胶州湾海域鱼类群落种类组成及多样性

为了解胶州湾海域鱼类群落结构特征,根据2016—2017年间对胶州湾海域进行的4个航次底拖网调查数据,采用相对重要性指数、生态多样性指数和典范对应分析(canonical correspondence analysis,CCA)、非线性多维标度排序(non-metric multidimensional scaling,NMDS)等方法分析了胶州湾海域鱼类群落的种类组成和多样性特征。结果表明:调查共采集到鱼类46种,隶属2纲10目30科41属,以硬骨鱼纲鱼类为主(45种,97.83%)。其中,鲈形目(Perciformes)最多(22种,47.83%),其次是鲉形目(Scorpaeniformes),占15.22%。种类数季节变化明显,以夏季最高,23种;秋季最低,16种。优势种组成以赤鼻棱鳀(Thryssa kammalensis)、褐菖鲉(Sebastiscus marmoratus)、褐牙鲆(Paralichthys olivaceus)、大泷六线鱼(Hexagrammos otakii)、许氏平鮋(Sebastes schlegeli)和矛尾鰕虎鱼(Chaeturichthys stigmatias)等鱼类为主。多样性分析显示,鱼类物种多样性存在明显的季节差异。多样性指数(H′)季节变化范围为1.668—2.453,以夏季最高,春季最低;均匀度指数(J′)季节变化范围为0.577—0.808,以秋季最高,春季最低;丰富度指数(D′)季节变化范围为2.431—3.123,以冬季最高,秋季最低。典范对应分析表明,水温、盐度、水深和pH是影响胶州湾海域鱼类群落物种组成的主要环境因子,且水温和pH是影响鱼类群落结构及多样性时空变化的主要因子。与历史调查资料相比,由于人类活动对胶州湾生态系统的干扰,鱼类群落结构发生了较大变化,优势种组成更替明显,多样性水平降低,鱼类群落结构趋向简单化。     

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.     

Comparative genetic isolation patterns for multiple headwater fishes in three geographic regions

Headwater‐resident fishes may be prone to a high rate of isolation and a pronounced hierarchical genetic structure due to a combination of niche preference and dendritic effects of river networks. Genetic isolation patterns were compared using microsatellites in six headwater fishes, Fundulus olivaceus, Semotilus atromaculatus, Erimyzon claviformis, Etheostoma artesiae, Etheostoma whipplei and Etheostoma parvipinne, in three geographic regions that included drainages of small, medium and large sizes in the southern United States. All species showed hierarchical nesting of genetic populations and there were clear and mostly consistent differences between species and regions that were identified through summary statistics derived from two independent analyses. For species comparisons, a high isolation grouping (increased number of isolated genetic clusters or sites within regions) and a low‐isolation grouping (decreased number of clusters or sites) were identified. Species group placement was related to niche breadth along the river continuum and presumed abundance and variability of preferred microhabitats, with increased headwater specialization among species being associated with placement in the high‐isolation grouping. There was a weakly significant positive effect of drainage size on the number of isolated clusters or sites across all species. Regional patterns were shared in two species, with the region containing the smallest drainages having lower rates of isolation in both datasets. This study shows the effects of regional and species characteristics on genetic isolation for headwater species, which are especially prone to isolation due to spatial, dendritic effects of river networks.     

Isolation and characterization of polymorphic microsatellite markers of Anopheles sinensis,a malaria vector mosquito in the East Asia region

Eleven polymorphic dinucleotide (GA and CA) microsatellites were isolated and characterized in the mosquito Anopheles sinensis; this species is distributed over the East Asia region and is a primary vector of malaria, particularly in Korea. The number of alleles per locus ranged from 4 to 13. The observed heterozygosity (H_O) and expected heterozygosity (H_E) varied from 0.30 to 0.89 and from 0.59 to 0.90, respectively. These microsatellites could be useful in studying the evolution of the widely distributed A. sinensis in diverse environments.     

