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ecological indicators 8 (2008) 564–572

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Annual variations of biotic integrity in the upper Yangtze River using an adapted index of biotic integrity (IBI)

Di Zhu a,b,c,1, Jianbo Chang a,b,c,* a Institute of Hydrobiology, Chinese Academy of Sciences, 7# Southern Road of East Lake, Wuhan, Hubei Province, 430072 China b Institute of Hydroecology, Ministry of Water Resources and Chinese Academy of Sciences, 578# Xiongchu Avenue, Wuhan, Hubei Province, 430079 China c The Graduate School of the Chinese Academy of Sciences, Beijing 100039 China article info abstract

Article history: Adaptive modification and use of Karr’s index of biotic integrity (IBI) for the upper Yangtze Received 15 February 2007 River, including 12 metrics in five categories, have typically occurred in line with the data Received in revised form collected by 6-year commercial fisheries investigation. These investigations were under- 24 May 2007 taken annually in four sections of the Upper Yangtze main channel between 1997 and 2002. Accepted 19 July 2007 These four monitoring sections (Yibin – YB, Hejiang – HJ, Mudong – MD, and Yichang – YC) were selected because they represent the part of the river that will be covering a 1000 km stretch that includes the future Three Gorges Reservoir (TGR), upstream of the Three Gorges Keywords: Dam (TGD), an area influenced by the construction of TGD. In addition, historical data were Fish assemblages used to show changes in the watershed by comparison with field investigations recently. Index biotic integrity (IBI) The biotic integrity of the four sections were calculated and classified into different levels Three Gorges Dam (TGD) annually for recognizing its spatial and temporal variations. It was observed that IBI scores Upper Yangtze River were becoming lower diminishingly since 1997 in all the four sections. Because all the data were collected before the impoundment of the Three Gorges Reservoir, it is obvious that human activities, especially over-fishing, must be crucial factor instead of damming in the upper Yangtze River in that period. # 2008 Published by Elsevier Ltd.

1. Introduction Van Dolah et al., 1999). Fish assemblages were considered to be an appropriate end-point for assessing stream integrity due to The index of biological integrity (IBI) originally developed by their high public visibility, their position in the food chain and Karr (1981) and established by Karr et al. (1986) had previously high sensitivity to water quality (Karr, 1981; Karr et al., 1986). been used in the United States (Karr, 1999a; Karr et al., 1986; Human influences, such as changes in water chemistry or Karr, 1999b) and became increasingly adaptive elsewhere, e.g. physical habitat modifications, could alter fish assemblages by in Europe (Simon and Sanders, 1999). Many groups of disrupting their structures and functions (Fig. 1). Varieties in organisms had been used as indicators to estimate environ- fish assemblage could be detected through changes in mental quality. Algae, benthic invertebrates and fish were components of the community, functional groups, species typical species in biological monitoring (Matthews et al., 1982; diversity, and relative abundance (Wootton, 1990). The fish-IBI

* Corresponding author at: Institute of Hydroecology, Ministry of Water Resources and Chinese Academy of Sciences, 578# Xiongchu Avenue, Wuhan, Hubei Province, 430079 China; Tel.: +86 27 8718 9023. E-mail address: [email protected] (J. Chang). 1 Main research ﬁelds: Ecology of Fishes and Conservation Biology, Aquatic Ecosystem Health Assessment. 1470-160X/$ – see front matter # 2008 Published by Elsevier Ltd. doi:10.1016/j.ecolind.2007.07.004 Author's personal copy

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Fig. 1 – Aftermath of river basin environmental structure changes.

