The HMA-LMA Dichotomy Revisited: an Electron Microscopical Survey of 56 Sponge Species

Volker Gloeckner, Markus Wehrl, Lucas Moitinho-Silva, Christine Gernert, Peter Schupp, Joseph R. Pawlik, Niels L. Lindquist, Dirk Erpenbeck, Gert Woerheide, Ute Hentschel

Research output: Contribution to journalArticlepeer-review

156 Scopus citations


The dichotomy between high microbial abundance (HMA) and low microbial abundance (LMA) sponges has been long recognized. In the present study, 56 sponge species from three geographic regions (greater Caribbean, Mediterranean, Red Sea) were investigated by transmission electron microscopy for the presence of microorganisms in the mesohyl matrix. Additionally, bacterial enumeration by DAPI-counting was performed on a subset of samples. Of the 56 species investigated, 28 were identified as belonging to the HMA and 28 to the LMA category. The sponge orders Agelasida and Verongida consisted exclusively of HMA species, and the Poecilosclerida were composed only of LMA sponges. Other taxa contained both types of microbial associations (e.g., marine Haplosclerida, Homoscleromorpha, Dictyoceratida), and a clear phylogenetic pattern could not be identified. For a few sponge species, an intermediate microbial load was determined, and the microscopy data did not suffice to reliably determine HMA or LMA status. To experimentally determine the HMA or LMA status of a sponge species, we therefore recommend a combination of transmission electron microscopy and 16S rRNA gene sequence data. This study significantly expands previous reports on microbial abundances in sponge tissues and contributes to a better understanding of the HMA-LMA dichotomy in sponge-microbe symbioses.
Original languageEnglish (US)
Pages (from-to)78-88
Number of pages11
JournalBiological Bulletin
Issue number1
StatePublished - 2014
Externally publishedYes

Bibliographical note

KAUST Repository Item: Exported on 2021-10-07
Acknowledgements: We gratefully acknowledge the marine operations personnel at the National Undersea Research Center (Key Largo, Florida), the Ruder Boskovic Institute (Rovinj, Croatia), the Hellenic Center for Marine Research (HCMR, Crete, Greece), and the Coastal and Marine Resources Core Lab at KAUST (Thuwal, Saudi Arabia), in particular T. Ravasi and M. Berumen, for expert help during sponge collection. The crews of the R/V Seward Johnson II and F. G. Walton Smith (Harbor Branch Oceanographic Institute) are acknowledged for excellent support during field work. Financial support was provided by the DFG, SFB567-TPC3 to U.H. LM-S was supported by a grant from the German Excellence Initiative to the Graduate School of Life Sciences, University of Wuerzburg.
This publication acknowledges KAUST support, but has no KAUST affiliated authors.


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