Length–weight relationships for estuarine fishes in South Brazil

The present study reports the length‐weight relationships (LWRs) for 18 estuarine species sampled in Guaratuba Bay, South Brazil. For the majority of these 18 species the LWRs are known from the literature, but these estimates do not consider sexes separately which is done in this contribution. Different fishing gears were used in the samplings (cylindrical nets – 1 mm mesh size, bottom trawls – 250 mm mesh size in the arms and 12 mm mesh size in the bag, beach seine – 5 mm mesh size and hook and line fishery) between September 2007 to April 2014. The specimens were sexed and the LWRs were calculated for each sex separately. There were differences between sexes in growth type, showing the importance of sexing in these studies. We reported for the first time (based on FishBase) the LWRs for two species: Ctenogobius shufeldti and Hypleurochilus fissicornis.     

A comparative study of two goby shrimp associations in the Caribbean Sea

In Curacao (Netherland Antilles, Caribbean Sea), two species of gobies, Nes longus (N. longus) (Nichols 1914) and Ctenogobius saepepallens (C. saepepallens) (Gilbert & Randall 1968) with their associated shrimp Alpheus floridanus (A. floridanus) (Kingsley 1878) were observed. Data were collected on feeding behaviour, distances from their burrows, and interactions among conspecifics. Results confirm that the partnership of C. saepepallens and its shrimp is facultative, but show differences to former observations. Possible reasons for this are discussed.     

Length–weight relationships for 15 fish species from the Three Gorges Reservoir

The length–weight relationships (LWRs) for 15 fish species from the Three Gorges Reservoir (TGR) were described in this paper. Specimens were collected using gill nets (mesh size: 6, 8, 10, 12 cm), cage net (mesh size: 1 cm), benthic fyke net (mesh size: 1 cm), hook longlines (80 m long, 3 barbless hooks per meter line) and electrofishing (power: 1,500 w; distance of electrodes: 1–2 m; water depth: 0.2–1.0 m; water area: 1–2 m²; catch by dip net [mesh size: 0.4 cm]) at four sections of the TGR, monthly in June–August and October–November in 2017 and 2018. The first LWR reference for Zacco acutipinnis (Bleeker, 1871), Discogobio brachyphysallidos Huang, 1989, Squalidus nitens (Günther, 1873), Leptobotia pellegrini Fang, 1936, Sinibotia reevesae (Chang, 1944), Pseudobagrus tenuifurcatus (Nichols, 1931), Pseudobagrus medianalis (Regan, 1904), Liobagrus marginatoides (Wu, 1930), Glyptothorax fokiensis (Rendahl, 1925), and Ctenogobius szechuanensis (Liu, 1940) and new maximum total length for 12 species are provided.     

Length–weight relationships for 25 fish species from three coastal lagoons in Southeastern Brazil

This work analyzes the relationship between length and weight for 25 fish species belonging to 15 families in three mixohaline/hypersaline coastal lagoons in Southeastern Brazil. The study presents the first estimation of L–WRs for six species (Anchoa tricolor, Brevoortia aurea, Jenynsia multidentata, Ctenogobius boleosoma, Microgobius meeki and Bathygobius soporator) and maximum lengths for four species (Atherinella brasiliensis, Jenynsia multidentata, Poecilia vivipara and Microgobius meeki) that are greater than previously recorded.     

The Spatial Pattern of the Small Fish Community in the Biandantang Lake – A Small Shallow Lake Along the Middle Reach of the Yangtze River, China