was commonly used and accepted worldwide as a reliable tool Dam was constructed in 1981 and has led to sharp declines in to assess water condition now (Novotny et al., 2005). The IBI the populations of migratory fish previously occurring in great had become a family of multi-metric indices that were numbers in the upper Yangtze River, especially the three regionally adapted and calibrated, because rivers of different endemic ancient fish species, Chinese sturgeon (Acipenser regions, as well as their fish communities, were distinctive sinensis), River sturgeon (A. dabryanus), and Chinese paddlefish (Kesminas and Virbickas, 2000). (Psephurus gladius)(Dudgeon, 2000; Xie, 2003; Young, 2003). The Despite many outstanding works on IBI had already been Three Gorges Dam (TGD) (38 km upstream from the TGD) is done (Novotny et al., 2005; Simon et al., 2000), it was still of going to a massive human intervention which will fragment utmost importance for us to continue this work in Chinese an area of about 58,000 km2 with the formation of a reservoir Yangtze River basin. The objectives of this study were to: (a) of 1080 km2 in an area of the former Yangtze River bed. develop potential metrics of fish indicator for the upper This study reach of the river is influenced by TGD and is Yangtze River; (b) quantify fish assemblage differences in the 1040 km long, including the main channel of the upper early 6 years of Three Gorges Dam (TGD) construction; and (c) Yangtze River. Four monitoring stations were set up at provide a baseline for future water quality assessment in the different reaches, from the upper to the lower reach. These upper Yangtze River. were at Yibing (YB), Hejiang (HJ), Mudong (MD) and Yichang (YC), respectively (Fig. 2). The Yibin (YB) station was located in Yibin county, covering a monitoring stretch of 21 km, 2. Materials and methods including the lower reach of the Jinsha River. The Mudong (MD) station was located in Mudong town in a distance of 2.1. Study area 50 km from ChongQin City. The station represented a location at the deepest part of the TGD Reservoir. The monitoring reach The River is the third longest river in the world; its total length covered a stretch of 30 km. The Hejiang (HJ) station was is about 6300 km with a basin area of about 180,000 km2. The located in Hejiang county of the Sichuan Province with a river is distinctive in its species diversity and abundance, monitoring stretch of 60 km. Finally, the Yichang (YC) station while comprising the largest components of the fish resources was located in Yichang City, with a monitoring reach of 25 km in China (Chang, 1999; Wu, 2003; Young, 2003). However, the from Gezhouba Dam to Gulaobei. Yangtze River has experienced major changes over the past decades (Chang, 1999). Most of the water resources are 2.2. Data collection methods and analyses disproportionately degraded by human activities such as water pollution, agricultural land use and irrigation farming, Fishery investigations had been conducted in Yangtze River dam construction and over-fishing (Chang, 1995; Young, 2003). from 1950s till 2002 covering different reaches, together with These man-made impacts are now of highest concern with the field investigations, these data provided very important regard to the disruption of the integrity of Chinese inland baseline information, which were of tremendous value for waters (J.B. Chang, 1999; Chang, 1999). River damming is the assessment of ecological effects of human activities. The most dramatic anthropogenic factor affecting freshwater biological data (1997–2002) were obtained from the TGD environments (Baxter, 1997; Dudgeon, 2000). The Gezhouba monitoring database of the Institute of Hydrobiology (IHB), Author's personal copy

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Fig. 2 – Study areas selected in the upper Yangtze River and distribution of four monitoring stations: Yibing (YB), Hejiang (HJ), Mudong (MD) and Yichang (YC). (TGD represent the location of Three Gorges Dam and GZD represent the location of Gezhouba Dam).

