Establishment of the Baikalian endemic amphipod Gmelinoides fasciatus Stebb. in Lake Ladoga

Gmelinoides fasciatus Stebb., a small amphipod from the Lake Baikal basin, was discovered in July 1988 in Lake Ladoga, the largest European lake. G. fasciatus likely invaded Lake Ladoga as a consequence of its intentional introduction, aimed at enhancing fish production, in some Karelian Isthmus lakes close to Lake Ladoga's western shore in the early 1970's. Benthos studies conducted in 1989 and 1990 revealed that G. fasciatus was well established in littoral communities along the western and northern shores of Lake Ladoga. G. fasciatus was the dominant species in these littoral communities and contributed over 70% of the macroinvertebrate biomass. The species was abundant in different macrophyte beds and stony littoral areas, both in heavily polluted and undisturbed sites. The maximum abundance and biomass of G. fasciatus was about 54,000 ind m^–2 and 160 g (wet wt.) m^–2. Negative impacts of G. fasciatus on native species have been observed. Studies are needed to identify the effects of G. fasciatus on the functioning of littoral communities and to predict and control the spread of this amphipod.     

Food composition and feeding rate of the lake Baikal invader <Emphasis Type="Italic">Gmelinoides fasciatus</Emphasis> (Stebbing, 1899) in Lake Ladoga

The feeding of the Baikal invader Gmelinoiudes fasciatus (Stebbing, 1899) in Lake Ladoga has been studied based on field and experimental data. The food spectrum of this amphipod was revealed; it includes many plant and animal species. Differences in the feeding of G. fasciatus living in different littoral biotopes were shown. The ecological and physiological rations of this species were determined. The effect that the bottom substrate has on the feeding rate of the amphipod was estimated. The introduction of G. fasciatus into Lake Ladoga provided a more adequate utilization of the energy accumulated by the primary producers and its transfer to higher trophic levels. This Baikal amphipod occupied a niche that had been, in effect, vacant. This made the invader capable of maintaining the quantitative parameters of its population at a very high level, and it largely reorganized the flow of matter and energy in the littoral zone of the lake.     

Distribution and diet of the roughskin sculpin, <Emphasis Type="Italic">Trachidermus fasciatus</Emphasis>, larvae and juveniles in the Chikugo River estuary,Ariake Bay,Japan

Larvae and juveniles of the roughskin sculpin Trachidermus fasciatus were collected during four cruises in March and April 2001 to study the distribution and diet of the fish in the Chikugo estuary in the northern Ariake Bay, Japan. Sampling was conducted at seven stations covering an area approximately 30 km in length along the estuary, with salinity ranging from nearly 0 to about 30 PSU. Gut contents were analyzed by separating, identifying, and counting the prey organisms. Plankton samples were collected during each cruise to study the numerical composition and abundance of copepods in ambient water. A total of 1790 larvae and juveniles of T. fasciatus were collected; they were distributed in the five uppermost stations, covering approximately 20 km and ranging in salinity from 0.4 to 27.4 PSU. The fish fed almost exclusively on a single calanoid copepod species, Sinocalanus sinensis, which was numerically the most abundant in the ambient water at the upper part of the Chikugo River. At the lower part of the river, the fish positively selected S. sinensis while negatively selecting other species. T. fasciatus larvae experienced a high proportion of empty guts and low feeding intensity at around 9.0 mm body length, which appears to be associated with commencement of exogenous feeding. The proportion of empty guts reduced sharply at subsequent stages and was accompanied by an increase in feeding intensity. The oligohaline and mesohaline areas are important nursery grounds, and S. sinensis is an important prey copepod species for the larval and juvenile T. fasciatus in the Chikugo estuary.     

