Spatial variation in density of stream benthic fishes in northern Hokkaido, Japan: does riparian vegetation affect fish density via food availability?

The densities of two benthic fishes, the Siberian stone loach (Noemacheilus barbatulus) and the wrinklehead sculpin (Cottus nozawae), and the biomass of their food resources (i.e., periphyton and benthic invertebrates) were compared between forest and grassland streams in northern Hokkaido, Japan, to examine whether riparian deforestation had positive effects on the benthic fishes via enhancement of food availability. The comparisons indicated that riparian vegetation had little influence on periphyton, invertebrates, or fishes. Regression analysis indicated that spatial variations in loach and sculpin densities were explained more by substrate heterogeneity, competitor abundance, or both, rather than by food abundance. However, when the two species were combined as benthic insectivores, a strong correlation was found between total benthic fish density and invertebrate biomass. Our results suggest that, although total benthic fish abundance was food limited, riparian vegetation had no positive effects via food availability on the benthic fishes in our streams.     

A comparison of ventilation rates and haemoglobin concentrations between two species of loach,Noemacheilus barbatulus (L.) and Cobitis taenia (L.)

The mean haemoglobin concentration of Noemacheilus barbatulus was found to be significantly higher than that of Cobitis taenia. Under conditions of reduced oxygen saturation, both species achieved maximum rates of ventilation at 10% 0₂. An alteration in opercular beat pattern accounted for the increased ventilation rates between 20% and 30%. A slightly higher tolerance for lowered oxygen concentrations was demonstrated by Cobitis taenia with disorientation and aerial respiration occurring at lower oxygen tensions than in Noemacheilus barbatulus.     

Electron microscopical and autoradiographical studies on the so-called yolk-nuclei in the oocytes of Nemacheilus barbatulus (L.) and Phoxinus phoxinus (L.) (Pisces, Teleostei) (author's transl)

The yolk-nuclei in the oocytes of the teleosts Noemacheilus barbatulus (L.) and Phoxinus phoxinus (L.) were investigated by electron microscopy, autoradiography and ultrahistochemistry. Yolk-nuclei were only found in stage I. They consist of mitochondria, an osmiophilic material and in Noemacheilus partly of dictyosomes. It was demonstrated by marking with [3H]-uridine, that the osmiophilic material contains RNA. The osmiophilic material gets into the juxtanuclear cytoplasm. There it is surrounded by mitochondria. The oocytes of Noemacheilus and Phoxinus contain up to 40 yolk-nuclei, which are only visible by electron microscopy. The yolk-nuclei of both species dissolve in early stage II. Their components disperse in the cytoplasm.     

An osmotic induction method for externally marking saltwater fishes,Stigmatopora argus and Stigmatopora nigra,with calcein

Calcein marking via osmotic induction and overnight immersion was compared in saltwater fishes. Immersion in a salt solution for 10 min followed by 30 min in a 500 mg l^?1 calcein solution produced the highest fluorescent mark in 40 min with no effect on survival.     

Fish abundance and habitat relationships in forest and grassland streams, northern Hokkaido, Japan

The relationships between habitat variables and population densities of masu salmon (Oncorhynchus masou), rosyface dace (Leuciscus ezoe), Siberian stone loach (Noemacheilus barbatulus) and wrinklehead sculpin (Cottus nozawae) were examined by data collected at 55 reaches in forest and grassland streams in northern Hokkaido, Japan. Regression analysis suggested that salmon and dace densities were affected by water temperature (negative for salmon, positive for dace) and structural habitat factors (woody debris for salmon, pools for dace). Salmon density was higher in forest reaches than in grassland reaches, whereas dace density was higher in grassland reaches, suggesting that the removal of riparian forest had raised water temperature and allowed upstream invasions by dace. In contrast to salmon and dace, neither the density of loach nor sculpin differed between the forest and grassland reaches. For their densities, a negative effect of each on the other was most important, suggesting a strong effect of interspecific competition between loach and sculpin on their distributions. However, regression models also suggested that substrate heterogeneity mediated the outcome of their interspecific competition. On the basis of the results, a scenario is predicted for a fish-assemblage change with a typical land-development process in Hokkaido, and the importance of leaving or restoring riparian buffer for conservation and restoration of stream habitat is emphasized.     

