The inland distribution of brackish-water Gammarus species in the area of the Mersey and Weaver River Authority

(1) Many inland saline waters exist in Cheshire and South Lancashire mostly in association with the Cheshire Salt Field. (2) The presence of brackish-water Gammarus species in this area has been known for many years but has never previously been fully documented. (3) The saline waters are described in detail. (4) The distribution of three species of Gammarus in all these waters is also described. (5) Theories are put forward to explain the presentday distribution of the species in relation to the possible points of entry into the area.     

Amino acid requirements for the growth and production of some exocellular products of Staphylococcus aureus

A simple, defined synthetic medium has been developed for the growth of a toxic-shock-syndrome-associated Staphylococcus aureus strain (FRI 1187) in continuous culture, which gives a high growth yield and assayable amounts of acid phosphatase, haemolytic activity, hyaluronate lyase and toxic-shock-syndrome toxin-1. It consists of multiple ions, ammonium sulphate, glucose, cystine, aspartate, glutamate, arginine, glycine, proline, nicotinic acid and thiamine.     

Separating Components of Variation in Survival of Mule Deer in Colorado

ABSTRACT Survival is an important parameter for understanding population dynamics of mule deer (Odocoileus hemionus) and other large herbivores. To understand long-term dynamics it is important to separate sampling and biological process variation in survival. Moreover, knowledge of correlations in survival across space and between young and adults can provide more informed predictions of survival in unsampled areas. We estimated survival of fawn, yearling, and adult mule deer from 4 spatially separated regions of Colorado, USA, from 1997 to 2008. We also estimated process variance in survival across time for each age and site using Markov chain Monte Carlo (MCMC) methods. Finally, we estimated correlations in survival among sites and ages with MCMC methods. Average winter fawn survival was 0.721 (SD = 0.024) for the 4 regions. Average winter adult female survival was 0.935 (SD = 0.007). Annual adult female survival ranged from 0.803 (SD = 0.017) to 0.900 (SD = 0.028) for the 4 regions, excluding hunting mortality. The correlation between fawn and adult female survival was high, 0.563 (SD = 0.253). Correlations in winter fawn survival were higher between populations at the same latitude than they were for populations to the north and south. We used survival estimates from our analysis to inform prior distributions for a Bayesian population dynamics model from one population in Colorado and compared that model to one with noninformative prior distributions. Population models including informative prior distributions based on our results performed better than those noninformative prior distributions on survival, providing more biologically defensible results when data were sparse. Knowledge of process distributions of survival can help wildlife managers better predict future population status and understand the likely range of survival rates.     

QUIET SONG IN SONG BIRDS: AN OVERLOOKED PHENOMENON

ABSTRACT

The theory of communication networks offers functional arguments for the evolution of unobtrusive signals in birds. The vulnerability of interacting conspecifics to predation and to eavesdropping by neighbours during both territorial disputes and courtship would select for short range signals such as the quiet songs of birds. In addition to suggesting contexts in which quiet songs should be used, we use our knowledge of the physics of sound transmission to make predictions about the physical structure of such songs relative to the well studied full songs. We present support for these predictions in six species where quiet singing has been observed.     

Abundance,species richness and feeding preferences of introduced molluscs in native grasslands of Victoria,Australia

Abstract Introduced molluscs have invaded endangered, remnant native grasslands of south‐eastern Australia, but few studies have investigated their distribution, abundance or potential impact. Molluscs were surveyed in grassland sites across an urban to rural transect west of Melbourne, Australia. It was confirmed that several introduced mollusc species have invaded these areas. Three snail and five slug species were identified, none of which was native to Australia. The most common species was the brown field slug (Deroceras panormitanum). Mollusc capture and species richness were positively related to the degree of urbanization in the surrounding landscape. There was also a negative relationship with fire frequency. Feeding trials revealed selective herbivory by the black‐keeled slug (Milax gagates) among native plants. Anecdotal evidence that variable glycine (Glycine tabacina) and button wrinklewort (Rutidosis leptorrhynchoides) are palatable to molluscs was supported. Mollusc herbivory may potentially lead to reduced fitness of palatable species, and changes in community composition and structure.     

