The life and work of Hiroya Kawanabe: the priest ecologist

Hiroya Kawanabe was born the son of a Buddhist priest and teacher of Japanese literature, who died when Kawanabe was very young. Kawanabe also studied Buddhism by himself, and passed the examination to be a priest of his sect while still in high school. He studied zoology and ecology at Kyoto University and earned his doctorate under the guidance of Denzaburo Miyadi, a well-known Japanese ecologist, in 1960. During his academic career at Kyoto University, Kawanabe advanced to hold the chair of Animal Ecology as Professor in the Department of Zoology. Kawanabe's doctoral research concerned the social behavior and population ecology of the ayu, Plecoglossus altivelis, an amphidromous fish that lives in streams as adults and grazes algae. His research lead to the discovery that social structure changed from territoriality to schooling as population density increased, and also varied with changes in food and habitat. During this work, he pioneered the use of underwater observation to study ecolo gy of freshwater fishes in streams. Kawanabe also observed ayu social structure from the northern to southern limits of their range, and advanced the theory that the more stable territoriality in the Lake Biwa population was a relic social structure to guarantee food supply during earlier glacial periods when productivity was lower. Additional work on stream fishes in central Japan and Okinawa Island led Kawanabe to propose that interactions among individuals affect interspecific relationships, and thereby, community structure. Discussions with Charles Elton, the famous British ecologist of Oxford University, strengthened Kawanabe's view that communities could be best understood as the whole of interrelationships among organisms. Kawanabe advanced these ideas during a joint study he led with a host of Japanese and Zairean scientists on the fishes of Lake Tanganyika, beginning in 1979. This work, as well as additional research on Lake Biwa in Japan, led to a deeper understanding of the complexity of biotic interactions (including competition, predation, mutualism, commensalism, and indirect effects) that promote the high species diversity in these ecosystems. In addition to basic research, Kawanabe was part of research teams organized during the 1960s by D. Miyadi to study the effects of public works projects on natural environments and biota in Lake Naka-umi and Lake Biwa. During the late 1980s he expanded his network to an international venue, both by organizing and hosting important international ecological meetings in Japan, such as the Fifth International Ecological Congress, and by increasing his international activities to promote global biodiversity. In 1991, Kawanabe founded the Center for Ecological Research at Kyoto University to study the interrelationships among organisms and their environments. Recently retired from the University, he became Director General of the new Lake Biwa Museum in 1996, and continues to promote conservation of biodiversity worldwide through an international network of scientists and organizations.     

Research on fish ecology in Japan: a brief history and selected review

Fish play an important role in the culture of Japan, supplying the primary source of food protein. Research on fish ecology in Japan began developing about 1955, and paralleled that in North America and Europe, but has a number of unique differences. Two main research foci, stream fish ecology and ecology of Lake Biwa, were founded by H. Kawanabe and his colleagues while graduate students in D. Miyadi's laboratory at Kyoto University in the 1950s. The focus on studies of individual differences in ecology, life history, and behavior by direct observation that were developed in this laboratory had a pervasive influence on research that has continued to the present. In the 1980s, Kawanabe, who had succeeded Miyadi as laboratory head, also co-organized a major research project on the complex communities of cichlid fishes in Lake Tanganyika, which has involved nearly every major Japanese investigator in fish ecology since. A review of research conducted by Japanese investigators in stream fish ecology, ecology of fishes in lakes Biwa and Tanganyika, and marine reef fish ecology revealed a wealth of literature of which most English-speaking fish ecologists are unaware. The most striking difference between Western and Japanese research is the focus on detailed observations and experiments in natural habitats of individual differences in behavior, life history, and ecology, and how these ultimately affect processes at the population and community level, as amply demonstrated by Kawanabe's early work on ayu, Plecoglossus altivelis. This approach predated by 20–30 years the current interest in individual differences and individual-based models in North America and Europe.     