Chinese Academy of Sciences (CAS). Most of the data were represent the best physical, chemical, and biological condi- obtained by field investigations and others were derived from tions. We modified the index and developed biological literatures. Twice investigations were conducted in May–July expectation for the upper Yangtze River fish assemblages. and September–December from 1997 to 2002 at the four These expectations were developed with the assumption that monitoring stations. The duration of investigation was 20 days ‘‘least impact’’ conditions would emerge from the cumulative every time. The catches were collected from fishing boats and data set. fish markets, the commercial fishing boats were sampled Yangtze Rivers has been dammed, channeled and dredged. according to the principle of random sampling at each station. Also, it is home to large urban areas and numerous point The information of fishing boat, fishing gears and fishing sites source dischargers, not to mention being the ultimate were recorded at the same time. At the four sites, fish repository for non-point source inputs. As a result of these collection was conducted according to the same method of perturbations, reference condition is rare, and may be absent commercial fishery investigation. in so developed river. The reference expectations used in the Two main fishing gears (gill net, long-line) among others paper were derived from the historical data, which came from (casting net, electro-fisher, hoop net and seine) were found in database of IHB, CAS and some came from literatures and the investigations in the upper Yangtze River. The mesh sizes unpublished data, including our own observations. of the gill nets ranged between 20 and 250 mm while the size compositions of catches generally portrayed the relative selectivity of the different mesh sizes. Long-line fishing was 3. Results the capture of fish by entrapment of fishhook with bait or no bait, there was floating and demersal long-line, the fish 3.1. Fish assemblages inhabiting in different depth of river could be caught. Fishers who pursued maximal commercial benefits were Appearing within four river reaches the following numbers of believed to attempt to capture fish. All catches were collected fish species had been recorded: 97 in YB, 120 in HJ, 91 in MD, and counted. Every fish specimen was measured, weighted, and 116 in YC (Table 1). The characteristics of fish assemblages labeled and conserved in the formalin solution. Referring to of upper Yangtze River had been described including struc- the ‘‘synopsis freshwater fishes of China’’ (Ichthyologic ture, tolerance, main trophic guilds, and appearance in Department, 1976) and ‘‘The Fishes of Yangtze Rive’’ (Zhu, investigations. 1995), fish specimens were identified. Fish were sampled and dissected proportionally to study the parasite and the 3.2. Development of an IBI for the upper Yangtze River availability of anomalies and get information in detail. We employed a linear regression to determine if the IBI scores of A variety of potential IBI metrics were considered, including four sections were significantly change trend during that many from existing studies in lakes (Zhu and Chang, 2004) and period. others (Chang and Cao, 1999; Young et al., 2003) who suggested a unique fish fauna for the Yangtze River. Candidate metrics of 2.3. Reference conditions derived IBI have been identified according to the original IBI (Karr et al., 1986) as well as IBIs’ applications elsewhere (Hughes, 1999; Reference condition was a critical element of IBI to assess the Lyons et al., 2000; Oberdorff and Hughes, 1992). Finally quality or health of the aquatic ecosystem (Karr, 1981; Karr preliminary metrics were selected based on their broad et al., 1986). The establishment of reference condition was applicability and stability across the previous studies and based on identification of minimally disturbed sites that their consistent related to environmental degradation. Twelve Author's personal copy

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Table 1 – Occurrence of native fish species in the upper Yangtze River basin with indication of their trophic guilds (BI = benthic insectivores; O = omnivores; C = carnivores), environmental tolerance (T = tolerance) and others (CIS = commercial interests species; E = endemic species; Y = yes; * = presence) with MC = main channel; YB = Yibin, HJ = Hejiang, MD = Mudong and YC = Yichang Species CIS T Feeding MC YB HJ MD YC

Abbotina obtusirostris Wu et Wang E** Abbotina rivularis (Basilewsky) * * * * * Acheilognathus chankaensis (Dybowski) * * Acheilognathus gracilis Nichols ** Acheilognathus macropterus (Bleeker) * * * * Acipenser dabryanus Dume´ril E BI***** Acipenser sinensis Gray BI***** Acrossocheilus monticola (Gu¨ nther) E BI * * * * * Acrossocheilus yunnanensis (Regan) * * Ancherythroculter kurematsui (Kimura) E C * * * * * Ancherythroculter nigrocauda Yih et Woo EC*** Anguilla japonica Temminck et Schlegel C* * * Aphyocypris chinensis Gu¨ nther ***** Aristichthys nobilis (Richardson) * * * Botia reevesae Chang E *** Botia superciliaris Gu¨ nther **** Culter dabryi Bleeker ** Culter alburnus Basilewsky * Culter mongolicus mongolicus (Basilewsky) * Carassius auratus (Linnaeus) Y T O * * * * * Channa argus (Cantor) C * * * * Cobitis sinensis Sauvage et Dabry ** Coilia brachygnathus BI * * Coreius guichenoti (Sauvage et Dabry) E Y T BI * * * * * Coreius heterodon (Bleeker) Y BI * * * * * Ctenopharyngodon idellus (Cuvier et Valenciennes) Y * * * * * Culter alburnus Basilewsky C***** Culter mongolicus mongolicus (Basilewsky) C * * * * Culter oxycephaloides Kreyenberg et Pappenheim C***** Culter oxycephalus Bleeker C***** Cultrichthys erythropterus (Basilewsky) C * * * * * Cyprinus (Cyprinus) carpio Linnaeus YTO***** Elopichthys bambusa (Richardson) C * * * * * Euchiloglanis davidi (Sauvage) E BI * * * * * Euchiloglanis kishinouyei Kimura E BI***** Fufu obscurus ** Garra pingi pingi (Tchang) Y * * Glyptothorax fukianensis (Rendahl) * * * * Glyptothorax sinense (Regan) BI * * * * * Gnathopogon imberbis (Sauvage et Dabry) BI * * * * * Gobiobotia ﬁlifer (Garman) Y BI * * * * * Hemibarbus labeo (Pallas) BI * * * * * Hemibarbus maculatus Bleeker BI***** Hemiculter bleekeri Warpachowski ***** Hemiculter leucisculus (Basilewsky) * * * * * Hemiculter tchangi Fang *** Hemiculterella sauvagei Warpachowski E** Hemiirhamphus kurumeus ** Hemisalanx brachyrostralis (Fang) * * Hypophthalmichthys molitrix (Cuvier et Valenciennes) * * * * * Jinshaia abbreviata (Gu¨ nther) E * * * Jinshaia sinensis (Sauvage et Dabry) E * * * * * Leiocassis crassilabris Gu¨ nther Y BI* *** Leiocassis longirostris Gu¨ nther Y C***** Leptobotia elongata (Bleeker) E Y T C * * * * * Leptobotia microphthalma Fu et Ye E BI***** Leptobotia pellegrini Fang C***** Leptobotia rubrilabris (Dabry) E C * * * * Leptobotia taeniops (Sauvage) C * * * * * Lepturichthys ﬁmbriata (Gu¨ nther) * * * * * Liobagrus marginatus (Bleeker) BI * * * * * Macropodus chinensis (Bloch) ** Author's personal copy

