Development of a preliminary index of biotic integrity (ibi) based on fish

Hydrobiologia 418: 57–72, 2000. © 2000 Kluwer Academic Publishers. Printed in the Netherlands.

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Development of a preliminary index of biotic integrity (IBI) based on fish assemblages to assess ecosystem condition in the lakes of central Mexico
John Lyons1, Altagracia Guti´ rrez-Hern´ ndez2 , Edmundo D´ e a iaz-Pardo3 , Eduardo Soto-Galera3 , 4 & Ra´ l Pineda-L´ pez5 Martina Medina-Nava uo
Department of Natural Resources and University of Wisconsin Zoological Museum, 1350 Femrite Drive, Monona, WI 53716-3736, U.S.A. 2 Insurgente Oaxagueño No. 80–5, Villas Morelianas, Morelia, Michoac´ n Mexico a 3 Escuela Nacional de Ciencias Biologicas, Instituto Polit´ cnico Nacional, Carpio y Plan de Ayala, Colonia Santo e Tom´ s, M´ xico D.F. C.P. 11340 Mexico a e 4 Laboratorio de BiologiaAcu´ tica, Facultad de Biologia, Universidad Michoacana de San Nicolas de Hidalgo, ´ ´ ´ a Morelia, Michoac´ n Mexico a 5 Facultad de Ciencias Naturales, Universidad Aut´ noma de Quer´ taro, Ciudad Universitaria, Cerro de los o e Campanas, Quer´ taro, Quer´ taro C.P 76010 Mexico e e
Received 2 February 1999; in revised form 29 July; accepted 19 August 1999
1 Wisconsin

Key words: M´ xico, lake,fish, biotic integrity, IBI, ecosystem health e

Abstract The lakes of central Mexico have great cultural, economic, and biological value, but they are being degraded at an accelerating rate. We employed historical data on fish communities from 19 of these lakes and case studies of community responses to environmental degradation from four of the best-studied, Xochimilco, Cuitzeo, Chapala, andPátzcuaro, to construct a preliminary index of biotic integrity (IBI). This IBI was designed to be an easily applied method for assessing lake ecosystem health and evaluating restoration efforts. The IBI had 10 metrics: number of total native species, number of common native species, number of native Goodeidae species, number of native Chirostoma species, number of native sensitive species, percent ofbiomass as tolerant species, percent of biomass as exotic species, percent of biomass as native carnivorous species, maximum standard length of native species, and percent of exotic invertebrate parasite species on or in native fishes. Initial applications of the index showed promise, accurately ranking the relative degradation of the four case-study lakes. Further tests of the index are warranted,and more data are needed to standardize sampling procedures, improve species classifications, and refine metric scoring criteria.

Introduction Tropical highland lakes have played a key role in the development of the cultures and nation states of Latin America. Nowhere is this better illustrated than in central Mexico, where an extensive and diverse lake district occurs. The waters and biota ofthese lakes were instrumental in the rise of great pre-Columbian civilizations such as the Aztecs (Méxica) and Tarascans (P’uréhpecha) (Tamayo & West, 1964; SerraPuche, 1980; Alcocer-Durand & Escobar-Briones,

1991). After the Spanish conquest in the 16th century, the lake district, stretching from just east of Mexico City to well to the west of Guadalajara, was the political, economic, andcultural center of what eventually became the nation of México. Today the lakes continue to play an important societal role as sources of water, fisheries, and recreation, and they are highly valued by the Mexican people (Chacón-Torres, 1993; De la Lanza-Espino & García-Calderón, 1995). They are also of great interest to aquatic scientists, having unique limnological and biotic characteristics and sup-58 porting numerous endemic species (DeBuen, 1944; Barbour, 1973a; Miller & Smith, 1986; Lyons et al., 1998). Human modifications of central Mexican lakes began well before the Spanish conquest (e.g., O’Hara et al., 1993), but have been greatly amplified in the last 100 years (De la Lanza-Espino & GarcíaCalderón, 1995). Since 1900, several lakes have been substantially reduced in size or...