Length–weight relationships of six species of the genera Cobitis and Sabanejewia (Cobitidae) in Iranian river systems

Length‐weight relationships (LWRs) were estimated for six spined loach species from Iran. Data were collected between 2010 and 2015. These represent the first reports of length–weight data for five of the species (Cobitis avicennae, Cobitis faridpaki, Cobitis keyvani, Sabanejewia aurata and Sabanejewia caspia) while also providing additional data on the remaining species (Cobitis linea). Five of these species are endemic and the remaining S. caspia, is native to the country. Estimated b values obtained for the studied species ranged from 2.381 for S. aurata to 3.411 for C. keyvani.     

Length-weight relationships of 6 fish species caught in a Mediterranean lake (Trichonis-NW Greece)

In the present study the length–weight relationships (LWRs) of 6 fish species which are endemic to Western Greece, caught in the natural Lake Trichonis by experimental gillnets and electrofishing were estimated. Benthic (mesh size 5–55 mm; height 1.5 m; length 30 m) and pelagic (mesh size 6.25–55 mm; height 6 m; length 27.5 m) Nordic type multimesh gillnets were used seasonally, between February 2019 and November 2019, at different depth zones (0-57m). Electrofishing (80 Hz) conducted in the littoral zone of the lake during four samplings (2018, 2019). All the estimated LWRs were highly significant (p < .05) with high correlation coefficient (r² ≥ 0.962). The estimated b values ranged from 3.058 to 3.344. For five of the studied species (Trichonis spined loach (Cobitis trichonica Stephanidis 1974), Trichonis blenny (Salaria economidisi Kottelat 2004), Trichonis rudd (Scardinius acarnanicus Economidis 1991), Acheloos roach (Leucos panosi (Bogutskaya & Iliadou 2006)) , Hellenic minnowroach (Tropidophoxinellus hellenicus (Stephanidis 1971)) new maximum total body lengths (TL) were recorded, while for two species (T. hellenicus and L. panosi) LWRs are presented for the first time.     

Length‐weight relationships of seven fish species from the Wutong River,northeast China

Length‐weight relationships (LWR) were calculated for seven fish species from the Wutong River, northeast China(47°58'‐47°10'N; 130°07'‐130°48'E), including Ladislavia taczanowskii Dybowski, 1869; Gobio cynocephalus Dybowski, 1869; Rhynchocypris lagowskii (Dybowski, 1869); Lefua costate (Kessler, 1876); Cobitis lutheri Rendahl, 1935; Cobitis sibirica Gladkov, 1935; Perccottus glenii Dybowski, 1877. All fish specimens were collected by electric fishing gear (voltage, 12 V) and gillnets (mesh size: 1.1 cm × 1.1 cm, 1.4 cm × 1.4 cm, 1.8 cm × 1.8 cm, 2.5 cm × 2.5 cm) from May to July 2017. The a values ranged from 0.0038 (Cobitis lutheri) to 0.0084 (Lefua costata), and b values from 2.716 (Lefua costata) to 3.450 (Perccottus glenii) and r² values from 0.973 (Cobitis lutheri) to 0.995 (ladislavia taczanowskii). This study provides the first published the LWRs for the five species, and new maximum total lengths were recorded for two species, including Gobio cynocephalus and Lefua costata.     

Length‐length and length‐weight relationships for four fish species from Naolihe National Nature Reserve,Heilongjiang, China

In this study the length‐length and length‐weight relationships for four fish species from Naolihe National Nature Reserve in China belonging to three families and four genera were analyzed. They are Perccottus glenii Dybowski, 1877; Rhodeus sericeus Pallas, 1776; Cobitis lutheri Rendahl, 1935; and Misgurnus mohoity Dybowski, 1869. Fish samples were collected in May 2017 from Naolihe National Nature Reserve by fish catching cage (31*41 cm caliber, 16 m length, 3–5 mm mesh diameter), and identified as to species in the laboratory according to S. Q. Zhu (Synopsis of freshwater fishes of China, Jiangsu Science and Technology Publishing House, Nanjing, China, 1995).     

Pediocin production in milk by Pediococcus acidilactici in co-culture with Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus

The production of pediocin in milk by Pediococcus acidilactici was evaluated in co-culture with the dairy fermentation cultures Streptococcus thermophilus and Lactobacillus delbrueckii ssp. bulgaricus. The cultures were tested singly and in different combinations in milk (0 or 2% fat content) during incubation at 40°C for up to 10 h. Cell-free milk samples taken every 60 min were tested for bacteriocin activity against Listeria monocytogenes. Pediocin activity was not detectable when P. acidilactici was inoculated into milk as a monoculture. When P. acidilactici was grown in combination with the yogurt starter cultures S. thermophilus and Lb. delbrueckii ssp. bulgaricus, pediocin concentration reached 3,200–6,400 units ml⁻¹ after 8 h of incubation. The results showed that pediocin producing pediococci may be useful adjunct components in mixed cultures of S. thermophilus and Lb. delbrueckii ssp. bulgaricus to amplify the bioprotective properties of fermented dairy foods against Listeria contamination.     

