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.     

In situ experiments on the effects of increased sediment loads on littoral rocky shore communities in Lake Tanganyika, East Africa

1. Two in situ experiments investigated the responses to artificially increased sediment loads of the gastropod and fish communities, and of the whole benthos, of the rocky shores of Lake Tanganyika. Sediments were emptied once onto randomly selected quadrats using SCUBA, with control quadrats receiving no addition of sediment. Quadrats were monitored up to 6 months after sediment addition. 2. While the abundance of Lavigeria grandis (Mollusca; Gastropoda) was reduced greatly by the addition of sediment, low abundance and biomass of the whole gastropod community on sediment‐impacted quadrats 6 months after sediment addition suggests more general impacts of inundation in the longer term. 3. Benthic invertebrate communities inundated by sediment had significantly fewer individuals and numbers of taxa than control communities. No significant community recovery was recorded on sediment‐impacted quadrats within the timescale of the experiment. A short‐term period of high turbidity brought about by the emptying of sediments onto sediment‐impacted quadrats also caused severe decreases in benthic invertebrate abundance on controls 10 days after sediment addition. This suggests that even short‐term pulses of sediment may have significant detrimental effects on littoral communities. 4. Although significant impacts of sediment on fish community dynamics were found, and a significant reduction in the number of benthic algivorous species was recorded immediately after sediment addition, littoral fish communities showed strong resistance overall to the addition of sediments. This apparent resistance, however, may be a consequence of the small scale at which the experiment took place. Littoral fish communities were also shown to be more dynamic than indicated previously.     

A recently landlocked brackish-water lagoon of Lake Tanganyika: physical and chemical characteristics,and spatio-temporal distribution of phytoplankton

Monthly measurements of physical and chemical characteristics were made at two localities in the eastern part of a recently landlocked lagoon of Lake Tanganyika. Variables analysed were: temperature, pH, conductivity, sodium, potassium, magnesium, calcium, carbonate, bicarbonate, chloride and sulphate. Large seasonal fluctuations of salinity were recorded (1.68–8.21 g l^–1). The seasonal water input controlled algal seasonality mainly through its effect on salinity and indirectly through its influence on nutrient concentration by dissolution and dilution of the excrements of the numerous cattle and other organic matter. Phytoplankton was mainly composed of Cyanophyta and Euglenophyta. Euglenophyta dominated during the dry periods with high salinity and probably very high nutrient levels, while Cyanophyta preferred moderate salt and nutrient concentrations during the rainy periods. The phytoplanktonic community was composed of a large number of perennial and a reduced quantity of annual organisms.A spatial study of the recently landlocked lagoon revealed an ascending salinity gradient, principally due to a sodium bicarbonate/carbonate enrichment, between locations near the lake and more inland situated stations. These facts point to a lake water supply and a salt concentration by evaporation in the swamps. Proportionally lower magnesium, calcium and potassium values were recorded at high salinities, due to chemical precipitation and biotic factors.A blue-green algal bloom was observed in the eastern water-body (salinity: 4.64 g l^–1); simultaneously an important development of diatoms dominated the western water-body (salinity: 2.18 g l^–1). No significant differences in morphometry, exposure, water temperature or nutrient levels (nitrate, nitrite, ammonia, orthophosphate) were observed. The relatively low salinity and high nutrient concentration in the western water-body probably favoured diatom development during the rainy season. The relatively higher salinity in the eastern water-body during the rainy season was probably responsible for the dominance of blue-green algae through its negative influence on silica concentration and notwithstanding the high inorganic nitrogen concentration.     

Scaling up: examining the macroecology of ectomycorrhizal fungi

Ectomycorrhizal (ECM) fungi play major ecological roles in temperate and tropical ecosystems. Although the richness of ECM fungal communities and the factors controlling their structure have been documented at local spatial scales, how they vary at larger spatial scales remains unclear. In this issue of Molecular Ecology, Tedersoo et al. (2012) present the results of a meta‐analysis of ECM fungal community structure that sheds important new light on global‐scale patterns. Using data from 69 study systems and 6021 fungal species, the researchers found that ECM fungal richness does not fit the classic latitudinal diversity gradient in which species richness peaks at lower latitudes. Instead, richness of ECM fungal communities has a unimodal relationship with latitude that peaks in temperate zones. Intriguingly, this conclusion suggests the mechanisms driving ECM fungal community richness may differ from those of many other organisms, including their plant hosts. Future research will be key to determine the robustness of this pattern and to examine the processes that generate and maintain global‐scale gradients of ECM fungal richness.     

