Articles

Title:	Metalimnetic bloom of Planktothrix rubescens in relation to environmental conditions
Authors:	Lenard Tomasz
Abstract:	Studies were carried out in the mesotrophic, dimictic Rogóźno Lake of the Łęczna-Włodawa Lakeland (Eastern Poland). The studies were done bi-weekly from May to the end of August, 2006. The aim of this study was to investigate the variability of the metalimnetic population of the Cyanoprokaryota species Planktothrix rubescens (DeCand. ex Gom.) Anagn. et Kom. at two depths (6 m and 7 m), where this species was most numerous. During the study period, the level of P. rubescens in the metalimnion fluctuated within a broad range, with a maximum level of 23.7 ind. 106 dm^-3 (98% of the total number of phytoplankton). The highest abundance peaks of this species always occurred below the euphotic zone in low light conditions with Kd values of approx. 1.2. The chlorophyll a concentration in the metalimnion ranged from 14.4 to 91.7 μg dm^-3 and was always higher then in the epilimnion. Oxygen concentration in the water was characteristic for heterograde positive with maximum values at a depth of 6 m and exceeding 22 mg dm^-3 (220%). In the bloom layer (6 m and 7 m), the temperature ranged between 6.5 and 12ºC, pH between 7.9–9.0, while water conductivity was 320–370 μS cm^-1. The relatively high concentrations of biogenic compounds, especially P–PO4 (max. 0.101 mg dm^-3), TP (max. 0.212 mg dm^-3), N–NH4 (max. 0.226 mg dm^-3), and TN:TP ratio of 15–25:1 (at peaks levels) created optimum conditions for the growth of this species.
DOI:
Type of paper:	Original research paper
Pages:	45 to 53
Cytation:	Lenard T., 2009, Metalimnetic bloom of Planktothrix rubescens in relation to environmental conditions, Oceanol. Hydrobiol. Stud., 38(Supl. 2): 45-53
Keywords:	Planktothrix rubescens, physical-chemical parameters, PAR, chlorophyll a, trophy, Łęczna-Włodawa Lake District
Year:	2009
Category:
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