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Table 1 (Continued ) Species CIS T Feeding MC YB HJ MD YC

Macropodus opercularis (Linnaeus) * * * * Macrura reevesii ** Megalobrama pellegrini (Tchang) E T O * * * * * Megalobrama pellegrini (Tchang) * * Micropercops swinhonis (Gu¨ nther) * * * Misgurnus anguillicaudatus (Cantor) O * * * * * Monopterus albus (Zuiew) BI * * * * * Mylopharyngodon piceus (Richardson) BI * * * * * Mystus macropterus (Bleeker) BI * * * * * Myxocyprinus asiaticus (Bleeker) BI * * * * Neosalanx taihuensis Chen ** * Ochetobius elongatus (Kner) BI * * * * * Odontobutis obscurus (Temminck et Schlegel) * * Onychostoma sima (Sauvage et Dabry) * * * * * Opsariichthys bidens Gu¨ nther C***** Oryzias latipes (Temminck et Schlegel) * * Parabotia fasciata Dabry BI***** Parabramis pekinensis (Basilewsky) * * * * * Paracheilognathus imberbis ** * Paracobitis potanini (Gu¨ nther) E T BI * * Paracobitis variegatus (Sauvage et Dabry) BI * * * Paramisgurnus dabryanus Sauvage O***** Pelteobagrus fulvidraco (Richardson) T C * * * * * Pelteobagrus nitidus (Sauvage et Dabry) Y BI * * * * * Pelteobagrus vachelli (Richardson) Y T BI * * * * * Percocypris pingi pingi (Tchang) E C * * * * * Phoxinus oxycephalus (Sauvage et Dabry) BI * * * * * Platysmacheilus nudiventris Lo, Yao et Chen E*** Procypris rabaudi (Tchang) E Y T O * * * * * Psephurus gladius (Martens) C * * * * * Pseudobagrus brevicaudatus (Wu) Y BI * * * * * Pseudobagrus emarginatus (Regan) BI * * * * Pseudobagrus pratti (Gu¨ nther) BI * * * * * Pseudobagrus tenuis (Gu¨ nther) BI * * * * * Pseudobagrus truncatus (Regan) BI * * * Pseudobagrus ussuriensis (Dybowski) BI * * * * * Pseudobrama simoni (Bleeker) * *** Pseudolaubuca engraulis (Nichols) O * * * * * Pseudorasbora parva (Temminck et Schlegel) T * * * * * Rhinogobio cylindricus Gu¨ nther E YTBI***** Rhinogobio typus Bleeker YTBI***** Rhinogobio ventralis (Sauvage et Dabry) E Y BI * * * * Rhinogobius giurinus (Rutter) BI * * * * * Rhodeus lighti (Wu) *** Rhodeus ocellatus (Kner) ***** Rhodeus sinensis Gu¨ nther T * *** Sarcocheilichthys nigripinnis (Gu¨ nther) * * * Sarcocheilichthys sinensis Bleeker BI***** Saurogobio dabryi Bleeker YT * *** Saurogobio dumerili Bleeker BI***** Saurogobio gymnocheilus Lo, Yao et Chen *** Schizothorax (Racoma) davidi (Sauvage) BI * * * * * Schizothorax (Schizothorax) chongi (Fang) E * * * * Schizothorax (Schizothorax) prenanti (Tchang) E * * * * * Semilabeo prochilus (Sauvage et Dabry) * * * * * Silurus asotus Linnaeus Y C***** Silurus meridionalis Chen Y C***** Sinilabeo rendahli (Kimura) E T * * * Siniperca chuatsi (Basilewsky) Y C * * * * * Siniperca kneri Garman C***** Siniperca scherzeri Steindachner C***** Sinogastromyzon sichangensis Chang ** Sinogastromyzon szechuanensis szechuanensis Fang E ***** Spinibarbus sinensis (Bleeker) Y O * * * * * Squalidus argentatus (Sauvage et Dabry) Y BI * * * * * Squalidus wolterstorfﬁ O* *** Author's personal copy

