Rhinogobius Giurinus Research Articles

Morphological of Development Eggs, Larvae and Juveniles Rhinogobius giurinus in Botongcheon Stream

Morphological of Development Eggs, Larvae and Juveniles Rhinogobius giurinus in Botongcheon Stream

Sources and fate of omega-3 polyunsaturated fatty acids in a highly eutrophic lake

Omega-3 polyunsaturated fatty acids (ω3-PUFA) are central to the growth and reproduction of aquatic consumers. Dissolved nutrients in aquatic ecosystems strongly affect algal taxonomic composition and thus the production and transfer of specific ω3-PUFA to consumers at higher trophic levels. However, most studies were conducted in nutrient-poor, oligotrophic lakes, leading to an insufficient understanding of how water nutrients affect algal ω3-PUFA and their trophic transfer in consumers in highly eutrophic lakes.We conducted a field investigation in a highly eutrophic lake and collected basal food sources (phytoplankton, periphyton and macrophytes) and aquatic consumers (invertebrates, zooplankton and fish), and measured their fatty acid (FA) composition.Our results showed that periphyton and phytoplankton were both important sources of ω3-PUFA supporting the highly eutrophic lake food web. High water nutrient levels led to low ω3-PUFA levels in phytoplankton and periphyton, resulting in decreased nutritional quality. Consequently, ω3-PUFA of invertebrates and zooplankton reflected variations in ω3-PUFA of phytoplankton and periphyton, respectively.The ω3-PUFA levels of fish decreased as phytoplankton and periphyton ω3-PUFA decreased. Among fish, the Redfin Culter (Cultrichthys erythropterus) and Bar Cheek Goby (Rhinogobius giurinus) exhibited significantly higher levels of EPA and DHA compared to the Pond Loach (Misgurnus anguillicaudatus), which may have been caused by their different feeding modes.Decreases in the ω3-PUFA levels of basal food sources may be one of the causes leading to the reduction of trophic links in aquatic food webs.Our study elucidated the sources and fate of ω3-PUFA in highly eutrophic lakes, complemented previous studies in oligo- and mesotrophic lakes, and emphasized the role of high-quality food sources. Our results offer new perspectives for the conservation and management of highly eutrophic lake ecosystems.

First complete mitochondrial genome of the endemic goby, Rhinogobius davidi (Gobiiformes: Gobiidae: Gobionellinae), in China

The first complete mitochondrial genome of the freshwater goby Rhinogobius davidi was determined by high-throughput sequencing. This genome was 16,627 bp in length and consisted of 13 protein-coding genes, 22 transfer RNA genes, 2 ribosomal RNA genes, and 2 non-coding control regions. Phylogenetic analysis based on the amino acid sequences of 13 mitochondrial protein-coding genes from R. davidi and 23 relatives suggested that R. davidi had a close mitogenome relationship with Rhinogobius giurinus. This complete genome of R. davidi will provide basal molecular data for future studies on taxonomy, comparative genomics, and adaptive evolution in Rhinogobius.

Application of the Gini Index on the Evaluation of the Environmental Heterogeneity and Habitat Suitability Index for Larval Gobies

Spatial environmental heterogeneity in the Yangtze River Estuary (YRE) is always mentioned but rarely quantified and included in the evaluation process. This study introduced the habitat suitability index evaluation model based on the Gini index (HSIgini) to evaluate the optimal ranges of suitable environmental factors for three typical estuarine gobies, i.e., Rhinogobius giurinus, Acentrogobius pflaumii, Odontamblyopus rubicundus, and their habitat quality. The evaluation was carried out based on field surveys conducted in the spring and summer of 2018–2020. The Lorentz curve and Gini index were used to evaluate the spatial environmental heterogeneities in the YRE. The spatial heterogeneity of environmental factors in the Yangtze Estuary ranged from 0.62 to 0.05, with the highest Gini index for salinity and the lowest for temperature. The combination of environmental factors had significant spatial effects on habitat, with temperature showing mainly seasonal effects. The study indicated that the YRE is a good habitat for gobies and that there is spatial and seasonal differentiation in the habitats of different species, greatly reducing interspecific competition. Environmental heterogeneity is important for biological processes and should be incorporated into the modeling of bio–environmental relationships in future research to provide a basis for environmental and biological conservation and management.

