Three-dimensional migratory behaviour of European silver eels (Anguilla anguilla) approaching a hydropower plant

The global population of European eel (Anguilla anguilla) is rapidly declining, and migration barriers in rivers are believed to be one of several key causes. While progress has been made in the development of bypass solutions, they are often constructed based on a limited knowledge of swimming behaviour. A bypass close to the stream bed is often recommended at fish passage facilities to accommodate downstream eel migration. The results of this recommendation are poorly studied, and the few studies that exist show varying bypass efficiencies. The current study used acoustic telemetry with depth sensors to explore the three-dimensional migratory behaviour of downstream-migrating silver eels. The eels were tracked as they approached a hydropower plant with a state-of-the-art angled bar rack and full-depth bypass. Downstream and upstream swimming differed in preferred vertical and lateral positions. During periods of local downstream movement, the density of observations was largest in the upper middle section, away from the river boundaries and in higher velocities. Conversely, when moving upstream, eels tended to avoid the upper layers of the middle part of the river, swimming closer to the riverbed and using the bank areas to a greater extent. Downstream-moving fish swam higher in the water column during night and in turbid conditions (high discharge). When approaching the impassable bar rack and the full-depth bypass, the eels searched most intensely but not exclusively along the bottom third of the rack, often exploring at new depths after changing direction. The impediment passage efficiency was 100% when both bypass solutions were considered. The study provides knowledge of the swimming behaviour of silver eels, which is relevant for the design of bypass solutions for eels at migration barriers.     

A review of selected South- and East Asian Tanytarsus v.d. Wulp (Diptera: Chironomidae)

Male and pupa of Tanytarsus calorifontis sp. n. are described. Diagnoses, hypopygium drawings for the examined species and distribution are given for: Tanytarsus akantertiusSasa & Kamimura, T. angulatus Kawai, T. atagoensis Tokunaga,T. bathophilusKieffer, T. boninensis Tokunaga, T. formosae (Kieffer), T. formosanusKieffer, T. infundibulusChaudhuri & Datta, T. kikuchiiSasa, Kawai & Ueno, T. konishii Sasa & Kawai, T. mcmillani Freeman, T. mendax Kieffer, T. miyakobrevis Sasa & Hasegawa, T. monstrosus Chaudhuri et al., T. ogasaquartus Sasa & Suzuki, T. ogasatertius Sasa & Suzuki, T. okuboi Sasa & Kikuchi, T. oscillans Johannsen, T. ovatus Johannsen, T. oyamai Sasa, T. pollexus Chaudhuri & Datta, T. shouautumnalis Sasa, T. shoudigitatus Sasa, T. takahashii Kawai & Sasa, T. tamaundecimus Sasa, T. tonebeceus Sasa & Tanaka, T. tusimatneousSasa & Suzuki, T. unagiseptimus Sasa, T. uraiensis Tokunaga, T. yakuheiusSasa & Suzuki and T. yunosecundus Sasa. Tanytarsus ikiefeus Sasa & Suzuki is a new junior synonym of T. konishii. Tanytarsus ikifegeus Sasa & Suzuki, T. miyakoflavus Sasa & Hasegawa,T. oyabepallidus Sasa, Kawai & Ueno, T. simantoopeus Sasa et al. and T. tusimatheius Sasa & Suzuki are new junior synonyms of T. okuboi. Tanytarsus nippogregarius Sasa & Kamimura is a new junior synonym of T. bathophilus. Tanytarsus cultellus Chaudhuri & Datta and T. sibafegeus Sasa et al. are new junior synonyms of T. oscillans.Tanytarsus insulus (Guha et al., 1985) is a new junior synonym of T. ovatus. Tanytarsus sakishimanus Sasa & Hasegawa, T. vinculus Chaudhuri et al., T. parvistylus Chaudhuri & Datta, T. fusciabdominalis Guha et al. and T. euformosanus Kikuchi & Sasa are new junior synonyms of T. formosanus. Tanytarsus tsutaprimus Sasa, T. tokarajekeus Sasa & Suzuki, T. tusimatlemeus Sasa & Suzuki, T. tusimatopeus Sasa & Suzuki and T. yakugeheuus Sasa & Suzuki are new junior synonyms of T. shouautumnalis. Tanytarsus togasiroidus Sasa & Okazawa is a new junior synonym of T. shoudigitatus. Tanytarsus tusimatjekeus Sasa & Suzuki and T. tusimatkeleus Sasa & Suzuki are new junior synonyms of T. akantertius, and Tanytarsus tusimatpequeus Sasa & Suzuki is a new junior synonym of T. tusimatneous. Virgatanytarsus toganiveus (Sasa & Okazawa), Cladotanytarsus utonaiquartus (Sasa) and Zavrelia tusimatijeus (Sasa & Suzuki), all previously placed in Tanytarsus, are new combinations.     

