Sediment tolerance mechanisms identified in sponges using advanced imaging techniques

Brian W. Strehlow*, Mari Carmen Pineda, Alan Duckworth, Gary A. Kendrick, Michael Renton, Muhammad Azmi Abdul Wahab, Nicole S. Webster, Peta L. Clode

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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Abstract

Terrestrial runoff, resuspension events and dredging can affect filter-feeding sponges by elevating the concentration of suspended sediments, reducing light intensity, and smothering sponges with sediments. To investigate how sponges respond to pressures associated with increased sediment loads, the abundant and widely distributed Indo-Pacific species Ianthella basta was exposed to elevated suspended sediment concentrations, sediment deposition, and light attenuation for 48 h (acute exposure) and 4 weeks (chronic exposure). In order to visualise the response mechanisms, sponge tissue was examined by 3D X-ray microscopy and scanning electron microscopy (SEM). Acute exposures resulted in sediment rapidly accumulating in the aquiferous system of I. basta, although this sediment was fully removed within three days. Sediment removal took longer ( > 2 weeks) following chronic exposures, and I. basta also exhibited tissue regression and a smaller aquiferous system. The application of advanced imaging approaches revealed that I. basta employs a multilevel system for sediment rejection and elimination, containing both active and passive components. Sponges responded to sediment stress through (i) mucus production, (ii) exclusion of particles by incurrent pores, (iii) closure of oscula and pumping cessation, (iv) expulsion of particles from the aquiferous system, and (v) tissue regression to reduce the volume of the aquiferous system, thereby entering a dormant state. These mechanisms would result in tolerance and resilience to exposure to variable and high sediment loads associated with both anthropogenic impacts like dredging programs and natural pressures like flood events.

Original languageEnglish
Article numbere3904
JournalPeerJ
Volume2017
Issue number11
Number of pages26
ISSN2167-8359
DOIs
Publication statusPublished - 2017
Externally publishedYes

Keywords

  • 3D X-ray microscopy
  • Scanning electron microscopy
  • Sediments
  • Sponge

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