Lifetime list of publications by Hiroya Kawanabe

Hiroya Kawanabe produced more than 780 scientific papers, popular articles, governmental reports, chapters in books, edited or co-edited books, encyclopedia entries, and Japanese translations of books from 1952 until the compilation of this bibliography (Fall 1997). He was the sole or first author of 88% of these publications and shared authorship with 286 collaborators. Eighty-nine percent of his publications were in Japanese, others were in English, German, Chinese, Korean and Italian. His publications were devoted mainly to four topics: (1) ecology of freshwater fishes, especially the territorial behavior of ayu, Plecoglossus altivelis, and interspecific relationships and food segregation among fishes from 1956; (2) fish community ecology in Lake Tanganyika since 1979; (3) political articles on ecological research after 1991; and (4) museum activities after 1996. He also produced a number of newspaper articles (over 25% of total publications) addressing topics not only of science but literature, culture and philosophy. Kawanabe's articles in newspapers were produced mainly when he was the Director of the Center for Ecological Research of Kyoto University, and most of these articles concentrated on promoting the development of ecological research in Japan. The publications are arranged chronologically by year. The decision to add Japanese titles was based on the fact that their English translations, which follow in parentheses, are often too loose and imprecise. Unfortunately, our printers could not insert these titles in the Japanese characters so Roman transliterations had to be substituted.     

An interview with Hiroya Kawanabe

When Eugene K. Balon first suggested publishing the present special volume, Tamotsu Iwai and Masahide Yuma asked me to inverview Hiroya Kawanabe. This was presumably because Kawanabe and I were associated in many ways for a long time, as students attending the same lectures and exercises, as young researchers involved in surveys of the ayu fish, lakes Naka-umi, and Biwa-ko, as co-authors of several papers, as joint revisers of some dictionaries, as commensals in pubs, and so on. Kawanabe loves classical music, literature, and hot-spring baths.Actually, this is not the record of an interview by me of Kawanabe. During our frequent chats in coffee shops and nomiya pubs in Kyoto and Otsu, I picked out several topics and sent questions incorporating them to Kawanabe. I received written answers from him, rearranged them together with questions, added some comments and further questions, and rendered these for his consideration. The narration in the form of an interview was thus prepared. M.J. Grygier of the Lake Biwa Museum and G.C. Kearn of the University of East Anglia took the job of revising the English, for which we are grateful. I should add one thing. Kawanabe always addresses people as san in Japanese, not sensei – a very common way to refer to professors and teachers – and he himself likes to be called san. So, I adopted -san as a suffix for the names of people throughout his narration.     

Effects of zooplankton on the sinking flux of organic carbon in Lake Biwa

To clarify the roles of zooplankton in the sedimentation of seston from the epilimnion, the sinking flux of particulate carbon was measured along with primary production rate and zooplankton biomass from July 1996 to October 1997 at a pelagic site in the north basin of Lake Biwa. During the study period, the flux varied seasonally from 66 to 510 mg C m⁻² day⁻¹ and was low in summer when zooplankton, composed mainly of Eodiaptomus japonicus and Daphnia galeata, were abundant. Simple correlation analysis revealed that the sinking flux correlated neither with the primary production rate nor with the amount of sestonic carbon above the sediment trap. However, the particle elimination rate, estimated as the difference between the primary production rate and the sinking flux, correlated positively with the zooplankton biomass. These results suggest that zooplankton play a substantial role in decreasing the sinking flux in Lake Biwa. Received: March 6, 2000 / Accepted: October 7, 2000     

Morphological and phylogenetic characterizations of freshwater Thioploca species from Lake Biwa,Japan, and Lake Constance,Germany