The spatial pattern of the small fish community was studied seasonally in 1996 in the Biandantang Lake. Based on plant cover, the lake was divided into five habitats, arranged in the order by plant structure complexity from complex to simple: Vallisneria spiralis habitat (V habitat), Vallisneria spiralis–Myriophyllum spicatum habitat (V–M habitat), Myriophyllum spicatum habitat (M habitat), Nelunbo nucefera habitat (N habitat), and no vegetation habitat (NV habitat). A modified popnet was used for quantitative sampling of small fishes. A total of 16 fish species were collected; Hypseleotris swinhonis, Ctenogobius giurinus, Pseudorasbora parva, Carassius auratus and Paracheilognathus imberis were the five numerically dominant species. In both summer and autumn, the total density of small fishes was about 10indm^–2. Generally, Ctenogobius giurinus, a sedatory, benthic fish, was distributed more or less evenly among the five habitats, while the other four species had lower densities in the N habitat and NV habitat, which had the simplest structures. The distribution of the small fish species showed seasonal variations. In winter, most species concentrated in the V habitat, which had the most complex structure. In spring, the fish had low densities in the N and NV habitat, and were more or less evenly distributed in the other habitats. In summer, the fish had a low density in the NV habitat, and were evenly distributed in the other habitats. In autumn, the fish had higher densities in the V–M and M habitats than in the others. Generally, spatial overlaps between the dominant species were higher in winter than in the other seasons. It was suggested that the variations in the importance of predation risk and resource competition in habitat choice determined the seasonal changes of spatial patterns in the small fishes in the Biandantang Lake.     

Length–weight relationships of two sympatric species (Knipowitschia byblisia Ahnelt, 2011 and K. caunosi Ahnelt, 2011) in Köycegiz Lake,Turkey

This study provides basic information on length–weight relationships for Knipowitschia byblisia Ahnelt, 2011 and Knipowitschia caunosi Ahnelt, 2011, two endemic species of Köycegiz Lake Basin (Southern‐West of Turkey). Samplings were carried out seasonally from 2014 to 2015 by means of beach seine nets with mesh sizes from 10 to 35 mm. A total of 343 individuals from the two fish species were examined, with more specimens belonging to K. byblisa (90.4%). The total length–weight relationships were calculated as: W = 0.0054 TL^3.384for K. byblisia and W = 0.0058 TL^3.417for K. caunosi, respectively.     

Genetic variation amongst viviparid snails in the genus Mekongia (Prosobranchia: Viviparidae) in Thailand

Allozyme variation in viviparid snails from the genus Mekongia in Thailand were examined across the different species, subspecies and geographical locations (river drainage systems). Using horizontal starch gel electrophoresis, 11 presumed allozyme loci (eight polymorphic) from eight enzyme systems were screened. Heterozygosity was moderately low (Hexp = 0.000–0.109, mean = 0.037). One population of Mekongia pongensis (Nong Khai) was monomorphic at all 11 examined loci in contrast to the other two populations, suggesting bottleneck within this population. Populations were more differentiated in the Mekongia sphaericula complex (F_ST = 0.587) than in either the Mekongia swainsoni complex (F_ST = 0.161) or M. pongensis species (F_ST = 0.073). Mekongia sphaericula sphaericula and Mekongia sphaericula extensa exhibited fixed allele differences at two loci, a high genetic distance (D = 0.265–0.300) and a potential polyphyletic relationship, suggesting two distinct lineages (species).     

Length–weight and length–length relationships of two goby species,Neogobius caspius (Eichwald, 1831) and Proterorhinus nasalis (De Filippi, 1863) from the southern Caspian Sea

The present study provides the length–weight (LW) and length–length (LL) relationships for two goby species, Neogobius caspius and Proterorhinus nasalis, which were captured in the southern Caspian Sea. Total length (TL) and standard length (SL) were determined as well as weight. Specimens were collected monthly from September 2014 to August 2015 by beach seine (mesh size 10 mm). The LW parameter b for these species was 3.17 and 2.99, respectively, with a high coefficient of determination (r² > .95). All LLRs were highly correlated (r² > .97). Both species had no previous LWR and LLR estimates in FishBase.     

Phylogenomics and multigene phylogenies decipher two new cryptic marine algae from California,Gelidium gabrielsonii and G. kathyanniae (Gelidiales,Rhodophyta)

