Tridentiger Trigonocephalus Research Articles

Effects of Estuarine Environmental Heterogeneity on the Habitat of Gobiidea Species Larvae

AbstractIn aquatic ecosystems around the world, gobies comprise one of the most diverse groups of fishes in estuaries. The Yangtze River estuary, the biggest estuary in the western Pacific, is a major habitat for larval gobies, with the peak spawning and breeding season occurring during late spring and summer. To investigate the adaptation mechanism of larval gobies to environmental factors, three models (a global generalized linear model, a generalized additive model, and a geographically weighted Poisson regression) were used to simulate and forecast the major habitat distributions of larval gobies based on the survey data from 2018 to 2020. Six species of gobies were studied:Rhinogobius giurinu,Odontamblyopus rubicundus,Tridentiger barbatus,Parachaeturichthys polynema,Tridentiger trigonocephalus,andTrypauchen vagina. The habitats for brackish speciesT. barbatuswere mainly in freshwater (where, using the practical salinity scale, salinity is 0–1) of the south branch, whereas the marine speciesP. polynemawas mainly caught in oligohaline waters (where salinity is 1–5) of the north branch. The other euryhaline species were near the exit of the north branch or dispersed throughout the surveyed region. Year, season, salinity, and sample location had significant effects (P < 0.001) on determining the habitat distributions of larval gobies. The geographically weighted Poisson regression identified that the temperature, depth, distance from the coast, and chlorophyllahad a significant effect (P < 0.001) on the local distribution of habitats. This work supplements information about the distribution of major habitats and their interactions with the environment for the ecologically important species of goby in the Yangtze estuary during the larval stage, and the conclusions provide a basis for the management of aquatic ecosystems and biological habitats.

Fast fitting of neural ordinary differential equations by Bayesian neural gradient matching to infer ecological interactions from time‐series data

Abstract Inferring ecological interactions is hard because we often lack suitable parametric representations to portray them. Neural ordinary differential equations (NODEs) provide a way of estimating interactions non‐parametrically from time‐series data. NODEs, however, are slow to fit, and inferred interactions usually are not compared with the ground truth. We provide a fast NODE fitting method, Bayesian neural gradient matching (BNGM), which relies on interpolating time series with neural networks and fitting NODEs to the interpolated dynamics with Bayesian regularisation. We test the accuracy of the approach by inferring ecological interactions in time series generated by an ODE model with known interactions. We compare these results against three existing approaches for estimating ecological interactions, standard NODEs, ODE models and convergent cross‐mapping (CCM). We also infer interactions in experimentally replicated time series of a microcosm featuring an algae, flagellate and rotifer population, in the hare and lynx system, and the Maizuru Bay community featuring 11 species. Our BNGM approach allows us to reduce the fitting time of NODE systems to only a few seconds and provides accurate estimates of ecological interactions in the artificial system, as true ecological interactions are recovered with minimal error. Our benchmark analysis reveals that our approach is both faster and more accurate than standard NODEs and parametric ODEs, while CCM was found to be faster but less accurate. The analysis of the replicated time series reveals that only the strongest interactions are consistent across replicates, while the analysis of the Maizuru community shows the strong negative impact of the chameleon goby on most species of the community, and a potential indirect negative effect of temperature by favouring goby population growth. Overall, NODEs alleviate the need for a mechanistic understanding of interactions, and BNGM alleviates the heavy computational cost. This is a crucial step availing quick NODE fitting to larger systems, cross‐validation and uncertainty quantification, as well as more objective estimation of interactions, and complex context dependence, than parametric models.

Ecological carrying capacity and carbon sequestration potential of bivalve shellfish in marine ranching: A case study in Bohai Bay, China

