Early Silurian ‘algal meadows’ of Anticosti Island, eastern Canada: an analogue to modern sea grass meadows?

Abstract

In modern marine ecosystems, sea‐grass and chlorophyte meadows play an important ecological role by serving as a carbon sink. Despite their generally limited areal distribution, the high productivity of sea‐grass meadows makes them an efficient assimilator of CO2. During the early Palaeozoic, complex life was virtually confined to the marine environment, with algae being one of the common carbon‐fixers, alongside abundant calcifying cyanobacteria, rhodophytes, chlorophytes and charophytes, as well as non‐skeletal dinoflagellates and acritarchs. Fossil and molecular data indicate that marine thallophytic algae first appeared in the Early Proterozoic and became widespread in the Palaeozoic, although their fossil record is sporadic because of their soft‐bodied nature; in the absence of angiosperm sea grass and mangroves and poorly understood phytoplankton biomass, thallophytic algae were probably major primary producers. In this article, we suggest that thallophytic algae may have played a significant role as a carbon sink in the Early Silurian, analogous to modern sea‐grass meadows or kelp forests, based on the well‐preserved Early Silurian thallophytic algal meadow from Anticosti Island, eastern Canada.