Molecular surveys are leading to the discovery of many new cryptic species of marine algae. This is particularly true for red algal intertidal species, which exhibit a high degree of morphological convergence. DNA sequencing of recent collections of Gelidium along the coast of California, USA, identified two morphologically similar entities that differed in DNA sequence from existing species. To characterize the two new species of Gelidium and to determine their evolutionary relationships to other known taxa, phylogenomic, multigene analyses, and morphological observations were performed. Three complete mitogenomes and five plastid genomes were deciphered, including those from the new species candidates and the type materials of two closely related congeners. The mitogenomes contained 45 genes and had similar lengths (24,963–24,964 bp). The plastid genomes contained 232 genes and were roughly similar in size (175,499–177,099 bp). The organellar genomes showed a high level of gene synteny. The two Gelidium species are diminutive, turf‐forming, and superficially resemble several long established species from the Pacific Ocean. The phylogenomic analysis, multigene phylogeny, and morphological evidence confirms the recognition and naming of two new species, describe herein as G. gabrielsonii and G. kathyanniae. On the basis of the monophyly of G. coulteri, G. gabrielsonii, G. galapagense, and G. kathyanniae, we suggest that this lineage likely evolved in California. Organellar genomes provide a powerful tool for discovering cryptic intertidal species and they continue to improve our understanding of the evolutionary biology of red algae and the systematics of the Gelidiales.     

Comparison of Polyphenol Profile and Antimutagenic and Antioxidant Activities in Two Species Used as Source of Solidaginis herba – Goldenrod

European Pharmacopoeia accepts two equivalent species Solidago canadensis L. and S. gigantea Aiton as goldenrod (Solidaginis herba). We compared phytochemical profile of both species from invasive populations in Poland. Further, we compared in vitro antimutagenic and antioxidant activities of solvent extracts from aerial (AP) and underground parts (UP). In S. gigantea, flavonoid profile was dominated by quercetin glycosides, with quercitrin as the major compound. In S. canadensis, quercetin and kaempferol rutinosides were two major constituents. Caffeoylquinic acids (CQAs) were less diverse with 5‐CQA as a main compound. In UP, over 20 putative diterpenoids were detected, mostly unidentified. Several CQAs were present in higher amounts than in AP. Antioxidant and antimutagenic activities were different between species and organs, with the strongest inhibition of lipid peroxidation by Et₂O and AcOEt fractions from AP of both species (IC₅₀ 13.33 – 16.89 μg/mL) and BuOH fraction from S. gigantea UP (IC₅₀ = 13.32 μg/mL). Chemical mutagenesis was completely inhibited by non‐polar fractions, but oxidative mutagenesis was inhibited up to 35% only by S. canadensis. No clear relationship was found between chemical profiles and antimutagenic activity. In conclusion, both species have diverse activity and their phytochemical profiles should be considered in quality evaluation. UP of these weeds can also provide potential chemopreventive substances for further studies.     

Species richness and similarity of metazoan parasite communities in three species of leatherjacket (Oligoplites: Pisces: Carangidae) from the Pacific coast of Mexico

Species richness and similarity in metazoan parasite communities of fishes can be influenced by several biotic (age, body size, vagility, feeding and social behavior, among others), and local abiotic (temperature, salinity, etc.) factors. The parasite communities of three species of Oligoplites, marine fishes from the Pacific coast of Mexico, were quantified and analyzed. Four hundred sixty‐eight leatherjackets (O. altus, n=94; O. saurus, n=260; and O. refulgens, n=114) were collected from February 2016 to June 2017 from five locations. Twenty‐eight species of metazoan parasites were recovered and identified: four species of Monogenea (adults), nine of Digenea (seven adults and two metacercariae); two of Cestoda (larvae); four of Nematoda (two adults and two larvae); four of Acanthocephala (two adults, one juvenile, and one cystacanth); four of Copepoda; and one Pentastomida (larvae). At the component community level, species richness ranged from 9 in O. saurus to 19 in O. altus. Different species of helminth dominated the component communities of each species of host. Community composition and species richness of parasites differed among the three species of host, locations, and sampling years. Host feeding behavior, body size, and vagility had the most influence on these differences.     

Discards in bottom‐trawl fishery in the western Black Sea (Turkey)

The aim of this study was to estimate the discards of target and non‐target species from bottom trawlers (rhombic and 40 mm cod end mesh size nets) in the Black Sea. On‐board sampling was conducted on the southwestern coasts of the Black Sea in the fishing ports of Rumelifeneri and Igneada for a total of 66 hauls on two commercial bottom trawlers from October 2012 to April 2013 and from October 2013 to April 2014. A total of 32 species were captured, including 25 species of fish, three crustacea, two echinodermata and two mollusca. Mullus barbatus and Merlangius merlangus euxinus were the target species, whereas 24 species were always discarded. Scophthalmus maximus and Pomatomus saltatrix were always retained. The two regions were similar in terms of catch and discard compositions, CPUE, DPUE and discard ratio. Discarding is important in the Black Sea commercial bottom trawl fishery and accounts for as much as 31.4% of the total bottom trawl catch. The results showed that the discard rates varied among species, depths (p = .04) and seasons (p = .0001). Finally, it was concluded that in the western Black Sea, when the impacts of depth and season are considered, that the discard quantity can be reduced.     

