More than One Way to Limit Algae: Trace Metal-Nutrient Colimitation of Algal Production
Algae use diverse mechanisms to acquire and sequester nutrients to support metabolism and growth. Some mechanisms include the use of trace metals as enzyme cofactors to support electron transfer proteins, for photosynthesis and respiration, or to produce enzymes that allow for use of less common organic nutrient sources. Much of what is understood about stream nutrient limitation focuses on just N and P, although trace metals support several underlying metabolic pathways that may also cause apparent nutrient limitation. We present data from streams in the Great Lakes basin that span a gradient of pristine to urban and low to high inorganic nutrient concentrations. We used trace metal nutrient diffusing substrates (tNDS) with different combinations of elements to identify trace metal-nutrient co-limitation of algae. Metal-nutrient co-limitation was observed in streams with low dissolved inorganic nutrients. Chlorophyll a concentrations showed that 80% of streams with low inorganic P were Zn-P co-limited. Net primary production estimates showed that streams with low inorganic N were Ni-N co-limited. We suggest that while a stream may appear N or P limited, the metabolic mechanism underlying this result may be due to trace metal co-limitation.
Fitzgibbon, Andi and Costello, David PhD(2019). More than One Way to Limit Algae: Trace Metal-Nutrient Colimitation of Algal Production. Environmental Science & Design Research Initiative. Paper 18.