EAPSI: Determining the Effect of Ammonium on Algae and their Physiology in the Waters of the Hangzhou and Taihu Regions of China

Jackson Melanie, Westfield NJ

Investigators

Abstract

China?s marine and freshwaters are among the most nitrogen polluted in the world. Nitrogen pollution has been linked with severe water quality impairment, ranging from nuisance and toxic algal blooms, oxygen depletion, loss of fisheries, and changes in biodiversity. Although the effect of total nutrient loading has been well explored in terms of promoting the growth of algae (algal blooms), the effects of changing nitrogen forms and proportions on algal community composition and productivity are poorly understood in systems experiencing prolonged nutrient loading. In this study, it is hypothesized that nitrogen in the form of ammonium will favor the development of harmful algal blooms, including cyanobacteria and will reduce primary production, compared to when nitrogen in the form of nitrate is available. This project will involve a series of experiments on natural waters collected from the Hangzhou and Taihu regions of China to assess the physiological response of algae to the addition of changing nitrogen forms. This research involves collaboration with Dr. Mengmeng Tong, well known for her expertise in toxic algal blooms, at Zhejiang University, Ocean College. Eutrophication observed in China is of particular concern, considering nutrient loads are rising and relative nitrogen (N) forms reaching aquatic ecosystems are changing, resulting in increasing reduced (e.g. NH4+) compared to oxidized forms of N (NO3-). Not all algae have the same response to nutrient enrichments, and some algae have preferences for different nutrient forms. Natural samples will be variably enriched with NH4+ and NO3- and will be incubated under natural light and temperature conditions for several days during which phytoplankton community composition, biomass accumulation, and productivity will be tracked. Recognizing that the classic limiting nutrients nitrogen and phosphorus (P) are typically available in excess in these nutrient impacted systems prompts this study to focus specifically on how changing N form in the presence of adequate nutrient supplies alter phytoplankton community composition and physiology. This NSF EAPSI award is funded in collaboration with the Chinese Ministry of Science and Technology.