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Tzu-Ching Wu, Fi-John Chang
Identification of ecological flow regime related to fish community: A quantitative ecology approach
1 Department of Bioenvironmental Systems Engineering, National Taiwan University
The pivotal difficulty in developing ecological flow regime is how to take into account the interaction and relation between flow regime and river ecosystem.
In this study we propose a framework of considering the relation between ecological flow regime and fish communities based on the gradient analysis technique used in quantitative ecology theory. Dummy variables for representing synthetic environment gradient could be used to identify ecohydrological niche of each specific fish species.
IntroductionIntroduction A quantitative ecology approach connect ecohydrology with fish communities
General flow variables
General flow variables
High/low flow variables
High/low flow variablesFrequency
variablesFrequency variables
hydrologic statisticshydrologic statistics
FunctionalFunctional
DiversityDiversityRobustRobustRiver EcosystemRiver Ecosystem
numbernumber
structurestructurespeciesspeciesFish CommunityFish Community
Time variables
Time variables
Gradient analysisGradient analysis
MethodsMethods Taiwan Ecohydrologic Indicator System (TEIS)
The TEIS provides a means to integrate hydrological, ecological, and human management influences using a new synthesis of hydrologic statistics, and provides a useful tool for the ecosystem-based water resources management in Taiwan (Chang et al., 2008) . The TEIS includes hydrologic statistics for magnitude, frequency, duration, rate of change, and timing.* Chang, F.J., Tsai, M.J., Tsai, W.P. and Herricks, E.E., 2008. Assessing the ecological hydrology of natural flow conditions in Taiwan. Journal of Hydrology, 354(1-4): 75-89.
Develop the Gradient analysis framework with TEIS and Fish community This ecological flow regime approach will focus on a gradient method of analysis to establish optimal habitat conditions related to Taiwan ecohydrological indicators (TEIS). A model of ecological response will be developed and use modified flows to species response in the habitat gradient axis of hydro-ecological location.
The Gradient analysis (Ordination) The gradient analysis (ordination) is a quantitative ecological approach for the interpretation of field data on plant and animal assemblages and their environment, and achieve an effective data reduction, expressing multi-dimensional relationships into low-dimensional data.
Detrended Correspondence Analysis (DCA)DCA is an eigenvector ordination technique based on CA, and it overcome the problem of "Arch effect“ (Hill and Gauch,1980).
Canonical Correspondence Analysis (CCA)CCA is a constrained ordination technique developed to relate biological assemble and environment factor variation patterms (Ter Braak,1986).
Stepwise multiple regression Stepwise multiple regression
Monte Carlo permutation test Monte Carlo permutation test
Establish 14 fish species Fuzzy membership function
Establish 14 fish species Fuzzy membership function
Detrended Correspondence Detrended Correspondence AnalysisAnalysis (DCA) (DCA)
Canonical Correspondence Canonical Correspondence Analysis (Analysis (CCA)CCA)
ResultResult
DCA Biplot Diagram
-2 4
-16
fish5
fish9
fish10
fish19
fish24
fish28
fish38
fish41
fish43
fish50
fish51
fish59
fish60
fish63
SPECIES
DCA1
DCA2
CCA Biplot Diagram
-0.6 0.8
-0.4
1.0
fish5
fish9
fish10
fish19
fish24
fish28
fish38
fish41
fish43
fish50
fish51fish59
fish60
fish63
low_evw
revw
md_higd
q3
q19
min_30wR
low_ev3R
SPECIES
ENV. VARIABLES
CCA1
CCA2
Fish fuzzy membership function on first synthetic gradient (CCA1)
DCA2
-4 -2 0 2 4
Mem
bership
0.0
0.2
0.4
0.6
0.8
1.0
1.2 fish 1fish 5fish 9fish 10fish 19fish 22fish 23fish 24fish 28fish 37fish 38fish 41fish 43fish 44fish 48fish 50fish 51fish 59fish 60fish 63fish 78fish 90
Fish fuzzy membership function on Second synthetic gradient (CCA2)
DCA 1
-4 -2 0 2 4
Mem
bership
0.0
0.2
0.4
0.6
0.8
1.0
1.2fish 1fish 5fish 9fish 10fish 19fish 22fish 23fish 24fish 28fish 37fish 38fish 41fish 43fish 44fish 48fish 50fish 51fish 59fish 60fish 63fish 78fish 90
Developing Fish fuzzy menbership function on synthetic gradient of TEIS
The development of fish fuzzy membership functions that effectively integrates hydrologic regimes and the state and condition of ecosystems uses a gradient method to evaluate the distribution of species, explore the relationship between indicators of TEIS, identify fish communities in relation to habitat, and assess ecological response to hydrological factors .
Future Application Future Application Integrating gradient analysis results in Multi-Objective water Resources Management
The future work of this research will identify approaches to meet human and ecosystem needs achieving the joint goals of establishing a management framework applicable to the Shihmen Reservoir while modifying operational schemes to meet ecological objectives. We expect to provide rule curves that modify procedures for reservoir storage capacity and the control of reservoir discharges. We will use the historical reservoir operations and establish new operational rules based on ecological objective functions and constraints.
Study area & DataStudy area & Data
Taiwan Dahan river Basin
Taiwan’s land area is approximately 36,000 km2 with mountains reaching 3952 m. In this relatively small area, hydrologic monitoring has been conducted for over 50 years. We collect historical records of fisheries data available from bioassessments and identification of flow recording locations that can be related to fish sampling locations in Dahan river Basin. TEIS hydrologic statistics calculated for the location and the sampling period are organized.
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