Filamentous, gliding, sulfide-oxidizing bacteria of the genus Thioploca were found on sediments in profundal areas of Lake Biwa, a Japanese freshwater mesotrophic lake, and were characterized morphologically and phylogenetically. The Lake Biwa Thioploca resembled morphologically Thioploca ingrica, a brackish water species from a Danish fjord. The diameters of individual trichomes were 3 to 5.6 microm; the diameters of complete Thioploca filaments ranged from 18 to 75 micro m. The cell lengths ranged from 1.2 to 3.8 micro m. In transmission electron microscope specimens stained with uranyl acetate, dense intracellular particles were found, which did not show any positive signals for phosphorus and sulfur in an X-ray analysis. The 16S rRNA gene of the Thioploca from Lake Biwa was amplified by using newly designed Thioploca-specific primers (706-Thioploca, Biwa160F, and Biwa829R) in combination with general bacterial primers in order to avoid nonspecific amplification of contaminating bacterial DNA. Denaturing gradient gel electrophoresis (DGGE) analysis of the three overlapping PCR products resulted in single DGGE bands, indicating that a single 16S rRNA gene had been amplified. With the same method, the Thioploca from Lake Constance was examined. The 16S rRNA sequence was verified by performing fluorescence in situ hybridization targeted at specific motifs of the Lake Biwa THIOPLOCA: Positive signals were obtained with the bacterial probe EUB-338, the gamma-proteobacterial probe GAM42a, and probe Biwa829 targeting the Lake Biwa THIOPLOCA: Based on the nearly complete 16S rRNA sequence and on morphological similarities, the Thioploca from Lake Biwa and the Thioploca from Lake Constance are closely related to T. ingrica and to each other.     

Does the seston of Lake Biwa release dissolved inorganic nitrogen and phosphorus during aerobic decomposition?: Its implication for eutrophication

Seston was collected from depths of 5 and 60 m in the north basin and a depth of 0 m in the south basin of Lake Biwa in the summer of 1985 and decomposed in the laboratory under aerobic conditions for three months. There was no net release of dissolved inorganic phosphorus from any seston, in contrast with the liberation of dissolved inorganic nitrogen. From this result and other available data, it is suggested that almost all phosphorus entering Lake Biwa and remaining within it is finally transformed into particulate phosphorous, transported to the bottom sediments, and fixed there without being recycled. Thus, this mechanism seems to play an important role in the prevention of rapid eutrophication of Lake Biwa, in spite of high external phosphorus loading.     

Long‐term isolation of the coastal plant Calystegia soldanella (Convolvulaceae) in ancient freshwater Lake Biwa,Japan

Lake Biwa is an ancient freshwater lake that was formed approximately 4 Mya and harbours many coastal plants that commonly inhabit the seashore. We used chloroplast DNA haplotype analysis using two spacer sequences and simple sequence repeat (SSR) analysis using eight nuclear microsatellite markers to detect genomic signatures indicating long‐term isolation of inland populations of Calystegia soldanella in Lake Biwa from coastal populations. We used 348 samples from 63 populations for haplotype analysis and 478 samples from 27 populations for SSR analysis covering the inland and coastal distribution of the species. We detected seven haplotypes, and the distribution pattern of these haplotypes was geographically highly structured between Lake Biwa and the coast. Nuclear SSR analysis also supported genetic differentiation between Lake Biwa and coastal populations (analyses of molecular variance, 43%), and the grouping of Lake Biwa and coastal populations by a Neighbour‐joining tree. In addition, genetic diversity of the inland populations (mean H_E = 0.153) was significantly lower than that of coastal populations (mean H_E = 0.328). These results suggested that inland populations at Lake Biwa have been isolated from coastal populations for a very long time. The inland populations most likely experienced a bottleneck effect, resulting in sufficient in situ genetic divergence to clearly distinguish them from coastal populations. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 51–66.     

