Investigating effects of depth and size on pumping rate and filtering efficiency of the Caribbean reef sponge Aplysina lacunosa

Marine sponges provide an important link between the benthic and pelagic environments of coral reef ecosystems, yet there is relatively little known about them. Past studies have indicated that depth and size could be contributing factors in tube sponge filter feeding strategies. This study investigated the effects of depth and size on pumping rate and filtering efficiency of Aplysina lacunosa, a common Caribbean reef sponge. At two different depths, several parameters of the sponges were measured: tube length, wall thickness, tissue volume, pumping rate (using fluorescein dye), and filtering efficiency (percent reduction in turbidity between the ostia and osculum). Water samples collected from the water column had similar food availabilities between the two depths. There was a positive relationship between sponge size and pumping rate but not filtering efficiency. Additionally, no relationship was found between depth and sponge pumping rate and filtering efficiency, which is consistent with my finding that food availability did not differ across depths. The filter feeding strategy of A. lacunosa may be unique in the context of other benthic filter feeders in that its pumping rate but not filtering efficiency is affected by size and that neither pumping rate nor filtering efficiency are affected by depth. Further investigations are needed to learn more about the biology of A. lacunosa and its significance to Caribbean coral reefs.

This student research was retrieved from Physis: Journal of Marine Science XVIII (Fall 2015)19: 40-46 from CIEE Bonaire.