Competition for spawning sites between two gobiid fishes, Bathygobius fuscus and Eviota abax, derived by alteration of mating tactics of the former

Interspecific competition for spawning sites between two gobiid fishes, Bathygobius fuscus and Eviota abax, was studied on a rocky shore. Large males (LM: 55–80mm in standard length: SL) and small males (SM: 34–52mm SL) of B. fuscus acted as nest holders and sneakers, respectively, in the early spawning season (July). The sympatric male E. abax (22–33mm SL) was smaller than SM B. fuscus, and synchronically used rocky holes much smaller than those of LM B. fuscus. In this season, aggressions between the two species were rarely observed. In late season (August), as the number of the LM decreased, the SM converted their tactics to nest holding, occupying nests of a sizes similar to those of E. abax. Eviota abax males were dispossessed by SM and shifted their nest sites to cavities between cobbles and sandy bottom, which might be poorer nest sites than rocky holes.     

Splash dispersal of Coniothyrium minitans in the glasshouse

Coniothyrium minitans, a mycoparasite with biocontrol activity against Sclerotinia sclerotiorum, was found to disperse during glasshouse trials where overhead irrigation was used. Consequently, the role of water splash in dispersal of C. minitans was investigated using soil-incorporated inoculum and a range of irrigation regimes found to occur in the glasshouse. The resulting inoculum deposition over horizontal distances up to 2 m was measured. Using drops < 6 mm diameter at 680 mm h^-1, C. minitans was splash-dispersed at least 2.0 m, whereas with drops > 6 mm diameter at 30 mm h^-1 it was dispersed to only 1.75 m. Irrigation with droplets < 1mm diameter at 49 mm h^-1 failed to disperse inoculum beyond 0.5 m. The dispersal gradient produced by drops < 6 mm diameter at 680 mm h^-1 was best described mathematically by the power function, whereas irrigation with drops > 6 mm diameter at 30 mm h^- resulted in a gradient described well by power or exponential functions. The latter regime produced a significantly steeper gradient than irrigation with drops < 6 mm diameter at 680 mm h^-1. C. minitans was isolated using an Andersen air sampler at concentrations of 2839 cfu m^-3 or 22 cfu m^-3 during irrigation with drops < 6 mm diameter at 680 mm h^-1 or > 6 mm diameter at 30 mm h^-1, respectively. After irrigation, deposition of C. minitans-canying aerosol particles declined exponentially and distance from source had no effect on the amount of inoculum isolated. Conidia of C. minitans, splash-dispersed by irrigation with drops < 6 mm diameter at 680 mm h^-1 were able to infect sclerotia of S. sclerotiorum such that almost all sclerotia at 0.5 m from the inoculum source, and c. 50% of those at 2.0 m, became infected with the mycoparasite.     

Rapid long‐distance migration in Norwegian Lesser Black‐backed Gulls Larus fuscus fuscus along their eastern flyway

We studied the long‐distance migration of Lesser Black‐backed Gulls Larus fuscus fuscus breeding in northern Norway along their eastern flyway using geolocators in 2009 and 2010. The majority of birds wintered in lakes in East Africa and the southeast Mediterranean was the most important stopover area. Larus f. fuscus along the eastern flyway travelled at a net travel speed of 399 and 177 km/day during the autumn and spring migration, respectively, higher than published travel speeds for Dutch Larus fuscus migrating along the western flyway. The results suggest that the long‐distance migratory Norwegian L. f. fuscus seek to minimize time spent in transit, whereas lower travel speed during northerly spring migration may reflect differences in wind patterns or food conditions between spring and autumn.     

Attraction of fruit flies of the genus Bactrocera to colored mimics of host fruit

In tests on feral populations of polyphagous Bactrocera tryoni (Froggatt) adults on host guava trees, both sexes were significantly more attracted to Tangletrap‐coated 50 mm diameter spheres colored blue or white than to similar spheres colored red, orange, yellow, green, or black or to Tangletrap‐coated 50 mm diameter yellow‐green guava fruit. In contrast, in tests on feral populations of oligophagous Bactrocera cacuminata (Hering) on host wild tobacco plants, both sexes were significantly more attracted to Tangletrap‐coated 15 mm diameter spheres colored orange or yellow than to other colors of spheres or to Tangletrap‐coated 15 mm diameter green wild tobacco fruit. Both sexes of both tephritid species were significantly more attracted to blue (in the case of B. tryoni) or orange (in the case of B. cacuminata) 50 mm spheres displayed singly than to blue or orange 15 mm spheres displayed in clusters, even though fruit of wild tobacco plants are borne in clusters. Finally, B. tryoni adults were significantly less attracted to non‐ultraviolet reflecting bluish fruit‐mimicking spheres than to bluish fruit‐mimicking spheres having a slightly enhanced level of ultraviolet reflectance, similar to the reflectance of possible native host fruit of B. tryoni, whose bluish skin color is overlayed with ultraviolet‐reflecting waxy bloom. Responses to fruit visual stimuli found here are discussed relative to responses found in other tephritid species.     

