Explaining the vast diversity of microbes found in many ecosystems1,2
is a challenge for microbial ecology. Environments with
chemical or other abiotic gradients such as temperature have
been a key resource for studying microbial ecology. For example,
studies in Winogradsky columns3, microbial mats4, mine drainage
sites5, hydrothermal vents6 and dimictic lakes7 have provided
insight about the relationships between environmental parameters,
microbial diversity and ecosystem functions. Microbial surveys with
spatial scales comparable to those of the ecosystem gradients can
identify groups of spatially correlated organisms and relate the
distribution of those organisms to the environmental gradients.