Additionally, reduced abundances of R. odorabile on inner-shelf reefs may also be explained by the significantly lower reproductive output compared to mid- and outer-shelf reefs ( Whalan et al., 2007). Increased siltation and exposure to fine sediments have previously been shown to reduce the reproductive output of the temperate sponge Cymbastela concentrica ( Roberts et al., 2006). Although there is no experimental evidence detailing the impacts of fine suspended clay and terrestrial sediments on the reproductive output of tropical sponges, Whalan et al. (2007) provided correlative evidence linking increased turbidity on inner-shelf coral reefs to reduced reproductive output of R. odorabile. Both Roberts et al. (2006) and Whalan et al. (2007) proposed that the reproductive output of sponges is compromised as a result of increased energy drains due to higher maintenance costs associated with living in sub-optimal habitats exposed to excessive siltation and turbidity. The increased respiration activity of R. odorabile exposed to fine suspended sediments measured in this study ( Fig. 8) provides supportive experimental evidence of the negative impact of elevated suspended sediments (turbidity) on the energetic requirements of sponges. In particular, increased metabolic responses of R. odorabile exposed to fine-clay sediments adds further weight to the hypothesis that benthic habitats exposed to excessive siltation and turbidity due to terrigenous run-off and other anthropogenic disturbances may be sub-optimal for sponges and potentially other sensitive filter feeding organisms.