IntroductionShellfish play an important role in ecological restoration and as carbon (C) sinks, but studies on their ecological carrying capacity (ECC) and C sequestration potential are sparse.MethodsIn this study, we selected a 57-hectare artificial oyster reef in a typical marine ranching in Bohai Bay, China, to evaluate the ECC and their C sequestration potential of bivalve shellfish, and projecting their impact on functional groups in the system, with an Ecopath with Ecosim (EwE) food web model. We conducted four biological surveys to obtain the biomass measurements, with one conducted in each of the summer, autumn, and winter of 2019 and one in the spring of 2020; and the functional groups included in the surveys comprised fish, cephalopods, crustaceans, snails, bivalve shellfish, annelids, other macrobenthos, meiobenthos, starfish, sea cucumbers, zooplankton, phytoplankton, and detritus.Results and DiscussionThe EwE model prediction results showed that the ECC of bivalve shellfish was established to be 282.66 t/km2, far more than the existing quantity of 187.76 t/km2. Therefore, at present, the ecosystem of the study marine ranching is not yet mature. Moreover, our ecological network analysis parameters indicated that the marine ranching ecosystem will be mature and stable when the bivalve shellfish population reaches its ECC. However, the increase in bivalve shellfish biomass will result in a decrease in the population sizes of species competing for food resources with bivalve shellfish, mainly gobiid fish such as Tridentiger bifasciatus, Tridentiger trigonocephalus, Tridentiger barbatus. Simultaneously, when the bivalve shellfish reach their ECC, 29.23 t of CO2 can be sequestrated by bivalve shellfish, comprising 14.32 t being removed from the ecosystem as prey and 14.91 t being stored on the seafloor through biodeposition.ConclusionTherefore, the research demonstrated that, within the scope of ECC, the increasing bivalve shellfish can improve the C sequestration capacity of the marine ranch ecosystem, and effective management of bivalve shellfish in marine ranching can improve the economic benefits and C sink service functions of marine ranching.

Whole-Genome Survey Analyses Provide a New Perspective for the Evolutionary Biology of Shimofuri Goby, Tridentiger bifasciatus.

Simple SummaryGobies form a group of small fish that are extremely adaptable to their environment. However, genomic resources for Gobiidae species are scarce. In this study, high-throughput sequencing technology was used to generate the whole genome data for the shimofuri goby (Tridentiger bifasciatus). In addition to providing basic genomic information, the mitochondrial whole genome, microsatellite markers, and single-copy homologous genes are also explored. The PSMC model is used to provide the historical population dynamics of the shimofuri goby. The results of this study provide a reference for the assembly of a complete genome map and biological research of the shimofuri goby.The shimofuri goby (Tridentiger bifasciatus) is a small and highly adaptable goby, distributed along the coasts of China, the Sea of Japan, and the west coastal and estuarine areas of the Northwest Pacific. Next-generation sequencing was used to generate genome-wide survey data to provide essential characterization of the shimofuri goby genome and for the further mining of genomic information. The genome size of the shimofuri goby was estimated to be approximately 887.60 Mb through K-mer analysis, with a heterozygosity ratio and repeat sequence ratio of 0.47% and 32.60%, respectively. The assembled genome was used to identify microsatellite motifs (Simple Sequence Repeats, SSRs), extract single-copy homologous genes and assemble the mitochondrial genome. A total of 288,730 SSRs were identified. The most frequent SSRs were dinucleotide repeats (with a frequency of 61.15%), followed by trinucleotide (29.87%), tetranucleotide (6.19%), pentanucleotide (1.13%), and hexanucleotide repeats (1.66%). The results of the phylogenetic analysis based on single-copy homologous genes showed that the shimofuri goby and Rhinogobius similis can be clustered into one branch. The shimofuri goby was originally thought to be the same as the chameleon goby (Tridentiger trigonocephalus) due to their close morphological resemblance. However, a complete mitochondrial genome was assembled and the results of the phylogenetic analysis support the inclusion of the shimofuri goby as a separate species. PSMC analysis indicated that the shimofuri goby experienced a bottleneck event during the Pleistocene Glacial Epoch, in which its population size decreased massively, and then it began to recover gradually after the Last Glacial Maximum. This study provides a reference for the further assembly of the complete genome map of the shimofuri goby, and is a valuable genomic resource for the study of its evolutionary biology.

