Influence of re-orientation on alignment to flow and tissue production in a Spongia sp. (Porifera: emospongiae:Dictyoceratida)

Spongia individuals on intertidal reefs in Darwin Harbour displayed a distinct tendency to orientate towards a strong uni-directional water flow, their longest axis facing across the water current. Individuals rotated by 90� re-orientated tissue to face across the prevailing currents. There were significant differences in growth between re-orientated sponges, and both moved control and undisturbed control treatments. Compared to mean growth rates of - 1.27 cm year-3 (from undisturbed controls) and - 1.68 cm year -1 (from moved controls), re-orientated individuals had significantly higher growth rates (46.15 cm year-1). Increased volumetric growth of re-orientated individuals was not a result of re-arrangement of existing tissue but a consequence of the production of more sponge tissue, evident by an increase in sponge volume. Increased tissue production identified in this study may be beneficial to researchers growing sponges for aquaculture purposes. � 2003 Elsevier B.V. All rights reserved.