Marine sponges in Kane’ohe Bay has a unique feeding strategy: they get important components of their diet from bacteria living in their own bodies.
In research conducted by a doctoral student Joy Leilei Shih in the School of Earth and Ocean Science and Technology at the University of Hawaii in Mānoa, a new application of a technique that relies on natural stable isotopes was used to examine the diet of M. grandis recovered sponges Kane’ohe The Bay. The study found that amino acids, the building blocks of proteins in tissue, came from microbes living in the sponge itself.
The importance of research on marine sponges
Coral reefs are one of the Hawaiimost important natural resources and support the state’s fisheries and economy. Marine sponges are key components of coral reef ecosystems. The invasive Indo-Australian sponge Mycale grandis was first documented on the islands in the late 1990s. M. grandis now sits in and near major ports on the major Hawaiian Islands as well as Kane’ohe The Bay.
Shih and his colleagues discovered that the diet of M. grandis did not come from photosynthetic microbes (as seen in corals), and the diet did not follow the general patterns of other multicellular animals. Instead, the isotopic patterns of the sponge and its symbiotic microbes were not different from each other, indicating that the sponge feeds on the uptake of amino acids from its symbiotic microbes.
“While we knew that sponge symbionts play an important role in their diet, the mechanism by which this happened was unknown,” Shih said. “The only way to produce the observed isotopic amino acid pattern, or the fingerprint, if you will, is through the direct transfer of amino acids from their symbiotic bacteria. “
Added Chris Wall, a EUH Mānoa postdoctoral researcher and co-author of the study, “The patterns we detected in M. grandis and its symbionts are very interesting, as they suggest that sponges can actively capture materials in seawater to meet the needs of their microbial community, which in turn provides the sponge with essential tissue building blocks.
Importance of Findings
The researchers’ new approach to studying sponge feeding strategies can be applied to future research on other marine sponges in Hawaii and elsewhere. Sponges play an important role in the nutrient dynamics of coral reefs, and in the future, they may rise to dominate coral reefs as corals decline due to direct pressure from human activity and the climate change.
This work can help policymakers design better-informed conservation plans and provide new information on sponge biology that shows the importance of marine microbes in the diet of an invasive sponge.