PRODUCTIVITY AND DIVERSITY IN A CROSS‐FEEDING POPULATION OF ARTIFICIAL ORGANISMS

Cross‐feeding interactions are a common feature of many microbial systems, such as colonies of Escherichia coli grown on a single limiting resource, and microbial consortia cooperatively degrading complex compounds. We have studied this phenomenon from an abstract point of view by considering artificial organisms that metabolize binary strings from a shared environment. The organisms are represented as simple cellular automaton rules and the analog of energy in the system is an approximation of the Shannon entropy of the binary strings. Only organisms that increase the entropy of the transformed strings are allowed to replicate. This system exhibits a large degree of species diversity, which increases when the flow of binary strings into the system is reduced. Investigating the relation between ecosystem productivity and diversity we find that diversity is negatively correlated with biomass production and energy uptake, while it correlates positively with energy‐uptake efficiency. By performing invasion experiments, we show that the source of diversity is negative frequency‐dependent selection acting among the different species, and that some of these interactions are intransitive, another mechanism known to promote diversity.     

Seasonal flooding decreases fruit-feeding butterfly species dominance and increases spatial turnover in floodplain forests of central Amazonia

The seasonal flood pulse in Amazonia can be considered a primary driver of community structure in floodplain environments. Although this natural periodic disturbance is part of the landscape dynamics, the seasonal inundation presents a considerable challenge to organisms that inhabit floodplain forests. The present study investigated the effect of seasonal flooding on fruit-feeding butterfly assemblages in different forest types and strata in central Amazonia. We sampled fruit-feeding butterflies in the canopy and the understory using baited traps in adjacent upland (unflooded forests—terra firme), white and blackwater floodplain forests (várzea and igapó, respectively) during the low- and high-water seasons. Butterfly abundance decreased in the high-water season, especially of dominant species in várzea, but the number of species was similar between seasons in the three forest types. Species composition differed between strata in all forest types. However, the flood pulse only affected butterfly assemblages in várzea forest. The β-diversity components also differed only in várzea. Species replacement (turnover) dominated the spatial β-diversity in igapó and terra firme in both seasons and várzea in the high-water season. Nonetheless, nestedness was relatively higher in várzea forests during the low-water season, mainly due to the effect of dominant species. These results emphasize the importance of seasonal flooding to structure butterfly assemblages in floodplain forests and reveal the idiosyncrasy of butterfly community responses to flooding in different forest types. Our results also suggest that any major and rapid changes to the hydrological regime could severely affect floodplain communities adapted to this natural seasonal hydrological cycle, threatening the existence of these unique environments.     

Caries in the infundibulum of the second upper premolar tooth in the horse

Background  

Swedish equine dental practices have empirically found that the prevalence of infundibular caries as a primary disorder in the first permanent premolar teeth (P2) of the horse upper jaw has increased during the last 10 years. A previously unknown bacterial species, Streptococcus devriesei (CCUG 47155^T), which is related to Streptococcus mutans, has recently been isolated from these carious lesions. To understand the aetiology of caries in horses, it is essential to elucidate the relationship between S. devriesei and P2 infundibular caries.     

Trajectories of sleepiness and insomnia symptoms in Norwegian nurses with and without night work and rotational work

Numerous cross-sectional studies report high prevalence rates of sleepiness and insomnia in shift workers, but few longitudinal studies exist. We investigated trajectories of sleepiness and insomnia symptoms in a sample of Norwegian nurses across four measurements, spanning a total of four years (sleepiness) and five years (insomnia). The participants completed the Epworth Sleepiness Scale and the Bergen Insomnia Scale at each measurement instance. Latent growth curve models were used to analyse the data. Separate models examined night work (night work, entering and leaving night work) and rotational work (rotational work, entering and leaving rotational work) as predictors for trajectories of sleepiness and insomnia symptoms, respectively. Baseline values of sleepiness and insomnia were higher among rotational shift workers than among workers with fixed shifts (day or night). The results showed that night work throughout the period and entering night work during the period were not associated with different trajectories of sleepiness or insomnia symptoms, compared to not having night work. The same results were found for rotational work and entering rotational work, compared to not having rotational work. Leaving night work and leaving rotational work were associated with a decrease in sleepiness and insomnia symptoms, compared to staying in such work.     

Determination of small amounts of noradrenaline using a fluorescence histochemical method

Summary Using the Hayashi method, the distribution of glucosaminidase was studied throughout sequential molar development. Conspicuous activity was observed in certain cellular components of the stellate reticulum and dental papilla. The outer enamel epithelium, stratum intermedium and ameloblasts displayed less intense reactions.Supported by PHS Grant No. 2800-02 —Tooth Germ Development, National Institute of Dental Research, National Institutes of Health.Lieutenant Commander, Dental Corps, United States Navy.     

HPLC determination of xylulose formed by enzymatic xylose isomerization in lignocellulose hydrolysates

Summary In the concentration range appropriate for enzymatic xylose isomerization, xylulose was measured in a lignocellulose hydrolysate using HPLC with two hydrogen loaded ion exchange columns in series. Spent sulphite liquour (SSL) was used as a model for lignocellulose hydrolysates. In buffer the separation took 22 minutes and in SSL the analysis time was 47 minutes due to the presence of ethanol. The enzymatic isomerization of xylose to xylulose was followed directly in SSL, providing a method for the direct determination of xylose isomerase activity in lignocellulose hydrolysates.