ABOUT THE FIND OF PARASITES <i>KUDOA NOVA</i> AND <i>KUDOA NILUFERI</i> (MYXOSPOREA: KUDOIDAE) IN THE MUSCLES OF INVASIVE GOBIES <i>TRIDENTIGER TRIGONOCEPHALUS </i>AND <i>GOBIUS CRUENTATUS</i> (ACTINOPTERYGII: GOBIIDAE) IN THE BLACK SEA

The data on parasitizing of two species of myxosporeans of the genus Kudoa in the muscles of two species of invading gobies in the Black Sea off the coast of Sevastopol are presented. One isolate was found in the chameleon goby Tridentiger trigonocephalus , and the other one was found in the red-mouthed goby Gobius cruentatus . It is assumed that the source of infection for the invading fish were native gobies, in which the above species of parasites were previously known. A decrease in the size of spores and polar capsules was noted, as well as a slight disturbance in the shape of spores for K. niluferi , which might be associated with parasitizing in an unusual host and in another region. Molecular genetic identification of myxosporeans from two species of gobies confirms that the studied isolates belong to the genus Kudoa . Two 18S rDNA sequences of these isolates turned out to be very similar, but not identical to each other (differences of 4.87%), and also similar to two known species of goby myxosporeans from the Black Sea - K. nova and K. niluferi . The results obtained are the first evidence of the parasitizing of Myxosporea representatives in both species of gobies in the places of invasion, and also make up the lack of information on genomic variability of parasites of chameleon and red-mouthed gobies in the native range.

Length–weight relations of 11 goby species (Actinopterygii: Gobiiformes) from mangroves along the Ba Lat estuary of the Red River, Vietnam

Presently reported study examined the length–weight relations for 11 goby species collected from a mangrove estuary of the Red River, Vietnam. A total of 1097 individuals of the following species, representing three goby families, were analyzed: Butis butis (Hamilton, 1822); Butis koilomatodon (Bleeker, 1849); Acentrogobius moloanus (Herre, 1927); Acentrogobius viridipunctatus (Valenciennes, 1837); Apocryptodon madurensis (Bleeker, 1849); Aulopareia unicolor (Valenciennes, 1837); Glossogobius giuris (Hamilton, 1822); Gobiopsis macrostoma Steindachner, 1861; Mugilogobius abei (Jordan et Snyder, 1901); Tridentiger barbatus (Günther, 1861); and Tridentiger trigonocephalus (Gill, 1859). The regression slope values (b) ranged from 2.909 to 3.621. The majority of species had positive allometric or isometric growth pattern with b ≥ 3, except for only one species (G. giuris) which had a negative allometric growth with b = 2.909. This study provided the first LWR information of four gobies that have not been reported in FishBase yet. Besides, the reference for LWRs of other gobies at an ecologically important area like Ba Lat Estuary is also provided.

Length–weight relations of 11 goby species (Actinopterygii: Gobiiformes) from mangroves along the Ba Lat estuary of the Red River, Vietnam

Presently reported study examined the length–weight relations for 11 goby species collected from a mangrove estuary of the Red River, Vietnam. A total of 1097 individuals of the following species, representing three goby families, were analyzed: Butis butis (Hamilton, 1822); Butis koilomatodon (Bleeker, 1849); Acentrogobius moloanus (Herre, 1927); Acentrogobius viridipunctatus (Valenciennes, 1837); Apocryptodon madurensis (Bleeker, 1849); Aulopareia unicolor (Valenciennes, 1837); Glossogobius giuris (Hamilton, 1822); Gobiopsis macrostoma Steindachner, 1861; Mugilogobius abei (Jordan et Snyder, 1901); Tridentiger barbatus (Günther, 1861); and Tridentiger trigonocephalus (Gill, 1859). The regression slope values (b) ranged from 2.909 to 3.621. The majority of species had positive allometric or isometric growth pattern with b ≥ 3, except for only one species (G. giuris) which had a negative allometric growth with b = 2.909. This study provided the first LWR information of four gobies that have not been reported in FishBase yet. Besides, the reference for LWRs of other gobies at an ecologically important area like Ba Lat Estuary is also provided.

<span>Molecular-genetic identification of chameleon goby Tridentiger trigonocephalus (Gill, 1859) in the Black Sea</span>

The article focuses on the molecular-genetic identification of the chameleon goby, which has recently become established in the Black Sea basin. The natural range of the chameleon goby are the seas of the Far-East. Genetic variation was studied for the16S rRNA mtDNA gene. The obtained genetic data were compared with similar data of chameleon goby from the natural range and other species from the Tridentiger genus. We determined that, according to the 16S rRNA gene, the identification of the goby from the mouth of the Chernaya River as a species of Tridentiger trigonocephalus was confirmed, and the parameters of the variability indicate an extremely low genetic variability for this gene. According to the authors, the adaptive success of the chameleon goby in the conditions of the Black Sea basin is similar to such of invasive species, namely pumpkinseed (Lepomis gibbosus) and stone moroko (Pseudorasbora parva).