Where do fish go when stranded on land? Terrestrial orientation of the mangrove rivulus Kryptolebias marmoratus

The goal of the present study was to determine which sensory cues the mangrove rivulus Kryptolebias marmoratus, a quasi-amphibious, hermaphroditic fish, uses to orient in an unfamiliar terrestrial environment. In a laboratory setting, K. marmoratus were placed on a terrestrial test arena and were provided the opportunity to move toward reflective surfaces, water, dark colours v. light colours, and orange colouration. Compared with hermaphrodites, males moved more often toward an orange section of the test arena, suggesting that the response may be associated with camouflage or male–male competition, since only males display orange colouration. Younger individuals also moved more often toward the orange quadrant than older individuals, suggesting age-dependent orientation performance or behaviour. Sloped terrain also had a significant effect on orientation, with more movement downhill, suggesting the importance of the otolith-vestibular system in terrestrial orientation of K. marmoratus. By understanding the orientation of extant amphibious fishes, we may be able to infer how sensory biology and behaviour might have evolved to facilitate invasion of land by amphibious vertebrates millions of years ago.     

Retinal vascularisation in the loach Noemacheilus rupicola rupicola: coexistence of falciform process and vitreal vessels

Synopsis The coexistence of a fully developed falciform process and vitreal vessels, a hitherto unknown situation in teleostean intraocular vascularisation, has been noted in the loach Noemacheilus rupicola rupicola. Possible implications of this vascular development for the species have been highlighted.     

Communication and camouflage with the same 'bright' colours in reef fishes

Reef fishes present the observer with the most diverse and stunning assemblage of animal colours anywhere on earth. The functions of some of these colours and their combinations are examined using new non-subjective spectrophotometric measurements of the colours of fishes and their habitat. Conclusions reached are as follows: (i) the spectra of colours in high spatial frequency patterns are often well designed to be very conspicuous to a colour vision system at close range but well camouflaged at a distance; (ii) blue and yellow, the most frequently used colours in reef fishes, may be good for camouflage or communication depending on the background they are viewed against; and (iii) reef fishes use a combination of colour and behaviour to regulate their conspicuousness and crypsis.     

Quantitative sampling of fishes in a simple system: failure of conventional methods

In a capture-mark-recapture fish density estimate carried out in a small freshwater pond in southern Ontario, Canada, a lift net and minnow traps were used as catching gear. Both worked well for initial captures, but most recaptures were in the traps. Density estimates within reasonable confidence limits were possible for only two species, creek chub (Semotilus atromaculatus) and common shiner (Notropis cornutus). The other 13 species present were either missed entirely or not captured or recaptured sufficiently so estimates for them were inadequate. Subsequent collection of fishes after rotenone poisoning verified the estimates for the two species, if the size selectivity of the gear and the possible effects of marking and limitations of collecting after poisoning were considered.     

The effects of marking and capture on recapture frequencies of butterflies

Summary As a preliminary to a population study using markrelease-recapture techniques, specimens of the Satyrid buttfly Melanargia galathea (L.) were subjected to a number of marking and capture techniques. Although the adults are thought to display both aposematic and cryptic coloration, the use of marks of different sizes and colours had no significant effect on recapture frequencies. However, repeated disturbance due to capture was found to significantly reduce recapture frequency. The influence of the different techniques on recapture frequencies could not be detected reliably by excessively low recapture rates, or by comparisons to Poisson distributions. It is suggested that these comparisons are of limited value as measures of the suitability of a marking or handling scheme. Subsequent work showed that capture affected recapture rates of several other species. Moreover, these effects could not be readily predicted from knowledge of the biology of these species. The implications of these findings are discussed.     

Gyrodactylus gvozdevi n. sp. (Gyrodactylidae: Monogenea) from Noemacheilus dorsalis (Kessler) in Kazakhstan

Gyrodactylus gvozdevi n. sp. (Gyrodactylidae: Monogenea) is described from the skin of the freshwater fish Noemacheilus dorsalis (Kessler) (Cobitidae: Cypriniformes) from Kazakhstan. This species is most closely related to G. pseudonemachili Ergens & Bykhovsky, 1967 in the shape and size of the anchors and both the ventral and dorsal bars, but can be distinguished from it by the shape and size of the hookproper of the marginal hooks.     

