Australia: The Land Where Time Began

A biography of the Australian continent 

Microbial Mat – Controls on Abundance and Diversity in Modern Marine Microbialites

In the Precambrian microbialites were the most abundant macrofossils. The concurrent complex metazoan radiation and the decline of microbialite abundance and diversity during the terminal Proterozoic and early Phanerozoic have historically been associated with each other. In a similar manner the apparent resurgence of microbialite following the mass extinctions of the Palaeozoic and Mesozoic has frequently been linked to drastic declines of diversity and abundance of metazoans. According to Tarhan et al. it has increasingly been found that in certain modern shallow, normal marine carbonate environments that microbialites are relatively common, foremost among these environments being the Bahamas. Tarhan et al. say that for the first time they present data collected from the Exuma Cays in the Bahamas, characterising systematically the relationship between cyanobacteria that build frameworks, microbialite fabrics, and microbialite-associated abundance and diversity of metazoans. This study documents the coexistence of diverse microbialite control of both infaunal metazoan communities, demonstrating that the predominant control for both microbialite fabric and metazoan community structure is microbial mat type.   It is suggested by these findings that it is necessary that the prevalent interpretations of interaction between microbialites and metazoans be rethought and these findings also imply that microbialites are not passive recipients of alteration that is mediated by metazoans. Also this work supports the theory that certain microbialites from the Precambrian may have acted as havens for early complex metazoan life, and not bereft of metazoans, as had been the traditional belief.

Sources & Further reading

1. Tarhan, L. G., N. J. Planavsky, C. E. Laumer, J. F. Stolz and R. P. Reid (2013). "Microbial mat controls on infaunal abundance and diversity in modern marine microbialites." Geobiology 11(5): 485-497.