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GCPLCC Instream Flow Project
DRAFT Regional Flow-Ecology Hypotheses:
Examples and Format
October 19, 2012
Categories of Flow-Ecology Hypotheses
• Biotic Interactions– Species– Guild– Community
• Water quality– DO– Temperature
• Physical Habitat- Availability
• Energy Supply- OM Transport
GCPLCC Regional Flow-Ecology HypothesesSubsistence Flows
Ecoregion: Coastal River Class: small, low gradient, warm streams and rivers
Subsistence Flow Hypothesis #1: Dissolved oxygen and temperature are adversely affected by reduced magnitude of subsistence flows
Effected species: All fish, mussels, and other riverine species sensitive to and unable to avoid low oxygen and high temperatures
0
-
+
- +0
Wat
er Q
ualit
y Pa
ram
eter
Altered subsistence flow – magnitude
Source: Sabine-Neches BBEST Biological Overlay Appendix XIII
Dissolved Oxygen
Temperature
GCPLCC Regional Flow-Ecology HypothesesSubsistence Flows
Ecoregion: Coastal River Class: small, low gradient, warm streams and rivers
Subsistence Flow Hypothesis #1: Dissolved oxygen and temperature are adversely affected by reduced magnitude of subsistence flows
Effected species: All fish, mussels, and other riverine species sensitive to and unable to avoid low oxygen and high temperatures
0
- +0
Alte
red
Wat
er Q
ualit
y Pa
ram
eter
Altered subsistence flow – magnitude
Source: Sabine-Neches BBEST Biological Overlay Appendix XIII
Dissolved Oxygen
Temperature
Alternate Graphical F-EH Format
GCPLCC Regional Flow-Ecology HypothesesSubsistence Flows
Ecoregion: All River Class: headwaters, streams, and small rivers
Subsistence Flow Hypothesis #2: Extended periods of subsistence flows strands fish in pools and other isolated bodies of water (e.g., oxbows) where they become concentrated and predation increases.
Effected species: Channel and blue catfish, small mouth buffalo, gar , and other large and small fish
0
-
+
- +0
Abun
danc
e
Altered subsistence flow – duration
Source: Sabine-Neches BBEST Biological Overlay Appendix XIII
Predatory species
Prey
GCPLCC Regional Flow-Ecology HypothesesBase Flows
Ecoregion: All River Class: All
Base Flow Hypothesis #1: Sediments become more stable during periods of extended base flow, which is beneficial for many mussel species. (Vaughn and Taylor 1999, Strayer 2008)Base Flow Hypothesis #2: Mussels feed on higher densities of water-column food resources during periods of extended base flow (Rypel et al. 2009)
Effected species: All mussel species (e.g., Quadrula fragosa (Winged mapleleaf), Leptodea leptodon (Scaleshell)
0
-
+
- +0
# of
mus
sel s
peci
es
Altered base flow – duration
Source: Sabine-Neches BBEST Biological Overlay Appendix XIII
GCPLCC Regional Flow-Ecology HypothesesBase Flows
Ecoregion: All River Class: headwaters, streams, and small rivers
Base Flow Hypothesis #3: Sight-oriented predatory fish can exploit prey populations that are at high densities and in clear water during extended periods of base flows, especially during summer and fall.
Effected species: Sight-oriented predatory fish and their prey
0
-
+
- +0
Abun
danc
e
Altered base flow – duration
Source: Sabine-Neches BBEST Biological Overlay Appendix XIII
Predatory fish species
Prey
GCPLCC Regional Flow-Ecology HypothesesBase Flows
Ecoregion: River Class: headwater, streams, and small rivers, moderate gradient
Base Flow Hypothesis #4: Reduced base flow exposes riffles reducing the extent of available habitat and the abundance of riffle-obligate species.
Effected species: All riffle-obligate species (e.g., Etheostoma spectabile (Orangethroat darter))
0
-
+
- +0
Abun
danc
e of
riffl
e-ob
ligat
e s
peci
es
Altered base flow – magnitude
Source: TNC-OK
GCPLCC Regional Flow-Ecology HypothesesHigh Flow Pulses
Ecoregion: River Class:
High Flow Pulse Hypothesis #1:.
Effected species:
0
-
+
- +0
Para
met
er
Altered High Flow Pulses– duration
Source:
Parameter #1
Parameter #2
GCPLCC Regional Flow-Ecology HypothesesOverbanking Flows
Ecoregion: River Class:
Overbanking Flow Hypothesis #1:.
Effected species:
0
-
+
- +0
Para
met
er
Altered Overbanking Flow– duration
Source:
Parameter #1
Parameter #2
