Spiculous skeleton formation in the freshwater sponge Ephydatia fluviatilis under hypergravity conditions
Bart, M.C.; de Vet, S.J.; de Bakker, D.M.; Alexander, B.E.; Van Oevelen, D.; van Loon, E.E.; van Loon, J.W.A.; de Goeij, J.M. (2019). Spiculous skeleton formation in the freshwater sponge Ephydatia fluviatilis under hypergravity conditions. PeerJ 6: 6055. https://dx.doi.org/10.7717/peerj.6055
In: PeerJ. PeerJ: Corte Madera & London. e-ISSN 2167-8359, more
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| Author keywords |
Freshwater sponges; Gemmule; Spicules; Hypergravity; Skeleton construction |
| Authors | | Top |
- Bart, M.C.
- de Vet, S.J.
- de Bakker, D.M., more
- Alexander, B.E.
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- Van Oevelen, D., more
- van Loon, E.E.
- van Loon, J.W.A.
- de Goeij, J.M.
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| Abstract |
Successful dispersal of freshwater sponges depends on the formation of dormantsponge bodies (gemmules) under adverse conditions. Gemmule formation allows thesponge to overcome critical environmental conditions, for example, desiccationor freezing, and to re-establish as a fully developed sponge when conditions are morefavorable. A key process in sponge development from hatched gemmules is theconstruction of the silica skeleton. Silica spicules form the structural support for thethree-dimensional filtration system the sponge uses to filter food particles fromambient water. We studied the effect of different hypergravity forces (1, 2.5, 5, 10,and 20 ? g for 48 h)—as measure for environmental stress—on the ability ofdeveloping sponges to set-up their spiculous skeleton. Additionally, we assessedwhether the addition of nutrients (i.e., dissolved 13C- and 15N-labeled amino acids)compensates for this stress. Our results show that freshwater sponges canwithstand prolonged periods of hypergravity exposure and successfully set-uptheir skeleton, even after 48 h under 20 ? g. Developing sponges were found to takeup and assimilate dissolved food before forming a functional filtering system.However, fed and non-fed sponges showed no differences in skeleton formation andrelative surface area growth, suggesting that the gemmules’ intrinsic energy fulfills theprocesses of skeleton construction. Additionally, non-fed sponges formed osculasignificantly more often than fed sponges, especially under higher g-forces.This suggests that the eventual formation of a filtration system might be stimulatedby food deprivation and environmentally stressful conditions. These findingsindicate that the process of spiculous skeleton formation is energy-efficient and highly resilient. The uptake of dissolved food substances by freshwater sponges maycontribute to the cycling of dissolved organic matter in freshwater ecosystems wheresponges are abundant. |
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