Acrossocheilus Paradoxus Research Articles

DNA metabarcoding for dietary analysis of Holland's carp (Spinibarbus hollandi) to evaluate the threat to native fishes in Taiwan.

DNA metabarcoding analysis for gut contents has been shown to compensate the disadvantage of traditionally morphological identification and offer higher resolution of prey items in an efficient way. Holland's carp (Spinibarbus hollandi) is a freshwater fish native to southern and eastern Taiwan. In the past two decades, this species has been introduced as a sport fish into the river basins of northern and western Taiwan. The large body size and active predation make it a potential threat for native fishes, but which native species are preyed by Holland's carp remains unknown. In this study, the diet from the gut contents of Holland's carp from the Zhonggang River, an invaded basin, was examined using DNA metabarcoding from 51 individuals and by morphological examinations on 140 samples. Detritus of plants were found in 83.6% samples (117 individuals). Twenty fish species of seven families were identified by DNA metabarcoding, including species of all water layers. Taiwan torrent carp (Acrossocheilus paradoxus) and Rhinogobius spp. are the most common prey items. Based on the results of this study, Holland's carp is considered an opportunistic omnivore because of its diverse diet items, which is an important trait for successful invasive fish species. The population decline of Opsariichthys pachycephalus may not result from the invasion of Holland's carps. Nonetheless, the time lag between successful invasion and the samplings of this study may be a concern because the population size of O. pachycephalus may have declined and become difficult to prey. The Holland's carps consumed the least species in winter; nonetheless, the occurrence frequencies of preys among seasons were not significantly different probably because of limited temperature fluctuation. The smallest Holland's carps consumed the least prey species compared to other size categories, similar to the relationship of prey species number to size of invasive largemouth bass (Micropterus salmoides).

Mitochondrial diversity and phylogeography of Acrossocheilus paradoxus (Teleostei: Cyprinidae)

Mitochondrial DNA cytochrome b sequences (1141 bp) in 229 specimens of Acrossocheilus paradoxus from 26 populations were identified as four lineages. The pairwise genetic distances among these four lineages ranged from 1.57 to 2.37% (mean= 2.00%). Statistical dispersal-vicariance analysis suggests that the ancestral populations were distributed over mainland China and Northern and Western Taiwan. Approximate Bayesian computation approaches show that the three lineages in Taiwan originated from the lineage in mainland China through three colonization routes during two glaciations. The results indicated that during the glaciation and inter-glacial periods, the Taiwan Strait was exposed and sank, which contributed to the dispersion and differentiation of populations. Furthermore, the populations of A. paradoxus colonized Taiwan through a land bridge to the north of the Formosa Bank, and the Miaoli Plateau in Taiwan was an important barrier that limited gene exchange between populations on both the sides.

Length-weight relationships of six fish species from the headstream region of the Dongjiang River, China

Dongjiang River, a main tributary of the Pearl River, is geographically situated in South China. The present study describes the length–weight relationships (LWRs) of six fish species (Acrossocheilus paradoxus, Barbodes semifasciolatus, Onychostoma elongatum, Microphysogobio fukiensis, Microphysogobio kiatingensis, Metzia lineata) from the headstream region of the river including five Chinese endemic species (A. paradoxus, B. semifasciolatu, O. elongatum, Mi. fukiensis, Mi. kiatingensis). Fish species of five genera of the same family were collected quarterly from April 2012 to October 2014 by using non-selective fishing gears: drag nets (5 m, mesh-size 3 cm), drift gillnets (30 × 15 m, mesh-size 5 mm), fish cages (4 m, mouth opening 40 × 40 cm), scoop nets (mesh-size 0.5-1 cm), and electro-fishing (12V, 200 Hz). The parameter a and b in the LWR equations (W = a Lb) ranged from 0.0014 to 0.0228, and 2.89 to 3.18, respectively. Compared with FishBase, this study provides the first LWR records for four cyprinids (A. paradoxus, B. semifasciolatu, O. elongatum, Me. lineata) and a new record of maximum body length for O. elongatum.

