Marine archaeal community structure from Potter Cove, Antarctica: high temporal and spatial dominance of the phylum Thaumarchaeota

Abstract

Archaeal communities represent a significant fraction of the Antarctic marine microbial plankton and surely play a relevant role in the proper functioning of the ecosystem. We studied the archaeal community structure in surface water samples from Potter Cove, Antarctica. Temporal and spatial variability was investigated along a whole year cycle using DGGE and 16S rRNA gene sequencing from clone libraries. Additionally, photosynthetic pigments, suspended particulate matter (SPM), salinity and temperature were measured. The multivariate analysis performed using diversity, dominance and richness indexes, and environmental data evidenced a seasonal pattern in the archaeal community and revealed that spring–summer samples clustered separately from autumn to winter ones. High salinity and high values of diversity and richness were related to autumn–winter samples, whereas the spring–summer samples were associated mainly with higher values of temperature, SPM, Chl-a, carotenoids and archaeal dominance. The phylogenetic analysis of five independent clone libraries (467 sequences) showed that 448 sequences fell into a clade containing Nitrosopumilus maritimus and other sequences of ammonia-oxidizing archaea which belong to the Thaumarchaeota phylum. A high fraction of these sequences (62 %) constituted a single cluster containing only highly similar Potter Cove representatives, which probably belong to the same species. Fifteen sequences were affiliated to a group closely related to the order Thermoplasmatales (Euryarchaeota). This work represents a first step towards obtaining a deep understanding of the structure of archaeal communities from Antarctic coastal marine environments and contributes to cover the current gap in knowledge of the dynamics of the archaeoplankton in the Antarctic seas.