Spring home ranges of white bass in irrigation reservoirs of the Republican River Basin, Nebraska

Abstract –  Fishery biologists have documented small home ranges, relative to available habitat, for many littoral freshwater fishes. Home ranges for pelagic species, such as white bass Morone chrysops , are generally not well described, yet are thought to be large. We studied white bass movement using acoustic telemetry in two irrigation reservoirs of the Republican River basin in south-western Nebraska. Acoustic transmitters were implanted in fall of the previous year and tracking occurred a minimum of once per week throughout spring (mid-March to May) 2007 and 2008. Linear home ranges were calculated from observed locations of individual fish. Twelve of the twenty-seven tagged fish with at least five locations exhibited localised home ranges throughout the spring whereas the remaining fish exhibited home ranges extending across large portions of each reservoir. Home range size was not correlated with fish size or condition.     

Characterization of pea accessions by SRAP's markers

Sequence-related amplified polymorphism (SRAP) and morphological markers to estimate the genetic relations among forty pea varieties (Pisum sativum L.) were studied. Data on 15 morphological traits were collected and analyzed. A total of 162 polymorphic SRAP's bands were scored using seven combinations of primers. Cluster analysis and both principal component and principal coordinate analysis were carried out. The varieties were grouped in four clusters through procrustes generalized analysis. Relationships among varieties revealed by molecular markers were significantly correlated with those based on the agronomic traits, suggesting that the two systems give similar estimates of genetic relations among the varieties. Parents selection depend on the specific objectives in further breeding programs.     

Behavioural transition during the estuarine migration of wild Atlantic salmon (Salmo salar L.) smolt

Abstract –  Ultrasonic telemetry and hydrodynamic modelling were used to study the migratory behaviour of 54 wild Atlantic salmon ( Salmo salar ) smolt captured in freshwater during their downstream migration and tracked in 2 years through a shallow estuary system. A high-density, fixed array of receivers provided detailed spatial and temporal resolution of behaviour in the second year of study. Smolt migration in the river occurred mostly at night and downstream migration was slower during the day. In the estuary, smolt moved seaward on ebbing tides and landward on flooding tides. The effect of current velocity was greater during the night than during the day. We documented for the first time that current velocity and diurnal period only accounted for approximately one-third of the variation in smolt ground speeds in the estuary, indicating that smolt movements were far less passive than previously reported. Smolt energetic status had no effect on smolt swimming behaviour or migratory performance. With an increase in salinity, smolt seaward movements during flooding tides were more frequent, and overall seaward ground velocity increased. The increase in salinity experienced by the smolt during their migration through the leading edge of saltwater intrusion thus induced a behavioural transition from a more passive, fluvial migration to a more active- and seaward-oriented migration.     

Alternative migratory strategies are widespread in subyearling Chinook salmon

Variation in life history traits within and across species is known to reflect adaptations to different environmental drivers through a diversity of mechanisms. Trait variation can also help buffer species and populations against extinction in fluctuating environments and against anthropogenic disturbances. Here, we examine the distribution and drivers of Ocean‐type Chinook salmon (Oncorhynchus tschawytscha) juvenile migratory life histories. We defined alternative migratory strategies according to whether individuals reared in the stream (natal rearing) or left shortly after hatching to rear elsewhere (non‐natal rearing). We then evaluated the frequency of migratory strategies across 16 populations with time series extending up to 25 years and evaluated the environmental variables that influenced variation in migration strategy. We found bimodal migration patterns and abrupt transitions in migrant sizes across all populations, supporting the widespread nature of alternative migratory strategies. Additionally, we found that the amount of freshwater rearing habitat available to juveniles, relative juvenile density and spring flow patterns significantly influenced the overall migration pattern for populations. Smaller streams and higher conspecific densities generally produced more non‐natal rearing migrants and larger streams and lower conspecific densities producing more natal rearing migrants. Our results shed light on previously unexplored patterns of juvenile migratory strategies and encourage broader consideration for how current conservation actions perform at protecting juvenile migratory diversity.     

Beyond conidiobolomycosis – the other ‘zygomycoses’

Disease resulting from infection by Zygomycetes fungi (including two groups of coenocytic fungal pathogens: the Mucormycota and the Entomophthoramycota) has been collectively referred to as zygomycosis. Clinical disease associated with both the Mucormycota and the Entomophthoramycota is rarely encountered in horses. Potentially life-threatening, mucormycosis is an angioinvasive disease that principally affects immunocompromised individuals. The order of Entomophthorales include two genera: Conidiobolus and Basidiobolus. The most common of these, Conidiobolus coronatus, typically causes chronic necrohaemorrhagic tumefactions in the nostrils, nasal passages and nasopharyngeal walls of immunocompetent equine hosts, most commonly seen in the south-eastern USA and parts of Australia. Infection by Basidiobolus ranarum is reported less frequently and usually causes solitary ulcerative skin lesions with pruritus. This short commentary intends to complement the accompanying review of conidiobolomycosis by summarising reported cases of mucormycosis and basidiobolomycosis in horses. Moreover, some new information regarding taxonomic challenges to traditional ‘Zygomycosis’ classification is presented.     

Light quality and growth of Norway spruce (Picea abies (L.))

Seedling of Norway spruce (Picea abies L.) were grown under three different light qualities in fluid-roof growth chambers. Blue light with a high red/far-red ratio decreased shoot length as well as total plant dry weight compared to natural light. Yellow light with a low blue/red ratio did not significantly affect the plants. The effects of light quality were generally the same at 18, 24 and 28 °C day temperature. Plant growth was reduced at temperatures above 24 °C.