Length–weight and length–length relationships and seasonal condition factors for two mudskippers,Periophthalmus modestus (Cantor, 1842) and P. magnuspinnatus (Lee,Choi & Ryu, 1995) (Gobiidae), on tidal flats of Korea

Presented are the length–weight and length–length relationships and condition factors for two mudskippers, Periophthalmus modestus and Periophthalmus magnuspinnatus, on the tidal flats of Korea. Values of the exponent b, estimated by nonlinear least squares from weight and length data, were 3.031 for P. modestus and 3.044 for P. magnuspinnatus. All relationships between total and standard length were linear (r² > 0.974). The condition factors were significantly higher during the post‐spawning season than at other times for both species.     

Length–weight relationships for 39 species of moray eel from the waters around Taiwan

Length–weight relationships were determined in 39 muraenid species belonging to seven genera collected during 2003–2008 from the waters around Taiwan. Various fishing methods were used to collect both the adult and pre‐adult moray eel specimens. Length–weight relationship records of 28 species are provided for the first time. New maximum size records of six species were also established: 61.2 cm for Gymnothorax monostigma, 88.2 cm for G. niphostigmus, 68.6 cm for G. shaoi, 53.9 cm for G. taiwanensis, 73.2 cm for G. thyrsoideus, and 37.3 cm for U. micropterus.     

Length–weight relationships of three fish species from the Tajan River,Iran

The study describes the length–weight relationships for two Cobitid species, namely Cobitis keyvani and Sabanejewia aurata, plus a Gobiid species, Ponticola gorlap, all from the Tajan River in Mazandaran province, Iran.     

Length–weight relationships of three fish species from Moyangjiang River,China

Length‐weight relationships were determined for three fish species [Tachysurus argentivittatus (Regan, 1905); Rhodeus spinalis Oshima, 1926; Liniparhomaloptera disparis (Lin, 1934)]. All fish sample were collected using gillnets (15 × 5 m, mesh‐size 5 mm) from Moyangjiang River, China. Samples were collected quarterly from July 2006 to August 2007. The parameter b of length‐weight relationship varied from 2.52 for Rhodeus spinalis to 3.27 forLiniparhomaloptera disparis.     

Length–weight relationships for ten endemic fish species of Anatolia

This study presents the first references available for length–weight relationships (LWRs) of ten endemic fish species: Oxynoemacheilus eregliensis (Banarescu & Nalbant, 1978), Seminemacheilus lendlii (Hankó, 1925), Cobitis turcica Hankó, 1925, Capoeta antalyensis (Battalgil, 1943), Capoeta caelestis Schöter, Özulug & Freyhof, 2009, Capoeta pestai (Pietschmann, 1933), Gobio gymnostethus Ladiges 1960, Gobio hettitorum Ladiges, 1960, Pseudophoxinus antalyae Bogutskaya, 1992 and Scardinius elmaliensis Bogutskaya, 1997 from the inland water systems of Turkey.     

Length–weight and length–length relationships of four fish species from the middle reaches of the Minjiang River,southwest China

Length–weight (LWR) and length–length (LLR) relationships are reported for Glyptothorax fokiensis (Rendahl, 1925), Microphysogobio kachekensis (Oshima, 1926), Pseudobagrus brevicaudatus (Wu, 1930), and Sinibrama taeniatus (Nichols, 1941) from the middle reaches of the Minjiang River and its tributaries, Sichuan Province, in southwest China. A total of 675 specimens were obtained between 2013 and 2016 using various types of fishing gear and electroshock fishing techniques. Standard length and total length for each individual were measured by digital slide caliper and each body weight was taken by digital balance. The b‐values for LWRs varied from 2.617 to 3.249 (r² > .954), and the LLRs were highly correlated (r² > .983; p < .01).     

Length–weight and length–length relationships of five fish species in the Atrai River,Dinajpur, Bangladesh

A total of 502 specimens were obtained during monthly samplings from July to December 2015, by fishermen using seine nets, gillnets and cast nets. Length–weight (LWRs) and length–length (LLRs) relationships were estimated for five fish species collected from the Atrai River in the northwestern region of Bangladesh. The values of slope (b) in LWRs (r² > .913, p < .001) were determined as 2.899 for Aspidoparia jaya, 3.059 for Gagata cenia, 3.004 for Gagata youssoufi, 2.755 for Salmophasia bacaila, and 3.222 for Salmophasia phulo, respectively. The linear relationships in TL, FL and SL were highly correlated (for all cases: r² > .897, p < .001). No previous information on LWRs (except for G. cenia) and LLRs (except for S. bacaila) of these selected species were found in FishBase.     

