Impact of abiotic factors on microbialite growth (Great Salt Lake, Utah, USA): a tank experiment

Abstract

Microbialites are microbial communities that create a carbonate structure. They are abundant in the Great Salt Lake, a hypersaline lake in the arid Great Basin of the USA, where they contribute to overall primary production, seasonally up to 55%. While the microbial diversity of microbialites has been investigated, how abiotic factors affect the abundance of their primary constituents is not well understood. We examined how microbialite primary producers respond to varying levels of temperature, salinity, and nitrogen within ranges observed in the Great Salt Lake. All abiotic factors and their interactions significantly affected the maximum chlorophyll-a abundance, suggesting that these factors co-limit microbialite primary producers in the Great Salt Lake. Maximum chlorophyll-a concentrations increased with nitrogen additions and showed a parabolic relationship with salinity and temperature with peaks around 60 ppt and 20°C, respectively. While salinity had a strong effect on microbialite primary producers, we found that temperature and nitrogen were more impactful, accounting for 40 and 30% of the variance in maximum abundance, respectively, while salinity contributed just 15%. Our results show the importance of the interplay of abiotic factors on Great Salt Lake microbialites and highlight the need for increased study of benthic communities in inland saline lakes.