Coexistence strategies of invaded gobies in the Dianchi Lake, Yunnan, China

Gobiids are widespread invasive species, with many species from this group usually invade into the same ecosystem simultaneously. Understanding the mechanisms underlying the coexi-stence of different gobiid species in the sympatric habitats is a key issue in fish invasion ecology. Incorporating morphological analyses, spatial distribution survey, and trophic analyses, we examined the coexistence strategy of Mugilogobius myxodermus and related species (the earlier invaders) in Dianchi Lake, Yunnan, China. Our results showed significant differences in morphology and spatial distribution among the four invasive gobies species (i.e., M. myxodermus, Micropercops swinhonis, Rhinogobius giurinus and Rhinogobius cliffordpopei). The spatial niche index of M. myxodermus was the highest. Food composition between M. myxodermus and other gobies was significantly different, with the former mainly feeding on Chydorus ovalis and Cypris sp. The trophic diversity index of M. myxodermus was the highest. Overall, we found that morphological differences, spatial niche diffe-rentiation, and trophic niche differentiation contributed to the coexistence of the gobies in Dianchi Lake, which could help M. myxodermus reduce interspecific competition. Importantly, the feeding strategy is the key factor determining population size and habitas of M. myxodermus during their competition with the other gobies, and finally contributing to the dominant position in the study area.

The aquatic benthic food webs: The determinants of periphyton biofilms in a diversion canal and its upstream reservoir

Excessive accumulation of periphyton biofilms could cause a series of environmental problems in the South-to-North Water Diversion (SNWD) Canal. To better understand the determinants of periphyton biofilms, we applied generalized linear models (GLMs) and structural equation modelling (SEM) to compare and quantify the relative importance of multiple factors on the periphyton biofilm biomasses in the SNWD Canal and its upstream Danjiangkou Reservoir. The excessive accumulation of periphyton biofilms in the SNWD Canal was obviously higher than that of the reservoir. Our data indicate that water temperature is the most important abiotic factor for explaining the biofilm biomass. Biotic factors for explaining the biofilm biomasses are quite different in the two ecosystems. Evidence from GLMs and SEM shows that prawns (Macrobrachium nipponense) have a significant negative direct effect on the reservoir biofilm biomass, while gobies (Rhinogobius giurinus) have a significant positive indirect effect via molluscs on the canal biofilm biomass. The Bayesian mixing models from stable isotope data also verify that biofilms are a major component of the reservoir prawn diets (72.5 ± 1.9%). However, in the canal, biofilms are the major component of the canal mollusc diets (70.2 ± 19.8%), and a rather high proportional contribution of molluscs is found for the goby diets (67.4 ± 8.0%). These results suggest the main paths of benthic food chains in the two ecosystems. In this study, we reveal the determinants of periphyton biofilm accumulation, which may provide useful information for biomanipulation in the SNWD and its upstream reservoir.

Broad Diet Composition and Seasonal Feeding Variation Facilitate Successful Invasion of the Shimofuri Goby (Tridentiger bifasciatus) in a Water Transfer System

The diet composition of an invasive population of Shimofuri goby (Tridentiger bifasciatus) was investigated bimonthly during the period from September 2015 through August 2016 in Nansi Lake, a storage lake of the East Route of the South-to-North Water Transfer Project, China. The diet consists of a broad spectrum of prey items, including mollusca (Bellamya sp. and Physa sp.), aquatic insects (Odonata sp., Chironomidae sp., and Cirolanidae sp.), other macroinvertebrates (Nematoda sp. and Rhynchobdellida sp.), shrimp (Palaemon modestus and Gammarus sp.), fish (Rhinogobius giurinus and Tridentiger bifasciatus), fish eggs, and detritus. Dominant diets shifted from Rhynchobdellida sp. and unidentified digested food in July to P. modestus during September and November, and then shifted to both P. modestus and R. giurinus. Additionally, cannibalism was observed in March before spawning season of the goby, during which large males (SL > 70.0 mm) predated on small-sized ones. We suggest that broad spectrum of prey items and apparent seasonal shifting of dominant diets in the invasive goby fish, which might be an important mechanism favoring its successful invasion in water transfer system.

