Optimized biophysical model for Icelandic cod (Gadus morhua) larvae

A characteristic of biophysical models (BPM) is that they contain a number of parameters that are poorly known or only known within a range of possible values. This paper describes an efficient optimized BPM developed to simulate the Icelandic cod pelagic 0‐group survey data. The method is based on presenting the results as a probability density function (PDF) that a particle released from a given spawning drifts downstream to a given grid location some time later. The model determines egg production model parameters (peak spawning time, spawning duration, number of eggs released) for each of 15 spawning grounds as the solution of a bound constrained optimization problem that minimizes model‐data misfits in abundance and age distributions. The model is applied to simulating the 2002 and 2003 summer survey data. The model does a reasonable job of simulating the observed inshore / offshore abundance gradient and spatial age gradient for each year. Problem areas are explained from the point of view of model limitations. We caution that the results from an optimized model should always be assessed with the model’s limitations in mind and with respect to whatever biological data are available.     

Nesting Habitat Selection by Crested Tits Parus cristatus in a Pine Plantation

Habitats surrounding nest boxes used and not used by crestedtits were compared at Culbin Forest, a plantation composed largelyof Scots and Corsican pines. Crested tits preferred to nestin boxes where the trees were thinner (median d.b.h. 13.7 cm).Diameter was correlated with tree height and negatively correlatedwith tree density. The ideal nesting site for crested tits maytherefore be a combination of a large rotten stump (rare inpine plantations) in which to nest and surrounding cover ofmoderately-sized closely-space trees (rare in semi-natural pineforests).     

The Effects of Nitrogen Fertiliser at Different Rates and Times of Application on the Growth of Sitka Spruce in Upland Britain

At seven experiment sites in Scotland and northern England theeffects of different rates (0 to 150 kg N ha^–1) and seasonof nitrogen (N) fertiliser application on the height growthof Sitka spruce were examined. A comparison of urea and ammoniumnitrate was included to determine the most effective sourceof N. At each site, height and foliar nutrient concentrationswere measured. The sites chosen displayed different degrees of N-deficiencywhich was reflected in foliar N levels and height growth responses.The largest responses to application of N occurred at the mostdeficient sites and foliar N concentration of the untreatedcrop could be used to predict the likely magnitude of response.However, neither the season of application nor the differentfertilisers used had any effect on height growth.     

The Effects on Song-Bird Populations of Upland Afforestation with Spruce

1. Large coniferous plantations have been established widely inuplands previously used for rearing sheep and cattle, causingfundamental changes in the wild life of these areas.
2. Breedingsong-birds were censused in south-west Scotland onupland moorlandgrazed by sheep and in spruce plantations atdifferent stagesof growth.
3. The commonest song-bird species were meadow pipitand skylarkon unplanted areas, meadow pipit in establishmentplantation,willow warbler and wren in thicket, and goldcrest,chaffinchand wren in polestage and thinned plantations.
4. Totalsong-bird densities were 40–70 pairs km^–2on unplantedheather, 70–130 pairs km^–2 on unplantedgrass, 125–200pairs km^–2 on 6 year old trees, 230–290pairs km^–2on 12–14 year old trees, and 300–440pairs km^–2on trees over 20 years old. Bird species diversitywas alsogreatest in trees over 20 years old, with one exception.
5. Manybird species depend on unafforested moorland, but werenot censusedsince they are too sparsely distributed. Theirloss is to beset against the gain in numbers of smaller songbirds followingafforestation which was inferred from the studyplots. Fromthe standpoint of bird conservation, diverse foreststructureand the retention of some large unafforested uplandareas isadvocated.

     

Pharmacokinetics of an orally administered methylcellulose formulation of gallium maltolate in neonatal foals

Chaffin, M. K., Fajt, V., Martens, R. J., Arnold, C. E., Cohen, N. D., O’Conor, M., Taylor, R. J., Bernstein, L. R. Pharmacokinetics of an orally administered methylcellulose formulation of gallium maltolate in neonatal foals. J. vet. Pharmacol. Therap. doi: 10.1111/j.1365‐2885.2009.01150.x. Gallium is a trivalent semi‐metal with anti‐microbial effects because of its incorporation into crucial iron‐dependent reproductive enzyme systems. Gallium maltolate (GaM) provides significant gallium bioavailability to people and mice following oral administration and to neonatal foals following intragastric administration. To study the prophylactic and therapeutic effects of GaM against Rhodococcus equi pneumonia in foals, we developed a methylcellulose formulation of GaM (GaM‐MCF) for oral administration to neonatal foals. Normal neonatal foals were studied. Six foals received 20 mg/kg and another six foals received 40 mg/kg of GaM‐MCF orally. Serial serum samples were collected and serum gallium concentrations were determined using inductively coupled plasma mass spectroscopy. Gallium was rapidly absorbed (T_max of 4 h), and a mean C_max of 0.90 or 1.8 μg/mL was achieved in foals receiving 20 or 40 mg/kg respectively. Marked variability existed in C_max among foals: only half of the foals receiving 20 mg/kg attained serum concentrations of >0.7 μg/mL, a level suggested to be therapeutic against R. equi by previous studies. Mean elimination half‐life was 32.8 or 32.4 h for foals receiving 20 or 40 mg/kg respectively. The results of this study suggest that at least 30 mg/kg orally every 24 h should be considered in future pharmacodynamic and efficacy studies.     

Ovulation,Pregnancy Rate and Early Embryonic Development in Vernal Transitional Mares Treated with Equine‐ or Porcine‐FSH

The objective of this study was to compare the efficacy of purified equine‐ and porcine‐FSH treatment regimes in mares in early vernal transition. Mares (n = 22) kept under ambient light were examined ultrasonographically per‐rectum, starting January 30th. They were assigned to one of two treatment groups using a sequential alternating treatment design when a follicle ≥ 25 mm was detected. In the eFSH group, mares were treated twice daily with equine‐FSH, and in the pFSH group mares were treated twice daily with porcine‐FSH; treatments were continued until follicle(s) ≥ 35 mm, and 24 h later hCG was administered. Oestrous mares were inseminated with fresh semen and examined for pregnancy on days 11–20 post‐ovulation. In the eFSH group, 11/11 (100%) mares developed follicle(s) ≥ 35 mm, 8/11 (73%) ovulated and 6/8 (75%) conceived. In the pFSH group, 5/11 (45%) developed follicle(s) ≥ 35 mm, 4/11 (36%) ovulated and 3/4 (75%) conceived. Treatment with eFSH resulted in a greater ovarian stimulation; higher number of pre‐ovulatory‐sized follicles, higher number of ovulations and higher number of embryos (p < 0.05). Following ovulation, serum progesterone concentrations were correlated with the number of CLs and supported early embryonic development; maternal recognition of pregnancy occurred in all pregnant mares. We concluded that eFSH can be used to effectively induce follicular growth and ovulation in vernal transitional mares; however, if bred, diagnosis and management of twins’ pregnancies would be required prior to day 16 because of the increased risk of multiple embryos per pregnancy. Conversely, the current pFSH treatment regime cannot be recommended.