Morphological and Phylogenetic Characterizations of Freshwater Thioploca Species from Lake Biwa, Japan, and Lake Constance, Germany

Filamentous, gliding, sulfide-oxidizing bacteria of the genus Thioploca were found on sediments in profundal areas of Lake Biwa, a Japanese freshwater mesotrophic lake, and were characterized morphologically and phylogenetically. The Lake Biwa Thioploca resembled morphologically Thioploca ingrica, a brackish water species from a Danish fjord. The diameters of individual trichomes were 3 to 5.6 μm; the diameters of complete Thioploca filaments ranged from 18 to 75 μm. The cell lengths ranged from 1.2 to 3.8 μm. In transmission electron microscope specimens stained with uranyl acetate, dense intracellular particles were found, which did not show any positive signals for phosphorus and sulfur in an X-ray analysis. The 16S rRNA gene of the Thioploca from Lake Biwa was amplified by using newly designed Thioploca-specific primers (706-Thioploca, Biwa160F, and Biwa829R) in combination with general bacterial primers in order to avoid nonspecific amplification of contaminating bacterial DNA. Denaturing gradient gel electrophoresis (DGGE) analysis of the three overlapping PCR products resulted in single DGGE bands, indicating that a single 16S rRNA gene had been amplified. With the same method, the Thioploca from Lake Constance was examined. The 16S rRNA sequence was verified by performing fluorescence in situ hybridization targeted at specific motifs of the Lake Biwa Thioploca. Positive signals were obtained with the bacterial probe EUB-338, the γ-proteobacterial probe GAM42a, and probe Biwa829 targeting the Lake Biwa Thioploca. Based on the nearly complete 16S rRNA sequence and on morphological similarities, the Thioploca from Lake Biwa and the Thioploca from Lake Constance are closely related to T. ingrica and to each other.     

Recent colonization by a coastal plant of inland habitats at an ancient freshwater lake,Lake Biwa: multilocus sequencing and a demographic history of Lathyrus japonicus (Fabaceae)

Ancient lakes have been recognized as “long‐term isolated islands” in terrestrial ecosystems. Lake Biwa, one of the few ancient lakes that formed around 4 million years ago, harbors many coastal species that commonly inhabit seashores. The beach pea, Lathyrus japonicus, is a typical coastal species of this freshwater lake, where morphological, physiological, and genetic differentiations have been reported between Biwa and coastal populations. Whether Biwa populations were isolated for long periods throughout Pleistocene climatic oscillations and subsequent range shifts is unclear. We assessed population genetic structure and demography of beach pea in this ancient freshwater lake using the sequences of eight nuclear loci. The results of STRUCTURE analyses showed evidence of admixture between Biwa and coastal populations, reflecting recent gene flow. The estimated demographic parameters implemented by the isolation with migration model (IM model) revealed a recent divergence (postglacial period) of Biwa populations, with some gene flow from Biwa to coastal populations. In addition, Biwa populations were significantly smaller in size than the ancestral or coastal populations. Our study suggests that a Holocene thermal maximum, when transgression could allow seeds from coastal plants to access Lake Biwa, was involved in the origin of the Biwa populations and their genetic divergence. Thus, coastal populations might have migrated to Lake Biwa relatively recently. Our study concluded that ancestral migrants in Lake Biwa were derived from small founding populations and accelerated genetic isolation of Biwa populations during short‐term isolation.     

Geographic color variation of Phelotrupes auratus (Coleoptera,Geotrupidae) in the Kinki region,central Japan: A quantitative spectrophotometric analysis

We investigated geographic color variation of the beetle Phelotrupes auratus in the Kinki region of central Japan using a spectrophotometer. The reflectance spectrum of the dorsal surface of the elytron was measured for beetles collected from 23 sites. We focused on λmax(α), the wavelength at the peak (α peak) between 400 and 700 nm (human visual sensitivity range), for analyses of color variation. In populations distributed on the Kii Peninsula, in the southern part of the Kinki region, average λmax(α) values were lower (480–497 nm) than in populations distributed in the area west of Lake Biwa, the western part of the Kinki region (618–633 nm). For populations distributed in the areas south and southeast of Lake Biwa, a geographic cline of λmax(α) was observed approximately along an east–west transect, with average λmax values varying continuously from 624 to 557 nm. The easternmost populations along this cline had almost the same λmax(α) values as the populations distributed west of Lake Biwa. The coefficient of variation for λmax(α) tended to be larger in populations with intermediate averages than those with lower or higher average values.     

