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USGS Data Series 423
National Water-Quality Assessment Program
Aliquots of the algal RTH samples were assessed for assemblage composition, biomass as chlorophyll a (Chl a), and ash-free dry mass (AFDM). For DTH algal samples, only assemblage data were assessed. The assemblage aliquots were preserved in 5-percent buffered formalin and sent to the Academy of Natural Sciences of Philadelphia for identification and enumeration (Charles and others, 2002). The biomass aliquots from the RTH samples were filtered on 45-micron glass-fiber filters, packed in dry ice, and sent to the NWQL for analysis.
Macroinvertebrate samples were preserved in 10-percent buffered formalin and sent to the NWQL for taxa identification and enumeration. Invertebrate samples were processed by using standard NAWQA protocols (Moulton and others, 2000) for RTH (randomized 300-organism count) and QMH (fixed processing time designed to maximize the number of taxa enumerated) samples.