Conservation & Threats

Neither Haliclona cymaeformis nor Ceratodictyon spongiosum have been reported to be found in nature without their symbiotic partner, therefore direct threats for one of the partners is necessarily an indirect threat to the other one, too. Thus, the risks involved might be higher in number than in single organisms, even though symbioses between sponges and algae are often very beneficial for both parties.

Haliclona/Ceratodictyon is one of the rare organisms that survive in the highly turbulent waters of shallow reefs and reef flats, due to the strong support structure its algae partner provides (Trautman et al., 2000). On the one hand, this circumstance turns out to be very beneficial for respiration and nutrient uptake, but on the other hand the constantly stirred sediment particles can clog the sponge’s inhalant canals. This can lead to the sponge terminating to pump water and consequently could affect functions such as feeding or respiration (Trautman et al., 2000). Heavy turbulences can also lead to fragmentation of the association.
Additionally, algal blooms can also be a threat to Haliclona/Ceratodictyon, especially filamentous brown algae (order Ectocarpales) that cover the symbiotic association. Especially Haliclona cymaeformis suffers from these incidents because sponge tissue that gets in contact with the brown algae, sloughs off. (Trautman et al., 2003)
The seastar Culcita schmideliana is the only known organism that feeds on the Haliclona/Ceratodictyon association, but it cannot be found in Australia (Trautman et al., 2003).