RESIDUES OF THE BETA-AGONIST CLENBUTEROL IN TISSUES OF MEDICATED FARM-ANIMALS

Reports of the illegal use of clenbuterol as a growth promotant prompted the development of a competitive enzyme immunoassay for this drug. This procedure was utilized to study the elimination of clenbuterol from tissues in sheep medicated with both therapeutic and growth-promoting doses of the drug. The results indicated that prior to removal of medication clenbuterol was widely distributed throughout the animal tissues. However as the withdrawal periods increased fluid targets such as urine and bile became less effective at detecting clenbuterol usage. At both therapeutic and growth-enhancing concentrations of clenbuterol liver samples remained positive up to the maximum withdrawal time given in this experiment (15 days). Concentrations of clenbuterol likely to cause food poisoning (> 100 ng/g) were only detected in liver samples taken prior to the removal of medication. The highest recorded concentration of clenbuterol in muscle was 22.5 ng/g.

Ritual, Play and Animals in early human societies: Manipulating the Bones in temple period Malta: Eating and Augury in the Maltese Temples.

Examination of antiquarian records and feasting ritual in prehistoric Malta

Potential hazard to human health from exposure to fragments of lead bullets and shot in the tissues of game animals

Lead is highly toxic to animals. Humans eating game killed using lead ammunition generally avoid swallowing shot or bullets and dietary lead exposure from this source has been considered low. Recent evidence illustrates that lead bullets fragment on impact, leaving small lead particles widely distributed in game tissues. Our paper asks whether lead gunshot pellets also fragment upon impact, and whether lead derived from spent gunshot and bullets in the tissues of game animals could pose a threat to human health.

Arsenic residues in predatory birds from an area of Britain with naturally and anthropogenically elevated arsenic levels

Birds of prey forage over large areas and so might be expected to accumulate contaminants which are elevated but heterogeneously distributed in the general environment. The aim of this study was to test the hypothesis that arsenic levels in raptors from a region with elevated environmental arsenic concentrations were higher than those in birds from an uncontaminated part of Britain. Arsenic concentrations in the liver, kidney and muscle of kestrels, Falco tinnunculus, sparrowhawks, Accipiter nisus, and barn owls, Tyto alba, from south-west (SW) England, an area with naturally and anthropogenically (through mining) elevated environmental arsenic concentrations, were compared with those in birds from SW Scotland, where no such geochemical anomaly exists. Arsenic residues in kestrels from SW England were approximately three times greater than those in birds from SW Scotland for the three tissue types analysed. This was not the case for the other species in which arsenic residues were similar in birds from both regions. It is suggested that differences between species in both diet and arsenic metabolism could explain why kestrels have elevated arsenic tissue burdens in response to general environmental contamination but sparrowhawks and barn owls do not.

Understanding how animals fight with Lloyd Morgan's canon

Various game theory models have been used to explain animal contests. Here we attend to the presumed cognitive abilities required by these models with respect to information gathering and consequent decision making. Some, such as the hawk/dove game and self-assessment models require very limited cognitive ability. By contrast, the broadly accepted sequential assessment model requires that contestants know their own abilities and compare them with information gathered about their opponent to determine which has the greater resource-holding power. However, evidence for assessment of relative abilities is sparse and we suggest that this complex ability is probably beyond most animals. Indeed, perceptual limitations may restrict information about an individual's own displays and thus preclude comparison. We take a parsimonious view and conclude that simple summation of causal factors accounts for changes in fight motivation without requiring mutual evaluation of relative abilities. © 2012 The Association for the Study of Animal Behaviour.

Freshwater pearl mussels show plasticity of responses to different predation risks but also show consistent individual differences in responsiveness

Animals often show behavioural plasticity with respect to predation risk but also show behavioural syndromes in terms of consistency of responses to different stimuli. We examine these features in the freshwater pearl mussel. These bivalves often aggregate presumably to reduce predation risk to each individual. Predation risk, however, will be higher in the presence of predator cues. Here we use dimming light, vibration and touch as novel stimuli to examine the trade-off between motivation to feed and motivation to avoid predation. We present two experiments that each use three sequential novel stimuli to cause the mussels to close their valves and hence cease feeding. We find that mussels within a group showed shorter closure times than solitary mussels, consistent with decreased vulnerability to predation in group-living individuals. Mussels exposed to the odour of a predatory crayfish showed longer closures than control mussels, highlighting the predator assessment abilities of this species. However, individuals showed significant consistency in their closure responses across the trial series, in line with behavioural syndrome theory. Our results show that bivalves trade-off feeding and predator avoidance according to predation risk but the degree to which this is achieved is constrained by behavioural consistency. © 2011 Elsevier B.V.

Predicting the predatory impacts of the “demon shrimp” Dikerogammarus haemobaphes, on native and previously introduced species

Biological invasions continue to exert pressure on ecosystems worldwide and we thus require methods that can help understand and predict the impacts of invasive species, on both native species and previously established invaders. Comparing laboratory derived functional responses among invasive and native predators has emerged as one such method, providing a robust proxy for field impacts. We used this method to examine the likely impacts of the Ponto–Caspian amphipod Dikerogammarus haemobaphes, known as the “demon shrimp”, a little investigated invader in European freshwaters that has recently established in the British Isles. We compared the functional responses on two prey species of D. haemobaphes with two other amphipod species: Dikerogammarus villosus, a congeneric invasive with well-documented impacts on macro-invertebrate communities and a native amphipod, Gammarus pulex. Prey species were native Chironomus sp. and the invasive Chelicorophium curvispinum, a tube-building amphipod also originating from the Ponto–Caspian region. D. villosus showed higher Type II functional responses towards both prey species than did D. haemobaphes and G. pulex, with the latter two predators exhibiting similar impacts on the native prey. However, D. haemobaphes had higher functional responses towards the invasive C. curvispinum than did G. pulex, both when prey individuals were tubeless and resident in their protective mud tubes. Thus, we demonstrate that functionally equivalent invasive congeners can show significantly different impacts on prey, regardless of shared evolutionary history. We also show that some predatory invaders can have impacts on native prey equivalent to native predator impacts, but that they can also exert significant impacts on previously introduced prey. We discuss the importance of invasion history and prey identity when attempting to understand and predict the impacts of new invaders.