Fig. 6: Temporal shifts in regional nitracline gradients align with relative community dominance.

a Illustrative example highlighting a cruise (Winter 2015) where the regional slope in nitracline depth is relatively low. The black line indicates the regional slope in the nitracline depth with a 95% confidence interval around the model fit (glm). Points indicate individual samples taken during this cruise. The color of the points indicates cyanobacteria communities that were identified by SOMs as either “nearshore” (blue) or “offshore” (red). b Illustrative example highlighting a cruise (Summer 2019) where the regional slope in nitracline depth is much greater. The black line indicates the regional slope in the nitracline depth with a 95% confidence interval around the model fit (glm). Points indicate individual samples taken during this cruise. The color of the points indicates cyanobacteria communities that were identified by SOMs as either “nearshore” (blue) or “offshore” (red). c–g Proportion of samples per cruise that were identified by SOMs as “nearshore” communities relative to the slope in the nitracline across the entire region. Shapes represent the different seasons during which cruises took place (circle = winter, square = spring, diamond = summer, triangle = fall) and the colors represent samples that were collected from 2014–2016 (red), 2017–2018 (blue), or 2019–2020 (gold). Data were fitted as separate linear models per phase, shading represents the 95% confidence interval around the model fit.