Document Type

Article

Journal/Book Title/Conference

Canadian Journal of Fisheries and Aquatic Sciences

Volume

63

Issue

10

Publisher

National Research Council Canada

Publication Date

2006

First Page

2236

Last Page

2248

DOI

10.1139/F06-113

Abstract

To examine how salinity and nutrient supply interact to control phytoplankton community composition, nutrient limitation, and dinitrogen (N2) fixation rates in the Great Salt Lake (Utah, USA), we conducted a series of bioassay experiments with plankton from both Gilbert Bay, where salinities are near 160 g·L–1, and Farmington Bay, where salinities range from 10 to 90 g·L–1. Six-day nutrient addition bioassay experiments showed that the extant phyto plankton communities in both bays were limited by nitrogen (N). However, in 28- to 30-day factorial bioassay experiments in which both salinities and nutrient supply were manipulated, phosphorus stimulated chlorophyll a as much as 500% when salinities were less than 70 g·L–1 and N2-fixing cyanobacteria were present. At salinities greater than 70 g·L–1, or with additions of combined N, N2 fixation ceased. When N2-fixing cyanobacteria were absent, the plankton community was routinely N-limited regardless of salinity. The results of these experiments suggest that nutrient limitation of phyto plankton communities may change depending on salinity levels, because salinity controls whether N2-fixing cyanobacteria will be present in the phytoplankton community. Therefore, both salinity and nutrient supply must be considered when making water quality decisions for hypersaline systems such as the Great Salt Lake.

Comments

Originally published by the National Research Council - Canada. Publisher's PDF can be accessed through the Canadian Journal of Fisheries and Aquatic Sciences.