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Table 1 (Continued ) Species CIS T Feeding MC YB HJ MD YC

Squaliobarbus curriculus (Richardson) O * * * * * Tor (Folifer) breviﬁlis breviﬁlis (Peters) BI * * * * * Toxabramis swinhonis Gu¨ nther * *** Xenocypris argentea Gu¨ nther ** * Xenocypris fangi Tchang E *** Xenocypris microlepis Bleeker * *** Xenocypris yunnanensis Nichols E ***** Xenocyprisdavidi Bleeker * *** Xenophysogobio boulengeri Tchang E TBI***** Xenophysogobio nudicorpa Huang et Zhang E*** Zacco platypus (Temminck et Schlegel) O * * * * L.marginatoides E ***

Total 23 16 140 96 120 104 115

metrics, which best represent the fish assemblages’ char- tolerant to many pollutants. In this author’s opinion, several acteristics and the patterns of degradation in upper Yangtze carps should be classified as the most tolerant species, not just River, are obtained and described below (Table 2). crucian carp. A good example is carp which is not only tolerant to a wide array of physical disturbances, but it is one of the few 3.2.1. Species richness and composition species that is known to be tolerant to a broad array of The number of species is plotted against the sites, which give a toxicants (e.g., ammonia, chlorine, heavy metals). This metric more reliable measure of the species richness adjusted to is the complement to ‘‘number of intolerant species’’ and is employee fishing effort. We, therefore, followed Hughes and comparable to Hughes and Oberdorff’s percent tolerant Oberdorff (1999) and Karr et al. (1986) in favoring only native individuals (Hughes, 1999). Like Karr’s (Karr, 1981) original species versus all species for this metric involved in the study. percent green sunfish metric, it distinguishes between low and This is because the total native species in the upper Yangtze moderate water quality. River are included in the calculations of the expected richness. Intolerant species (Karr and Fausch, 1986; Lyons et al., 2000) The number of native species is a measure of biological diversity are that previously very abundant but presently occurs only that typically decreases with increased degradation of habitat occasionally because of environmental deterioration. Intoler- while not considering the undesirable influence of alien species, ant species are also sensitive to many types of environmental although they may affect native species. Cyprinidae, Bagridae stressed and tend to be absent in the presence of environ- catfishes, and Cobitidae are very common in Yangtze River, mental degradation (high suspended solids, increased tem- sometimes comprising the groups of fishes thriving under such peratures and siltation, decreased dissolved oxygen), and are harsh conditions (Zhu and Chang, 2004). the last to reappear after restoration. Number of families in fishery catches is chosen as a metric of intolerance adversely, 3.2.2. Tolerant/intolerant species it will become more in a better quality of ecosystem. These fishes were considered as very tolerant species to be able to accommodate a variety of environmental conditions 3.2.3. Trophic guilds because they were very common in the catches of most Trophic groups selected include benthic insectivorous, omni- sections, especially for the crucian carp are thought most vores, and carnivores. Criteria separating these groups are not

Table 2 – Metrics and scoring criteria used in the IBI for the upper Yangtze River Attributes Metrics IBI scoring

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Species richness and composition %total number of native ﬁsh species >50% 30–50% <30% %number of species in the family Cyprinidae >50% 25–50% <25% %number of species in Bagridae catﬁshes >15% 5–15% <5% %number of species in the family Cobitidae >20% 5–20% <5%