Experimental studies of migration in bugs of the genus Dysdercus

Summary Using a tethered flight technique, migration was studied in the African cotton stainer bugs Dysdercus fasciatus Sign., D. nigrofasciatus Stål, and D. superstitiosus (F.) (Heteroptera: Pyrrhocoridae). The flight system of males of all three species matures in 4–6 days post-eclosion, and flight can continue throughout life. Fed females of D. fasciatus do not fly, but rather histolyse the flight muscles and develop oocytes. Fed females of D. nigrofasciatus and D. superstitiosus exhibit some flight at 4 days post-eclosion, but flight is essentially absent at 6 days when flight muscle histolysis and oögenesis are in progress. Starved females of all three species undertake considerable flight and do not histolyse the flight muscles or develop oöcytes. In starved pairs coupling frequency is lowered permitting increased migration. The three species are thus facultative migrants using starvation as a releasing cue. D. fasciatus feeds on baobab (Adansonia) fruits which are seasonally abundant and is the most opportunistic species with the highest reproductive potential and no flight in the presence of food. D. nigrofasciatus feeds on a variety of herbaceous annuals and perennials; it follows an intermediate migration and reproductive strategy. Finally D. superstitiosus is the most catholic in its food habits and has the lowest reproductive potential. Both of the latter species retain some flight capacity even when fed, presumably so that individuals can locate suitable host plants.     

Environmental heterogeneity limits the local dominance of an invasive freshwater crustacean

The impacts of an exotic species may vary along environmental gradients. We tested the hypothesis that site-specific heterogeneity in the physico–chemical environment alters the dominance of two competing amphipods: Gammarus fasciatus, the dominant native species in the upper St. Lawrence River, and Echinogammarus ischnus, a euryhaline Ponto-Caspian species that invaded the river in the late 1990s. E. ischnus has replaced G. fasciatus as the dominant amphipod at some sites, while remaining inferior at other sites—even several years after invasion. We tested the effect of water chemistry (conductivity) on the outcome of interactions between these two species in the laboratory and in the river in 2006 and 2007. Field experiments involved transplanting both species to different sites along a gradient of conductivity within the river, whereas the laboratory experiments examined interspecific predation in water collected from these sites. The laboratory experiments revealed that these species are mutual predators and their rate of predation on each other varies with conductivity; E. ischnus is the dominant predator at higher conductivity, while G. fasciatus dominates at lower conductivity. The field experiments showed interannual variation, but supported the lab results at high conductivity in 2006 and at low conductivity in 2007. E. ischnus was more sensitive than G. fasciatus to variation in conductivity, which apparently mediates this invader’s ability to replace or dominate the native species in a heterogeneous environment.     

Genetic Demography of the Kuznetsk Basin Population: Changes in Marriage Assortativeness with Respect to Ethnicity and Age in the Belovo City Population with Time

A genetic demographic study has been performed in the city of Belovo with the use of the data on marriages contracted there in 1970 and 1994–1999. Marriage assortativeness with respect to age has been found to be the strongest and remain unchanged during the lifetime of one generation (r = 0.730 in 1970 and r = 0.801 in 1994–1999). Monoethnic marriages were substantially more frequent than interethnic ones in the Belovo population during the period studied, although the ethnic marriage assortativeness considerably decreased (K = 0.386 in 1970 and K = 0.141 in 1994–1999). Panmixia has been observed in the Russian population of Belovo. Other Eastern Slavs (Ukrainians and Belarussians) are characterized by negative marriage assortativeness and panmixia; positive marriage assortativeness has been found in other ethnic groups.__________Translated from Genetika, Vol. 41, No. 7, 2005, pp. 938–942.Original Russian Text Copyright © 2005 by Lavryashina, Ulyanova.     

Ethological Isolation,Sexual Behavior and Pheromones in the Fasciatus Species Group of the Lizard Genus Eumeces

Ethological isolation was found among North American members of the fasciatus species group of Eumeces. Ethological isolation was investigated by staging a series of interspecific and intraspecific heterosexual encounters. No male E. laticeps or E. fasciatus courted heterospecific females. In both species, males courted and copulated with conspecific females in a significantly higher frequency of trials than with heterospecific females. However, male E. inexpectatus courted females of all three species, courting conspecific females and female E. laticeps at similar frequencies, but female E. fasciatus at a significantly lower frequency. No females of any of the three species were sexually receptive to heterospecific males, but forced copulation occurred in two of nine courtships of female E. fasciatus by male E. inexpectatus. Thus, ethological isolation in the fasciatus group appears to be complete with the possible exception of occasional forced copulation between male E. inexpectatus and female E. fasciatus. Preliminary evidence on the role of chemical stimuli in maintaining ethological isolation was obtained from experiments involving interspecific transfers of female odors. Male E. inexpectatus courted female E. fasciatus labelled with the odor of female E. inexpectatus in a significantly greater proportion of trials than they courted such females lacking the conspecific female odor. In a similar experiment, male E. fasciatus did not court female E. inexpectatus even if the females bore odors of female fasciatus.     

