Annually reoccurring bacterial communities are predictable from ocean conditions

Abstract

Factors influencing patterns in the distribution and abundance of plant and animal taxa modulate ecosystem function and ecosystem response to environmental change, which is often taken to infer low functional redundancy among such species, but such relationships are poorly known for microbial communities. Using high-resolution molecular fingerprinting, we demonstrate the existence of extraordinarily repeatable temporal patterns in the community composition of 171 operational taxonomic units of marine bacterioplankton over 4.5 years at our Microbial Observatory site, 20 km off the southern California coast. These patterns in distribution and abundance of microbial taxa were highly predictable and significantly influenced by a broad range of both abiotic and biotic factors. These findings provide statistically robust demonstration of temporal patterning in marine bacterial distribution and abundance, which suggests that the distribution and abundance of bacterial taxa may modulate ecosystem function and response and that a significant subset of the bacteria exhibit low levels of functional redundancy as documented for many plant and animal communities.

Fig. 1.

Multiple lines of evidence for temporal cyclicity in bacterial biodiversity at 5-m depths in open-ocean samples from coastal California waters. This figure provides three examples selected from Table 1. (Left) DFA scores that evidence annually repeated multivariate patterns in bacterioplankton. (Center) Autocorrelations from TSA (i.e., 95% confidence intervals illustrated by lines). Note evidence for strong, steady, seasonal patterns reflected by the sinusoidal pattern in autocorrelations as lag size increases. (Right) DFA scores and their predicted values based on MRA (see Table 1). (Top) DFA scores based on relatively high abundance (summed amplified DNA of OTUs over the 4.5 years, with OTUs representing >0.2% of the total amplified DNA). (Middle) DFA scores based on commonness (OTUs in 50% or more of the samples over the 4.5 years). (Bottom) DFA scores based on arbitrarily selected taxa, in this case, the first quarter (44 OTUs), i.e., shortest fragment lengths in ARISA analyses (Table 1).