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| Habitat Overview |
This habitat is defined by aquatic to semi-aquatic species that are associated with rivers that possess extensive areas of riffles: there must be at least a moderate current and plentiful rocks present. All species in this habitat must be able to cope with the scouring action of the rivers.
The Odonates included in this habitat perch as adults on exposed rocks located well out in the water. Foraging and mating take place in the vicinity of the riffles. Nymphs of Neurocordulia are rock-clingers (also clinging to roots and woody debris) (Tennessen, 2018) and may therefore also stick close to the riffles. So may the nymphs of the two damselflies, who live within aquatic vegetation (Schwiebert, 2007). The nymphs of the Gomphurus species, on the other hand, may reside in substrates located away from the rocks. Gomphurus nymphs are burrowers who live in substrates -- sometimes buried quite deeply -- ranging from sand, silt, gravel, and mud (Tennessen, 2018). All of these species generally require the well-oxygenated waters associated with riffle habitats and are usually found only in unpolluted rivers.
Virtually all examples of this habitat occur west of the Fall-line and include species that occur in both the Piedmont and Mountains or in the Piedmont alone. Species restricted to the cooler rivers of the mountains are treated in the Montane Rocky Rivers habitat.
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| Related NHP Natural Communities |
Only a single NHP Natural Community (Schafale and Weakley, 1990; Schafale, 2012) intersects this habitat: Rocky Bar and Shore. Most of the subtypes of this community represent shoreline vegetation or that found on gravel and sand bars and can be found along non-rocky rivers and streams. Two subtypes that include riffle species more specifically are the Riverweed Subtype and Water Willow Subtype. |
| Determining Species |
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| Candidates for Inclusion |
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| Habitat Sub-sets |
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| Distribution Map | |
| Distribution |
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| Survey Coverage Map |
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| Survey Coverage |
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| Survey Priorities |
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| Average Imperilment of Habitat Members |
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| Habitat Conservation Status |
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| High Quality Habitat Occurrence Table |
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| High Quality Habitat Occurrences |
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| Protected Habitat Occurrences |
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| Threats and Trends |
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| Status Summary |
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| Stewardship Recommendations |
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| References |
Schwiebert, E., 2007. Nymphs, Stoneflies, Caddisflies, and Other Important Insects: Including The Lesser Mayflies (Vol. 2). Rowman & Littlefield.
Tennessen, K.J., 2018. Dragonfly Nymphs of North America: An Identification Guide. Springer. |
| Updated on |
2019-09-08 18:48:50 |
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