Study on the swimming ability of endemic fish in the lower reaches of the Yangtze River: A case study

The swimming abilities of Spinibarbus hollandi, Siniperca chuatsi, Siniperca loona, Odontobutis sinensis and Rhinogobius giurinus were tested in this study, including induced swimming speed (Uind), critical swimming speed (Ucrit) and constant acceleration test speed (UCAT). The results showed that the Uind of the experimental fish in the Huishui River ranged from 5 to 30 cm/s. The average Ucrit of fish was 68.2 cm/s and 5 times the average Uind. The average UCAT was 97.6 cm/s and 7 times the Uind. The swimming speed of fish is related to their body size. The results showed that the swimming speed was more correlated with the shape than the body length of fish. The relationships between the three speeds and the shape of the experimental fish wereUind=9.809S0.128Ucrit=37.954S0.185, andUCAT=58.418S0.099. The differences in Uind between the five fishes were not obvious, while there were significant differences in Ucrit and UCAT between the five fish species. The results of this study suggested that Spinibarbus hollandi, Siniperca chuatsi, and Siniperca loona have stronger swimming abilities than Odontobutis sinensis and Rhinogobius giurinus.

Ten novel microsatellite markers for the freshwater sleeper Micropercops swinhonis (Günther, 1873), with testing of cross-species amplification in two other fishes from suborder Gobioidei

Ten novel polymorphic microsatellite loci were developed for the freshwater sleeper Micropercops swinhonis, a relatively abundant and broadly distributed lake-dwelling fish in Asia, using next generation sequencing. These markers were tested in a population of 48 individuals, and characteristics suggest that they may be useful for population genetic studies. The average number of alleles per marker was 6.6 (range: 2–26), the average expected heterozygosity was 0.55 (range: 0.081–0.955), and the average polymorphic information content value per marker was 0.507 (range: 0.077–0.942). No marker showed significant deviation from Hardy-Weinberg Equilibrium following Bonferroni correction of significance values, and no markers showed evidence of null alleles, large allele dropout, or scoring errors from stutter bands. Two markers had successful amplification in Odontobutis potamophila, and one marker had successful amplification in Rhinogobius giurinus. These novel markers may be useful for further research in population genetic studies involving M. swinhonis.

The effect of water velocity on feeding efficiency of juvenile Chinese sturgeon, Acipenser sinensis

The effect of water velocity on feeding of benthic cruising foragers, like sturgeons, is poorly understood. Using an artificial endless stream, we conducted experiments with wild juvenile Chinese Sturgeon, Acipenser sinensis, to test the hypothesis that water current speed affects juvenile feeding efficiency on the Barcheek Goby, Rhinogobius giurinus, a common wild prey. Feeding consumption (Fc) of juveniles was positively related to water current speed (current speed in cm−1: mean Fc value) follow: 0: 2.33; 11:7.33; 31: 10.67; and 41: 13.7. Thus, current speed had a significant effect on foraging efficiency by sturgeon. The results indicate foraging by wild A. sinensis juveniles on gobies occurs mostly during flood and neap tidal flows when current velocities are fastest.

Gobioecetes biwaensis n. g., n. sp. (Monogenea: Dactylogyridae) from the gills of a freshwater gobiid fish, Rhinogobius sp. BW Takahashi & Okazaki, 2002, with a redescription of Parancyrocephaloides daicoci Yamaguti, 1938

A description is given of Gobioecetes biwaensis n. g., n. sp. (Monogenea: Dactylogyridae) on the gills of a freshwater gobiid fish, Rhinogobius sp. BW Takahashi & Okazaki, 2002 from Lake Biwa, Shiga Prefecture and Rhinogobius sp. from Sento Imperial Palace, Kyoto Prefecture, Japan. This monogenean is most similar to Parancyrocephaloides rhinogobius Ling, 1973, proposed here as Gobioecetes rhinogobius n. comb., collected from the gills of Rhinogobius giurinus (Rutter, 1897) in Hupei Province, China, but can be differentiated from it in that ventral hamuli of G. biwaensis are larger than those of G. rhinogobius and in that in G. biwaensis, ventral hamuli are larger than dorsal ones, but in G. rhinogobius, ventral and dorsal hamuli are almost equal in size. The new genus is characterized by the absence of a bar supporting dorsal hamuli. Parancyrocephaloides daicoci Yamaguti, 1938, the type species of the genus, is redescribed based on newly collected specimens from a marine dactylopterid, Dactyloptena peterseni (Nyström, 1887) and the type specimens, revealing that it has a pair of vestigial bars supporting dorsal hamuli. The generic diagnoses of Gobioecetes n. g. and Parancyrocephaloides are given and systematic position of these genera in Dactylogyridae is discussed in this paper.

