Current and Historical Resource Nitrogen Supply Affects the Eco‐Physiological Traits and the Ionome of a Diazotrophic Cyanobacterium

Abstract

Diazotrophic cyanobacteria can overcome nitrogen (N)‐limitation by fixing atmospheric N 2 ; however, this increases their energetic, iron, molybdenum, and boron costs. It is unknown how current and historic N‐supplies affect cyanobacterial elemental physiology beyond increasing demands for elements involved in N‐fixation. Here, we examined the changes in pigment concentrations, N‐storage, and the ionome (i.e., multivariate elemental composition) of the freshwater diazotroph Dolichospermum flosaquae adapted to an N‐gradient for two temporal scales: 27 days and 45 months. We found short‐term adaptation of Dolichospermum to low N‐supply decreased pigment concentrations, N‐storage, N:carbon (C), and increased boron:C, calcium:C, and magnesium:C than high N‐supply adapted populations. Dolichospermum adapted to low N‐supplies for 45 months had higher pigment concentrations, N‐storage, and lower boron:C, calcium:C, magnesium:C, and phosphorus:C than the short‐term adapted populations when grown in low N‐supplies. Our results highlight the connections between the ionome and physiology, identifying the previously unrecognised roles of elements that can be used to advance physiological patterns.

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