Inferring changes in foliar mass and area from foliage cover: A mechanistic model

Measuring foliar area or mass directly is destructive, and precludes long‐term, repeated observations of individual trees as they suffer or recover from foliar damage. Instead, foliage cover indices are often used as a proxy for foliar mass. Patterns of fluctuations in foliage cover indices can be used to infer qualitative changes in canopy health. However, foliage cover is not necessarily linearly related to foliar area or mass, and this may confound the detection of significant foliar damage, and comparisons of herbivore browse impacts between individual trees, tree species or sites. I derived a mechanistic model to quantify the relationship between foliar area or mass and foliage cover measured as the proportion of sky occluded by leaves. This one parameter model is close to linear for single‐tiered trees, but increasingly non‐linear for multi‐tiered trees. I compared the non‐linear model to a linear model using foliage cover data from an artificial defoliation experiment on two single‐tiered, sub‐canopy species and from simulated photographic images of single‐ and multi‐tiered canopies. The non‐linear model had lower errors than the linear model, and errors did not increase with foliage density (leaf area per unit area), variation (of leaf sizes within and between canopies) or leaf geometry. The non‐linear model can be easily parameterized from relatively low‐cost observations of foliage cover, independently of empirical measurements of foliar area or mass, and is applicable to a wide range of tree species. It should therefore help managers quantify how changes in foliage cover due to natural fluctuations or foliar damage affect foliar area and mass, and can be used to quantify parameters for models of browse impacts in mixed forest.     

The relationship between possum density and browse damage on kamahi in New Zealand forests

To minimize the impacts of introduced pests and to justify and prioritize pest control, managers need to know the relationship between pest density and damage. This relationship can be difficult to quantify because pest impacts can be highly variable. In New Zealand, introduced brushtail possums (Trichosurus vulpecula) browse a wide range of native forest species. However, possum browse is extremely patchy making it difficult to quantify the relationship between density and damage, meaning the benefits of reducing possum densities are poorly understood. We quantified patterns of possum browse on kamahi (Weinmannia racemosa), a common canopy tree species, at 21 forest sites that were repeat‐measured over an 8‐year period in the North Island, New Zealand, during which time possum densities fluctuated widely. We fitted a multilevel statistical model in order to quantify the relationship between possum density and browse damage while simultaneously quantifying how browse varied among trees, sites and years. Higher possum densities were associated with greater browse damage, but browse was also patchily distributed among trees at the same site, and among sites and years for a given possum density. This heterogeneity meant there was no simple density damage relationship, with the relationship differing from tree to tree and among sites and years. Our results show that at most sites reductions in possum density would have little benefit in reducing the probability of heavy browse on kamahi trees, but at a few sites there would be substantial benefits. This approach provides insights into the pattern and potential causes of variability in possum impacts, and a quantitative basis for prioritizing sites for possum control.     

Effect of myrrh and thyme on Trichinella spiralis enteral and parenteral phases with inducible nitric oxide expression in mice

Trichinellosis is a serious disease with no satisfactory treatment. We aimed to assess the effect of myrrh (Commiphora molmol) and, for the first time, thyme (Thymus vulgaris L.) against enteral and encysted (parenteral) phases of Trichinella spiralis in mice compared with albendazole, and detect their effect on inducible nitric oxide synthase (iNOS) expression. Oral administration of 500 mg/kg of myrrh and thyme led to adult reduction (90.9%, 79.4%), while 1,000 mg/kg led to larvae reduction (79.6%, 71.3%), respectively. Administration of 50 mg/kg of albendazole resulted in adult and larvae reduction (94.2%, 90.9%). Positive immunostaining of inflammatory cells infiltrating intestinal mucosa and submucosa of all treated groups was detected. Myrrh-treated mice showed the highest iNOS expression followed by albendazole, then thyme. On the other hand, both myrrh and thyme-treated groups showed stronger iNOS expression of inflammatory cells infiltrating and surrounding encapsulated T. spiralis larvae than albendazole treated group. In conclusion, myrrh and thyme extracts are highly effective against both phases of T. spiralis and showed strong iNOS expressions, especially myrrh which could be a promising alternative drug. This experiment provides a basis for further exploration of this plant by isolation and retesting the active principles of both extracts against different stages of T. spiralis.