Nitrogen and phosphorus phytoplankton growth limitation in the northern Gulf of Mexico

Aquatic Microbial Ecology

R. Eugene Turner¹  Nancy N. Rabalais¹ 

关键词: Nutrient limitation;    Algal community;    Eutrophication;    Hypoxia;    N:P ratios;    Mississippi River;   

DOI  :  10.3354/ame01607

学科分类：生物科学（综合）

来源: Inter-Research

【 摘 要 】

ABSTRACT: We conducted 158 bioassays to determine phytoplankton growth limitation in the northern Gulf of Mexico and made the following observations. Light limitation occurred where salinity was <20; at higher salinities, phytoplankton biomass yield became mostly limited by N or by a co-limitation of N plus P (NP). The number of N-limited bioassays was 5 times greater than the P-limited bioassays. NP synergism occurred where salinity was >20, and represented 59% of all samples that were not light-limited. The interaction of N and P co-limitation was frequently synergistically additive, i.e. the combined effects of N and P limitation together created a greater response than the sum of either separately. The dissolved inorganic nitrogen:phosphate ratio (DIN:Pi) and various concentrations of DIN and Pi did not offer reliable chemical boundaries describing likely areas of exclusive N or P limitation in these bioassays. We conclude that reducing N loading to the shelf is a prudent management action that will partially remediate eutrophic conditions, including those that lead to hypoxia, but the omission of a concurrent reduction in P loading would be shortsighted.

【 授权许可】

Unknown