| Comments |
P.167 right column bottom paragraph: "Despite the fact that sponges feed on microorganisms, large numbers of extracellular bacteria populate the mesohyl matrix of many demosponges. These types of sponge have been termed ‘bacteriosponges’ or ‘high-microbial-abundance sponges’ (Vacelet & Donadey, 1977, Hentschel et al., 2003). However, the mesohyl of other sponges that coexist in the same habitat are essentially devoid of microorganisms (‘low-microbial-abundance sponges’) (Fig. 3). In the bacteriosponges, bacterial population densities may reach 10^8–10^10 bacteria per gram of sponge wet weight, exceeding seawater concentrations by 2–4 orders of magnitude, whereas in the low-microbial-abundance sponges, they are within the range of natural seawater (10^5–10^6 bacteria per gram of sponge wet weight) (U. Hentschel, unpublished data). Because the high-microbial-abundance sponges are typically larger than their low-microbial abundance counterparts whose mesohyl is essentially devoid of bacteria, it is tempting to speculate that the presence of internal microbial biomass contributes to their larger size." |