Available Data
Data for over 2,000 fish community, 5,000 invertebrate community, and 6000 algae community samples are available for retrieval. These data subsets of samples that have been collected by the NAWQA program. More data becomes available as new samples are collected and as additional samples are reviewed.
Sample Types
Biological community samples are collected within a defined length of stream,
or "reach", at sites
investigated for NAWQA ecological studies. Sampling reaches are established at
a site by using a combination of geomorphic characteristics (Moulton and others,
2002). In general, reach length ranges from 150 to 300 meters for wadeable
streams and from 500 to 1000 meters for nonwadeable streams (Fitzpatrick and
others, 1998).
Sampling approaches vary depending on the biological community that is
targeted (e.g. fish) and the sampling objectives (i.e. generating a list of taxa
that are present, estimating the proportional abundance of each taxon). For detailed information about sampling methods and procedures see
Moulton and others (2002).
Fish Community Samples
A fish community sample consists of a representative sample of the fish
community collected from the entire sampling reach. Such a sample contains most, if not
all, species in the sampling reach at the time of sampling in numbers
proportional to their actual abundance. One or more sampling methods or
collection efforts are used to acquire a sample (Moulton and others,
2002).
Invertebrate Community Samples
Two general types of invertebrate samples are collected. Richest
Targeted Habitat (RTH) samplesare semi-quantitative samples that represent
that habitat in the reach, usually erosional, where maximum taxa richness is
likely to be observed. For example, invertebrate RTH samples typically are
collected from riffles in moderate to high gradient streams dominated by
coarse-grained substrates; in low-gradient streams dominated by fine-grained
substrates RTH samples are often collected from woody snags. Qualitative
Multihabitat (QMH) samples are qualitative samples that document the
presence of invertebrate taxa in addition to those taxa found in RTH samples.
For QMH samples, separate discrete collections are taken from each of the
instream habitats present in the reach and then combined into a composited
sample (Moulton and others,
2002).
Algae Community Samples
Four general types of invertebrate samples are collected. Richest
Targeted Habitat (RTH) samples are semi-quantitative samples that represent
that habitat in the reach, usually erosional, where maximum taxa richness is
likely to be observed. For example, algae RTH samples typically are
collected from riffles in moderate to high gradient streams dominated by
coarse-grained substrates, and from woody snags in low-gradient streams dominated by fine-grained
substrates. Depositional
Targeted Habitat (DTH) samples are semi-quantitative samples that are collected from fine sediments in depositional habitat in the reach. Qualitative
Multihabitat (QMH) samples are qualitative samples that document the
presence of algae taxa in addition to those taxa found in RTH samples.
For QMH samples, separate discrete collections are taken from each of the
instream habitats present in the reach and then combined into a composited
sample (Moulton and others,
2002). Phytoplankton (PHY) samples are quantitative samples collected from the water column. Phytoplankton are floating or weakly swimming microscopic algae.