Elsevier

Ecological Engineering

Volume 96, November 2016, Pages 86-93
Ecological Engineering

A habitat similarity model based on vague sets to assess Schizothorax prenanti spawning habitat

https://doi.org/10.1016/j.ecoleng.2016.04.007Get rights and content

Abstract

Schizothorax prenanti (S. prenanti) is a second-class provincial protected endemic fish within the upper reaches of the Min River. The spawning season of S. prenanti extends from March to April. Habitat alteration and the construction of multistage dams have resulted in a rapid decline of the S. prenanti population. To assess the potential effects of a reduced flow volume on the S. prenanti spawning habitat area in downstream of dams, we combined River 2D and a habitat similarity evaluation model through the following steps. First, we conducted surveys of S. prenanti and the substrate composition in a natural habitat reach and a hydropower-affected reach. Second, hydraulic simulations were performed over a range of flows using River 2D. Third, vague sets of habitat variables were individually defined based on multi-expert opinions. Fourth, we estimated the weighted similarity of the S. prenanti spawning habitat using input variables (water depth, velocity) from River 2D. Fifth, we verified the model with S. prenanti survey data. Hydraulic simulations for velocity and depth yielded accuracies of approximately 84–97% and 81–98%, respectively. The weighted similarity simulations showed that weighted similarity increased with the flow up to a threshold range of approximately 130–150 m3/s; beyond this range, the weighted similarity decreased. The weighted similarity in the natural habitat reach was higher than in the restored reach at the same flow volume due to geography. The habitat similarity model provides restoration targets and thresholds for decision makers to develop a proactive conservation strategy for wetland management.

Introduction

Schizothorax prenanti (S. prenanti) is a second-class provincial protected endemic fish within the upper reaches of the Min River (Ding, 1994). However, multistage dams have been constructed in the upper Min River, and these disturbances have altered historic hydro-geomorphic processes and the original hydraulic conditions of the habitat in these regions (Hou et al., 2010), resulting in a decline of available spawning areas for S. prenanti. To maintain appropriate habitat conditions for S. prenanti and other aquatic organisms to complete their life cycles, habitat restoration efforts should be conducted in the hydro-effected reaches. (Ahmadi-Nedushan et al., 2008, Ahmadi-Nedushan et al., 2006, Dong, 2007, Wheaton et al., 2004a, Wheaton et al., 2004b).

The physical habitat structure is the primary determinant of species composition in river. The most important physical habitat variables include water depth, water velocity, cover and substrate composition. The protection and rehabilitation of the habitats of target species, such as juvenile Atlantic salmon, brown trout (Armstrong et al., 2003), Chinese sturgeon (Yang et al., 2007) and S. prenanti (Chen et al., 2013), have been widely studied in recent years. Tharme (Tharme, 2003) and Leclerc (Leclerc et al., 1995) reviewed different methods for environmental flow assessment, including traditional methods such as hydrological, hydraulic, habitat simulation and holistic approaches (Tharme, 2003, Ahmadi-Nedushan et al., 2006, Milhous et al., 1984). Ahmadi-Nedushan et al.(2006) reviewed statistical methods for the evaluation of aquatic habitat suitability for in-stream flow assessment and habitat suitability indices to calculate the amount of weighted usable area.

Vague set theory (Gau and Buehrer, 1993) is an extension of classic fuzzy set theory (Zadeh, 1965) and is based on the central concept or membership functions (Ye, 2007). In a previous study, Wheaton et al., 2004a, Wheaton et al., 2004b showed that appropriate riverbed restoration designs are produced by imitating the attributes of either a present-day or historical natural analogue. Compared with traditional habitat modeling, the fuzzy logic approach presents advantages in imitating historical natural analogues and dealing with the uncertainties that are often inherent in habitat modeling. Vague sets can be used as an alternative to habitat suitability curves, which are describe habitat requirements in habitat and holistic modeling (Lee and Chen, 2014, Moir et al., 2005, Hong and Choi, 2000, Bovee, 1986, Jorde et al., 2001, Fukuda et al., 2011, Marsili-Libelli et al., 2013).

In this study, we combined River 2D, which predicts local variations in depth and velocity at a given flow, and a vague-based similarity evaluation that assesses habitat quality for fish using hydraulic indexes to assess the potential effects of a reduced flow volume on S. prenanti spawning habitat area in downstream of dams. This approach is illustrated by two case studies involving a reach of natural S. prenanti spawning habitat in the Weimen reach and a restoration reach downstream of the Jiangshe Dam. The study species and sites along the Min River (China) are introduced in Section 2.1, followed by an introduction to substrate evaluation (Section 2.2), description of the field measurements (Section 2.3), the ideas pertinent to the hydrodynamic model (Section 2.4) and the habitat similarity assessment model (Section 2.5). The results may provide flow volume thresholds for S. prenanti spawning habitat for managers in the development of S. prenanti habitat restoration.

