial environment. Fifty benthic foraminiferal taxa (>125 mu m) were identified in samples from the various subenvironments within the aquarium. The ecological conditions in the aquarium appeared to be optimal for both symbiont-bearing foraminifera and hermatypic corals. Among the four symbiontic foraminiferal species identified, Heterostegina depressa was the most abundant and it was dominant in all samples. Overall, foraminiferal densities in the aquarium were relatively high compared to those in the natural environment emulated. Although foraminifera are not generally recognized as inhabitants of saltwater aquaria, they can play an important ecological role in this type of closed environment.