Human health risk assessment of toxic elements in fish species collected from the river Buriganga,Bangladesh

Abstract

Multielement (48) analysis was carried out of various fish species collected from river Buriganga, the most polluted river in Bangladesh to assess human health risk by toxic elements. Sixteen elements that is, Be, V, Cr, Mn, Ni, Cu, Zn, As, Se, Mo, Cd, Ba, Hg, Pb, Bi, and U, were taken into account due to their toxicities on human health. Results show that concentrations of elements in various fish species were higher in winter than those in monsoon. Among 16 elements, Mn, Cu, Zn, Cd, Ba, Pb were above Food Safety Guideline in some fishes in winter. THQ and TTHQ/HI values were less than 1 for all fishes in monsoon while THQ and TTHW/HI values were more than 1 for most of fishes in winter. These results suggesting non-carcinogenic health hazard through consumption of contaminated fishes. Only As showed low cancer risk while no cancer risk was observed for other toxic elements in monsoon. In winter, Pb showed only moderate cancer risk for Mystus vittatus (site-7) while for other fishes low cancer risk was found by Pb. It can therefore be concluded that there is human health risk in consuming of fishes collected from river Buriganga especially in winter.     

Length–weight relationships of 11 deep‐sea fishes from the western Bay of Bengal and Andaman waters,India

Length–weight relationships (LWRs) are presented for 11 deep‐sea fishes caught in the western Bay of Bengal and Andaman waters during August 2010 using a 38 m high speed demersal trawl II (HSDT II, crustacean version, codend mesh size 40 mm) and a 45.6 m Expo model demersal trawl (codend mesh size 30 mm). The b values ranged from 2.34 to 3.3 and the coefficient of variation (r²) ranged from .82 to .98. LWR estimates of eight deep‐sea fishes are provided for the first time. The estimated LWR values were compared with the Bayesian LWR estimates available in FishBase, based on models developed to improve the accuracy and predictability of species‐specific growth parameters of data‐poor species.     

Length–weight relationship of nine fish species from Skadar Lake (Adriatic catchment area of Montenegro)

This study provides data on the length–weight relationships (LWR) of nine fish species sampled between 2010 and 2014 from Skadar Lake, Montenegro. Also provided are the first comprehensive data of LWRs for three freshwater fishes for which no LWR information was available in the FishBase data bank. The b parameter values ranged from 2.936 to 3.271, while values of the a parameter ranged from 0.002 to 0.014.     

Length–weight relationship of six notothenioid species from sub‐Antarctic waters (Beagle Channel,Argentina)

This study presents length‐weight relationships (LWR) for six species of fishes of the Suborder Notothenioidei that inhabit the sub‐Antarctic waters of the Beagle Channel (Argentina). These species represent five of the nine families of this Suborder. The specimens belong to historical fish collections in the area (from 1987 to 1990) using gill and trammel nets. All species but Eleginops maclovinus had no previous LWR estimates. The coefficient of determination (r²) ranged from 0.91 to 0.99 and b values ranged from 2.74 to 3.2. Harpagifer bispinis was the only species with a b value lower than three. This information is useful to predict the weight from the length data and to provide insights into the ecology of sub‐Antarctic nototheniod fish.     

Long-term stability of the seasonal succession of different zooplankton species in a brackish water lagoon (southern Baltic Sea)