Occurrence and distribution of yellow grub trematodes (Clinostomum complanatum) infection in Taiwan.

Digenetic trematodes of the genus Clinostomum are widely distributed in many species of freshwater fish and are known to cause the zoonotic disease Halzoun. Humans may become accidental hosts if they ingest raw freshwater fish containing metacercaria of Clinostomum complanatum, which causes pharyngitis or laryngitis. The yellow grub parasitizing cultivated ayu (Plecoglossus altivelis) and loach (Misgurnus anguillicaudatus) was one of the most serious problems in fish farms from 1977 to 1979 in Taiwan. The present study revealed, for the first time, frequent occurrence of C. complanatum metacercaria in various fish species in a natural environment, the Dahan River, in Taiwan. We examined 1503 fish specimens belonging to four families and 162 snails representing six species. C. complanatum metacercaria was mainly from the fish family Cyprinidae, and only cercaria from the snail Radix swinhoei was recovered. The prevalence and mean intensity of metacercaria were 9.8% and 9.35 parasites/infected fish, respectively. The prevalence of cercaria was low, 0.62%, in snails. Acrossocheilus paradoxus, Zacco barbata, Zacco pachycephalus, Zacco platypus, Onychostoma barbatula, and Hemibarbus labeo are new host records. Metacercariae were primarily found in the operculum, mandible, muscle, and oral cavity of fish. Morphological description and molecular analysis with 18S rDNA sequencing allowed for rapidly identifying C. complanatum. Encysted and excysted metacercariae cultivated at 22°C in physiological saline died within 60h. The mean intensity of infection increased with an increasing length of Z. pachycephalus. We found no association between monthly parasite prevalence and mean intensity at each sampling location. No C. complanatum metacercaria survived after 8h of salting. The Dahan River has suitable conditions and hosts (snails, fish, and fish-eating birds) for maintaining the life cycle of C. complanatum.

A model for predicting tourist carrying capacity and implications for fish conservation

Tourism development in protected areas inevitably induces a decline in the ecological environment and species survival. However, the degree of impact depends on target species’ environmental quality tolerance and the number of tourists. Each fish can tolerate a specific level of water quality. Water quality should not deteriorate below this level as a result of tourism. In this study, we used regression analysis and habitat suitability curve method to determine the number of tourists that could visit an area without inducing a decline in water quality that would negatively impact the survival of protected fishes. A regression model indicated that of the ten water quality parameters evaluated, dissolved oxygen, biochemical oxygen demand, and ammonia-nitrogen were most impacted by tourists. A habitat suitability curve was produced for each target fish population and water quality parameter. These curves were used to determine suitable water quality for fish survival. The curves were then combined to determine the acceptable number of tourists for management of water quality suitable for fish survival. In order to maintain suitable water quality for the survival of Varicorhinus barbatulus, Candidia barbatus, and Acrossocheilus paradoxus, the threshold number of tourists at the study site is 3,000–3,600 people per week.

Acrossocheilus paradoxus affects benthic resources and communities in a subtropical stream in Taiwan

The effects of benthic fish on stream benthic resources and communities have not been effectively studied in subtropical East Asia. This study examined the effects of the Acrossocheilus paradoxus benthic fish on benthic resources and communities in Jiaolong Creek, Central Taiwan. A cage experiment with a no‐fish control and a fish treatment was used to study the effects of A. paradoxus on the mass of algae and detritus and on the density and community structure of algae and macroinvertebrates. Additional diets, nutrient excretion rates, and feeding scars of this fish were also examined. A. paradoxus fed primarily on algae and detritus. The fish treatment had lower chlorophyll a, phaeophytin a, and ash‐free dry mass than the no‐fish control. Areas of concentrated feeding scars by A. paradoxus had consistently lower chlorophyll a than adjacent non‐feeding areas. The mean density of macroinvertebrates was lower in the fish treatment; however, the taxa richness and diversity were higher. Algal and macroinvertebrate communities differed between treatments. A. paradoxus altered the benthic resources and communities in this study.