Infection Status with Digenetic Trematode Metacercariae in Fishes from Coastal Lakes in Gangwon-do, Republic of Korea.

The infection status of digenetic trematode metacercariae (DTM) was investigated in fishes from coastal lakes in Gangwon-do, the Republic of Korea (Korea). All fishes collected in 5 lakes were examined with the artificial digestion method. More than 10 species, i.e., Metagonimus spp., Pygidiopsis summa, Centrocestus armatus, Metorchis orientalis, M. taiwanensis, Clinostomum complanatum, Echinostoma spp., Stictodora spp., Diplostomum sp. and Diplostomid No. 1. by Morita (1960), of DTM were detected in fishes from 5 coastal lakes in Gangwon-do. Metagonimus spp. metacercariae were found in 52 (41.3%) out of 126 sea rundace, Tribolodon hakonensis, from 5 lakes, and their density was 14.6 per fish infected. P. summa metacercariae were detected in 48 (84.2%) out of 57 mullets from 5 lakes, and their density was 316 per fish infected. C. armatus metacercariae were detected in 7 (14.6%) T. hakonensis and 3 (15.0%) Tridentiger brevispinis from Hyang-ho, and 5 (19.2%) Acanthogobius flavimanus from Gyeongpo-ho. Stictodora spp. metacercariae were found in 4 fish species, i.e., Tridentiger obscurus, Tridentiger trigonocephalus, Chelon haematocheilus, and Acanthogobius lactipes, from Gyeongpo-ho. Total 15 C. complanatum metacercariae were detected in 2 (9.1%) crucian carp, Carassius auratus, from Songji-ho. M. taiwanensis metacercariae were found in T. hakonensis from Hyang-ho and Gyeongpo-ho and in Pseudorasbora parva from Gyeongpo-ho. Total 11 M. orientalis metacercariae were detected in 3 (6.3%) T. hakonensis from Hyang-ho. From the above results, it was confirmed that various species of DTM are infected in fishes from coastal lakes in Gangwon-do, Korea.

강진만 연안에서 저인망에 어획되는 어류의 종조성 및 계절 변동

The fishes were caught by otter trawl from January to October in 2000 in coastal waters off Gangjin bay. A total of 3,327 fishes were sampled and classified into 69 species, 35 families, and 8 orders. Of the 8 orders, Perciformes, Scorpaeniformes, and Pleuronectiformes accounted for approximately 77.33% of the fishes in this area. Of 69 species identified, Leiognathus nuchalis, Synechogobius hasta, Tridentiger trigonocephalus, Cryptocentrus filifer, and Pholis fangi accounted for 35.65% of the fishes collected. The highest number of individuals was found in Autumn, while the lowest in winter. The richness index was the highest in spring(RI=10.320) and the lowest in winter(RI=5.093). The evenness index was the highest in winter(E=0.842) and the lowest in summer(E=0.798). The diversity index was the highest in spring(H’=3.410) and the lowest in winter(H’=2.865).

두줄망둑 (Tridentiger trigonocephalus) 자치어의 골격발달

두줄망둑 (Tridentiger trigonocephalus) 자치어의 골격발달

서해연안 조간대에 서식하는 두줄망둑(Tridentiger trigonocephalus) 자치어의 먹이생물

To investigate the feeding habits of Tridentiger trigonocephalus juveniles captured in the intertidal zone of Dodun-ri, Seocheon-gun from the end of May to early June 2012, the gut contents were observed. Feeding incidence of the juveniles increased twice a day, first in the morning and second in the afternoon. The major food organisms of the juveniles (6.5〜10.0 ㎜ NL) were composed of copepods (65.4%), amphipods (2.0%), shrimp larvae (14.5%), polychaete larvae (22.6%), and etc. These food items held more than 2 percentage in the dry weight of the total food items.