Identification and distribution of fish eggs and larvae in the water-level fluctuation zone of Three Gorges Reservoir

PDF HTML阅读 XML下载 导出引用 引用提醒 三峡消落区鱼卵、仔稚鱼种类的鉴定及分布 DOI: 作者: 作者单位: 1. 中国水产科学研究院 长江水产研究所, 农业部淡水生物多样性保护重点实验室, 湖北 武汉 430223;2. 中国水产科学研究院 长江水产研究所, 农业部长江中上游渔业资源环境重点野外科学观测试验站, 湖北 武汉 430223;3. 重庆市水产科学研究所, 重庆 401121 作者简介: 阮瑞(1985-),男,博士,从事鱼类分子遗传学研究.E-mail:ruan.rui@163.com 通讯作者: 中图分类号: S93 基金项目: 农业部长江流域渔政管理办公室"三峡水库消落对消落区鱼类产卵孵化的影响调查与损失评估"项目. Identification and distribution of fish eggs and larvae in the water-level fluctuation zone of Three Gorges Reservoir Author: Affiliation: 1. Key Laboratory of Freshwater Biodiversity Conservation, Ministry of Agriculture of China;Yangtze River Fisheries Research Institute, Chinese Academy of Fisheries Science, Wuhan 430223, China;2. Fishery Resources and Environmental Science Experimental Station of The Upper-Middle Reaches of Yangtze River, Ministry of Agriculture of China;Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China;3. Chongqing Fishery Science Institute, Chongqing 401121, China Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:三峡库区水位从每年3月的175 m逐步降低至6月的145 m，水位下降时间与库区部分鱼类产卵同步，对鱼类早期资源造成了严重的影响。本研究以距离大坝150 km至330 km范围的消落区为研究区域，通过普查方法收集暴露于水面或残留于浅滩的鱼卵和仔稚鱼，利用DNA条形码技术鉴定其种类，初步分析其鱼类组成和分布。通过对收集的样本进行mtCO I序列比对分析，可将其分为14种序列类型，其中10种类型鉴定到种的水平。鲤（）占测序样本比例最大，分别为50.0%、24.6%，且分布范围最广。在研究区域内，干流上游样品数量和种类均比下游多，另外，在支流磨刀溪采集了733粒鱼卵和108尾仔稚鱼、鉴定到9种鱼类，是本次研究中样品和种类最多的区域，表明磨刀溪受三峡库区消落影响最严重，间接暗示了该支流鱼类资源丰富，应给予重点保护。本研究旨在为全面评估三峡库区消落对鱼类早期资源的影响奠定基础。 Abstract:Three Gorges Dam is a vital project in the development and harnessing of the Yangtze River. Water-level fluctuation zone of Three Gorges Reservoir, which refers to the area along the Three Gorges Reservoir banks bounded by minimum (145 m) and maximum (175 m) water levels of the Three Gorges Reservoir, has provoked a series of ecological problems, which included soil erosion, reduction in ecosystem types, decrease in biodiversity and so on. However, effect of water level fluctuating on fish of early life history stages in the water-level fluctuation zone was not yet reported. In this study, the research area was between 150 km and 330 km from Three Gorges Dam, where fish eggs and larvae, exposed to water or remained in shallows, were collected. Based on distribution of sampling places, the research area was divided into 8 regions, which were mainstream (down), Meixi River, mainstream (middle), Shilu River, Modaoxi River, Tangxi River, mainstream (up), and Pengxi River. According to sampling time and place, and morphological characters of fish eggs and larvae, 132 samples were preserved, including 1735 fish eggs and 150 larvae. Twenty-four samples were collected in mainstream. But only one sample in respective mainstream (middle) and mainstream (down) included respective one and nine larvae, in which no fish egg was found. In Modaoxi River, a tributary of Three Gorges Reservoir, there were the most samples in this study, and 59 samples were collected including 733 fish eggs and 108 larvae. Due to insufficient morphological diagnostic characters in kraurotic fish eggs and larvae, it is easy to misidentify in the genus or species level. So, this study was employed DNA barcoding technology to identify the samples. DNA barcoding technology could be used as a rapid tool to distinguish morphologically similar species, and survey many uncertain species and species composition. Previous researches have shown that only molecular identification could guarantee identification of fish eggs and larvae to the species level. Through mtCO I sequence alignment, and based on mtCO I sequences similarity values (species:>99%, genus:92%-99%, family:85%-92%), the samples were distinguished to 14 types, of which 10 types were identified to species:Cyprinuscarpio, Carassiusauratus, Hemiculterleucisculus, Rhinogobius nagoyae, Rhinogobius giurinus, Opsariichthysbidens, Acheilognathusmacro-pterus, Pseudorasboraparva, Hypophthalmichthys molitrix, and Rhinogobius, Rhodeus, and Rhodeusocellatus and . If fish DNA barcode database of Yangtze River or Three Gorges Reservoir could be completely and accurately constructed, and new molecular markers could be developed for fishes that can be not distinguished by mtCO I barcode, it would help to further identify fish eggs and larvae in the water-level fluctuation zone and investigate fish resources of the Yangtze River. had the largest proportion in the samples, 50.0% and 24.6% respectively, and widely distributed. The number and species of samples in upstream of mainstream was more than downstream in the research area. It may be not only related to its topography, and also its fish resources. In Modaoxi River, the number and species of samples was the most in this research area, which contained nine fish species. The result showed that it was more affected from the water level fluctuating, at the same time, it also indicated that fish resource were rich in Modaoxi River, which should be got more attention in the future fish resources investigation and protection in Three Gorges Reservoir. This study employed DNA barcoding technology to identify fish eggs and larvae collected in partial water-level fluctuation zone, which would contribute to comprehensively assessing the effect of water level fluctuating on fish resources in water-level fluctuation zone of Three Gorges Reservoir. 参考文献 相似文献 引证文献