While it has been widely suggested that freshwater fishes from East Asia invaded the western Palaearctic, details about this process are largely unknown. Here, using the cytochrome b gene, we evaluated the phylogenetic relationships of a small group of Eurasian primary freshwater fishes (Cobitidae), which are widely distributed and species rich in East Asia and Europe, with the purpose of inferring their invasion process of Europe from East Asia. Though phylogenetic relationships of cobitids were not well resolved, our analysis could identify three sister groups formed by the European and East Asian cobitids, which brought new insights into the biogeography of the genera Cobitis, Misgurnus, and Sabanejewia. The present results support the view that Asian cobitid fishes may have invaded Europe at least five times independently, and once reverse colonization of European cobitids to East Asia could also be found. Ancestral Sabanejewia might have been the first cobitids to cross Siberia and invade the EMZS (Euro-Mediterranean zoogeographic subregion) about 33.54 million years ago (MYA). One lineage of Cobitis and the ancestor of Misgurnus fossilis (Linnaeus) almost in the same time invaded the Europe, responding to 16.71 MYA and 16.59 MYA, respectively. Three different lineages of Cobitis were found to have invaded the EMZS from East Asia, and once reverse invasion to East Asia occurred to one subclade of European Cobitis. And our data also suggest that the diversity of East Asian cobitid fishes, especially of the genus Cobitis, is greatly underestimated. Handling editor: C. Sturmbauer     

Moving beyond the riverine barrier vicariant paradigm

One of the main goals of evolutionary biology is to understand the processes behind current patterns of biodiversity. Shared geographic distributions among unrelated species may result from a common history, providing a unique opportunity to assess the evolution of the landscape and the origins of biodiversity. Until recently, vicariance prevailed as the main evolutionary model to be tested, and the riverine barrier hypothesis the null model for taxa with river‐bounded distributions. In recent years, however, multispecies comparative approaches have unveiled idiosyncratic scenarios among codistributed species, suggesting that rivers may or may not play a role in the speciation process. In a From the Cover article in this issue of Molecular Ecology, Kopuchian et al. (2020) explore predictions of the riverine barrier hypothesis in a major subtropical river system, evaluating the degree of mitochondrial and nuclear genomic differentiation in seven bird species with allegedly morphological differentiation across the Paraná‐Paraguay river system. The authors show that in only one case, the genetic differentiation was concordant with the river. Interestingly, pairs presented disparate divergence times and/or distinct demographic histories. In most cases, putative contact zones broadly coincided with the transition of different ecoregions, such as the Espinal/Chaco ecological ecotone. These findings argue against the role of the Paraná‐Paraguay river system as a major biogeographic barrier and highlight the need to explore the role of ecology in species diversification. Here, we feature different perspectives for studying the processes governing species divergence and suggest a basic protocol to advance the study of riverine barriers.     

The curious case of Hermodice carunculata (Annelida: Amphinomidae): evidence for genetic homogeneity throughout the Atlantic Ocean and adjacent basins

Over the last few decades, advances in molecular techniques have led to the detection of strong geographic population structure and cryptic speciation in many benthic marine taxa, even those with long‐lived pelagic larval stages. Polychaete annelids, in particular, generally show a high degree of population divergence, especially in mitochondrial genes. Rarely have molecular studies confirmed the presence of ‘cosmopolitan’ species. The amphinomid polychaete Hermodice carunculata was long considered the sole species within its genus, with a reported distribution throughout the Atlantic and adjacent basins. However, recent studies have indicated morphological differences, primarily in the number of branchial filaments, between the East and West Atlantic populations; these differences were invoked to re‐instate Hermodice nigrolineata, formerly considered a junior synonym of H. carunculata. We utilized sequence data from two mitochondrial (cytochrome c oxidase subunit I, 16S rDNA) markers and one nuclear (internal transcribed spacer) marker to examine the genetic diversity of Hermodice throughout its distribution range in the Atlantic Ocean, including the Mediterranean Sea, the Caribbean Sea, the Gulf of Mexico and the Gulf of Guinea. Our analyses revealed generally low genetic divergences among collecting localities and between the East and West Atlantic, although phylogenetic trees based on mitochondrial data indicate the presence of a private lineage in the Mediterranean Sea. A re‐evaluation of the number of branchial filaments confirmed differences between East and West Atlantic populations; however, the differences were not diagnostic and did not reflect the observed genetic population structure. Rather, we suspect that the number of branchial filaments is a function of oxygen saturation in the environment. Our results do not support the distinction between H. carunculata in the West Atlantic and H. nigrolineata in the East Atlantic. Instead, they re‐affirm the older notion that H. carunculata is a cohesive species with a broad distribution across the Atlantic Ocean.     