Niche partitioning of fish assemblages in a mountain stream with frequent natural disturbances – an examination of microhabitat in riffle areas

Abstract – Microhabitat usage by different species of fish was studied to examine the potential for niche partitioning in riffle areas of a mountain river characterised by frequent natural disturbances. We randomly sampled 96 riffle‐area plots (mostly 1 m × 1 m) in a stream in south‐western Taiwan for fish abundance and microhabitat characteristics during the dry season from November 2008 to March 2009. Density and electivity values associated with microhabitat usage indicate the presence of niche partitioning among four major species of fish based largely on flow velocity and water depth. Hemimyzon formosanum, a herbivore, prefers higher velocity and shallower water but avoids sandy substrate. Onychostoma alticorpus, a herbivore, prefers lower velocity and deeper water. Rhinogobius nantaiensis, an omnivore, prefers higher velocity, shallower water and gravel‐sized substrate but avoids boulder substrate. Acrossocheilus paradoxus, an omnivore, prefers lower velocity and deeper water but avoids pebble‐sized substrate. The existence of differentiation of microhabitat preference and overlap of microhabitat usage suggests that interspecific competition is a factor affecting the structure of this fish assemblage, which may remain at early successional stages because of frequent disturbances in the stream. Study results also show that density and electivity detect preference differently. Density detects microhabitat preference for two herbivores while electivity detects microhabitat preference for two omnivores.

Characterization and genetic variations of satellite DNAs inAcrossocheilus paradoxus(Günther, 1868) (Cyprinidae) indicate population expansion

AHindIII repetitive DNA family fromAcrossocheilus paradoxus, a cyprinid fish endemic to Taiwan, was isolated and identified as a tandem arrangement of satellites in the genomic DNA. Cross‐hybridization revealed similar patterns across fish genera and two families and suggested that this repetitive DNA is a conserved satellite sequence in fish. Forty‐five monomeric repeat units of the repetitive DNA were cloned and sequenced, and found to be approximately 210 base pairs long and to have an average base composition of 52·8% A+T. Alignment analysis by examining 45 cloned repeat DNA strands from 22 individuals from nine different streams suggested that this repetitive DNA is highly polymorphic. The variability of sequences was mainly attributable to point mutations within the sequences. Genetic distances in all repeated DNAs ranged from 0 to 0·129 (average, 0·06). The high levels of genotype diversity and low levels of nucleotide diversity in satellites suggest population expansion ofA. paradoxus.

Acrossocheilus spinifer, a new species of barred cyprinid fish from south China (Pisces: Teleostei)

Acrossocheilus spinifer sp. nov. is described from the river basins in Fujian Province and the Han Jiang basin in Guangdong Province, south China. It is one of the barred Acrossocheilus species sharing five or six vertical bars on the flanks, with each bar being two scales in width. Acrossocheilus spinifer sp. nov. is morphologically most similar to Acrossocheilus wenchowensis, but distinguished from it by: a colour pattern of all vertical bars extending ventrally to the second scale row below the lateral line, and having the second bar placed posterior to the base of the last simple dorsal‐fin ray, a blunt snout; and a stout, last simple dorsal‐fin ray. Acrossocheilus spinifer sp. nov. resembles Acrossocheilus kreyenbergii and Acrossocheilus stenotaeniatus with which it shares a stout, last simple dorsal‐fin ray with a serrated posterior edge, but is separated from both species by having a narrow median interruption in the lower lip, a lower jaw fully covered by the lower lip when viewed ventrally and the second vertical bar placed posterior to the base of the last simple dorsal‐fin ray. The absence of a longitudinal stripe extending along the lateral line on the flanks in males readily distinguishes A. spinifer sp. nov. from four other species, namely Acrossocheilus fasciatus, Acrossocheilus paradoxus, Acrossocheilus parallens, and Acrossocheilus jishouensis.