Substrate color preference and feeding by juvenile Chinese sturgeon Acipenser sinensis: exploration of a behavioral adaptation

Experiments were conducted in artificial stream tanks with juvenile Chinese sturgeon, Acipenser sinensis, captured in the Yangtze Estuary to test two null hypotheses (1) juveniles have no preference for white or black substrates, and (2) white or black substrate color has no effect on juvenile feeding efficiency on the barcheek goby,Rhinogobius giurinus, a dark-colored prey of wild juveniles. Juveniles strongly preferred white substrate. However, in feeding tests, feeding efficiency by juveniles was similar on white or black substrates. Thus, substrate color had no effect on feeding efficiency. Results suggest the innate preference for white substrate is not a visual adaptation for capturing prey on a contrasting background, but is an adaptation predisposing juveniles to seek light-colored sandy substrate where forage abundance is greatest.

Digestive Physiological Characteristics of the Gobiidae: - Characteristics of CCK-producing Cells and Mucus-secreting Goblet Cells of Stomach Fish and Stomachless Fish.

In this study, we investigated the characteristics of CCK-producing cells and mucus-secreting goblet cells with respect to stomach fish and stomachless fish of the Gobiidae in order to provide a basis for understanding the digestive physiology. Hairychin goby (Sagamia geneionema), which is stomachless fish, the numbers of mucus-secreting goblet cells is highest in the posterior intestine portion (P<0.05), while CCK-producing cells are scattered throughout the intestine. Gluttonous goby (Chasmichthys gulosus), which is stomach fish, mucus-secreting goblet cells are most abundant in the mid intestine portion (P<0.05), whereas CCK-producing cells are observed only in the anterior and mid intestine portion. Trident goby (Tridentiger obscurus) which is stomach fish, mucus-secreting goblet cells were most abundant in the mid intestine portion (P<0.05). CCK-producing cells are found in the anterior and mid intestine portion. Giurine goby, Rhinogobius giurinus which is also stomach fish, the largest number of mucus-secreting goblet cells showed in anterior intestine portion except for esophagus (P<0.05). CCK-producing cells are present only in the anterior and mid intestine portion. In S. geneionema, digestive action occurs in the posterior intestine portion to protect and functions to activate digestion. In contrast, in C. gulosus, T. obscurus and R. giurinus, their digestive action occurs in the anterior and mid intestine portion to protect and functions to activate digestion. Further studies of the modes of food ingestion by these fish, the contents of their digestive tracts, and the staining characteristics of the goblet cells need to be carried out.