The reproduction of Chaetodon austriacus,C. fasciatus and C. paucifasciatus (Chaetodontidae,Perciformes) in the Jordan Gulf of Aqaba

Synopsis Aspects of the reproduction of three sympatric and endemic chaetodontids, Chaetodon austriacus, C. fasciatus and C. paucifasciatus, from the Jordan Gulf of Aqaba were investigated. Chaetodon fasciatus had a higher fecundity than the other species which, in turn, had similar fecundities. The major egg release of C. austriacus and C. paucifasciatus began in August, that of C. fasciatus in September. Based on the gonadosomatic index of both sexes, the spawning period of C. austriacus was from July through October, that of C. paucifasciatus from August through October and that of C. fasciatus from September through December. The maturity length of the three chaetodontids is given and reproductive isolation among the sympatric species is discussed.     

An energetic analysis of host plant selection by the large milkweed bug,Oncopeltus fasciatus

Summary The large milkweed bug, Oncopeltus fasciatus, is a specialized seed feeder that has been observed completing nymphal development in the field on only a small proportion of its potential host species within the genus Asclepias. In central Missouri only two of the six milkweed species studied, A. syriaca and A. verticillata, commonly supported nymphal O. fasciatus growth in the field. The seed of all six species, however, was equally suitable food for bugs reared in the laboratory. In laboratory preference tests, adult bugs chose to feed on the largest seeds, A. hirtella, but such a preference could not explain the observed field feeding patterns.One explanation to account for the observed host plant selection is based upon an energetic analysis. Only A. syriaca provided enough seed biomass for a clutch of O. fasciatus nymphs to develop on a single plant, and only A. verticillata grew in high enough density that a clutch could find sufficient food within the limited range of nymphal movement. These results illustrate a corollary of the resource concentration hypothesis: within a plant group whose members share similar secondary plant chemistries, the only species that will be viable hosts for a specialized herbivore are those that provide the minimal resource density necessary for the completion of nymphal development.In central Missouri, O. fasciatus has specialized on a critical resource density, not traits of individual Asclepias species. The appearance of host selection within the potential host plant spectrum is the result of a characteristic growth form, seed output, and dispersion pattern for each milkweed species that makes some species much more likely than others to produce sufficient seed resources.     

Population characteristics and life cycle of the Lake Baikal invader <Emphasis Type="Italic">Gmelinoides fasciatus</Emphasis> (Stebbing, 1899) (Crustacea: Amphipoda in Lake Ladoga

Dynamics of the size-age structure and sexual structure of the population and characteristics of reproduction and life cycle have been studied in the Baikal invader Gmelinoiudes fasciatus (Stebbing, 1899) in Lake Ladoga. The studied characteristics display both similar features with and differences from populations of this species in other waterbodies. It is found that the size and age structure of the G. fasciatus population changes in the circannian aspect under the influence of complex of environmental factors. The sexual structure of the population is dynamic, but a sex ratio of approximately 1: 1 is maintained in the circannian cycle. Six principal periods of hatching are recognized. The main factor determining the timing of the start and termination of the reproduction period in G. fasciatus is temperature. The weight of eggs oviposited by the female over the whole life cycle (about 21.5 cal in the energy equivalent) amounts to about 60% of the female body weight.     

Feeding selectivity,food assimilability and demand of the Baikal invader <Emphasis Type="Italic">Gmelinoides fasciatus</Emphasis> (Stebbing, 1899) in Lake Ladoga

Feeding selectivity and assimilability of the Baikal invader Gmelinoides fasciatus (Stebbing, 1899) in Lake Ladoga at feeding by various types of plant and animal food have been studied experimentally. The food demand has been assessed at different assimilation levels. Freshwater shrimp G. fasciatus has been shown to have distinct selective capacity with respect to different kinds of plant and animal food.     

