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- Title
Assessment of two mesh sizes for interpreting life cycles, standing crop, and percentage composition of stream insects.
- Authors
Zelt, Kenneth A.; Clifford, Hugh F.
- Abstract
Using Surber-type samplers and dip-net samplers, we assessed the efficiency of nets having pore sizes of 720 μm and 320 μm for determining standing crop and percentage composition of the stream fauna, and for collecting representative size-class specimens of Ephemeroptera and Plecoptera to be used in life-cycle studies. Except for one species, samples collected with either the 720-μm or 320-μm dip-net led to the same general inferences about the species' life cycle. Of fifty possible sample comparisons, there were twelve samples where the size-class frequencies of particular species collected in the 720-μm dip-net were significantly different from the size-class frequencies of the 320-μm dip-net; for five of these samples a deficit of large nymphs (> 5.0 mm) in the 320-μm net mainly contributed to the significant χ²- values. On one date, we used double-bag samplers with both the 720-μm and 320-μm nets attached to either the Surber or dip-net sampler. Approximately 50% of the insects by numbers passed through the 720 μm mesh of each sampler, but only 5 % by volume-biomass. Shape of the insect as well as body length was important in assessing mesh-size efficiencies. The 720-μm mesh of the double-bag dip-net sampler retained most of the Nemoura cinctipes (having stout appendages) and Epeorus longimanus (flattened) nymphs 2.0 mm in body length and larger; whereas most Baetis (streamlined) nymphs smaller than 3.0 mm and all Paraleuctra (needle-like shape) nymphs passed through the 720-μm mesh.
- Subjects
INSECT anatomy; MARINE insects; STREAM animals; AQUATIC insects; AQUATIC invertebrates; MARINE invertebrates; AQUATIC biology; MARINE biology
- Publication
Freshwater Biology, 1972, Vol 2, Issue 3, p259
- ISSN
0046-5070
- Publication type
Article
- DOI
10.1111/j.1365-2427.1972.tb00055.x