16S rRNA和COI基因序列对长江口虾虎鱼科鱼类种类鉴定和系统分类的对比研究

为了对比线粒体16S rRNA和COI基因片段在长江口虾虎鱼科鱼类种类鉴定和系统分类研究中的适用性，本文运用PCR技术，扩增了虾虎鱼科7属8种24个个体的线粒体16S rRNA和COI基因片段，并对其种间的序列差异进行比较分析。经比对后得到16S rRNA基因长度为535bp的序列，共编码178个氨基酸，24条16S rRNA序列共有12个单倍型，共检测到变异位点161个，约占总位点数的30.1%，插入/缺失位点15个，转换与颠换比值(Si/Sv)为1.51；同时，获得COI基因长度641 bp，共编码213个氨基酸，单倍型个数与16S rRNA序列相同，变异位点221个，所占百分比高于16S rRNA序列(约34.5%)，无插入/缺失位点，转换/颠换值为1.29。两种基因的转换/颠换值均小于2，因此对其做了相应的突变饱和性分析，结果显示，两种基因在虾虎鱼科鱼类中不存在突变饱和现象。遗传距离结果显示，16S rRNA基因种间序列变异程度均小于COI基因，16S rRNA基因的种内和种间平均遗传距离分别为0.002和0.169，种间约为种内遗传距离的84倍，种间遗传距离最小值存在于纹缟虾虎鱼和髭缟虾虎鱼之间为0.100；而COI序列的种内和种间平均遗传距离分别0.001和0.215，种间为种内遗传距离的215倍。因此，16S rRNA和COI序列均适用于虾虎鱼科的种类鉴定。基于16S rRNA和COI基因序列获得的UPGMA系统树显示虾虎鱼科鱼类均可形成单系群，不同之处在于16S rRNA基因序列主要表现种、属间序列差异，而COI则突出表现种、属、科间序列差异。因此，在应用这两种基因片段做系统分类研究时，应根据研究的不同系统水平选择适当的分子标记。 In order to compare the applicability of mitochondrial 16S rRNA and COI (mitochondrial cytoch-rome oxidase subunit I) in species identification and phylogeny of Gobiidae from Yangtze Estuary, this study investigated the genetic characteristics of these two gene fragments. The two gene fragments of 8 species in Gobiidae were amplified by PCR, and the sequence variation among in-terspecies was analyzed. A total of 535 bp, 12 haplotypes, 161 variation sites (about 30.1% of all), 15 insertion or deletion of sites were detected for 16S rRNA of 24 individuals, and 178 amino acids were encoded. All of the transitional pairs (si) was slightly more than that of the transversional pairs (sv), and the ratio (R = si/sv) was 1.51; while 641 bp and 221 variation sites were detected for COI, and no insertion or deletion of sites was found in the COI gene, the ratio of si and sv was 1.29. Both the ratios of the two genes from 24 individuals were less than 2, so mutation saturation of the two genes was analyzed. However, the result showed that there was no mutation saturation in the two genes of Gobiidae. The results of genetic distance showed that the degree of variation of 16S rRNA in interspecific sequence was less than that of COI sequence. Intraspecific and interspecific K2P genetic distances were respectively 0.002 and 0.169 for 16S rRNA sequences, and 0.001 and 0.215 for COI sequences. Genetic differences of 16S rRNA sequences between congeners were, on average, about 84 times higher than the differences within species, and the minimum value (0.100) was existed between Tridentiger trigonocephalus and Tridentiger barbatus; while genetic differences of COI sequences were 215 times between intraspecies and interspecies, which met Hebert’s species identification standard (more than 10 times the difference between intraspecies and interspecies). Therefore, 16S rRNA and COI sequences were both applicable for species identi-fication in Gobiidae. The UPGMA phylogenetic tree was constructed based on 16S rRNA and COI, which demonstrated that Gobiidae in the Yangtze Estuary was a monophyletic group. The major differences were that interspecies and genera were more emphasis for 16S rRNA gene, while it highlighted interspecies, genera and family more for COI gene. As a result, it is advisable to select appropriate molecular markers according to different classified levels when applying the two gene fragments for studying species identification and phylogeny.

