Effects of light and nutrients on plankton stoichiometry and biomass in a P-limited lake

James Elser, Paul Frost, Marcia Kyle, Jotaro Urabe, Tom Andersen

Research output: Contribution to journalArticle

21 Scopus citations

Abstract

A field enclosure experiment was performed over 12 weeks in a P-limited lake to test the hypothesis that light:nutrient balance affects pelagic communities by altering the C:P stoichiometry of seston and by influencing exudation of labile DOC by algae. Three levels of light intensity (ambient, 50% of ambient, 25% of ambient) were cross-classified with three levels of nutrients in a factorial design (n=2). Dissolved nutrient concentrations, seston C concentration and C:P ratios in small (< 1 μm) and larger (1-85 μm) size fractions were monitored, along with chlorophyll a concentration, abundance of bacteria and protozoa, and biomass and P-content of macrozooplankton. Algal exudation of recently-fixed C into the dissolved pool was also measured at the end of the experiment in selected enclosures. Treatments had no effect on seston C concentration but reduction of light intensity significantly decreased whole seston and large (1-85 μm) seston C:P ratios. However, the magnitude of these effects was modest and not likely to be ecologically significant. There were no effects of nutrient addition or light x nutrient interaction on seston stoichiometry. Algae tended to release a higher percentage of fixed C as DOC in high light enclosures but this difference was not statistically significant. There were no effects of treatments on the abundance of bacteria or protozoa but nutrient enrichment led to a statistically significant but generally modest increase in macrozooplankton biomass. No effects on zooplankton community composition or P-content were observed. Comparison of effect sizes and treatment variances indicated a high probability of type II error and thus our confidence in failing to reject the null hypothesis in most of the above cases was low. Thus, our data provide support for only some aspects of the light:nutrient hypothesis but more appropriate tests of the hypothesis should involve stronger treatments and/or increased replication in order to be better able to evaluate its validity.

Original languageEnglish (US)
Pages (from-to)101-112
Number of pages12
JournalHydrobiologia
Volume481
DOIs
StatePublished - Aug 1 2002

ASJC Scopus subject areas

  • Aquatic Science

Fingerprint Dive into the research topics of 'Effects of light and nutrients on plankton stoichiometry and biomass in a P-limited lake'. Together they form a unique fingerprint.

  • Cite this