Nontroglobitic Fishes in Bruffey-Hills Creek Cave, West Virginia, and other Caves Worldwide

Six species of fishes were tagged and released in September and November 1995 and on five dates between November 1998 and October 1999 inside Bruffey-Hills Creek Cave. Most of the tagged fishes were creek chub, Semotilus atromaculatus, and green sunfish, Lepomis cyanellus. The overall recapture rate was 2.6% as only three of 117 fishes were recaptured. Forty-nine days was the longest time of residence by two L. cyanellus and one S. atromaculatus, and movement of 83.4 m was observed only for the creek chub. Tag loss was confirmed as one factor in the low recapture rate. Nine species of fishes were collected in the cave, including Phoxinus oreas and Pimephales promelas, two species never collected in a cave. Most of the fishes were pigmented normally, but many creek chubs were depigmented and appeared white or pigmentless when first observed in the cave stream. Four species, Phoxinus oreas, Pimephales promelas, Ameiurus nebulosus, and Lepomis macrochirus, were collected for the first time in Bruffey-Hills Creek Cave and in the Bruffey and Hills creeks drainage. Although data from this study did not shed light on residence time of fishes in the cave, the consistent occurrence of epigean fishes in this cave was shown. A list of epigean fishes from caves worldwide was included along with a discussion of aspects of the ecology of epigean fishes in caves and of evolution of troglobitic fishes.     

Pelagic larval duration and population connectivity in New Zealand triplefin fishes (Tripterygiidae)

The relationship between pelagic larval duration (PLD) and population connectivity in marine fishes has been controversial, but most studies to date have focused on tropical taxa. Here, we examine PLD in 11 species of triplefin fishes from a temperate environment in the Hauraki Gulf, New Zealand, to describe daily increment patterns and settlement marks in the otoliths. The formation of daily increments was validated using larvae of known age and tetracycline marking of settled juveniles. Settlement mark identity was verified by comparing total increment counts from otoliths of recently settled fishes with PLD counts from post-settlement fishes. A similar pattern of three groups of increments across the otolith was found in all specimens examined. The settlement mark was similar in all species and occurred as a sharp drop in increment width within the area of transition in optical density. PLD was lengthy, compared to species of triplefins from elsewhere, and ranged between 54.4 ± 1.7 SE days in Bellapiscis lesleyae to 86.4 ± 2.6 SE days in Forsterygion malcolmi. Variation in PLD within species was high but did not mask interspecific differences. PLD was not phylogenetically constrained, as sister species differed significantly in PLD. PLD was compared with genetic population connectivity for eight of the study species using mitochondrial gene flow data from Hickey, Lavery, Hannan, Baker, Clements. Mol Ecol 18:680–696 (2009). The observed lack of correlation between PLD and gene flow suggests that dispersal is limited by other factors, such as larval behaviour and the availability of settlement habitat.     

Validation of annulus formation in sagittal otoliths of three tropical cichlids Oreochromis andersonii (Castelnau, 1861), Oreochromis macrochir (Boulenger, 1912), and Coptodon rendalli (Boulenger, 1896)

The periodicity of growth zone formation in sagittal otoliths of Oreochromis andersonii, Oreochromis macrochir and Coptodon rendalli from the Upper Zambezi region, southern Africa, was validated to test the hypothesis that a single growth zone is deposited annually. Edge analysis was carried out on 754 O. andersonii (54–492 mm TL), 601 O. macrochir (83–438 mm TL) and 622 C. rendalli (45–379 mm TL) caught between August 2010 and August 2011 in Lake Liambezi and the Kavango, Kwando and Upper Zambezi rivers. This was corroborated for O. andersonii (n = 17) and C. rendalli (n = 16) using a fluorochrome marking experiment conducted in a large earthen pond (625 m², 1.5 m deep) adjacent to the Kavango River. Both methods demonstrated that growth zone deposition occurred annually in juvenile and adult fishes. For edge analysis, the highest proportion of otoliths with an opaque margin was observed in summer from October to December. The fluorochrome marking experiment, however, revealed that opaque zone deposition took place in winter between June and September when water temperatures were lowest (17°C), indicating a lag between opaque zone deposition and detection on the otolith edge.     

Behaviour,feeding habits and ecology of the blind catfish Phreatobius sanguijuela (Ostariophysi: Siluriformes)

The subterranean fish Phreatobius sanguijuela, originally described from Bolivia, was captured in different wells near São Francisco do Guaporé, Rondônia State, Brazil. Thirty wells were investigated in April and July 2012, and September 2013. These surveys resulted in the capture of 58 individuals from eight wells and comprised three to 14 individuals per well. The capture of the individuals allowed a detailed evaluation of their colours in life, behaviour in the field and in captivity, aspects of their biology, confirmation of the species identification and provided new diagnostic characteristics to distinguish between P. sanguijuela and Phreatobius dracunculus. Cannibalism, territorialism, agonistic interactions and phototaxis behaviour were not observed. Phreatobius sanguijuela exhibited cryptobiotic habits and two behaviours under stressful conditions. The analysis of stomach contents reveals that this species apparently feeds on invertebrates, almost exclusively on earthworms. The sex ratio was 1:1. The absence of opercular movement during the resting period associated with intense blood irrigation of the skin indicates a possible cutaneous respiration as an alternative form of gas exchange. Local people often mistake P. sanguijuela for helminths and have the habit of releasing non‐native fishes into the wells or to use chemicals to eliminate them. The consequence of this habit for the conservation of the species requires further evaluation.     