The complete mitochondrial genome sequence and gene organization of Tridentiger trigonocephalus (Gobiidae: Gobionellinae) with phylogenetic consideration

The complete mitochondrial genome plays an important role in studies of genome-level characteristics and phylogenetic relationships. Here we determined the complete mitogenome sequence of Tridentiger trigonocephalus (Perciformes, Gobiidae), and discovered its phylogenetic relationship. This circular genome was 16 662 bp in length, and consisted of 37 typical genes, including 13 protein-coding genes, 22 tRNA genes, and two rRNA genes. The gene order of T. trigonocephalus mitochondrial genome was identical to those observed in most other vertebrates. Of 37 genes, 28 were encoded by heavy strand, while the others were encoded by light strand. The phylogenetic tree constructed by 13 concatenated protein-coding genes showed that T. trigonocephalus was closest to T. bifasciatus, and then to T. barbatus among the 20 species within suborder Gobioidei. This work should facilitate the studies on population genetic diversity, and molecular evolution in Gobioidei fishes.

Food habits of harbor seals (Phoca vitulina richardii) as an indicator of invasive species in San Francisco Bay, California

AbstractThe diet of harbor seals (Phoca vitulina richardii) in San Francisco Bay (SFB), California, was determined from July 2007 to July 2008 using prey hard parts recovered from 442 scats collected at five haul‐out sites. Twenty‐two species of fish and one species of crustacean were identified, but harbor seals primarily ate a nonnative invasive species, yellowfin goby (Acanthogobius flavimanus), which increased in dietary importance since the diet was last studied in 1991/1992. Additionally, another nonnative invasive fish species, chameleon goby (Tridentiger trigonocephalus), was found for the first time in the diet of harbor seals in SFB. Harbor seal diet was statistically different between years (1991/1992 and 2007/2008), between the pupping and nonpupping seasons, and between North SFB and South SFB haul‐out locations. The diet of harbor seals was significantly correlated with fish species caught in trawl surveys conducted by the California Department of Fish and Wildlife (CDFW) during the same time periods as this study (2007/2008). Harbor seals currently are influencing the health of the SFB ecosystem in a positive manner by consuming large quantities of nonnative invasive fish species.

Histological Analysis of Early Gonadal Development and Sex Differentiation in Chameleon Goby, Tridentiger trigonocephalus.

This study describes the developmental process of gonads in chameleon goby, Tridentiger trigonocephalus from the stage of hatching to 100 days after hatching (DAH). Based on histological observation, the primordial germ cells were observed in mesentery between mesonephric duct and gut at 15 DAH (total length, TL: 6.8±0.2 mm). At 20 DAH (TL: 7.9±0.1 mm), the primordial gonad began to protrude into peritoneal cavity and developed between mesonephric duct and gut. Initial ovarian differentiation was identified by the presence of ovarian cavity and oogonia in the gonads at 55 DAH (TL: 21.1±1.3 mm). Testicular differentiation started at 65 DAH (TL: 23.7±0.9 mm) with appearance of spermatogonial cells in the gonads. These findings indicate that sex differentiation in T. trigonocephalus occurs earlier in females than males, suggesting that this species can be classified as an undifferentiated gonochorist.

Trophic and spatial niche of five gobiid fishes in Jiaozhou Bay

The food composition,spatial and trophic niche width,trophic-spatial niche overlap for five gobiid fishes in Jiaozhou Bay were studied using the Shannon-Wiener index and Pianka overlap index.The trophicspatial niche overlap was calculated to describe the relationship between feeding competition and spatial distribution of these gobiid fishes.Results showed that all the five gobiid fishes could be classified as benthic carnivorous predators.Synechogobius ommaturus fed mainly upon shrimps,polychaetes and fish.The main prey items of Amblychaeturichthys hexanema,Odontamblyopus lacepedii,Tridentiger trigonocephalus and Tridentiger barbatus were some small benthic crustaceans such as copepods,amphipods and cumacea.Among the five gobiid fishes,A.hexanema had the highest trophic niche width value(2.65) and T.trigonocephalus had the highest spatial niche width value(2.01).O.lacepedii had the lowest values of trophic niche width(1.26) and spatial niche width(0.97).The trophic niche overlap values for five gobiid fishes ranged from 0.03 to 0.64,with A.hexanema and T. barbatus having the highest trophic niche overlap value(0.64).The spatial niche overlap values were between 0.08 and 0.91,with O.lacepedii and T.barbatus having the highest spatial niche overlap value(0.91).The trophicspatial niche overlap values ranged from 0.003 2 to 0.364 8,with A.hexanema and T.barbatus having the highest trophic–spatial niche overlap value(0.3648),which may result in intensive food competition.The competitions among other gobiid fishes were reduced by partitioning of trophic and spatial niches.