Phylogeny and historical demography of endemic fishes in Lake Biwa: the ancient lake as a promoter of evolution and diversification of freshwater fishes in western Japan

To elucidate the origins of the endemic fish of Lake Biwa, an ancient lake in Japan, and the role of the lake in the diversification of freshwater fish in western Japan, we established a molecular phylogenetic framework with an absolute time scale and inferred the historical demography of a large set of fish species in and around the lake. We used mtDNA sequences obtained from a total of 190 specimens, including 11 endemic species of Lake Biwa and their related species, for phylogenetic analyses with divergence time estimations and from a total of 2319 specimens of 42 species (including 14 endemics) occurring in the lake for population genetic analyses. Phylogenetic analysis suggested that some of the endemic species diverged from their closest relatives earlier (1.3–13.0 Ma) than the period in which the present environmental characteristics of the lake started to develop (ca. 0.4 Ma), whereas others diverged more recently (after 0.4 Ma). In contrast, historical demographic parameters suggested that almost all species, including endemic and nonendemic ones, expanded their populations after the development of the present lake environment. In phylogeographic analyses, common or very close haplotypes of some species were obtained from Lake Biwa and other regions of western Japan. The phylogenetic and historical demographic evidence suggests that there was a time lag between phylogenetic divergence and population establishment and that phenotypic adaptation of some endemic species to the limnetic environment occurred much later than the divergences of those endemic lineages. Population structure and phylogeographic patterns suggest that Lake Biwa has functioned not only as the center of adaptive evolution but also as a reservoir for fish diversity in western Japan.     

The production-to-respiration ratio and its implication in Lake Biwa,Japan

Production-to-respiration (P:R) ratio was estimated at an offshore site of Lake Biwa in order to examine whether the plankton and benthic community is subsidized with allochthonous organic carbon, and to clarify the role of this lake as potential source or sink of carbon dioxide. The respiration rate of protozoan and metazoan plankton was calculated from their biomass and empirical equations of oxygen consumption rates, and that of bacterioplankton was derived from their production rate and growth efficiency. In addition, the carbon mineralization rate in the lake sediments was estimated from the accumulation rate of organic carbon, which was determined using a ²¹⁰Pb dating technique. On an annual basis, the sum of respiration rates of heterotrophic plankton was comparable to net primary production rate measured by the ¹³C method. However, when the mineralization rate in the lake sediments was included, the areal P:R ratio was 0.89, suggesting that Lake Biwa is net heterotrophic at the offshore site with the community being subsidized with allochthonous organic carbon. Such a view was supported by the surface water pCO₂ that was on average higher than that of the atmosphere. However, the estimate of net CO₂ release rate was close to that of carbon burial rate in the sediments. The result suggests that the role of Lake Biwa in relation to atmospheric carbon is almost null at the offshore site, although the community is supported partially by organic carbon released from the surrounding areas.     

Role of phytoplankton size distribution in lake ecosystems revealed by a comparison of whole plankton community structure between Lake Baikal and Lake Biwa