Length–weight relationships of two fish species from Sanniang Bay of Guangxi,China

The length–weight relationships were determined for two fish species (Callionymus curvicornis Valenciennes, 1837 and Johnius fasciatus Chu, Lo & Wu, 1963) belonging to two families. Fish samples were collected using commercial trawls (mesh sizes: 70 mm) and the frequency of use three times during each sampling period from Sanniang Bay, China. Samples were collected quarterly from October 2016 to July 2017. The allometric coefficient (b) of length–weight relationship varied from 2.75 for Callionymus curvicornis to 2.92 for Johnius fasciatus. Length–weight relationships for these two fish species were determined for the first time.     

Der Einfluß des Subsozialverhaltens derspezialisierten SamensaugerOncopeltus fasciatus Dall. undDysdercus fasciatus Sign. auf ihre Ernährung

Zusammenfassung Die Nahrungsaufnahme von Einzeltieren und Gruppen der plantisugen WanzenO. fasciatus undD. fasciatus wird vergleichend quantitativ untersucht. In Gruppen (2–4 Individuen) beider Arten wird gegenüber solitären Wanzen sowohl die Anstichrate als auch die Saugtätigkeit und Nahrungsaufnahme erhöht, wobei artspezifische Unterschiede auftreten. Der Einfluß des Subsozialverhaltens zeigt sich an unteroptimalen Nahrungsquellen (fürO. fasciatus alteAsclepias syriaca-bzw. fürD. fasciatus Helianthus annuus-Samen) deutlicher als an optimalen (erntefrischeAsclepias-bzw.Gossypium-Samen). Die Funktion sowie Bedeutung des wäßrigen Speichels wird diskutiert. Im Vordergrund stehen hierbei die funktionellen Verknüpfungsmöglichkeiten des Subsozial verhaltens beider spezialisierter Samensauger mit der Bildung und Nutzung dieses Sekrets.

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The effect of subsocial behaviour of the seed-sucking bugsOncopeltus fasciatus dall. andDysdercus fasciatus sign. on their nutrition

Summary The quantitative uptake of food of isolated individuals or groups ofOncopeltus fasciatus andDysdercus fasciatus has been investigated comparatively. In groups of both species (2–4 members) the feeding activity and the volume of food ingested is increased. The subsocial behaviour is found to have more influence on unattractive food than on optimal one. The subsocial behaviour ofD. fasciatus andO. fasciatus exhibits intraspecific differences. The function and importance of the watery saliva is discussed emphasizing the functional relation of subsocial behaviour and economy of salivation of these seed-sucking species.

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Durchgeführt mit Unterstützung der Deutschen Forschungsgemeinschaft im Rahmen einer Herrn Prof. Kloft gewährten Sachbeihilfe.     

Sharks checking in to the sponge hotel: First internal use of sponges of the genus Agelas and family Irciniidae by banded sand catsharks Atelomycterus fasciatus

Trawl surveys within and surrounding two northwestern Australian marine parks revealed banded sand catsharks Atelomycterus fasciatus (family Atelomycteridae) taking refuge within large sponges of the family Irciniidae (Demospongiae: Dictyoceratida) and the genus Agelas (Demospongiae: Agelasida: Agelasidae). Five sponges contained a total of 57 A. fasciatus, comprising both sexes and both immature and mature individuals ranging from 102 to 390 mm total length (TL). In the same surveys, only five A. fasciatus were captured unassociated with sponges, suggesting that sponges are an important microhabitat for A. fasciatus and may provide a daytime refuge from predators. A southerly range extension is also reported for this species.     

Predictive factors for flea occurrence in red foxes (Vulpes vulpes) from semi-arid Mediterranean environments

The role of red fox as host for a wide range of parasites, particularly fleas and other arthropods causing vector-borne diseases, in combination with its capability to adapt to anthropized environments, makes this wild canid an epidemiologically remarkable species at the wildlife–domestic–human interface, especially in the present time of rise of emerging and re-emerging diseases. This study evaluated the prevalence and parasite intensity of fleas in 88 foxes from Murcia Region (Southeastern Spain) and determined the geographic distribution of areas with the highest potential risk of flea presence. Pulex irritans, Ctenocephalides felis, Spilopsyllus cuniculi and Nosopsyllus fasciatus were identified. The overall prevalence was 76.13%. This is the first time that N. fasciatus has been reported in foxes from Murcia Region. The predictive model established a certain pattern to determine the areas with the highest risk of acquiring fleas. Positive correlation of daily potential evapotranspiration (ET₀) in winter and the opposite effect occurring for ET₀ in summer were obtained, as well as positive correlations for mean daily temperature (T_mean) in summer and mean precipitation (P_mean) in winter and summer. The model was also found positively correlated in the forest habitat ecotone areas and the anthropized areas.     