Effects of body size on sex‐related migration vary between two closely related gull species with similar size dimorphism

Studies of migration have revealed multiple trade‐offs with other life‐history traits that may underlie observed variation in migratory properties among ages and sexes. To assess whether, and to what extent, body size and/or sex‐specific differences in competition for resources (e.g. breeding territories or winter food) may shape variation in migration distance and timing of arrival in ecologically and phylogenetically related species, we combined over 30 000 sightings of individually marked, sexually mature males and females of Herring Gulls Larus argentatus and Lesser Black‐Backed Gulls Larus fuscus with biometric measurements and phenological observations at a mixed breeding colony. In L. argentatus, larger males migrated further from the breeding colony, whereas migration distance was independent of body size in adult females. In L. fuscus, no relationship between body size and migration distance was apparent in either sex. Mean arrival dates at the breeding colony did not vary with migration distances but differed between males and females of L. argentatus (but not L. fuscus). As allometry at least partly explains sexual segregation in migration behaviour in L. argentatus, but not in L. fuscus, we conclude that the effect of body size on sex‐related migratory strategies may vary between closely related, sympatric species despite similar size dimorphism.     

Dispersal of Septoria nodorum Pycnidiospores by Simulated Raindrops in Still Air

Simulated raindrops, diameter c. 3 or 4 mm, fell 13 m down a raintower onto suspensions of Septoria nodorum pycnidiospores, depth 0.5 mm, or infected straw pieces. Splash droplets were collected on pieces of fixed photographic film. It was estimated that one drop generated c. 300 spore carrying splash droplets, containing c. 6000 spores, from a concentrated spore suspension (6.5 × 10⁵ spores/ml) and c. 25 spore-carrying droplets, containing c. 30 spores, from infected straw pieces (11 × 10⁶ spores/g dry wt). When the target was a spore suspension in water without surfactant, most spore-carrying droplets were in the 200—400 μm size category and most spores were carried in droplets with diameter >1000 μm. When surfactant was added to spore suspensions, most spore-carrying droplets were in the 0–200 μm category and most spores were carried in droplets with diameter 200–400 μm and none in droplets >1000 μm. Regression analyses showed a significant (p < 0.001) relationship between square root (number of spores per droplet) and droplet diameter; the slope of the regression line was greatest when surfactant was added to the spore suspensions. The distribution of splash droplets with distance travelled from the target was better fitted by an exponential model than by power law or Gaussian models. The distributions of spore-carrying droplets and spores with distance were fitted better by an exponential model than by a power law model. Thus regressions of log, (number collected) against distance were all significant (p < 0.01); the slopes of the regression lines were steepest when surfactant was added to the spore suspension. At a distance of 10 cm from target spore suspensions most splash droplets and spore-carrying droplets were collected at height 10–20 cm, with none above 40 cm; at a distance of 20 cm there were most at heights 0–10 cm and 40–50 cm.     

Age-related migration patterns in Larus fuscus spp.

Migration is a critical period in a bird’s life that can affect the fitness of individuals. Intra-population migratory patterns and the way different sex and/or age classes within a population differ in timing and/or distance of migration are not completely understood. The present study aims to observe inter- and intra-population migratory patterns in the western population of Lesser Black-backed Gulls (Larus fuscus spp.), shedding light on age-related differences of temporal patterns of occurrence in the Portuguese coastal areas during migration and winter. One thousand seven hundred and fifty-four colour ring records were analysed matching a 30-year period of observations on the Portuguese coast between 1975 and 2005. During migration, the graellsii population represents 90% of the migratory flow of L. fuscus through Portugal with the intermedius accounting for 9% and the fuscus population, being vestigial in this period, accounting for 1%. Nevertheless, interesting significant differences were observed between the age classes of the three populations during this period, the graellsii population having a large number of first winters (40% of the migratory contingent of this population) followed by immatures and adults whilst in the intermedius and fuscus populations, the largest age class is the adults. During winter, no inter-population differences were found. When comparing migration and winter periods, intra-population differences were found in the graellsii and fuscus populations regarding distribution and age classes. These results indicate different migratory routes amongst different populations suggesting a leapfrog migration in L. fuscus and also a differential age-related migration pattern that might result from first winters migrating further south in search of a wintering place since adults heavily occupy the closest wintering quarters in their attempt to arrive earlier at their breeding ground.     

