Complex interactions between marine sponges and their symbiotic microbial communities

Abstract

To investigate the importance of symbiont-derived nutrition to host sponges, we coupled manipulative shading experiments with stable isotope analyses of isolated symbiont and host cell fractions. Experiments were conducted with four common reef sponges: Aplysina cauliformis, A. fulva, Neopetrosia subtriangularis, and Niphates erecta. The sponge N. erecta lacks photosymbionts, had a higher growth rate under shaded conditions, and displayed no difference in chlorophyll a (Chl a) concentrations across treatments. Isotope values suggested that this sponge obtains nutrition from particulate organic matter in the water column. In contrast, sponges hosting cyanobacterial symbionts (Aplysina spp. and Neopetrosia) had lower growth rates and lower Chl a concentrations under shaded conditions, suggesting that these hosts rely on photosymbiont nutrition. d 15 N and d 13 C values of sponge and microbial cell fractions demonstrated that, while both carbon and nitrogen are transferred from symbionts to host cells in A. cauliformis, only carbon is transferred in N. subtriangularis, and only nitrogen is transferred in A. fulva. Under shaded conditions, shifts in symbiont d 13 C values were coupled to shifts in host d 13 C values in some, but not all, host species, suggesting that the stability of these interactions varies across host species. Symbiont-derived nutrients are transferred to the cells of host sponges, and the variability observed among host species indicates that these interactions are more complex than originally hypothesized.

Down under the tunic: bacterial biodiversity hotspots and widespread ammonia-oxidizing archaea in coral reef ascidians

“…For example, sponges, corals and ascidians are able to supplement their heterotrophic filter-feeding activities with fixed carbon sourced from photosynthetic symbionts (Muscatine and Porter, 1977;Pardy and Lewin, 1981;Freeman and Thacker, 2011), utilizing autotrophic symbiont metabolism to enhance their growth rates in nutrient-limited environments. Sponge symbionts are also responsible for the synthesis of vitamin B1, which animals need to obtain from their diet (Fan et al, 2012), while the cyanobacteria in the genus Prochloron appear to provide UV-absorbing molecules to their ascidian hosts .…”

Combined Effects of Experimental Acidification and Eutrophication on Reef Sponge Bioerosion Rates

“…These photosynthetic symbionts (zooxanthellae) provide sponges with a significant fraction of their carbon and energy via photosynthesis (Weisz et al, 2010;Fang et al, 2014). Since this affects diurnal patterns in the holobiont metabolism (Freeman and Thacker, 2011), bioerosion rates by C. caribbaea were determined at day and night.…”

Ultrastructure, Molecular Phylogenetics, and Chlorophyll a Content of Novel Cyanobacterial Symbionts in Temperate Sponges

“…by-products of symbiont photosynthesis [16,70]) while cyanobacterial symbionts receive 49 a sheltered habitat within sponge tissue (e.g., reduced grazing pressure and UV exposure) 50 and possibly benefit from the nitrogenous end products of host (animal) metabolism. In 51 addition to nutrient translocation, symbiotic Cyanobacteria may also provide a source of 52 defensive secondary metabolites [15,63].…”