Distribution,population structure and salinity tolerance of the invasive amphipod Gmelinoides fasciatus (Stebbing) in the Neva Estuary (Gulf of Finland,Baltic Sea)

In the early 1970s, the Baikalian amphipod Gmelinoides fasciatus (Stebbing) was intentionally introduced into several lakes in the Gulf of Finland basin in order to enhance fish production. By 1996, G. fasciatus successfully colonized the littoral zone of Lake Ladoga and, via the Neva River, invaded the Neva Bay, the freshwater part of the Neva Estuary. In 1999, G. fasciatus was first registered in the inner Neva Estuary, the very first record of the Baikalian amphipod in brackish waters of the Baltic Sea. Distribution, abundance, reproduction and population structure of G. fasciatus in the Neva Estuary were studied during 1998–2000. In some locations of the Neva Estuary, maximum densities of G. fasciatus reached 3500 ind. m⁻². In general, density and biomass of G. fasciatus in the freshwater part of the Neva Estuary were higher (around 1.5 fold) than in the brackish-water part. Fecundity of this amphipod averaged 10–20 eggs per female, depending on body size of females and season. In order to assess the possibility of further spread of G. fasciatus in the Baltic Sea, the salinity tolerance of this species was determined in a series of laboratory experiments. Our results showed that the invasive amphipod G. fasciatus is potentially able to colonize shallow coastal habitats of, for example, the Gulf of Bothnia, Gulf of Riga and other parts of the Baltic Sea with water salinities ranging from 1 to 5 psu.

     

Geographic variability in the gonadal development and sexual ontogeny of Hemigymnus,Cheilinus and Oxycheilinus wrasses among Indo-Pacific coral reefs

Patterns of reproductive ontogeny in four species of coral reef wrasses (F: Labridae) Hemigymnus melapterus, Hemigymnus fasciatus, Cheilinus fasciatus and Oxycheilinus digramma were investigated. Populations of each species were sampled from two island groups of the central Great Barrier Reef (GBR), Australia, and from coral reefs in the central Philippines. These three sampling locations span 30° of latitude. The GBR and Philippine reefs experience biologically significant differences in water temperature, geography and human activity. The studied wrasses are effectively unfished in Australia but heavily fished in the Philippines. Gonad weights, histology and demographic data were obtained across the entire size and age range of H. melapterus, C. fasciatus and O. digramma from all locations. Analysis identified three processes of male recruitment: functional gonochorism and both forms of protogynous hermaphroditism, monandry and diandry. The expression of these distinct sexual ontogenies was locality dependent. Populations of H. melapterus, H. fasciatus, C. fasciatus and O. digramma on the GBR showed consistently uniform patterns of sexual ontogeny, with all species being exclusively monandric. H. melapterus, C. fasciatus and O. digramma in the Philippines displayed complex sexual ontogenies, with all species showing histological evidence of both diandry and functional gonochorism. Reproductive investment in gonadal tissue, and population sex structure, also differed between GBR and Philippine coral reefs. Philippine populations had substantially lower gonado-somatic indices than populations on the GBR. Nonetheless, Philippine populations matured more rapidly and displayed a protracted timing of sex change over a large size and age range. Thus, mature females appeared earlier and persisted later into ontogeny in the Philippines than on GBR reefs. Protracted timing of sex change on Philippine reefs is likely linked to the presence of primary males in the population, which is known to reduce the strength of selection for mature females to undergo sex change and become male. Hypotheses based on social structure of fish populations, environmental factors and evolutionary history were developed to account for the different patterns of sexual ontogeny in the focal wrasses.     

