Manipulation of environmental variables and the effect on the growth of Haliclona sp.: Implications for open-water aquaculture

We examined how the physical environment influences the growth and survival of an undescribed Haliclona species. To determine the influence that water movement, light and sediment had on the sponge, explants of Haliclona sp. (approximately 8 cm³ in size) were transplanted into manipulated microenvironments at Hamelin Bay on the west coast of Western Australia near Perth. The sponge is typically found under limestone ledges and appears to have distinct limits on the microenvironment in which it is found. A three-factor orthogonal design was used to manipulate levels of light, water flow and sedimentation. Each factor had two experimental levels, creating environments with high and low water movement, high and low light, and upward and downward orientations to control sediment levels. The survival of explants was high (100%). However, all explants showed a regression in weight. Explants transplanted on to the underside of horizontal surfaces (downward orientations) demonstrated significantly less weight loss (P = 0.023), which was attributed to lower sediment exposure. Light and water movement did not significantly influence the sponge's growth.