The influence of the size distribution of phytoplankton on changes in the planktonic food web structures with eutrophication was examined using natural planktonic communities in two world-famous lakes: Lake Baikal and Lake Biwa. The size distribution of phytoplankton and the ratio of heterotrophic to autotrophic biomass (H/A ratio), indicating the balance between primary production and its consumption, were investigated in the lakes of different trophic status. The results revealed that microphytoplankton (>20μm) in mesotrophic Lake Biwa, and picophytoplankton (<2μm) or nanophytoplankton (2–20μm) in oligotrophic Lake Baikal, comprised the highest proportion of the total phytoplankton biomass. The H/A ratio was lower in Lake Biwa (<1) than in Lake Baikal (>1). The low H/A ratio in Lake Biwa appeared to be the consequence of the lack of consumption of the more abundant microphytoplankton, which were inferior competitors in nutrient uptake under oligotrophic conditions but less vulnerable to grazing. As a result, unconsumed microphytoplankton accumulated in the water column, decreasing the H/A ratio in Lake Biwa. Our results showed that food web structure and energy flow in planktonic communities were greatly influenced by the size distribution of phytoplankton, in conjunction with bottom-up (nutrient uptake) and top-down (grazing) effects at the trophic level of primary producers.     

Multiple colonizations of Lake Biwa by Sarcocheilichthys fishes and their population history

Rapid adaptation and speciation have not been well documented for organisms in Lake Biwa, Japan, the oldest ancient lake in East Asia. To examine these processes, we focused on the divergence of Sarcocheilichthys gudgeons and conducted phylogeographic and population genetic analyses using mitochondrial DNA sequences and microsatellite data. No remarkable genetic differentiation was found between two species, S. biwaensis and S. variegatus microoculus, both endemic to Lake Biwa, whereas this species group, including S. v. variegatus, was genetically divided into three major regional groups: the Lake Biwa, Ise Bay, and western groups. Divergent mtDNA haplotypes were included within the Lake Biwa and western groups, strongly suggesting secondary contacts among allopatrically isolated populations. Dating for mtDNA phylogeny using a geological constraint suggested the colonization of Lake Biwa by multiple Sarcocheilichthys lineages that diverged from each other in the early–middle Pleistocene. Coalescent-based population analyses indicated that the local populations colonized the rocky bottom habitat in Lake Biwa from other habitats after the Last Glacial Maximum, likely reflecting past environmental changes in the lake, including the disappearance of rocky areas during the glacial climate. Divergent morphological adaptation in Sarcocheilichthys associated with substrate type may have rapidly proceeded along with environmental changes.     

Light, nutrients and primary productivity in Lake Biwa: An evaluation of the current ecosystem situation

Simple correlation and multiple regression analyses were performed to examine the relationship between primary productivity and environmental factors in the north basin of Lake Biwa. The primary production rates used in the analyses were estimated monthly or bimonthly during the growing season (April–November) in 1992, 1996 and 1997 with the ¹³C method. Elemental (C, N and P) contents of seston were used to assess nutrient conditions. Analyses revealed that 86% of variance in depth-integrated primary production rates (areal PP) can be explained by changes in light intensity, and sestonic C, N and P concentrations. Water temperature had no effect on areal PP. To assess relative effects of light and nutrients on PP, the P:B ratio was estimated by normalizing PP with sestonic C. The areal P:B ratio correlated most significantly with the sestonic N:P ratio, followed by light intensity. When regression analyses were made at each depth, however, the P:B ratio correlated significantly only with the sestonic N:P ratio at 0 and 1 m depths, while light intensity was also incorporated into the regressions at deeper than 2.5 m. In these regressions, the P:B ratio was negatively correlated with sestonic N:P ratio but positively with light intensity. The results suggest that the primary production rate in this lake was mainly limited by P relative to N supply rates, but was not free from light limitation in a large part of the epilimnion. In Lake Biwa, the vertical water mixing regime as well as the nutrient supply seem to be important in determining the growth and composition of primary producers, since the surface mixing layer extends into 10–15 m depths during most of the growing season.     