Intolerance and tolerance Percent of tolerance individuals < 6% 6–12% >12% Number of families in ﬁshery catches >18 12–18 <12

Trophic guilds Percent of omnivores individuals <8% 8–15% >15% Percent of benthic insectivorous individuals >40% 20–40% <20% Percent of top carnivores individuals >15% 5–15% <5%

Abundance Catch per unit effort (CPUE, Kg/boat) >2 1–2 <1

Individual condition Percent of non-native ﬁsh species <1% 1–2% >2% Percent individuals with DELT <2% 2–5% >5% Author's personal copy

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sharply defined. Adults of omnivorous species proposed by Karr (1981) eat large proportions of both plants and animals for assessing disruption of the food web by stressors. We choose omnivores because they tolerate poor conditions. Top carni- vorous adults eat predominantly other fishes or large invertebrates for assessing loss of trophic diversity and keystone species (Lyons et al., 2000). Percent of benthic insectivorous individuals is used for assessing disruptions in secondary production, because invertebrates are respon- sible for much of the processing of organic matter in rivers. Disrupted invertebrate biomass and composition is presum- ably reflected in disruptions in insectivorous fishes. Those metrics are also widely used in IBIs (Hughes, 1999).

3.2.4. Abundance Catch per unit effort (CPUE), average catches of a fishing boat, Fig. 3 – Observed IBI scores for four upper Yangtze River, YC is a measure of relative fish abundance as a substitute of the (open circles), MD (squares), YB (left triangles) and HJ (right metric-relative number of individuals in the original IBI (Karr triangles) are plotted against years between 1997 and et al., 1986; Zhu and Chang, 2004), which evaluate fish 2002. The straight line shows the linear regression populations within a stream or river site. Human activities, between year and IBI scores. such as over-fishing will expectedly result in lower CPUE in the inland river. It is so reliable that it can be used to evaluate the fishery resource and fish abundance of in the Yangtze River. headwaters to estuary. Those downstream changes can be 3.2.5. Percent of non-native fish species described by longitudinal zonation concepts (Bram, 2003). Fish assemblages are considered to be biological integrity if no Most fish species find suitable living conditions in only a disturbance occurred. The presence of non-native fish species selected stretch of the entire river. Already in the 19th is considered as a disturbance factor (Ganasan and Hughes, century ichthyologists used this observation as the basis of a 1998; Lyons et al., 2000). Alien species are mostly accidental zonation system for river courses (Holcˇı´k, 1989), and the releases from fish farms, these species could alter the entire Yangtze River can be divided into several fishes zones. structure of native fish assemblages by competition and The upper Yangtze River was thought within the same fishes predation, sometimes extirpate some native species. Conse- zone with its own ecological characterizations (Chang and quently, the IBI should be negatively correlated with the Cao, 1999). quantity of non-native fish species present. The IBI is a regional index of analyzing and monitoring the impact of human disturbance (Fig. 1) on the structure of the 3.2.6. Percent individuals with DELT fish assemblages by comparing community structure of the Fish with abnormalities are rare in good ecosystem, but the present state with that of the reference situation. The number of abnormalities will increase with the human regional-based reference condition can be derived from an activities increases, so we continue to use the metric for aggregate of reference sites or some empirical model of assessing conditions of fish individuals. External anomalies expectations and may include knowledge of historical condi- includes deformities, eroded fins, lesions, tumors, diseases, tion or extrapolation from ecological principles (Lyons et al., and parasites (DELT) (Karr et al., 1986). The presence of 2000). In this paper, these expectations were developed with external anomalies indicates sublethal environmental stres- the assumption that ‘‘least impact’’ conditions would emerge ses, intermittent stresses, behavioral stresses, or chemically from the cumulative data set without having to choose contaminated substrates (Lyons et al., 2000). reference sites (Gammon and Simon, 2000). Most researchers, in the field of freshwater ecosystems, 3.3. IBI values evaluated the environment degradation induced by human activities using the fish-IBI methodology (Araujo et al., 2003; The IBI scores were becoming lower statistically in the 6-year Joy and Death, 2004; Paller et al., 2000). In his original scales and most IBI scores were classed as good and fair quality description of the IBI (1981), as well as in later papers (Karr (Fig. 3). The result of linear regression analysis showed that the and Chu, 1999; Karr et al., 1986), Karr emphasizes the need for obvious degenerative trend in the biotic integrity for some representative samples. In this paper, we used the data from uncertain reasons, but the increased human activities must be fishery investigations instead of the standardized protocols very important influencing factors. (Karr et al., 1986) for the following reasons:

