Temporal discontinuity of nutrient limitation in plankton communities

Abstract

Ideas on how various measures of nutrient limitation relate to plankton biomass and species composition are re-examined. While long-term and multi-lake studies typically focus on determining overall biomass, seasonal studies are more focused toward understanding species composition. We use physiological assays to assess short-term nutrient deficiency of nitrogen and phosphorus in two moderately fertile lakes. While biomass in the lakes was considered to ultimately be limited by total phosphorus, nutrient assays were variable in time. Nutrient ratios (TN:TP, PN:PP, PC:PP and PC:PN) did not predict shortterm deficiencies, notably that nitrogen deficiency occurred in these phosphorus-limited lakes. In one of our study lakes, there was a relaxation of phosphorus deficiency despite phosphate concentrations occurring below traditional detection limits. Following this period, there was an autumn bloom of Aphanizomenon flos-aquae. This relationship corresponds with other studies that have found A. flos-aquae to be a poor competitor for phosphorus. In contrast, phosphorus deficiency remained high prior to the autumn diatom bloom in our other study lake. Deficiency measures remain an excellent means of assessing physiological status of plankton communities and provide greater insight into species compositional changes, especially when other potential indicators like dissolved nutrient concentrations are inconclusive. Regardless of the nutrient limitation indicator used for a given study, it is critical to consider the appropriate scale of the measure.

Nutrient indicators of agricultural impacts in the tributaries of a large lake

“…Due to the predominance of heterotrophic activity in streams (Dodds et al 2004), it is imperative to gauge the effect of land use on C availability as well as nutrient availability (i.e., a stoichiometric approach) to understand fully how heterotrophic nutrient status may be mitigated by other controlling factors (Johnson et al 2009). The use of particulate ratios is also appealing because they are an integrative metric that has a "memory" of nutrient conditions (Davies et al 2010) in the upstream environment.…”

Indirect Interspecies Regulation: Transcriptional and Physiological Responses of a Cyanobacterium to Heterotrophic Partnership

“…It is much more difficult to interrogate species-resolved responses to partnership in natural systems, in which membership cannot be controlled. Typically, such studies have invoked only bulk measurements of physiological or biochemical activities derived from the entire community or have examined subsets, focusing on only the dominant members ( 19 ).…”

Mountain glaciers influence biogeochemical and ecological characteristics of high‐elevation lakes across the northern Rocky Mountains, USA

“…For instance, primary production in glacial lakes is higher (Slemmons and Saros 2012), is more often limited by P alone as opposed to N for non‐glacial lakes (Slemmons and Saros 2012; Warner et al 2017), and is generated by a distinct assemblage of phytoplankton (Slemmons and Saros 2012; Warner et al 2017). Such patterns may reflect the fact that phytoplankton assemblages in glacial lakes tend to be dominated by diatoms (Slemmons et al 2013), which are good competitors for P under high TN : TP ratios and low‐temperature conditions (Reynolds 1999; Davies et al 2010; Brauer et al 2012; Burson et al 2018). Although glacial lakes had elevated TP and NO 3 − , there was no direct association between the percentage of ice in a catchment and TP or NO 3 − concentrations (Supporting Information Fig.…”