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.     

Phylogeography of two closely related species of Allium endemic to East Asia: Population evolution in response to climate oscillations

This study investigated the effects of climate oscillations on the evolution of two closely related Allium species, A. neriniflorum and A. tubiflorum. We sequenced three cp DNA (cpDNA) fragments (rps16, rpl32‐trnL, and trnD‐trnT, together approximately 2,500 bp in length) of two closely related Allium species, with samples from 367 individuals in 47 populations distributed across the total range of these species. The interspecific and intraspecific divergence times of the two species were in the Quaternary glaciation. The population divergence was high for the cpDNA variation, suggesting a significant phylogeographic structure (N_ST = 0.844, G_ST = 0.798, p < 0.05). Remarkable ecological differentiation was also revealed by Niche models and statistical analyses. Our results suggest the speciation event of the two species was triggered by violent climatic changes during the Quaternary glaciation.     

Length–weight relationships of Barilius bendelisis (Hamilton, 1807), Barilius shacra (Hamilton, 1822) and Barilius barna (Hamilton, 1822) from Manas River in Assam,India

The present study describes the length–weight relationships (LWRs) for three ornamental hill stream fish species from the Manas River in Assam, India, namely, Barilius bendelisis (Hamilton, 1807), Barilius shacra (Hamilton, 1822), and Barilius barna (Hamilton, 1822). Fishes were collected on a monthly basis from March 2015 to February 2016 with cast nets (270 cm, 1.2 cm) and gillnets (7,500 × 130 cm, 5 cm). This is the first information on LWR data for two of the species.     

Assessing the taxonomic status of Osmoderma cristinae (Coleoptera: Scarabaeidae), endemic to Sicily,by genetic,morphological and pheromonal analyses

Resolving complexes of closely related and cryptic insect species can be challenging, especially when dealing with rare and protected taxa that are difficult to collect for genetic and morphological analyses. Until recently, populations of the genus Osmoderma (Scarabaeidae), widespread in Europe, were treated as a single species O. eremita (Scopoli, 1763) in spite of observed geographic variation in morphology. A previous survey using sequence data from the mtDNA cytochrome C oxidase I gene (COI) revealed the occurrence of at least two distinct lineages within this species complex: O. eremita in the west and O. barnabita Motschulsky, 1845, in the east. Interestingly, beetles confined to Sicily have been described as a distinct species, O. cristinae Sparacio, 1994, based on morphological traits. Only few Sicilian specimens were included in the former genetic analysis, and the results led to a still questionable taxonomic rank for these populations. To explore the robustness of the previous taxonomic arrangement for O. cristinae, a combination of genetic, morphological and pheromonal analyses was used. A 617‐bp fragment of the COI gene, aligned with O. cristinae and O. eremita sequences already available in GenBank, showed a clear genetic divergence between the two species (interspecific mean distance = 6.6%). Moreover, results from AFLP markers sustained the distinction of the two species. In addition, geometric morphometric analyses of the shape of male genitalia revealed a clear differentiation between the two species. Via scent analysis and field trapping, we demonstrated the production of the sex pheromone (R)‐(+)‐γ‐decalactone by males of O. cristinae, the attraction by conspecific individuals (mostly females) to this compound, and a lack of antagonistic effect of (S)‐(–)‐γ‐decalactone. The fact that O. eremita and O. eremita use the same compound for mate finding suggests that this sex pheromone has not undergone a differentiation and probably the allopatry of these two species compensates for the absence of a mechanism to avoid cross‐attraction. Our genetic and morphological data support the divergence of the two species and confirm the species status for O. cristinae, while sex pheromones are confirmed to be invariant among different species of the genus Osmoderma.     