Dispersal of Rhynchosporium secalis conidia from infected barley leaves or straw by simulated rain

Simulated rain (mean drop diameter c. 1 or 3 mm) was allowed to fall for 10 – 15 min on to barley leaves or straw infected by Rhynchosporium secalis (leaf blotch). The leaves were supported on a mesh through which run-off water drained and the straw was supported on a rigid surface on which run-off water collected. The numbers of R. secalis conidia and spore-carrying splash droplets collected by horizontal samplers (microscope slides and pieces of photographic film) decreased rapidly with increasing distance from and increasing height above the sources, with half-distances of 2 – 10 cm. Less than 10% of the spores or droplets reached heights of more than 30 cm. Incident drops 3 mm in diameter produced more spore-carrying droplets and dispersed more conidia than did 1 mm drops. The size category of splash droplets with the greatest proportion of the spore-carrying droplets dispersed by 3 mm drops was 200 – 400 μm, whether the source was infected barley leaves or barley straw. For leaves or straw the greatest proportions of spores were carried in droplets > 1000 μm in diameter. The mean diameter of spore-carrying droplets (478 μm) dispersed from free-draining leaves was less than that of droplets from straw plus run-off water (563 μm). However, the leaf source had more spores cm^-2 and the mean number of spores per droplet was greater (113 as opposed to 6·8) than for the straw source.     

Genetic Control of Mitosis: Mutation ff3Causes Premature Beginning of Telophase Chromatin Reorganization in Drosophila melanogaster

The effect of cell cycle mutation ff3 on chromosome segregation was studied on fixed cells of neural ganglia of Drosophila melanogasterlarvae. The cell distributions by diameter of interphase nuclei and by distance between sister chromatid sets were compared at anaphase and telophase. In the control wild-type strain Lausenne, the cell distribution by distance between sister chromatids in anaphase was similar to their distribution by nuclear size. The mean distance between segregating chromatids at anaphase (l _av) coincided with the mean diameter of interphase nuclei (d _av) and was 8.3 m. Cells passed to telophase when chromatids were at least 10 m apart. The mutant ff3 strain differed from the control strain Lausenne in cell distribution by interphase nuclear diameter and distance between sister chromatids in anaphase; the mean nuclear diameter and mean distance between segregating chromatids similarly increased to 9.3 m. A specific feature of mitosis in mutant strain ff3 was a premature beginning of telophase chromatin reorganization. This caused the occurrence of cells with abnormally short (less then the interphase nuclear diameter) distance between sister chromatid sets in telophase but not in anaphase, as if these cells had passed from anaphase to telophase prematurely, during the chromatid movement toward poles in anaphase A.     

Trophic ecology of two congeneric pipefishes (Syngnathidae) of the lower York River,Virginia

Synopsis The northern pipefish, Syngnathus fuscus, and the dusky pipefish, S. floridae, co-exist in eelgrass beds in the lower York River. To compare the trophic ecology of both pipefishes, gut contents of 3488 northern pipefish, and 1422 dusky pipefish were examined and quantified by dry weight. Samples were taken with a dip net from May through November 1992. Syngnathus fuscus fed mainly on amphipods (Gammarus mucronatus, Amphithoe longimana, and Caprella penantis), and to a lesser degree on copepods, and isopods (Edotea spp. and Erichsonella attenuata). Syngnathus floridae fed mainly on grass shrimps (Palaemonetes pugio, P. vulgaris, and Palaemonetes eggs), and to a lesser degree on copepods, isopods, and mysids (Mysidopsis bigelowi). No seasonal trends were observed in the feeding habits of these pipefishes. Specimens of both species smaller than 100 mm TL fed mainly on copepods. Larger S. fuscus fed on amphipods, while larger S. floridae fed on grass shrimps. Schoener's diet overlap index revealed high consumption of the same prey type by both pipefish species only in July, but only for those specimens smaller than 110 mm TL. Food partitioning between both pipefish was associated with different snout sizes and shapes.     