High frequency of multiple paternity in broods of a socially monogamous cichlid fish with biparental nest defence

In several animal taxa, genetic analyses have demonstrated that social monogamy and biparental brood care do not preclude polygamous reproduction. Few studies have been conducted in fish, but in fish species without alternative reproductive phenotypes, social monogamy was largely congruent with genetic parentage. In contrast to these findings, we report an exceptionally high level of multiple paternity in a socially monogamous cichlid fish with biparental nest defence ( Variabilichromis moorii ), inferred from microsatellite and mitochondrial data of 10 broods. Whereas all offspring in a nest shared a common mother, each brood was sired by 2 to > 10 males. None of the inferred sires was assigned a large proportion of the brood. Paternity was estimated as the minimum number of sires required to explain multilocus offspring genotypes, and as the maximum-likelihood number of sires given population allele frequencies. Analysis of simulated brood genotypes suggested that, although these two methods tend to under- and overestimate, respectively, the true number of sires, primary sires with many offspring in a brood would have been detected. Hence, the genetic data indicate that the nest tending males suffer substantial cuckoldry and provide alloparental care for a large number of unrelated fry. We have no data on the social status of the cuckolding males, but due to synchronous spawning of pairs and commitment to brood care of paired males, it is possible that most of the parasitic spawners are solitary males.     

Description of a new Lake Tanganyikan cichlid fish of the genus Cyprichromis(Perciformes: Cichlidae) with a note on sexual dimorphism

Cyprichromis coloratus , a new cichlid species, is described based on 41 type specimens from the Zambian coast of Lake Tanganyika. It differs from Cyprichromis microlepidotus by having fewer scales in the longitudinal line (41–44 v . 59–70 in C. microlepidotus ) and upper lateral line (31–36 v . 47–59), from Cyprichromis leptosoma by more dorsal‐fin spines (14–15 v . 11–13 in C. leptosoma ) and longitudinal line scales (41–44 v . 38–40), from Cyprichromis pavo by fewer dorsal‐fin spines and soft rays (29–31, usually 30, in total v . 30–32, usually 31, in C. pavo ), and from Cyprichromis zonatus by shallower body depth [24·0–28·5 (26·4 ± 1·1)% of standard length v . 24·5–30·5 (28·4 ± 1·3)% in C. zonatus ] and smaller eye [eye length 25·2–30·9 (27·2 ± 1·1)% of head length v . 27·9–33·3 (30·2 ± 1·2)%]. The new species is also separable from C. microlepidotus , C. pavo and C. zonatus by absence of distinct small spots on the body ( v . pearl grey and yellowish small spots along scale rows on body at least in males of C. microlepidotus and C. pavo ), its distinct dichromatism (particularly on the caudal fin) between males of the same population ( v . dichromatism absent in C. zonatus ) and absence of vertical bands ( v . three or four distinct vertical bands beneath dorsal fin base in live males of C. zonatus ). Cyprichromis coloratus n. sp. also exhibits sexual dimorphism, females having a larger head and males having longer pelvic fin, differences which are discussed in relation to reproductive behaviour. A key to the five species of Cyprichromis is included. A lectotype is designated for Cyprichromis leptosoma .     

基于恢复生态学的洞庭湖区“山水林田湖草”生态修复研究

实施洞庭湖区\"山水林田湖草\"生态修复工程,是践行生态文明理念、遵循自然规律、破解生态环境保护难题的关键措施。由于自然灾害及人类不合理利用等因素影响,洞庭湖区生态问题日益严重,对洞庭湖区生态系统均衡和可持续发展带来威胁。基于恢复生态学理论,以洞庭湖区为研究对象,采用物能循环和物能转化的生态学原则分析洞庭湖区存在土壤重金属污染、水环境、生物多样性与植被退化和农村土地利用的生态问题,明确了\"山水林田湖草\"生命共同体中各要素及相应形成的子系统存在的相互联系和相互制约的关系,厘清洞庭湖区生态系统的生态退化过程和生态退化机制,就此提出重构生态水体、重建生态地质地貌和重现生态景观的生态恢复策略,提出妥善解决和处理洞庭湖区的生态恢复及亟需进行环境整治问题,实现自然景观的恢复重构。通过构建洞庭湖区生态系统恢复的测度指标体系和洞庭湖区生态系统恢复的监测与管控,实现洞庭湖区\"山水林田湖草\"生态恢复的目标。     

国际化学生态学文献、实验室网络资源评介

本文介绍了国际上化学生态学的文献和网络资源 ,包括重要著作简介、杂志的特点和网址、实验室的工作内容和网址 ,一些网络讨论组 ,以及主要的组织机构和会议等。