Predation risk and feeding patterns of crucian carp

As part of an experimental study of the direct and indirect effects of piscivory on prey fish, the diets of crucian carp Carassius carassius were compared across sections of a divided pond; two sections were stocked with crucian carp alone and two with crucian carp plus perch Perca fluviatilis . Analysis of crucian gut contents indicated that the composition of invertebrate prey did not differ in the presence v . absence of perch. However, crucians, particularly small individuals (<10cm) that were most vulnerable to predation, displayed a lower intake of invertebrate prey in sections with perch. Although diet composition differed between crucians caught in inshore v. offshore habitats (with habitat use being related to crucian size and the presence or absence of perch), no clear pattern existed between habitat and total food intake. Overall, the major effects of predators on the diet of crucian carp appeared to be caused by increased ecological density (resulting from confinement of small crucians inshore) and reduced activity levels, rather than simple shifts to safer habitats.     

Do Insectivorous Birds use Volatile Organic Compounds from Plants as Olfactory Foraging Cues? Three Experimental Tests

Some insectivorous birds orient towards insect‐defoliated trees even when they do not see the foliar damage or the herbivores. There are, however, only a few studies that have examined the mechanisms behind this foraging behaviour. Previous studies suggest that birds can use olfactory foraging cues (e.g. volatile organic compounds (VOCs) emitted by defoliated plants), indirect visual cues or a combination of the two sensory cues. VOCs from insect‐defoliated plants are known to attract natural enemies of herbivores, and researchers have hypothesized that VOCs could also act as olfactory foraging cues for birds. We conducted three experiments across a range of spatial scales to test this hypothesis. In each experiment, birds were presented with olfactory cues and their behavioural responses or foraging outcomes were observed. In the first experiment, two different VOC blends, designed to simulate the volatile emissions of mountain birch (Betula pubescens ssp. czerepanovii) after defoliation by autumnal moth (Epirrita autumnata) larvae, were used in behavioural experiments in aviaries with pied flycatchers (Ficedula hypoleuca). The second experiment was a field‐based trial of bird foraging efficiency; the same VOC blends were applied to mountain birches, silver birches (B. pendula) and European white birches (B. pubescens) with plasticine larvae attached to the trees to serve as artificial prey for birds and provide a means to monitor predation rate. In the third experiment, the attractiveness of silver birch saplings defoliated by autumnal moth larvae versus intact controls was tested with great tits (Parus major) and blue tits (Cyanistes caeruleus) in an aviary. Birds did not orient towards either artificial or real trees with VOC supplements or towards herbivore‐damaged saplings when these saplings and undamaged alternatives were hidden from view. These findings do not support the hypothesis that olfactory foraging cues are necessary in the attraction of birds to herbivore‐damaged trees.     

Detecting early kidney damage in horses with colic by measuring matrix metalloproteinase -9 and -2, other enzymes,urinary glucose and total proteins

Background  

The aim of the study was to investigate urine matrix metalloproteinase (MMP-2 and -9) activity, alkaline phosphatase/creatinine (U-AP/Cr) and gamma-glutamyl-transpeptidase/creatinine (U-GGT/Cr) ratios, glucose concentration, and urine protein/creatinine (U-Prot/Cr) ratio and to compare data with plasma MMP-2 and -9 activity, cystatin-C and creatinine concentrations in colic horses and healthy controls. Horses with surgical colic (n = 5) were compared to healthy stallions (n = 7) that came for castration. Blood and urine samples were collected. MMP gelatinolytic activity was measured by zymography.     

Aphid response to elevated ozone and CO2

Numerous reports indicate that pollution stress caused by sulphur dioxide (SO₂), oxies of nitrogen or fluorides promote aphid growth on herbaceous and woody plants. At SO₂ exposures, the response curve of aphids is bell-shaped having the peak at 100 ppb. This curvilinear response is related to physiological stress responses of host plants exposed to pollutants. On the other hand, observations of aphid performance on ozone-exposed (O₃) or elevated carbon dioxide-exposed (CO₂) plants have given very variable results. Depending on the duration and concentration of O₃ or elevated CO₂ exposure or the age of the exposed plants, aphid growth on the same plants either decreased or increased in comparison to growth on control plants grown in filtered air. The results of these studies suggest that there is no general air pollution-induced plant stress that triggers aphid outbreaks on plants. Plants grown in elevated CO₂ usually have higher C/N ratios than plants grown in current ambient CO₂ atmosphere. A reduced proportion of nitrogen in the plant foliage decreases growth of chewing herbivorous insects, but the few studies of elevated CO₂ effects on sucking insects such as aphids have not yielded similar consistent effects. The present paper reviews recent studies of elevated CO₂ effects on aphids and discusses the effects of combined elevated O₃ and CO₂ exposures on aphid performance on woody plants using pine and birch aphids as examples.     

State of Lake Sysmäjärvi,Eastern Finland,after loading with mine water and municipal waste water for several decades

Hydrobiologia - The deep mining of copper and nickel at Outokumpu, Eastern Finland, lasted from 1910 to the late 1980s, during which period metalliferous waste water of high conductivity and...