Length–weight and length‐length relationships of four endemic fish species caught from Payra River,Southern Bangladesh

The present study estimated the length–weight relationship (LWR) and length‐length relationships (LLR) of four fish species, Ompok pabo (Hamilton, 1822), Acentrogobius cyanomos (Bleeker, 1849), Acentrogobius caninus (Valenciennes, 1837) and Gagata cenia (Hamilton, 1822) collected from the Payra river over a period of 1 year between July 2015–June 2016 using set bag nets and cast nets with a mesh size of 0.5 cm and <0.5 cm, respectively. Altogether 593 individuals of O. pabo (59), A. cyanomos (221), A. caninus (240) and G. cenia (73) were sampled and studied. LWRs of O. pabo, A. cyanomos, and A. caninus are presented for the first time in Fishbase.     

Range extension of a boreal amphipod Gammarus oceanicus in the warming Arctic

The recent (2008–2016) occurrence of a boreal intertidal amphipod Gammarus oceanicus along the Spitsbergen coast is compared with corresponding data from 1980 to 1994. We aimed to compare the pace of environmental changes in the area (ice retreat, temperature increase) with distribution change of G. oceanicus. Material for the study was collected from intertidal, at low water level from over 100 locations on Spitsbergen, the main island of Svalbard archipelago (expanding from 76 to 80°N). The west coast of the island has been exposed to a steady increase in sea surface and air temperature (2°C in 20 years), as well as a significant decrease in fast ice duration (from over 5 months to less than 1 per year). A total length of more than 3,600 km of the island's coastline has been recently impacted by warming. Of the two sibling Gammarus species that dwell in the Spitsbergen littoral, G. setosus, the local cold water species remains generally where it was observed about 20–30 years ago. By contrast, boreal G. oceanicus has expanded its distribution range by over 1,300 km along the west and north coasts of Spitsbergen and gained dominating position on the number of sites, where it was previously just an occasional species.     

Length–weight relationships of nine freshwater fish species from the Liujiang River,Guangxi, China

Studied were the length–weight relationships (LWRs) of 599 fish specimens covering four families, nine genera and nine species (Sinibrama macrops, Acrossocheilus parallens, Microphysogobio fukiensis, Squalidus wolterstorffi, Pseudohemiculter dispar, Tachysurus fulvidraco, Hemibagrus macropterus, Pseudobagrus crassilabris and Siniperca kneri) collected in the Liujiang River, a tributary of the Pearl River, in March 2014, September 2014 and March 2015. The b value varied between 2.385 (P. crassilabris) and 3.178 (P. dispar), with the mean b = 2.85 at P < 0.001 for all nine species.     

Using quantitative real-time PCR to study competition and community dynamics among Delaware Inland Bays harmful algae in field and laboratory studies

The Delaware Inland Bays (DIB) have experienced harmful algal blooms of dinoflagellates and raphidophytes in recent years. We used quantitative polymerase chain reaction (QPCR) techniques to investigate the community dynamics of three DIB dinoflagellates (Karlodinium veneficum, Gyrodinium instriatum, and Prorocentrum minimum) and one raphidophyte (Heterosigma akashiwo) at a single site in the DIB (IR-32) in summer 2006 relative to salinity, temperature and nutrient concentrations. We also carried out complementary laboratory culture studies. New primers and probes were developed and validated for the 18S rRNA genes in the three dinoflagellates. K. veneficum, H. akashiwo, and G. instriatum were present in almost all samples throughout the summer of 2006. In contrast, P. minimum was undetectable in late June through September, when temperatures ranged from 20 to 30 °C (average 25.7 °C). Dissolved nutrients ranged from 0.1 to 2.8 μM PO₄³⁻ (median = 0.3 μM), 0.7–30.2 μM NO_x (median = 12.9 μM), and 0–19.4 μM NH₄⁺ (median = 0.7 μM). Dissolved N:P ratios covered a wide range from 2.6 to 177, with a median of 40. There was considerable variability in occurrence of the four species versus nutrients, but in general P. minimum and H. akashiwo were most abundant at higher (>40) N:P ratios and dissolved nitrogen concentrations, while K. veneficum and G. instriatum were most abundant at low dissolved N:P ratios (<20) and dissolved nitrogen concentrations < 10 μM. The semi-continuous laboratory competition experiment used mixed cultures of K. veneficum, P. minimum, and H. akashiwo grown at dissolved N:P ratios of 5, 16, and 25. At an N:P of 16 and 25 P. minimum was the dominant alga at the end of the experiment, even at a temperature that was much higher than that at which this alga was found to bloom in the field (27 °C). P. minimum and H. akashiwo had highest densities in the N:P of 25. K. veneficum grew equally well at all three N:P ratios, and was co-dominant at times at an N:P of 5. H. akashiwo had the lowest densities of the three algae in the laboratory experiment. Laboratory and field results showed both interesting similarities and significant differences in the influences of important environmental factors on competition between these harmful algal species, suggesting the need for more work to fully understand HAB dynamics in the DIB.     

