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RIVER PLANKTON AND WATER QUALITY OF THE LOWER RIO GRANDE/RIO BRAVO, TEXAS, USA
Publication year - 2001
Publication title -
journal of phycology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 127
eISSN - 1529-8817
pISSN - 0022-3646
DOI - 10.1111/j.1529-8817.2001.jpy37303-36.x
Subject(s) - phytoplankton , environmental science , water quality , plankton , hydrology (agriculture) , eutrophication , nitrate , nutrient , biology , ecology , geotechnical engineering , engineering
DeYoe, H. R. Biology Department, University of Texas – Pan American, Edinburg, TX 78539 USA Little if anything is known about the algae in the lower Rio Grande/Rio Bravo (Laredo to Brownsville, TX) and basic water quality information is limited. This river supplies drinking, irrigation and industrial use water in this US‐Mexico border region. A long‐term monitoring program was initiated in March 1999 and continues to the present. Data from March 1999 to March 2001 is presented. Water samples were collected from the river upstream (2 sites) and downstream (1 site) of an urban area (McAllen‐Reynosa) and analyzed for nutrient concentrations (ammonium, nitrate‐nitrite and phosphorus), chlorophyll a concentration and phytoplankton composition and quantity. During the study, average summer and winter temperatures in this river segment ranged from 28.4‐30.1 °C and 17.5‐21.8 °C, respectively. The river is oligotrophic upstream of the urban area and hypereutrophic downstream of the urban area. Average chlorophyll level was highest at the downstream site both years (1999‐ 14.6 μg/l, 2000‐ 21.1μg/l). Each summer the downstream stretch experienced a cyanobacterial bloom consisting mostly of Microcystis aeruginosa although Merismopedia spp. and Oscillatoria spp. were common. Chlorophytes occurred at a low but consistent density in the warmer months. Diatoms were typically a minor component of the phytoplankton.