Academic journal article The American Midland Naturalist

Changes in the Diversity of Native Fishes in Seven Basins in Illinois, USA

Academic journal article The American Midland Naturalist

Changes in the Diversity of Native Fishes in Seven Basins in Illinois, USA

Article excerpt


A study of the fish faunas in all or parts of seven Illinois river basins revealed an average loss of 8.4 species per basin over approximately the last 100 y. In contrast, between the 1980s and 1990s, five basins showed an increase in the species richness (number of species) and two showed a statistically significant increase (paired t-test) in the species richness per sample site. Only the Kaskaskia River basin had a significant decline (paired t-test) in the species richness per sample site between the 1980s and 1990s. Minnows (Cyprinidae) had the largest number of species showing declines over the last 100 y and was followed in decreasing order by darters and perches (Percidae), catfishes (Ictaluridae), suckers (Catostomidae), topminnows (Fundulidae) and sunfishes (Centrarchidae). Changes in the overall fauna since the 1980s show an increase in species occurrence, but minnows and catfishes showed little net change and suckers, sunfishes and darters showed a positive increase in occurrence.


Across North America, fish faunas have been highly altered over the past 100-200 y. Many changes have been noted and summarized in various books that address regional or state faunas (see Forbes and Richardson, 1909; Minckley, 1973; Wydoski and Whitney, 1979; Trautman, 1981). Such texts generally discuss declines across much of the native fauna and list a number of factors considered to be responsible for the decline. Much of the information is based on general observations and often on data that are not quantitative or comparative in nature. However, long-term studies that are comparative and well quantified will provide a greater knowledge of large-scale faunal changes over long time periods. Comparative studies of fishes of this type are fairly rare (Anderson et al., 1995).

A number of studies have been published on the stability of fish populations in small streams over 3 to 12 y periods (see Grossman et al., 1990 and Matthews, 1998 for reviews of these works). These studies concentrate on short-term fluctuations and not long-term trends over larger areas.

Three recent studies have examined changes in species distributions over large areas and over longer time periods (approximately 30 or 100 y). Patton et al. (1997) resampled sites first visited in the 1960s. These sites covered a large portion of Wyoming. In 1986 Anderson et al. (1995) resampled 129 sites located throughout most of Texas. Their sites were first sampled in 1953. Both studies calibrated their methods to account for differences in methods and amount of sampling effort. The third study by Koel and Peterka (1998) encompassed the Red River of the North in the Minnesota, North Dakota and South Dakota. This study relied on published and unpublished records including museum specimen records and on personal communications. Although some of the records are unpublished or unsupported by vouchered specimens, they were able to extend the time period to 100 y.

In Illinois, the results of two statewide surveys of fishes have been published by Forbes and Richardson (1909) and Smith (1979). The former study was based on 1500 collections from 600 localities. The latter was based on 3000 collections from 2400 localities. Since the study of Smith (1979), efforts have been made to resurvey the state by biologists of the Illinois Department of Natural Resources (IDNR) and Illinois Natural History Survey (INHS; INHS is now an autonomous entity of IDNR). The early records and recent sampling efforts provide an excellent opportunity to study changes in fish distributions over a large geographic area. Hence, the goal of this study is to determine if there have been any changes in the species richness (the number of species) of native fishes within all or parts of seven river basins in Illinois between 1876-1905 and 1960-1998 (long time period) and between 1982-1986 and 1997-1998 (short time period). Individual species and overall pattern changes in the fauna also is discussed. …

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