Species composition and dynamics of larval and juvenile fishes in the surf zone of Mauritius

The importance of the surf zone as a nursery ground for larval and juvenile fishes has been widely recognized, however the zone has yet to be studied in Mauritius. Recently, the coastal area of the island has been increasingly affected by human activities, especially by tourism. We collected fish samples with a hand pulled seine net during the period of August 2001 to March 2003 to clarify the fish fauna and the dynamics of fishes in the surf zone. Two sampling sites adjacent to river mouth areas and one sampling site adjacent to a mangrove area were selected for comparison of fish fauna in relation to environmental conditions. A total of 9,429 fish larvae and juveniles, representing at least 112 species from 48 families were collected. The abundant species were hardyhead silverside, Atherinomorus lacunosus, bluespot mullet, Valamugil seheli, and Ambassis spp., each contributing 16.2, 12.4, and 11.8% of the total number of individuals, respectively. Estuarine species dominated in the surf zone adjacent to the river mouth areas. Species composition and diversity changed seasonally. The number of fish increased during the rainy season. Species diversity increased at the turn of the seasons from the dry season to the rainy season. We conclude that species composition in each site was affected by environmental factors, such as the scale of the flux from the rivers, which is related to the precipitation. The results indicated that freshwater from the river is a trigger to aggregate larvae and juveniles in the surf zone.     

Microsatellites loci isolated in the freshwater fish Brycon hilarii

We describe seven microsatellite loci, including tetra‐, tri‐ and dinucleotides, isolated from Brycon hilarii, which is a migratory fish inhabiting the Paraguay River basin (Brazil) and is highly valued for its meat quality. Three to eight alleles per locus were detected and the expected heterozygosity ranged from 0.31 to 0.81. Positive results were obtained with cross‐amplification in five other species of Brycon. These microsatellites provide a potential tool for wild population and aquaculture studies of B. hilarii and other species of the genus.     

Limnological aspects of the St. Clair River

The St. Clair River is a major navigable waterway transporting water southwards for 63 km from Lake Huron to Lake St. Clair at an average flow of 5 100 m3 s^-1. Water entering the river is low in suspended solids, organic carbon, phosphorus and nitrates, typical of clear, oligotrophic waters. In contrast to many large rivers, dissolved and colloidal solids account for 90 to 95 percent of the total solids load transported by the river, giving the river a turquoise colour common of glacial meltwater streams.The river supports a diverse floral and faunal community that includes 20 taxa of submergent macroflora, at least 300 benthic macroinvertebrates and 83 fishes. A number of exotic (European) species, including 3 plants, 4 molluscs and 11 fishes, occur in the river with the macroalga, Nitellopsis obtusa, zebra mussel (Dreissena polymorphora), Asian clam (Corbicula fluminea), and white perch (Morone americana) being the most recent invaders. Production is estimated to be 200 g m^-2 a^-1 ash-free dry mass for submergent macrophytes and periphyton, 7 g for macroinvertebrates and 5 g for fishes.The river also supports a variety of water-oriented recreational activities, is a source of municipal and industrial water, a receiver of municipal and industrial wastes, and a shipping corridor. Industrial discharges have adversely affected aquatic life, particularly in the nearshore areas along the Canadian shoreline south of Sarnia, Ontario. In addition, channel dredging and shoreline modifications (bulk-heading and backfilling) have destroyed large areas of valuable habitat in the main channel and along the shoreline. Improvements in the nearshore benthic macroinvertebrate community of the river over the past 20 years show that the river will respond to reductions in contaminants loadings.     