Selective predation on the broad‐toothed rat,Mastacomys fuscus (Rodentia: Muridae), by the introduced red fox,Vulpes vulpes (Carnivora: Canidae), in the Snowy Mountains,Australia

Abstract Since 1981 there has been debate over whether foxes (Vulpes vulpes Linnaeus) selectively prey on the broad‐toothed rat (Mastacomys fuscus Thomas) relative to the bush rat (Rattus fuscipes (Waterhouse)). In the present study, three areas of the argument are examined. (i) In a study of fox diet over 3 years at both alpine and subalpine altitudes, M. fuscus outnumbered R. fuscipes in faecal remains in all seasons, in all years, and at both altitudes. Overall, M. fuscus occurred in scats five times as frequently as did R. fuscipes in the alpine zone and twice as often in the subalpine zone. (ii) Data from population studies of M. fuscus and R. fuscipes showed no evidence that M. fuscus is trap shy; neither the pattern of captures of individuals caught once, twice and so on, nor the proportion of the estimated population of each species captured during trapping sessions was significantly different. (iii) The suitable habitat for M. fuscus within the potential home ranges of foxes contributing to the subalpine fox scat collection constituted approximately 50% of the total area. However, there was no significant difference between the numbers of fox trails encountered in habitat suitable or unsuitable for M. fuscus in 19 paired transects skied in winter, indicating no preferential foraging in either habitat. Selective feeding on M. fuscus was therefore established, but how that choice is exercised was not determined.     

Prey size selection and distance estimation in foraging adult dragonflies

To determine whether perching dragonflies visually assess the distance to potential prey items, we presented artificial prey, glass beads suspended from fine wires, to perching dragonflies in the field. We videotaped the responses of freely foraging dragonflies (Libellula luctuosa and Sympetrum vicinum—Odonata, suborder Anisoptera) to beads ranging from 0.5 mm to 8 mm in diameter, recording whether or not the dragonflies took off after the beads, and if so, at what distance. Our results indicated that dragonflies were highly selective for bead size. Furthermore, the smaller Sympetrum preferred beads of smaller size and the larger Libellula preferred larger beads. Each species rejected beads as large or larger than their heads, even when the beads subtended the same visual angles as the smaller, attractive beads. Since bead size cannot be determined without reference to distance, we conclude that dragonflies are able to estimate the distance to potential prey items. The range over which they estimate distance is about 1 m for the larger Libellula and 70 cm for the smaller Sympetrum. The mechanism of distance estimation is unknown, but it probably includes both stereopsis and the motion parallax produced by head movements.     

Modelling of fossil and contemporary data suggest the Broad-toothed rat (Mastacomys fuscus) currently occupies a small part of its available climatic niche: Implications of paleontological data for conservation of a threatened species

We use fossil, sub-fossil and contemporary records of the Broad-toothed rat, Mastacomys fuscus, to model changes in its range over the last 21 thousand years. Mastacomys fuscus was exposed to, and flourished in, a much broader range of environmental conditions in the recent past than it occupies today. It also currently occupies a much smaller range than it did in the Late Pleistocene. Apart from a weak response to sea-level rise in the Holocene, the decline of M. fuscus does not correlate with known climate change. Instead, the contraction of the species' distribution on mainland Australia to high-elevation areas occurred recently and rapidly. Small changes in the 1000 year BP and present-day projected distributions imply some contraction of the area of suitable climate to higher elevations of the mainland subspecies M. f. mordicus, up to 2200 m above sea level. However, M. f. mordicus also persists near sea level at Cape Otway (southwestern Victoria) and from sea level to 1500 m above sea level at Barrington Tops (eastern New South Wales, Australia). This suggests suitable habitat may still exist in coastal Victoria and the central Tablelands/Blue Mountains areas. This research highlights the importance and value of using sub-fossil data to understand changes in the distribution and niche occupation of threatened species as the basis for conservation planning.     

Ultrastructure of free neuromasts of Bathygobius fuscus (gobiidae) and canal neuromasts of Apogon cyanosoma (apogonidae)

Light and electron microscopic observations were made on the lateral line organs of the free neuromasts of the goby Bathygobius fuscus and the canal neuromasts of the cardinal fish Apogon cyanosoma. As in other lateral line systems, each neuromast consists of hair cells, supporting cells and mantle supporting cells, the whole being covered by a cupula. In B. fuscus the free neuromasts are mounted on papillae and have hair cells with stereocilia up to 2.5 μm long and a single kinocilium at least 25 μm long. Each neuromast is covered by a vane-like cupula that can be divided into two regions. The central region over the sensory area contains columns of myelin-like figures. These figures are absent from the outer region covering the mantle. The canal neuromasts of A. cyanosoma are diamond-shaped with up to 1,500 hair cells. The cupula is unusual in having a channel that lies over the sensory region. The hair cells have up to 45 stereocilia, the tallest reaching 2.5 μm, and a kinocilium at least 5 μm long. Tip links are shown for the first time between rows of stereocilia of the hair cells of lateral line neuromasts. The presence of tip links has now been demonstrated for all acousticolateral hair cell systems.     