Mitochondrial genetic diversity of Rhinogobius giurinus (Teleostei: Gobiidae) in East Asia

Rhinogobius giurinus (Gobiidae: Gobionellinae) is an amphidromous goby that is widely distributed in East Asia. However, little is known about its population structure. In this study, R. giurinus from Japan, Taiwan and mainland China were used to evaluate the population genetic structure using mitochondrial DNA cytochrome b gene sequences (1122 bp). In total, 123 sequences were analyzed from seventeen populations. All 44 mtDNA haplotypes were identified as belonging to ten haplogroups, and four haplogroups were only distributed in the upstream of the Yangtze River and Hainan Island. The phylogeny and geography did not have a significant relationship. Our results (1) found that the mtDNA genetic diversity of this species was less than that of the freshwater goby; (2) showed that the lack of a population genetic structure might result in its amphidromous life cycle and high migrating potentiality; (3) indicated that although it is an amphidromous species, R. giurinus could not migrate across a deep sea, such as the South China Sea and Pacific Ocean; and (4) considered that the Kuroshio Current might act as a barrier for gene flows between East Japan and East China.

Temporal Patterns of Larval Fish Occurrence in a Large Subtropical River.

Knowledge of temporal patterns of larval fish occurrence is limited in south China, despite its ecological importance. This research examines the annual and seasonal patterns of fish larval presence in the large subtropical Pearl River. Data is based on samples collected every two days, from 2006 to 2013. In total, 45 taxa representing 13 families and eight orders were sampled. The dominant larval family was Cyprinidae, accounting for 27 taxa. Squaliobarbus curriculus was the most abundant species, followed by Megalobrama terminalis, Xenocypris davidi, Cirrhinus molitorella, Hemiculter leuscisculus and Squalidus argentatus. Fish larvae abundances varied significantly throughout the seasons (multivariate analyses: Cluster, SIMPROF and ANOSIM). The greatest numbers occurred between May and September, peaking from June through August, which corresponds to the reproductive season. In this study, redundancy analysis was used to describe the relationship between fish larval abundance and associated environmental factors. Mean water temperature, river discharge, atmospheric pressure, maximum temperature and precipitation play important roles in larval occurrence patterns. According to seasonal variations, fish larvae occurrence is mainly affected by water temperature. It was also noted that the occurrence of Salanx reevesii and Cyprinus carpio larvae is associated with higher dissolved oxygen (DO) concentrations, higher atmospheric pressure and lower water temperatures which occur in the spring. On the other hand, M. terminalis, X. davidi, and C. molitorella are associated with high precipitation, high river discharge, low atmospheric pressure and low DO concentrations which featured during the summer months. S. curriculus also peaks in the summer and is associated with peak water temperatures and minimum NH3–N concentrations. Rhinogobius giurinus occur when higher atmospheric pressure, lower precipitation and lower river discharges occur in the autumn. Dominant fish species stagger their spawning period to avoid intraspecific competition for food resources during early life stages; a coexistence strategy to some extent. This research outlines the environmental requirements for successful spawning for different fish species. Understanding processes such as those outlined in this research paper is the basis of conservation of fish community diversity which is a critical resource to a successful sustainable fishery in the Pearl River.

Development of microsatellite markers for genetic diversity analysis in Glossogobius giuris (Hamilton, 1822) and Rhinogobius giurinus (Rutter, 1897)

Microsatellite-enriched libraries were constructed from Glossogobius giuris and Rhinogobius giurinus. BLAST analysis revealed significant homology of the clones with microsatellite-rich regions in other teleosts and other members of Gobiidae. Eight microsatellite primers were designed and tested for cross- amplification in two other goby species, Glossogobius celebius and Gobiopterus lacustris. Four primer pairs amplified putative microsatellite loci in all four species. Four other primer pairs amplified loci in at least two species. Primer Rh18 was the most informative and exhibited the greatest number of polymorphic alleles (PIC=0.7262; N a =7). Two other primers, Rh51 and Gi47 were also informative markers with PIC values ≥ 0.5. Using five primers, both G. giuris and R. giurinus samples exhibited moderately high values of genetic diversity based on the number of alleles (~5), percent polymorphism (53%), and observed (61%) and expected (58%) heterozygosities.