Comparative pattern of genetic structure in two Mediterranean killifishes Aphanius fasciatus and Aphanius iberus inferred from both mitochondrial and nuclear data

In this study, genetic variation was assessed in Aphanius fasciatus and Aphanius iberus characterized by similar ecological traits but with very different distribution ranges in the Mediterranean area. Five populations of A. iberus and five of A. fasciatus were analysed using five polymorphic microsatellite loci and partial mitochondrial control region (D‐loop) sequences. Congruent results were found with both nuclear and mitochondrial molecular markers. The results showed that similar levels of genetic divergence, based on mitochondrial control region sequences, are present among populations of A. iberus and among populations of A. fasciatus despite the very different geographic distance existing among the examined populations of the two species (low geographic distance in A. iberus and high in A. fasciatus). A possible explanation could be that the populations of A. iberus were isolated for a longer time than the populations of A. fasciatus supporting the hypothesis that the split in the lineage leading to A. iberus is older than the split in the lineage leading to A. fasciatus. The possibility that the wide circum‐Mediterranean distribution of A. fasciatus ensures the high connectivity of its populations, preventing, in some cases, local differentiation, however, cannot be ruled out.     

Developmental characteristics of two closely related species of Allonemobius and their hybrids

Summary Two species of ground crickets, Allonemobius fasciatus (from Corvallis, 44.3 N) and A. socius (from Gainesville, 30.3 N), and their hybrids were compared for nymphal development, wing form, and embryonic diapause. A. fasciatus matured more rapidly at a short photoperiod than at a long photoperiod and also than A. socius which showed no developmental response to photoperiod. The proportion of long-winged forms varied with nymphal photoperiod greatly in A. fasciatus but slightly in A. socius. A. fasciatus laid only diapause eggs, while A. socius responded to a long parental photoperiod and a high incubation temperature by averting diapause. A. fasciatus showed temperature-dependent shift of the diapause stage butA. socius entered diapause only at the early stage. These differences are related to their voltinism and distribution.Reciprocal crosses between the two species produced viable hybrids. In development rate, female hybrids were intermediate between their parents while male hybrids were closer to their mothers, suggesting that the development rate is controlled primarily by the X chromosome. Overdominance occurred in wing form; reciprocal crosses produced either higher or lower proportions of long-winged forms than their parents. Diapause of F1 hybrid embryos was determined only by the female parent and the paternal effect appeared in F2 embryos.     

Comparative analysis of gonadal morphology in six fish species of the Incertae Sedis genera in Characidae of occurrence in the São Francisco River Basin,Brazil

Martins, Y.S., Arantes, F.P., Sato, Y., dos Santos, J.E., Rizzo, E. and Bazzoli, N. 2012. Comparative analysis of gonadal morphology in six fish species of the Incertae Sedis genera in Characidae of occurrence in the São Francisco River Basin, Brazil. —Acta Zoologica (Stockholm) 93 : 48–56. This study presents a comparative analysis aiming to show the remarkable differences found in gonad morphology between six fish species from the genera Incertae Sedis in the Characidae family. Maturing ovaries of Astyanax fasciatus presented grayish color whilst the other species’ were yellowish in color. The cortical alveoli of the analyzed species are small (5.20 ± 1.44–8.28 ± 2.02 μm) and are formed by various discontinuous layers of vesicles except in the Bryconops affinis, where they are large (12.87 ± 2.41 μm) and form various continuous layers of vesicles. The pellucid zone is thin and varies from 2.44 ± 0.90 to 5.79 ± 1.90 μm and is thickest in B. affinis (10.57 ± 2.08 μm). Folds in the pellucid zone were observed in Astyanax bimaculatus, A. fasciatus, Hemigrammus marginatus, and Moenkhausia costae. The follicular cells of B. affinis are columnar (28.19 ± 13.71 μm), while they are squamous in other species (1.52 ± 0.64–2.12 ± 0.78 μm). This study showed that the morphologic and biometric characteristics of the B. affinis vitellogenic oocytes are statistically different than the analyzed other ones Incertae Sedis of the Characidae family. In advanced maturing testis of A. bimaculatus and A. fasciatus, the spermatozoa were embedded in acidophilic secretion which was gradually reabsorbed in the seminiferous tubules when males were partially spent.