An assessment of fish species assemblages in rice fields in West Bengal,India: implications for management

Wetlands such as rice fields and associated canals are congenial habitats for different fishes and provide the foundation of rice‐fish culture. The selection of suitable fish species determines the success for this linkage of aquaculture and agriculture. An assessment of fish assemblages in selected rice fields and associated canals in West Bengal, India documented the candidate species for culture and conservation in rice fields. Indigenous minnow traps made of bamboo were employed in the rice fields and canals for a period of 3 months, to collect and record the fish abundance. A total of 531 fishes representing 19 different species were caught from the rice fields in 30 sampling efforts. From the canals, 13 different fish species totaling 676 fishes were collected in 80 sampling efforts. The fish collected per trap in the rice fields (mean 17.7 ± 1.97 SE) remained significantly different (t = 4.461, df = 112; P < 0.001) from those of the canals (mean 8.05 ± 1.09 SE). Diversity indices ranged between 1.91 and 2.01, with a 53% similarity between the rice fields and canals. Among the fish species collected, Badis badis, Colisa fasciatus and C. lalia exhibited high abundance; the two species Heteropneustes fossilis and Mystus vittatus established as threatened fish categories, showed low abundance. The fish species collected were important as food resources and the ornamental fish trade, and many of them bear potential in regulating mosquitoes in the rice fields. These fish assemblages in the rice fields and associated canals suggest a rice‐fish culture potential for integrating food and health.     

Comparative morphology,phylogenetic relationships,and historical biogeography of plesiolebiasine seasonal killifishes (Teleostei: Cyprinodontiformes: Rivulidae)

Phylogenetic and biogeographical analyses were performed for the Plesiolebiasini, a group of 20 small and rare species of South American annual killifishes, some threatened with extinction, occurring in river basins of Brazil, Bolivia, Paraguay, and Argentina. The results of a maximum parsimony analysis of 142 morphological characters highly corroborate monophyly of the Plesiolebiasini. Monophyly of each plesiolebiasine genus is supported and Plesiolebias is hypothesized to be the sister group to a clade comprising the remaining plesiolebiasine genera (Papiliolebias, Pituna, Maratecoara, and Stenolebias), corroborating studies based on mitochondrial genes. The phylogenetic analysis supports sister group relationships between Papiliolebias and the clade containing Pituna, Maratecoara, and Stenolebias, and between Maratecoara and Stenolebias. The biogeographical analysis indicates a complex historical biogeographical scenario for plesiolebiasines. A vicariance event between the western Paraguay area and northern river basins may be related to the isolation of the Chaco region from the Amazon between the Late Oligocene and Early Miocene. A vicariance event involving the Paraguay River basin and northern rivers, and the multiple occurrence of area hybridism along the Araguaia depression are tentatively identified as a consequence of tectonic subsidence events occurring during the Pleistocene. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 162 , 131–148.     

Stable Isotope Analysis of Amphidromous Hawaiian Gobies Suggests Their Larvae Spend a Substantial Period of Time in Freshwater River Plumes

Synopsis We employed stable isotope analysis (δ¹³C, δ¹⁵N) to evaluate the sources of nutrients used by amphidromous gobiid fishes (Lentipes concolor, Sicyopterus stimpsoni, Awaous guamensis) caught migrating into and living in Hakalau Stream, Hawaii. Although considerable variation amongst the stable isotope values of stream items was noted across all 4 years of our study, the relationships between the fishes were relatively constant. Stable isotope values of recruiting gobies were consistently closer to those of both inshore plankton and freshwater adults than those of offshore plankton, suggesting that the larvae of these species derive much of their nutrition from inshore environments influenced by fresh water. Small differences between the stable values of these species further suggested that their larvae come from different inshore locations. After entering fresh water all species appear to swim rapidly upstream without feeding. Finally, once well upstream, adult L. concolor and A. guamensis appear to assume an omnivorous diet while adult S. stimpsoni rely upon autochthonous production within streams. We propose that freshwater food webs play an integral yet complex role in the lives of both larval and adult amphidromous Hawaiian fishes.     

