Bacteria push the limits of sensory precision to navigate dynamic seascapes

The limited precision of sensory organs places fundamental constraints on organismal performance. An open question, however, is whether organisms are routinely pushed to these limits, and how limits might influence interactions between populations of organisms and the environment. Here, we show that marine bacteria operate near the theoretical limit of chemosensory precision when navigating the kinds of chemical landscapes they encounter in the ocean. By combining a method to generate dynamic, replicable resource landscapes, high-speed tracking of freely moving bacteria, a new mathematical theory, and agent-based numerical simulations, we show that sensory noise ultimately limits when and where bacteria can detect and climb chemical gradients. Our results suggest that bacteria inhabit chemical landscapes that are typically dominated by noise that masks shallow chemical gradients, and that the spatiotemporal dynamics of bacterial aggregations can be predicted by mapping the region where chemical gradients rise above noise.