Coexisting invasive gobies reveal no evidence for temporal and trophic niche differentiation in the sublittoral habitat of Lake Erhai, China

AbstractNiche differentiation facilitates the coexistence of species within a community through avoidance of competition via mechanisms involving spatial, temporal and/or trophic dimensions. Where invasive species coexist in their non‐native range, niche differentiation could allow their persistence at higher levels of abundance. Here, we tested whether there was temporal and/or trophic niche differentiation between two congeneric invasive goby species (Rhinogobius cliffordpopei and Rhinogobius giurinus) in the sublittoral habitat of Lake Erhai (south‐west China) through quantifying their diel and seasonal rhythm of locomotion activities, feeding activities and diet composition. Both species displayed two similar diel peaks in activity and two main feeding periods (6:00–10:00 and 18:00–22:00), with rhythms of locomotion and feeding activity not differing significantly between the species in each season. Their diets had a high degree of overlap, being primarily composed of macrozooplankton, aquatic insects and shrimp larvae, with no diel changes across the seasons. Thus, in this habitat, there was no clear temporal or trophic niche differentiation between the invasive congeners, indicating their coexistence with high temporal and trophic overlap. In conjunction with data from the littoral and profundal habitats, the gobies revealed different strategies across the habitats (e.g. spatial segregation, trophic niche differentiation) that minimised their competitive interactions and promoted their coexistence. This suggests that the interactions of invasive fishes during the integration into native communities can be context dependent, varying according to factors including habitat and the availability of food resources.

Age, growth and population dynamics of two congeneric and invasive gobies, Rhinogobius giurinus and R. cliffordpopei (Actinopterygii, Gobiidae) in a plateau lake, southwestern China

Although many goby species have become widely established outside of their native ranges, little is known yet about invasive population biology. The age, growth and population dynamics of two introduced goby species (Rhinogobius giurinus and Rhinogobius cliffordpopei) were quantified in Lake Erhai (southwest China) with the general aim to improve empirical knowledge and management strategies. The results revealed that their lifespan ranges 2 years. The size and time at sexual maturity for R. cliffordpopei was lower than for R. giurinus. R. cliffordpopei displayed higher total mortality, fishing mortality and exploitation rates than R. giurinus, whereas the natural mortality of R. cliffordpopei was lower than that of R. giurinus. The catch per unit effort of benthic fyke nets was low from April to June in R. cliffordpopei and from July to September in R. giurinus, whereas it was high from July to September in R. cliffordpopei and from April to June in R. giurinus. Thus, several specific strategies are suggested to improve the cost-efficiency of the current management practices related to the mesh size of benthic fyke nets used for physical removals, the timing of deployment of control actions and the use of synergic control methods.

Temporal and spatial variation of fish assemblages in Dianshan Lake, Shanghai, China

Using multi-mesh gillnets and trawls, the fish communities in Dianshan Lake at 6 stations from Oct. 2009 to Jul. 2010 were investigated seasonally to reveal the biodiversity and its spatial and temporal distribution patterns. The long-term changes in their structural characteristics were then analyzed to identify the main influencing factors and several measures for lake restoration were put forward. Thirty six species, belonging to 9 family and 30 genera, were collected, amongst which, the order Cypriniformes accounted for 61.1% of the total species number. In terms of importance value, Cypriniformes was the predominant group, Coilia nasus the dominant species, while Cyprinus carpio and Rhinogobius giurinus were the subdominant taxa. The community types did not differ among stations, but between seasons. There were no significant differences between seasons and among stations in species diversity, but richness differed both spatially and seasonally. Along with the process of eutrophication and the drastic reduction of the area colonized by macrophytes from 1959 to 2009–2010, the fish diversity declined markedly, and species numbers of herbivores and piscivores declined proportionately more than those of invertivores, omnivores, and planktivores. The decline of potamophilus and river-lake migratory fish was more marked than those of sedentary, river-sea migratory, and estuarine fishes. Eutrophication concomitant with sharp reduction of macrophyte area and overfishing may be the main reasons for the decline in fish diversity in Dianshan Lake.