Section snippets

Study sites and species

S. prenanti is a native species of Min River and spawns in shallow areas with a rapid flow. Its spawning season extends from March to April in the upper Min River. In the present study, we selected a natural spawning site from the natural ecological reserve reach extending from the confluence of the Heishui and Min Rivers to Mao township (31.75°, 103.78°E to 31.75°N, 103.81°″E), which is located approximately 37 km upstream from the dam. The selected natural spawning site is presently undammed

Substrate composition analysis

Substrate samples of 1 × 1 × 0.5 m were collected in each of the following areas: (A) a region of riverbed in the middle of the river (cumulative weight of 858.8 kg, maximum particle size of 250 × 200 × 130 mm, and Dmax = 187 mm); (B) a region of riverbed along the riverside (cumulative weight of 765.4 kg, maximum particle size of 470 × 270 × 170 mm, and Dmax = 278 mm); and (C) a region of riverbed near Weimen Township (cumulative weight of 753.1 kg, maximum particle size of 300 × 300 × 70 mm, and Dmax = 185 mm).

The riverbed

Conclusion

We combined River 2D, which predicts local variations in depth and velocity at a given flow, and a vague-based similarity evaluation that assesses habitat quality for fish using hydraulic indexes to assess the potential effects of a reduced flow volume on the S. prenanti spawning habitat area in downstream of dams. The innovative aspects of this work are as follows: (a) the use of vague sets to simultaneously define spawning habitat presence/absence and uncertainty in the data and to

Acknowledgments

We are grateful to the Chengdu Engineering Corporation, Ltd., for providing the topographic information. Funding for this research was partially provided by the National Natural Science Foundation of China (Nos. 51479127 and 51279114).

Ben R. Hodges was partially supported by the U.S. National Science Foundation through Grant No. CCF-1331610 and the Open Fund of the State Key Laboratory of Hydraulics and Mountain River Engineering, SKHL1304. We are grateful to the anonymous reviewers for their

References (45)

  • L.A. Zadeh

    Fuzzy sets

    Inf. Control

    (1965)
  • B. Ahmadi-Nedushan et al.

    A review of statistical methods for the evaluation of aquatic habitat suitability for instream flow assessment

    River Res. Appl.

    (2006)
  • B. Ahmadi-Nedushan et al.

    Instream flow determination using a multiple input fuzzy-based rule system: a case study

    River Res. Appl.

    (2008)
  • K.D. Bovee

    Development and Evaluation of Habitat Suitability Criteria for Use in the Instream Flow Incremental Methodology

    (1986)
  • M.Q. Chen et al.

    Preliminary study on index system describing hydraulic characteristics of fish spawning ground

    J. Hydraul. Eng.

    (2013)
  • S.M. Chen

    1997: Measures of similarity between vague sets

    Fuzzy Sets Syst.

    (1995)
  • S.M. Chen

    Similarity measures between vague sets and between elements

    IEEE Trans. Syst. Man Cybern. B

    (1997)
  • M.Q. Chen

    Study on hydraulic characteristics of schizothorax prenanti spawning ground in the upper reach of minjiang river and its application

    Ph.D Thesis

    (2012)
  • R.H. Ding

    The Fishes of Sichuan, China

    (1994)
  • Z.R. Dong

    Principles and Technologies of Eco-hydraulic Engineering

    (2007)
  • W.L. Gau et al.

    Vague sets

    IEEE Trans. Syst. Man Cybern.

    (1993)
  • A.H. Ghanem et al.

    Two dimensional finite element flows model for aquatic habitats

    Ph.D.Thesis

    (1995)
  • Cited by (16)

    • Study of quality maintenance of fish habitats in small- and medium-sized mountain rivers with low flow rate

      2020, Ecological Engineering
      Citation Excerpt :

      Among them, S. dolichonema and Sp. malacanthuschengi are endemic to the Dadu River (Deng, 1996). Most of these endemic species inhabit rivers throughout the year and have a high degree of adaptability and a strong dependence on their habitats (Qin et al., 2016; Cao, 2017; Zhang et al., 2018; Ji et al., 2019). In this context, the habitat alternative for fish to create suitable habitats in small and medium tributaries has become a new concept being considered by many river ecological restoration decision-makers (Gao et al., 2012; Yang et al., 2015; Xue and Jiang, 2019).

    • Water flow and substrate preferences of Schizothorax wangchiachii (Fang, 1936)

      2019, Ecological Engineering
      Citation Excerpt :

      However, habitat conservation in China is focused on primary rivers and reservoirs and tributaries receive little attention. The habitat of large and small tributaries of the Yangtze River are severely fragmented by multistage dams (Qin et al., 2016) and few compensatory measures have been taken. The results of this study will enhance conservation efforts by providing guidance for protecting and restoring the habitat of riffle foraging fish.

    • Function, restoration, and ecosystem services of riverine wetlands in the temperate zone

      2019, Ecological Engineering
      Citation Excerpt :

      A recent global assessment has found that many ecosystem services are declining (Gunderson et al., 2016), pointing to riverine wetlands that have been severely altered or have completely disappeared. For example, a report showed that habitat alteration and the construction of multistage dams have resulted in a rapid decline of the S. prenanti population in Min river of China (Qin et al., 2016). A series of measures have been undertaken to protect the riverine wetlands thanks to the understanding of the great value of wetland ecosystem.

    View all citing articles on Scopus
    View full text