The vertical distribution of phytoplankton assemblages of Lake James, North Carolina in relation to mixing depth and nitrate and phosphate concentrations

Abstract

Phytoplankton, nitrate (NO3-) (mg L(.)1), and phosphate (Po-4-(3-)) (mg V) concentrations were studied in Lake James, NC, during 1997 and 1998. Depths of 2.0, 10, and 30 m were chosen for sampling to determine the vertical distribution of phytoplankton. At 2.0 and 10 m, the species diversity of Heterokontophyta was mainly represented by Mallomonas caudata (Ivanov); Chlorophyta by Chlamydomonas polypyrenoideum (Prescott); Bacillariophyta by Melosira granulata (Ehrenberg) Ralfs and Asterionella formosa (Hassall), respectively. At 30 m, the species diversity of Cryptophyta was mainly represented by Rhodomans minuta (Skuja); Bacillariophyta by Cyclotella glomerata (Bachmann), Synedra ulna (Nitzsch) Ehrenberg, and Tabellaria fenestrata (Lyngbye) Kutzing; and Cyanophyta by Chroococcus limeticus (Lemmermann) and Oscillatoria limnetica (Lemmermann). The purpose of this study was to determine the vertical distribution of phytoplankton in relation to nitrate and phosphate concentrations and the mixing depth in the water column of Lake James, North Carolina, USA.