Modeling Ocean Color Niche Selection by Synechococcus Blue‐Green Acclimaters

Abstract

The terms generalist and specialist in ecology refer to organisms with differences in tolerance or preference for food or habitat-generalists having weaker preferences and wider tolerances. Examples are abundant in the literature and range from generalist bird species able to adapt to disturbed environments (Viol et al., 2012) to the broad feeding habits of fish in Arctic lakes (Laske et al., 2018). Among photosynthetic organisms in aquatic environments, feeding and habitat preferences translate into nutrient and light color acquisition, or light intensity, temperature, and salinity tolerances. In cyanobacteria, preferential use of specific wavelengths of light in aquatic ecosystems provide colorful examples of specialists (strains possessing a fixed pigment composition), and generalists (strains able to change pigmentation to maximally absorb one wavelength over another (Bennett & Bogorad, 1973;Gan, Shen, & Bryant, 2014;Palenik, 2001;Tandeau de Marsac, 1977)). The latter is a trait called chromatic acclimation. In lakes, rivers, estuaries, and oceans, light attenuates exponentially with depth, and partitions into colors depending on the composition of the water. Aquatic cyanobacteria must be adapted to use these available colors. Examples include high turbidity and increased colored dissolved organic matter (CDOM) in lakes that result in mostly red light for photosynthesis, or blue light dominating in clear, deep, open ocean water (Holtrop et al., 2020;Stomp et al., 2007).

Chromatic Acclimating Synechococcus Dominate in Mesoscale Eddies

“…The chromatic acclimating Synechococcus requires approximately six generations, equivalent to several days, to adjust their PUB/PEB ratio in response to the prevailing ambient light color Palenik, 2001;Shukla et al, 2012). Previous study suggested that the vertical transport of water in the upwelling zone aligned with this chromatic acclimation process (Lovindeer et al, 2021). It was estimated that eddies with maximum SLA >0.5 cm possess a vertical velocity of up to 50 m day 1 , while weak eddies (maximum SLA <0.2 cm) have a vertical velocity of up to 15 m day 1 (Pilo et al, 2018).…”