Effects of sponge bleaching on ammonia oxidizing Archaea: Distribution and relative expression of ammonia monooxygenase genes associated with the barrel sponge Xestospongia muta.
Academic Article
Overview
Additional document info
View All
Overview
Abstract
Sponge-mediated nitrification is an important process in the nitrogen cycle, however, nothing is known about how nitrification and symbiotic Archaea maybe affected by sponge disease and bleaching events. The giant barrel sponge Xestospongia muta is a prominent species on Caribbean reefs that contains cyanobacterial symbionts, the loss of which results in two types of bleaching: cyclic, a recoverable condition; and fatal, a condition associated with the disease-like sponge orange band (SOB) syndrome and sponge death. Terminal restriction fragment length polymorphism (T-RFLP) analyses, clone libraries, and relative mRNA quantification of ammonia monooxygenase genes (amoA) were performed to characterize the ammonia oxidizing Archaea (AOA) community present in bleached, non-bleached and SOB tissues of cyclically and fatally bleached sponges. We found that non-bleached and cyclically bleached tissues of X. muta harbored a unique Crenarchaeota community closely related to those reported for other sponges. In contrast, bleached tissue from the most degraded sponge contained a Crenarchaeota population that was more similar to those found in sediment and sand. Although there were no significant differences in amoA expression among the different tissues, amoA expression appeared to increase with tissue deterioration, exhibiting a 50-fold increase in the most degraded sponge. Results suggest that a shift in the Crenarchaeota community precedes an increase in amoA gene expression in fatally bleached sponges, while cyclic bleaching did not alter the AOA community structure and its amoA gene expression.