(1) The size of Yangtze River created many problems, ﬁshes 4. Discussion were much more migratory (both longitudinally and horizontally) and at any given time some species and The physical, chemical and biological characteristics of many individuals were inaccessible because of depth natural large river changed gradually along its course from (Simon and Sanders, 1999; Seegert, 2000a,b); Author's personal copy

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(2) There were many kinds of freshwater fishes in Yangtze Three Gorges Project Construction Committee of China River, but human activities, particularly over-fishing, (SX2001-011, SX2003-008, SX2004-012). decreased the abundance. Field sampling with short time and small percentage of river cannot represent the entire references reach; (3) Fishery catches collection was a preferred method for the large river in the evaluation of fish assemblages, and had been conducted in four sections as a long-term monitoring Araujo, F.G., Fichberg, I., Pinto, B.C.T., Peixoto, M.G., 2003. A preliminary index of biotic integrity for monitoring the method. Because many riverine species regularly make condition of the Rio Paraiba do sul, southeast Brazil. long distance movements, particularly for spawning or Environ. Manage. 32 (4), 516–526. overwintering. Long-term monitoring data and sampling Baxter, R.M., 1997. Enviromental effects of dams and period can minimize the confounding influence of such impoundments. Annu. Rev. Ecology Systematics 8, 255–283. movements and avoid migratory periods as much as Chang, J., Cao, W., 1999. Fishery significance of the river- possible (Seegert, 2000b). It also benefited the comparison communicating lake and strategies for the management of fish resources. Resour. Environ. Yangtze Basin 8 (2), 153–157. of spatial and temporal changes of the biotical integrity. Dudgeon, D., 2000. Going with the flow: large-scale hydrological changes and prospects for riverine biodiversity in tropical Though these data might not be fully validated as the Asia. Bioscience 50, 793–806. sampling methods had not been calibrated, the field survey Ganasan, V., Hughes, R.M., 1998. Application of an index of itself may also contain some uncertainties. Therefore, it was biological integrity (IBI) to fish assemblages of the rivers believed that the data of 6-year period continuous survey were Khan and Kshipra (Madhya Pradesh), India. Freshwater Biol. sufficient enough to reflect the actual conditions of the fish 40, 367–383. Gammon, J.R., Simon, T.P., 2000. Variation in a great river index assemblages in the Yangtze River. It was also understood that of biotic integrity over a 20-year period. Hyrobiologia 422/ the data obtained from extensive time series were sufficient 423, 291–304. enough to allow the first attempt to a modified IBI for Holcˇı´k, J., 1989. The Freshwater Fishes of Europe. vol. 1. Part II. evaluation on temporal and spatial changes of biological General Introduction to Fishes. Acipenseriformes. AULA- integrity within a large river. The IBI based on the fishery Verlag, Wiesbaden, 469 pp. catches surveys need to be further tested and validated in Hughes, R.M., Oberdorff, T., 1999. 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Application of an adapted index the rates of biological and chemical processes. The repara- of biotic integrity to rivers of Lithuania. Hydrobiologia tion measurements should be employed in advance includ- 422–423 (0): 257–270. In: Assessing the Ecological ing (a) reinforcing the fishing management to reduce the Integrity of Running Waters. Kluwer Academic Publishers, extremely fishing; (b) constructing the nursery and con- Netherlands. ´ ´ servation center; (c) captive propagation and releasing; and Lyons, J., Gutierrez-Hern´ andez, A., Diaz-Pardo, E., Soto-Galera, E., Medina-Nava, M., Raúl Pineda-López, R., 2000. (d) building fish passage, e.g. the fish-ways. Development of a preliminary index of biotic integrity (IBI) based on fish assemblages to assess ecosystem condition in the lakes of central Mexico. Hydrobiologia 418 (1), 57–72. Acknowledgments Matthews, R.A., Buikema, J.A.L., Cairns, J.J., Rodgers, J.J.H., 1982. Biological monitoring: Part II. 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