Mechanisms of measuring the velocity and acceleration of an underwater target by the sonar of the dolphinTursiops truncatus

The performed study of peculiarities of echo-detection of moving underwater targets by the Black Sea bottlenosed dolphins,Tursiops truncatus, suggests that the biosonar can purposefully change the structure of its probe signal, depending on the problem to be solved. It was shown experimentally for the first time that the animal emits the two-pulse probe signal to measure the constant velocity, while the three-pulse one, to measure acceleration. This provides an essential advantage over the single pulse, as it becomes possible to measure simultaneously parameters of the movement and distance.     

Aspects of the respiratory biology of two New Zealand intertidal fishes, Acanthoclinus fuscus and Forsterygion sp

Synopsis Aerial and aquatic VO₂ measurements of Acanthoclinus fuscus and Forsterygion sp. showed that A. fuscus weighing up to 25 g obtained oxygen from air and water at similar rates, whereas the ratio of aerial to aquatic VO₂ for F. sp. was mass dependent. The Q₁₀ for aquatic respiration of A. fuscus and F. sp. was found to be 2.3 and 2.5, respectively. Aerial VO₂ measurements showed that A. fuscus could continue to increase its aerial VO₂ up to at least 25° C. In contrast the aerial VO₂ of F. sp. increased only between 5° C and 15° C and decreased between 20 and 25° C. The P_crits of both A. fuscus and F. sp. were found to be about 35 torr. Emergence in response to hypoxia occurred between 0 and 16 torr which suggested active emergence was an oxykinetic response and not a behaviour.to whom all correspondence should be addressed     

The Use of RAPD Markers to Assess Catfish Hybridization

Taiwan's endemic catfish Clarias fuscus is gradually disappearing from its native habitat, and has been proposed for genebank preservation. Environmental pressures, including exotic species interference and habitat destruction, as well as possible competitive advantages of the hybrids over this species. In order to quickly and effectively provide a reliable DNA fingerprint for the pure strain of C. fuscus we used RAPD markers to assess C. fuscus, C. mossambicus, and C.batrachus. Of the 200 primers screened to prime PCR amplification of DNA from wild-caught C. fuscus, 16 yielded reproducible DNA bands. Unique RAPD markers generated from 3 PCR primers (#211, #245 and #287) are shown to be alleles present in the genomes of C. mossambicus but absent in the genome of C. fuscus. Hybrids of C. fuscus and C. mossambicus, therefore, could possibly be distinguished by the use of these specific molecular markers. Catfish caught from the Mingder Dam were then cautiously removed from the preserved stock because of the appearance of hybrid markers in their genomes.     

Using citizen science to obtain data on large,floating gelatinous spheres from NE Atlantic,attributed to egg mass of ommastrephid squid (Oegopsida,Cephalopoda, Mollusca)

A total of 27 large, gelatinous spherical masses observed in coastal Norwegian waters from Nordland to Aust-Agder Counties in Norway, and off Lysekil in Sweden, Muljica Island in Croatia, Gulf of Naples in Italy, Reqqa Point in Malta, and Saint Mandrier in France, during the months of April to September 2001 to 2017, are reported. Individual spheres measured 0.3–2 m in diameter, averaging one metre (n?=?24, ±0.53 m), with all but four sighted in suspension in the water column between 0.5 and 52 m depth, in water temperatures ranging between 10–21°C. About half of all spheres contained a yellow-red streak through their gelatinous core. Tissue samples were not obtained. We attribute these gelatinous spheres to the egg masses of squid (Cephalopoda, Oegopsida), and most likely to the ommastrephid Todarodes sagittatus, given similarities with egg masses of T. pacificus.     

Variation in Immune Parameters and Disease Prevalence among Lesser Black-Backed Gulls (Larus fuscus sp.) with Different Migratory Strategies

The ability to control infections is a key trait for migrants that must be balanced against other costly features of the migratory life. In this study we explored the links between migration and disease ecology by examining natural variation in parasite exposure and immunity in several populations of Lesser Black-backed Gulls (Larus fuscus) with different migratory strategies. We found higher activity of natural antibodies in long distance migrants from the nominate subspecies L.f.fuscus. Circulating levels of IgY showed large variation at the population level, while immune parameters associated with antimicrobial activity showed extensive variation at the individual level irrespective of population or migratory strategy. Pathogen prevalence showed large geographical variation. However, the seroprevalence of one of the gull-specific subtypes of avian influenza (H16) was associated to the migratory strategy, with lower prevalence among the long-distance migrants, suggesting that migration may play a role in disease dynamics of certain pathogens at the population level.