Length‐weight relationships for nine fishes in the Nujiang River,Southwest of China

Length‐weight relationships (LWRs) were determined for nine fish species occurring in the Nujiang River. Fish were collected using gill nets, including two nets of 1.0 m depth (100 m long; mesh size 0.5 cm), two nets of 1.0 m depth (150 m long; mesh size 2.0 cm) and two nets reaching 1.5 m depth (mesh size 6.0 cm). Gill nets were set over night including different habitats (riffles and pools, vegetated and non vegetated zones) from four sections in July of the following 2 years: 2004 and 2008. The LWRs presented here include for all nine studied species (Pseudexostoma brachysoma Chu, 1979, Creteuchiloglanis gongshanensis [Chu, 1981], Glyptothorax zanaensis Wu, He & Chu, 1981, Glyptothorax dorsalis Vinciguerra, 1890, and Glyptothorax trilineatus Blyth, 1860, Schizothorax gongshanensis Tsao, 1964, Schizothorax meridionalis Tsao, 1964, Placocheilus cryptonemus Cui & Li, 1984, and Schistura longa [Zhu, 1982]), and new maximum standard length of four species not yet reported in the literature.     

The combined positive effects of two dominant species in an arid shrub-herbaceous community: implications from the performance of two associate species

To test the hypothesis that the species could be more beneficial in association with two-nurse species than with single-nurse species, we surveyed an arid shrub-herbaceous community primarily composed of two dominant species, Achnatherum splendens and Nitraria tangutorum and two associate species, Phragmites australis and Reaumuria soongorica in Northwest China. The performance (frequency, abundance, and size) of the two associate species in neighbored patches (patches formed by a dominant species which were closely adjacent to the patches formed by the other dominant species), isolated patches (patches formed by one dominant species with no neighbor), and open areas was compared to analyze the individual and combined effects of the two dominant species. A. splendens and N. tangutorum appeared to have reciprocal facilitation effects when growing adjacent to one another, as evidenced by the increased size of neighbored patches over isolated ones. The individual effects of A. splendens on the associate species should be generally neutral, since the frequency, abundance, size, and co-occurrence frequency of the two associate species in isolated A. splendens patches and open areas were the same (except for the significantly larger size of R. soongorica in isolated A. splendens patches). The individual effects of N. tangutorum were positive to the associate species R. soongorica, as evidenced by the fact that the frequency and abundance of R. soongorica was significantly higher (P < 0.05), and the size of two associate species was significantly larger (P < 0.05), in isolated N. tangutorum patches than in open areas. However, the frequency and abundance of P. australis, and the co-occurrence frequency of the two associate species in isolated N. tangutorum patches and in open areas were the same. In comparison to the isolated patches, there were significantly higher frequency and abundance (P < 0.05), larger sizes (P < 0.05), and higher co-occurrence frequency (P < 0.05) of the two associate species in neighbored N. tangutorum patches. Since the neighbored patches could be influenced by both dominant species, the combined effects of A. splendens and N. tangutorum were identified as positive and over-additive. We suggested that the indirect facilitation or synergistic effects could account for the combined effects of the two dominant species.     

Occurrence of Gobiidae larvae in a tropical Brazilian estuary,with particular emphasis on the use of size classes to categorize species guilds

The structure and seasonal dynamics of larvae of the Gobiidae family in the Mucuri Estuary (Bahia, Brazil) were studied for nine consecutive years. Sampling was conducted at three stations in the lower estuary channel, between 2002 and 2010, in relation to season, day and night and tidal variations. A total of 5802 Gobiidae larvae, representing 15 taxa (12 species and three morphotypes), were collected in the Mucuri Estuary during this time. The highest mean ± s.d. density of fish larvae, 54·7 ± 79·8 larvae 100 m^?3, was recorded during the flood tide and night sampling. Ctenogobius boleosoma was the most abundant species (68%), being dominant in the rainy and dry seasons and had a long reproductive period. This species was classed as a marine estuarine‐opportunist because it was observed at high frequencies and active larvae entering the estuary between 6·1 and 12·0 mm standard length (L_S). Gobionellus oceanicus, second in abundance (12%), occurred only in later larval stages but did not use the estuary as a preferred location for spawning, being classed a marine estuarine dependent. Microgobius carri (11%) was represented in all L_S classes and was resident in the estuary for spawning, remaining there throughout their life cycle. The other species were considered rare due to their low densities and could not be classified in any guild.