Impacts of natural disturbance on fish communities in the Tachia River, Taiwan

Extensive landslides triggered by the Chi-Chi earthquake of 21 September 1999 introduced debris into the middle section of Tachia River, while debris flow was subsequently induced by Typhoon Toraji on 30 July 2001. We compared population size, species composition, and diversity of the fish community during a six-year period before and after these disturbances. The dominant taxa were Acrossocheilus paradoxus, Crossostoma lacustre, Hemimyzon formosanum, Rhinogobius brunneus, Varicorhinus barbatulus and Zacco pachycephalus. H. formosanum and R. brunneus increased then decreased suddenly in abundance following the earthquake and the typhoon. Our results suggest that both resistance and resilience were important in maintaining long-term fish community structure. Fish community resistance at station 1 (downstream of the disturbance) was lower than at station 2 and station 3 (at and upstream of the disturbance). Fish communities recovered quickly after a few months, possibly reflecting a correlation between assemblage composition and seasonal variation. Our study illustrates the ecological variability that can be induced by hydrologic and evolutionary processes in a stream. Relative positions of habitats provide a spatial framework for evaluating stress effects of abiotic and biotic factors in regulating population size and community succession patterns.

Isolation and characterization of microsatellite loci in Acrossocheilus paradoxus (Cyprinidae) using PCR-based isolation of microsatellite arrays (PIMA)

Isolation and characterization of microsatellite loci in Acrossocheilus paradoxus (Cyprinidae) using PCR-based isolation of microsatellite arrays (PIMA)

Mitochondrial DNA phylogeography of Acrossocheilus paradoxus (Cyprinidae) in Taiwan.

Nucleotide sequences of 3' end of the cytochrome b gene, tRNA genes, D-loop control region, and the 5' end of the 12S rRNA of mitochondrial DNA (mtDNA) were used to assess the genetic and phylogeographic structure of Acrossocheilus paradoxus populations, a Cyprinidae fish of Taiwan. A hierarchical examination of populations in 12 major streams from three geographical regions using an analysis of molecular variance (AMOVA) indicates high genetic differentiation both among populations (PhiST = 0.511, P < 0.001) and among regions (PhiCT = 0.368, P < 0.001). Limited migration largely contributed to the genetic differentiation. High nucleotide diversity (1.13%) and haplotype diversity (0.80%) were detected among populations. The degree of genetic differentiation was correlated with geographical distance between populations, a result consistent with the one-dimensional stepping stone models. A neighbour-joining tree recovered by (DAMBE) supports the pattern of isolation by distance and reveals a closer relationship between populations of the central and southern regions. A minimum spanning network based on nucleotide substitutions reflected migration routes from populations of the central region to the northern and southern regions, respectively. Postglacial colonization and expansion can explain the phylogeographical pattern. Single and ancient migration events may have allowed the northern region to attain the monophyly of mtDNA alleles. In contrast, most populations within geographical regions are either paraphyletic or polyphyletic due to the relatively shorter time period for coalescence. Both low haplotype number and genetic variability suggest a bottleneck event in the Chingmei population of northern Taiwan. Based on coalescence theory, the monophyly of the Tungkang population of the southern region may be associated with a founder event.

Cloning and genetic variability of a HindIII repetitive DNA in Acrossocheilus paradoxus (Cyprinidae).

Thirty clones of a highly repetitive HindIII fragment of DNA from seven populations of Acrossocheilus paradoxus (Cyprinidae) were isolated and sequenced. The fragment represents a tandemly repeated sequence, with a monomeric unit of 270 bp, amounting to 0.08-0.10% of the fish genome. Higher units of this monomer appear as a ladder in Southern blots. The HindIII satellite DNA family is conserved in three genera of the Cyprinidae. Variation in nucleotide sequences of this repetitive fragment, which is A+T-rich, is distributed both within individuals and among populations. High overall nucleotide divergence (dij = 0.056 +/- 0.001) was detected among clones of the HindIII satellite DNAs of Acrossocheilus paradoxus. Based on the molecular clock hypothesis, the maximum evolutionary rate was estimated to be 5.3 x 10(-7) substitutions per site per year. Lineage sorting may have contributed to the genetic heterogeneity within individuals and populations. Cladistic analyses indicated a closer phylogeographic relationship between populations of the central and south regions in Taiwan.