Oxygen Consumption Rates of Sponges and the Effect of UV-B Radiation and Sediment
Sponges are an important part of many benthic ecosystems, but little is known of their physiology and ecology, which is alarming given the predicted rise in global environmental stress and observed increases in mortality and disease of these organisms. The overall aim of this study was to further understand the physiological processes of sponges and the influence of environmental stress on these organisms. Oxygen consumption rates were investigated, as this is an important measure of the energy required for all physiological activities. The impact of ultraviolet-B(UV-B) radiation and sedimentation on sponges were selected because their input into the marine environment has been predicted to increase in the future, yet little is known about their affect on these organisms. Oxygen consumption rates were measured from a number of temperate and tropical sponges in New Zealand and Indonesia. Variability in oxygen consumption rates was found within and between species from their respective habitats. Interestingly, oxygen consumption rates in the temperate sponges appeared to increase with the proportion of inorganic material (spicule load). Ultraviolet-B radiation, at 60microWcm-2, was found to have no affect on the oxygen consumption of model temperate and tropical sponges. Sponge oxygen consumption, however, increased with repetitive exposure to 2.5 g L-1of sediment, while rates decreased in specimens under higher levels at 8.5 and 16.5 g L-1. Explanations for differences in oxygen consumption rates were constrained by the low level of information on sponges at a species-specific level, and highlighted the needed for future bioenergetic research. The results from the UV-B and sedimentation work suggest that some sponge species may be able to tolerate increasing environmental stress with the onset of global climate change, although interactions between factors could have the potential to negatively affect these organisms.