Length–weight and length–length relationships for nine fish species from Lhasa River Basin,Tibet, China

The present study reports length–weight relationships (LWR) and length–length relationships (LLR) for five native freshwater fish species (Schizopygopsis younghusbandi, Triplophysa orientalis, T. tibetana, T. stewartii and T. stenura) and four introduced freshwater fish species (Pseudorasbora parva, Carassius auratus, Micropercops cinctus and Oryzias latipes) captured in the Lhasa River Basin, Tibet, China. Five of the LWRs are presented for the first time.     

Nucleotide diversity patterns of three divergent soybean populations: evidences for population‐dependent linkage disequilibrium and taxonomic status of Glycine gracilis

The level of linkage disequilibrium (LD) is a major factor to determine DNA polymorphism pattern of a population and to construct high‐resolution maps useful in localizing and gene cloning of complicated traits. Here, we investigated LD level of three soybean populations with different genetic backgrounds and taxonomic status of G. gracilis by comparing the DNA polymorphism patterns of four high‐diversity single‐copy nuclear genes. A total of 152, 22, and 77 accessions of G. soja, G. gracilis, and G. max were observed. The results indicated that G. max retained only 75.3 (π) and 39% (θ) of the nucleotide polymorphism found in G. soja. Four gene loci evolved according to neutrality in both G. max and G. gracilis populations, and three gene loci evolved according to neutrality in G. soja population by Tajima's and Fu and Li's test. However, one gene locus deviated from neutrality by Fu and Li's test in the G. soja population. Further, medial level of LD (average r² = 0.2426) was found in intragene in G. max and G. gracilis populations, but unexpected low level of LD (r² ≤ 0.0539) was found in G. soja population. Significant genetic differentiation was detected between G. max and G. soja populations and also between G. max and G. gracilis populations; however, nonsignificant genetic differentiation was found between G. gracilis and G. soja populations. The results suggest that LD level depends on genetic background of soybean population, and implicit that G. gracilis should be regarded as the variant of G. soja, not as an independent species.     

Length–weight relationships and length at first maturity for fish species in the upper Miranda River,southern Pantanal wetland,Brazil

Length–weight relationships (LWR) were estimated for 17 species and total length at first maturity (L50) for three species of freshwater fishes from the Miranda River, southern Pantanal, Brazil. The b values were compared for some species in the Paraguay River basin with the northern (Cuiabá River) part of the basin; differences in length–weight relationships were significantly different for Pseudoplatystoma corruscans, P. reticulatum (syn. P. fasciatum). First references on L50 and LWR are presented for two and eight fish species, respectively, as well as the new maximum total length for two species.     

Feeding by Heterotrophic Dinoflagellates and Ciliates on the Free‐living Dinoflagellate Symbiodinium sp. (Clade E)

To investigate heterotrophic protists grazing on Symbiodinium sp., we tested whether the common heterotrophic dinoflagellates Gyrodinium dominans, Gyrodinium moestrupii, Gyrodinium spirale, Oblea rotundata, Oxyrrhis marina, and Polykrikos kofoidii and the ciliates Balanion sp. and Parastrombidinopsis sp. preyed on the free‐living dinoflagellate Symbiodinium sp. (clade E). We measured the growth and ingestion rates of O. marina and G. dominans on Symbiodinium sp. as a function of prey concentration. Furthermore, we compared the results to those obtained for other algal prey species. In addition, we measured the growth and ingestion rates of other predators at single prey concentrations at which these rates of O. marina and G. dominans were saturated. All predators tested in the present study, except Balanion sp., preyed on Symbiodinium sp. The specific growth rates of O. marina and G. dominans on Symbiodinium sp. increased rapidly with increasing mean prey concentration < ca. 740–815 ng C/ml (7,400–8,150 cells/ml), but became saturated at higher concentrations. The maximum growth rates of O. marina and G. dominans on Symbiodinium sp. (0.87 and 0.61/d) were much higher than those of G. moestrupii and P. kofoidii (0.11 and 0.04/d). Symbiodinium sp. did not support positive growth of G. spirale, O. rotundata, and Parastrombidinopsis sp. However, the maximum ingestion rates of P. kofoidii and Parastrombidinopsis sp. (6.7–10.0 ng C/predator/d) were much higher than those of O. marina and G. dominans on Symbiodinium sp. (1.9–2.1 ng C/predator/d). The results of the present study suggest that Symbiodinium sp. may increase or maintain the populations of some predators.