Poster Title

Digital Imagery of Diatoms from the Upper Ohio River Basin

Institution

Northern Kentucky University

Abstract

As a cosmopolitan group of organisms, algae are important water quality indicators. Diatom taxonomy has been recorded from many aquatic systems all over the world. Distinguishing between diatom species involves observations of detailed physical characteristics and specific measurements. We are compiling a taxonomy database of diatom images from the Ohio River Basin as a baseline for identification of common species. The Ohio River was sampled every 5 miles from Pittsburgh, PA to Rising Sun, IN including selected tributaries. The samples were collected using a 10-µm mesh plankton net during the first week of August 2001 and 2002 as a part of River Run. Samples were boiled in concentrated Nitric Acid to remove all organic material in order to have an unobstructed view of diatom physical characteristics. The diatoms were mounted in Naphrax® mounting medium and counted under oil immersion (1000X) using a compound light microscope. The images were captured using an Olympus D-12 digital camera. Common taxa consisting of mostly centric forms include five species of Aulacosiera and five species of Cyclotella, which are found throughout the length of the river. These forms can be difficult to identify to species or variety. This database will be useful to distinguish between similar species found in the Ohio River Basin so that indicator species can be more easily identified.

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Digital Imagery of Diatoms from the Upper Ohio River Basin

As a cosmopolitan group of organisms, algae are important water quality indicators. Diatom taxonomy has been recorded from many aquatic systems all over the world. Distinguishing between diatom species involves observations of detailed physical characteristics and specific measurements. We are compiling a taxonomy database of diatom images from the Ohio River Basin as a baseline for identification of common species. The Ohio River was sampled every 5 miles from Pittsburgh, PA to Rising Sun, IN including selected tributaries. The samples were collected using a 10-µm mesh plankton net during the first week of August 2001 and 2002 as a part of River Run. Samples were boiled in concentrated Nitric Acid to remove all organic material in order to have an unobstructed view of diatom physical characteristics. The diatoms were mounted in Naphrax® mounting medium and counted under oil immersion (1000X) using a compound light microscope. The images were captured using an Olympus D-12 digital camera. Common taxa consisting of mostly centric forms include five species of Aulacosiera and five species of Cyclotella, which are found throughout the length of the river. These forms can be difficult to identify to species or variety. This database will be useful to distinguish between similar species found in the Ohio River Basin so that indicator species can be more easily identified.