Reproductive Cycle of Chameleon Goby, Tridentiger trigonocephalus in the Southern Coastal Waters of Korea.

The objective of this study was to characterize the reproductive cycle of the chameleon goby, T. trigonocephalus. Gonadal development was investigated using a histological method. Specimens were collected monthly, from April 2009 to March 2010. The gonadosomatic index (GSI) of females began to increase in April, reaching the maximum in May, and declined sharply in August. In males, the GSI began to increase in April and reaching the maximum in July. The annual reproductive cycle of T. trigonocephalus can be divided into four successive stages in females: the growing (November-March), maturing (April-May), ripe and spawning (June-July), and recovery (August-October) stages. Males passed through growing (November-March), maturing (April-June), ripe and spermiation (July-August), and recovery (September-October) stages. These results indicate the spawning season is from June to July. The relationship between fecundity (Fc) and body length (BL) was Fc=86.1511BL2.6506. Fecundity was ranged from 3,448-9,654 eggs in a BL of 4.8-7.2 cm and it was increased as BL increased.

Rapid acquisition of an appetitive conditioned response in an intertidal fish, Tridentiger trigonocephalus (Gobiidae), using an ethologically relevant conditioning paradigm

Intertidal fishes have elaborated spatial cognitive abilities. In this study, we developed an appetitive conditioning paradigm for an intertidal fish species (the chameleon goby; Tridentiger trigonocephalus) that involves spatial components and ethologically relevant cue stimuli. The gobies rapidly acquired the conditioned anticipatory behaviour after only a few trials of paired presentations of virtual tidal changes and food rewards (which were only available in specific locations during a simulated high tide). The conditioned responses were retained after exposure to a 1 month period without trainings or tidal changes. The rapid acquisition and long-term retention of the conditioned responses indicates that the learning paradigm, which used a combination of water level changes and food availability in specific spatial locations, is biologically significant for this species. Taken together, these results suggest that spatial tasks combined with virtual tidal changes provide a suitable paradigm for evaluating spatial cognitive mechanisms in intertidal fishes.

Analysis of fatty acid composition in different tissues of adult femaleTridentiger trigonocephaluscollected from the Yangtze Estuary

Research was made in this paper on the moisture,lipid content and fatty acid composition of muscle,liver and ovary of adult female Tridentiger trigonocephalus collected from the Yangtze Estuary at Ⅴ stage of ovary development.The results indicated that:(1) The moisture content in muscle,liver and ovary was reduced successively,and the value was significantly different among these three tissues(P0.05).The total lipid content in these three tissues was(1.32%±0.08%),(7.75%±0.38%),and(26.73%±0.59%),respectively.There was significant difference in total lipid content among these three tissues,and the highest was in ovary,followed by liver,and the lowest was in muscle.(2) The content of SFA in muscle was significant higher than that in liver and ovary.There was significant difference in SFA content among three tissues(P0.05).About the MUFA,C16:1 content of liver is the highest.The C16:1 content in muscle,liver and ovary were(11.90%±0.71%),(15.28%±2.42%) and(9.49%±0.37%) respectively,and there was significant difference among these three tissues(P0.05).The content of PUFA,3PUFA,6PUFA in ovary was significantly higher than that in muscle and liver(P0.05),but showed no significant difference between muscle and liver(P0.05).The total content of EPA and DHA in muscle,liver and ovary were increased successively.The total content of EPA and DHA in these three tissues was(30.17%±1.02%),(30.53%±0.50%) and(34.33%±0.71%),respectively.The content of EPA and DHA in ovary was significantly higher than that in muscle and liver(P0.05),but showed no significant difference between muscle and liver(P0.05).The ratio of EPA to DHA(EPA/DHA) in these three tissues was 1.50,1.75 and 1.59 respectively,and the ratio of total 3 polyunsaturated fatty acids to total 6 polyunsaturated fatty acids(∑ 3PUFA/∑ 6PUFA) in these three tissues was 6.44,8.05 and 7.00,respectively.The ratios of EPA/DHA and ∑ 3PUFA/∑ 6PUFA were highest in liver,followed by ovary,and the lowest was in muscle.