Studies on the toxicity of zinc sulphate and of cadmium sulphate to stone loach Noemacheilus barbatulus (L.) in hard water

The toxicity of zinc sulphate and cadmium sulphate to stone loach Noemacheilus barbatulus was examined in an attempt to explain the distribution of the species in two polluted streams. Stone loach in hard water were more sensitive than rainbow trout to zinc, but much more resistant to cadmium. Their disappearance from the Willow Brook, Northants, in 1971–72 could be accounted for by zinc toxicity. A behavioural change, the loss of the instinct to hide during daylight, occurred in subsequently lethal concentrations of cadmium. The accumulation of cadmium in several tissues was also determined.     

Growth,mortality and tag retention of small Anguilla anguilla marked with visible implant elastomer tags and coded wire tags under laboratory conditions

Growth, and potential marking‐related mortality of small European eel Anguilla anguilla (L.) after marking with visible implant elastomer tags (VIE) and coded wire tags (CWT) were investigated over a 6‐month period in a laboratory experiment. In addition, mark retention after marking was examined for another 16.5 months. Neither marking method had a significant effect on growth (P > 0.05) or mortality (P > 0.05). After 32 days detection of the VIE marks implanted on the ventral surface and along the base of the ventral tail fin margin was 98 and 100%, respectively, but decreased to 9 and 66% after 512 days. Retention of the CWT implanted in the dorsal musculature of A. anguilla was 99% after 32 days and did not change by day 512. It was therefore concluded that marking‐induced mortality was nil for both marking types over the 6‐month period. Generally, both methods are found to be suitable for marking young A. Anguilla. VIE tags, however, should be used for short‐time mark‐recapture experiments only, and should be injected at the base of the ventral fin margin. The use of CWTs seems to be the more suitable marking method for long‐term mark‐recapture experiments. Nevertheless, field tests are necessary to evaluate these marking methods.     

Bioluminescence and chemiluminescence literature: 1987 literature,part III

In studying beetle bioluminescence in the early 1960s, Dr McElroy and his colleagues found that the Jamaican click beetle, Pyrophorus plagiophthalamus, was capable of emitting different colours of light. They further found that the luciferin substrate used by this beetle was the same as that in the firefly, demonstrating that the different colours of bioluminescence were due to differences in the structure of the luciferases. We have recently cloned cDNAs from this beetle species which code for at least four different luciferases. The luciferases are distinguishable by their different colours of bioluminescence when expressed in Escherichia coli. The sequence differences between these different luciferases are few, so the amino acids responsible for the different colours of emission must also be few. Through the construction of hybrid luciferases, by rearranging fragments of the original cDNA clones, we have identified some of these amino acid determinants of colour.     

Influence of visual cues on host‐searching and learning behaviour of the egg parasitoids Telenomus podisi and Trissolcus basalis

Insect parasitoids use a variety of chemical and physical cues when foraging for hosts and food. Parasitoids can learn cues that lead them to the hosts, thus contributing to better foraging. One of the cues that influence host‐searching behaviour could be colour. In this study, we investigated the ability of females of the parasitoid wasps Telenomus podisi Ashmead and Trissolcus basalis Wollaston (both Hymenoptera: Scelionidae) to respond to colours and to associate the presence of hosts – eggs of Euschistus heros (Fabricius) (Hemiptera: Pentatomidae) – with coloured substrates after training (associative learning). Two sets of experiments were conducted: in one the innate preference for substrate colours was examined, in the other associative learning of substrate colour and host presence was tested in multiple‐choice and dual‐choice experiments. In the associative learning experiments, Te. podisi and Tr. basalis were trained to respond to differently coloured substrates containing hosts in two sessions of 2 h each, with 1‐h intervals. In multiple‐choice experiments, the wasps displayed innate preference for yellow substrates over green, brown, black, or white ones. Even after being trained on substrates of different colours, both parasitoids continued to show preference for yellow substrates. The response to the colours of substrates of both parasitoids was related with the orientation to the plant foliage during the search for hosts.