Reaction of algal epiphytes in Bryant Bog to elevated carbon dioxide levels.

Abstract

In today's scientific society, rising atmospheric carbon dioxide levels are of great concern. While many studies have been done on the effects of these rising levels on terrestrial ecosystems, only a small proportion have been concerned with aquatic ecosystems. Hein (1997) is one author concerned with stimulation of algal growth, and has documented the supplementation of inorganic carbon to aquatic ecosystems. We conducted an experiment in order to examine the effects of elevated CO2 levels on epiphytic algae found in sphagnum moss. We hypothesized that algae from Bryant Bog would be indirectly stimulated by the increased amounts of nutrients available due to increased nutrient leaching by sphagnum moss. The experiment was conducted in chambers designed for accelerating the atmospheric levels of CO2. We stimulated an additional set of samples, also in the chambers, with nitrate and phosphate to explore CO2 effects that may occur without these nutrient limitations. This gave a total of four treatments: a control treatment (C), an accelerated CO2 treatment (CO), an ambient CO2 with additional nutrients (NP), and a treatment with accelerated CO2 treatment and additional nutrients (CONP). The experiment showed no results correlated with an increase in the level of CO2. The nutrient-stimulated treatments, however, showed significant changes in the algal epiphyte community. Cell density was significantly higher in both the NP and CONP treatments than in the CO. Genera richness was signficantly lower in the NP and CONP than in the CO and C. The composition of the community did shift, although there were only two significant differences at the genera level. Higher numbers of Chlamydomonas and lower numbers of Anabaena were present in the CONP and NP than were found in the C and CO treatmnents.