Species diversity and abundance of freshwater fishes in irrigation ditches around rice fields

The relationships between environmental variables, distribution of freshwater fishes and their diet were investigated at 40 sites on irrigation ditches for rice fields in central Japan. Multivariate analyses showed that fish species richness and diversity in ditches was high when fishes were able to easily invade the rice fields. Natural stream beds not covered by concrete had greater total number and biomass of fishes in irrigation ditches. The connection between ditches and rice fields was of secondary importance. Canonical correlation analysis indicated that the two principal fish community variables, abundance and diversity, were respectively represented by the presence of the minnow, Gnathopogon elongatus elongatus, and the absence of the loach, Misgurnus anguillicaudatus. Most fishes in the irrigation ditches predominantly preyed upon aquatic insects such as ephemeropteran nymphs, chironomid larvae and trichopteran larvae, but aerial insects and benthic algae were also fed upon by a few species. Small fishes (<4 cm SL) preyed more on chironomid and less on trichopteran larvae than large (≥4 cm SL) fishes. The diet overlap between species was extremely high for small fishes in ditches weakly connected with rice fields. The recent changes in rice fields and irrigation ditches to increase production efficiency has led to a decrease in fish diversity. For the coexistence of rice production and fish diversity in rice areas, a new irrigation system, where fishes can easily invade rice fields and where plenty of invertebrates are available for fishes, should be developed.

[1]  S. Johnson,et al.  Seasonal Changes in Habitat Use by Juvenile Coho Salmon (Oncorhynchus kisutch) in Oregon Coastal Streams , 1992 .

[2]  D. Williams.  The Ecology of Temporary Waters , 1987 .

[3]  B. Coad,et al.  The Ecology of Temporary Streams III. Temporary Stream Fishes in Southern Ontario, Canada , 1979 .

[4]  H. Hakoyama,et al.  Spawning Behavior of Hemibarbus barbus (Cyprinidae) , 1997 .

[5]  Mauro Fasola,et al.  The value of rice fields as substitutes for natural wetlands for waterbirds in the Mediterranean region. , 1996 .

[6]  K. Winemiller,et al.  Fish Assemblage Structure in Relation to Environmental Variation among Brazos River Oxbow Lakes , 2000 .

[7]  M. L. Murphy,et al.  Effects of Clear-cut Logging with and without Buffer Strips on juvenile Salmonids in Alaskan Streams , 1986 .

[8]  C. O’Brien,et al.  Seasonal Variation in the Diets of Bluefish, Pomatomus saltatrix (Pomatomidae) and Striped Weakfish, Cynoscion guatucupa (Sciaenidae) in Southern Brazil: Implications of Food Partitioning , 2000, Environmental Biology of Fishes.

[9]  Simon J. Lane,et al.  The impact of changing irrigation practices in rice fields on frog populations of the Kanto Plain, central Japan , 1997, Ecological Research.

[10]  F. Castri,et al.  Biodiversity, science and development : towards a new partnership , 1997 .

[11]  D. L. Hanson,et al.  Recovery of Standing Crop and Production Rate of a Brook Trout Population in a Flood-damaged Stream , 1974 .

[12]  P. Moyle,et al.  Microhabitat Use by an Assemblage of California Stream Fishes: Developing Criteria for Instream Flow Determinations , 1985 .

[13]  Frederick J. Wrona,et al.  Resource Utilization Indices: An Assessment , 1981 .

[14]  Simon J. Lane,et al.  The impact of changes in irrigation practices on the distribution of foraging egrets and herons (Ardeidae) in the rice fields of central Japan , 1998 .

[15]  Y. Ono,et al.  Fish population responses to stream habitat improvement in a concrete-lined channel , 1996 .

[16]  K. Hosoya.  Freshwater fish fauna of the Yoshii River, Okayama Prefecture , 1982 .

[17]  S. Ross,et al.  The Response of Fishes to Periodic Spring Floods in a Southeastern Stream , 1983 .

[18]  Michal L. Jones,et al.  The Influence of Habitat Features on the Biomass and Distribution of Three Species of Southern Ontario Stream Salmonines , 2000 .

[19]  J. Trexler,et al.  Temporal and Spatial Dynamics of Larval and Juvenile Fish Abundance in a Temperate Floodplain River , 1994 .

[20]  C. Qualset,et al.  Biodiversity in agroecosystems , 1998 .

[21]  Michael J. Sullivan.  DISTRIBUTION OF EDAPHIC DIATOMS IN A MISSISSIPPI SALT MARSH: A CANONICAL CORRELATION ANALYSIS 1 , 1982 .

[22]  A. Koizumi,et al.  MOVEMENT AND SPAWNING OF SEVERAL FRESHWATER FISHES IN TEMPORARY WATERS AROUND PADDY FIELDS , 1988 .

[23]  Robert R. Miller,et al.  Cyprinid Fishes of Japan: Studies on the Life-History of Cyprinid Fishes of Japan , 1971 .

[24]  Michiaki Tanaka,et al.  Influence of different aquatic habitats on distribution and population density of Misgurnus anguillicaudatus in paddy fields. , 1999 .

[25]  N. Giri.  Multivariate Statistical Analysis : Revised And Expanded , 2003 .

[26]  R. Wallace.  An Assessment of Diet-Overlap Indexes , 1981 .

[27]  M. Fasola,et al.  Rice Fields Support a Large Portion of Herons Breeding in the Mediterranean Region , 1996 .

[28]  K. Maekawa,et al.  Reproductive regulation in the female Japanese minnow, Pseudorasbora parva (Cyprinidae) , 1997, Environmental Biology of Fishes.

[29]  Thomas W. Schoener,et al.  Nonsynchronous Spatial Overlap of Lizards in Patchy Habitats , 1970 .

[30]  Richard E. Sparks,et al.  Need for Ecosystem Management of Large Rivers and Their Floodplains These phenomenally productive ecosystems produce fish and wildlife and preserve species , 1995 .

[31]  J. Roff,et al.  Trout Biomass and Habitat Relationships in Southern Ontario Streams , 1986 .