Disturbance of the indigenous gene pool of the threatened brook lamprey Lethenteron sp. S by intraspecific introgression and habitat fragmentation

Artificial introduction and habitat fragmentation affect the indigenous gene pools of fluvial animals. To investigate the effect of human activities on the genetic population structure of vulnerable brook lamprey Lethenteron sp. S in a single river system, samples from 12 tributaries of the Jinzu River, Japan, were analyzed using mitochondrial and microsatellite DNA markers. Exogenous Lake Biwa (Japan) haplotypes and alleles were detected in lampreys from several Jinzu River tributaries. Since Lake Biwa is the source of the commercial ayu fish Plecoglossus altivelis that is introduced in the Jinzu River, the exogenous Lake Biwa lamprey genotypes in the Jinzu River probably originated from the Lake Biwa lampreys that were unintentionally introduced along with the ayu fish. Bayesian admixture and mitochondrial DNA analyses revealed various genetic disturbance phases of the exogenous genotypes in the Jinzu River, such as the six indigenous populations, four admixed populations with low frequencies (average admixture proportion = 0.02–0.04; exogenous haplotype proportion <0.01), one introgressed population (0.71 and 0.57) and one population almost displaced by exogenous genotypes (0.93 and 0.96). Samples from three tributaries with weirs were genetically differentiated from the others by using pairwise F _ST and Bayesian analyses; the results suggested isolation by the weirs. Reduced mitochondrial DNA diversity was observed in 1 of the 3 samples probably due to reduced population size. These findings indicate that the indigenous lamprey populations in the Jinzu River are seriously affected by introgression with exogenous genotypes via unintentional introduction and habitat fragmentation by weirs.     

Distributional survey of large branchiopods of rice paddies in Shiga Prefecture,Japan: a Lake Biwa Museum project based on lay amateur participation

A distributional survey of the large branchiopod crustaceans of the rice paddies of Shiga Prefecture, Japan, was conducted by the Lake Biwa Museum in May and June of 1999 and 2000. Collecting kits were issued to over 100 lay Field Reporters, who returned all samples, usually dried, to the museum for processing. Their 242 species-lots were augmented by 146 from Grygier, 46 from Ida, and 41 from other museum staff. Apart from this survey, 50 additional records in 1997–2000 were also taken into account. Seven species were recorded in the prefecture's southern half: Branchinella kugenumaensis (Ishikawa), Caenestheriella gifuensis (Ishikawa), and Lynceus biformis (Ishikawa) with wide distributions; Triops longicaudatus (LeConte) and Leptestheria kawachiensis Uéno limited to paddy areas around the south end of Lake Biwa; and Eulimnadia sp. mostly in remnant paddy areas threatened with urban development in Otsu city, with Triops granarius (Lucas) at a single such site in Otsu. In the prefecture's northern half, only B. kugenumaensis and C. gifuensis occurred to a limited degree. Possible reasons for these differences are discussed. Data pertaining to species co-occurrence and occurrence relative to the ongoing program of paddy field consolidation in the prefecture are presented and discussed. Success of the survey was due to the use of Field Reporters, who were able to provide a high degree of coverage of the study area, as well as the clearly defined habitat, the low number and easy recognizability of species, and the collection of voucher material from all sites. Conservation-related results included the listing of Eulimnadia sp. as a `rare' species by Shiga Prefecture.     

Development and characterization of 24 polymorphic microsatellite markers for bluegill sunfish, <Emphasis Type="Italic">Lepomis macrochirus</Emphasis>

The bluegill sunfish (Lepomis macrochirus) is a notorious exotic fish, which causes serious damages to freshwater ecosystems in the world. Therefore, it is a matter of urgency to control this species for the conservation of ecosystem. New microsatellite loci were developed for L. macrochirus using high throughput 454 GS-FLX+ pyrosequencing. We selected 24 primer pairs that were tested on 47 individuals from Lake Biwa, which encompasses the oldest and largest population of L. macrochirus in Japan. Allele per locus varied 2–17. Expected and observed heterozygosities ranged from 0.185 to 0.888 and 0.120 to 0.872, respectively. Applied to L. macrochirus in Lake Biwa, these markers could detect genetic differentiation among populations, which showed a pattern of isolation by distance. These markers are expected to be useful in the estimation of population structure and ecology of L. macrochirus.