Comparative ecology of the African pike, Hepsetus odoe, and tigerfish, Hydrocynus forskahlii, in the Zambezi River floodplain

The ecology of sympatric African pike, Hepsetus odoe (Hepsetidae), and tiger fish, Hydrocynus forskahlii (Characidae), were compared during high (May-August) and falling water (September-December) conditions in the Upper Zambezi R. drainage of Zambia. Both species were common in the central and southern regions of the river and associated floodplain, and Hydrocynus was common in the northern region in swift flowing tributaries where Hepsetus was rare. Hepsetus inhabited vegetated environments of river backwaters, lagoons, and sluggish tributaries, whereas Hydrocynus occupied the open water of the main river channel almost exclusively. During the period of annual flooding, juveniles of both species coexist in flooded savanna regions. Size distributions of adult Hydrocynus and Hepsetus changed relatively little between high and low water conditions. Stomach contents analysis indicated that adult size classes of both species are almost entirely piscivorous, and both show diet shifts with changes in size. Only very small seasonal diet shifts were noted. Approximately 50% of the diet of Hepsetus consisted of haplochromine cichlid fishes, but also included large numbers of tilapine cichlids and mormyrids, Hydrocynus consumed primarily cichlid fishes, but also consumed large percentages of Hepsetus and small characid fishes. Small size classes of Hepsetus fed heavily on small machokid catfishes (Synadontis spp.) and later shifted to a diet of cichlids and mormyrids, and small Hydrocynus preyed heavily on Barbus spp. (Cyprinidae), small characids, and mormyrids. Ratios of prey length-predator length averaged approximately 0·26 for Hydrocynus and nearly 0·40 for Hepsetus. The large potential for food resource competition appears not to be realized due to a very high degree of habitat partitioning between larger size classes of the two species. At the interface between river backwaters and channel habitats, Hydrocynus is a significant predator of Hepsetus, a factor that should further restrict the occurrence of the latter in open areas of the main channel.     

Genetic structure and evidence of anthropogenic effects on wild populations of two Neotropical catfishes: baselines for conservation

Genetic diversity and structure of Pseudoplatystoma corruscans and P. reticulatum, large migratory South America catfishes, where overfishing and the construction of numerous dams in their feeding and reproducing areas are affecting their migratory processes negatively, were studied using microsatellites in samples from Paraguay (that comprises the Pantanal biome), and the upper and lower Paraná Basins. Genetic diversity was in accordance to that observed for other large migratory fishes, but the most geographically isolated populations of P. reticulatum and those P. corruscans subject to anthropogenic effects (stocking and dams) showed lower genetic diversity and evidences of bottlenecks compatible with low effective population size. Pseudoplatystoma reticulatum presented subtle genetic differentiation within the Paraguay area, especially between the edges of its distribution. Pseudoplatystoma corruscans, in this same area, presented a quite homogeneous but significant genetic break between the Paraguay and upper Paraná populations, apparently resulting from natural and historical isolation between the basins until recently. These data demonstrates that, although these Pseudoplatystoma spp. are abundant in the Pantanal area, anthropogenic events are leading to negative effects on their populations, particularly in the upper Paraná Basin. Genetic differentiation observed along each species distribution demands conservation actions to preserve each population's biodiversity. These results represent important genetic information using new microsatellite markers and the first genetic study of P. reticulatum covering this area of its native distribution. Data may also contribute to a better understanding of species migration patterns and to be used as a baseline for proper management.     

Mariauxiella pimelodi n. g., n. sp. (Cestoda: Monticelliidae): a parasite of pimelodid siluroid fishes from South America

Mariauxiella pimelodi n. g., n. sp. (Cestoda, Monticelliidae, Othinoscolecinae) is described from the South American siluriform fishes Pimelodus ornatus and Pimelodus sp. caught in Brazil and Paraguay. When compared with other genera of South American monticelliids, the new genus exhibits the following morpho-anatomical characters: the particular development of the distal circular musculature of the suckers acting as a sphincter; the medullar ovary projecting numerous lobules into the dorsal cortex; and the uterus situated in the ventral cortex but with numerous outgrowths penetrating the medulla and reaching the dorsal cortex in pregravid proglottids. The new species is the fourth monticelliid cestode recorded from Pimelodus.