Abstract:

The marine microbenthos is composed of prokaryotic bacteria and archaea, and eukaryotic microalgae and protozoa that live in or on bottom sediments. Compared to those in pelagic systems, marine benthic habitats, particularly those in deep-sea, are highly heterogeneous and harbor diverse microbenthic communities whose abundance and productivity exceed those of the water column by one to several orders of magnitude in some cases. The marine microbenthos constitutes an essential component of marine biodiversity and ecosystems, particularly in marine biogeochemical cycles. Our understanding of microbial diversity and distribution within the benthos is greatly hampered by the lack of taxonomical data and undersampling. Estimation based on theories and statistics have yielded varied pictures of microbial diversity. Molecular evidence has also provided new insights into the microbial world. The present paper summarizes literature dealing with the biodiversity and geographical distribution of marine microbenthos, from bacteria to eukaryotic algae and protozoa. Striking progress has been made towards understanding the community structure, diversity and molecular phylogeny of benthic bacteria, while most benthic protozoa, with the exception of marine interstitial ciliates, are still an understudied group, largely due to taxonomic impediments and methodological limitations. Thus far, most research focuses on molecular and species diversity within marine microbenthos, while little research concerns habitat diversity. Our review highlights the need for more comprehensive investigation of the diversity, distribution and ecological role of the marine microbenthos.

Key words: microorganisms, marine sediment, biodiversity, biogeography, progress