Effect of the presence of the shore crab, <Emphasis Type="Italic">Carcinus maenas</Emphasis>, on burrowing behaviour and clearance rate of the common cockle, <Emphasis Type="Italic">Cerastoderma edule</Emphasis>

Bivalves demonstrate various morphological and behavioural adaptations to reduce the risk of being attacked by predators. This paper examines how the presence of the crab Carcinus maenas (L.), a natural predator of the cockle Cerastoderma edule (L.), affects its burrowing depth and clearance or feeding rate. Cockles were placed in experimental tanks and treated with three levels of predatory disturbance: (1) unfed crab loose inside the tank, (2) unfed crab inside a cage suspended in the water column and (3) no crab present. Cockles’ burrowing depth was measured in two sediment types: mud and sand. Cockles burrowed more deeply in treatments with no crabs. Burrowing depth in sand was significantly greater than in mud. Two factors may contribute to the reduction in burial depth of C. edule in the presence of C. maenas: the change in the vertical orientation of the cockle and the ‘cough response’. No significant difference was found in the cockles’ clearance rate among the different levels of predator threat.     

Incipient Forest Decline in the Province of Trento (Northern Italy). Preliminary Sem Observations and Consideration of Inorganic Components of Leaves and Roots

One year old needles of both healthy and damaged silver fir and Norway spruce from the area of Trento (Northern Italy) were observed by SEM. Needles of damaged trees show quite evident structural alterations of epidermis, expecially epicuticular waxes. Roots and needles of both fir and spruce are also tested for their metal content. Evidence is reported of an increasing concentration of Fe, Mg and Ca in roots of plants grown on alkali soil. Ca, and to a lesser extent Fe, Al and Pb, appears to be more present in old needles, whereas K and Mg exhibit higher amounts in young needles. Some indications are found between damage and the content of some metals such as Mg and Mn in needles.     

Applying the concept of agrodiversity to indigenous soil and water conservation practices in eastern Kenya

Agrodiversity – the diversity of cropping systems, crop species and farm management practices has received increasing attention in recent years as a way of spreading risk and supporting food security in resource-poor farming systems. This paper discusses the dynamic aspects of indigenous soil and water conservation (ISWC) practices in a semi-arid part of Kenya. The objective is to show the range of sources of variability and diversity that prevail in this environment, the responses of farmers to this variability, and the way farmers' rationalise the heterogeneity of soil and water management practices. Methods used included participatory surveys and evaluations, on-farm monitoring, soil and rainfall data analyses, and questionnaire surveys. Sources of variability affecting cropping systems and land management practices included rainfall, soil fertility, farmer resource level and farm productivity. A decision-tree was developed to examine how biophysical and socio-economic variability affected farmers' choice of ISWC. Different ISWC structures dominated on sandy and stony soils, respectively. Low resource farmers tended to choose cheaper and less labour demanding techniques, and constructed smaller ISWC structures than better endowed farmers. The largest diversity of ISWC practices was found on newly-opened land with mixed soils. Moreover, on-farm productivity levels indicated that costly investments in SWC are unfeasible, as this would further increase the risk for negative returns to farming. The wider implications of the results are that SWC interventions in marginal areas should build on the existing agrodiversity and an understanding of the complex interactions between environmental and socio-economic factors that give rise to differences in farming systems and land management practices.     

Egg testosterone affects wattle color and trait covariation in the ring-necked pheasant

Transfer of maternal hormones to the eggs is a major source of offspring phenotypic variation. The developmental and organizational effects of egg hormones can extend into adulthood and affect behavioral and morphological traits involved in sexual and reproductive behavior, with important consequences for offspring fitness. In this study, we injected testosterone (T) in egg albumen of captive ring-necked pheasant (Phasianus colchicus) eggs. We then assessed the consequences for chick growth, cell-mediated immunity, and multiple male secondary sexual traits at maturity by comparison with a control group. We also compared the covariation between traits in the two experimental groups. We found that control males had redder wattles than males from T-injected eggs, suggesting that attractiveness and reproductive success of the offspring might vary depending on maternal transfer of T to the eggs. T treatment also modified the covariation between cell-mediated immunity and wattle coloration and between the area of the wattle and the expression of another secondary sexual trait, the ear tufts. These effects are likely to translate into fitness differences among the offspring if mate acquisition depends on the simultaneous expression of several traits that are differentially affected by the same maternal contribution. Maternal effects mediated by egg hormones might affect the fitness of the offspring not only by directional modification of phenotypic traits, but also by facilitating or inhibiting their covariation. This suggests the possibility that female choice based on the relative expression of multiple secondary sexual traits exerts a pressure on how maternal transfer of androgens contributes to developmental programs.     

Assessing health risk from benzene pollution in an urban area

A health hazard, specifically the leukaemia risk, is evaluatedfrom different sources of benzene exposure with relation to apopulation living in an urban area of Italy. The population exposure is calculated for a reference year by sexand lyfestyle, with respect to smokers and non smokers. Potentialhealth risk is therefore quantified by means of mathematicalmodels and the relative significance of the different sources is described. The results of the analysis are useful for the identification ofappropriate risk reduction strategies to minimize exposure, inparticular when resulting from lifestyle and personal activities.     

Bioremediation of petroleum‐impacted soils from investigation‐derived wastes

Optimal conditions for bioremediation of investigation‐derived wastes from petroleum‐impacted soils (PIS) were determined through biotreatability experiments. The PIS was collected as extruded cores obtained during sample drilling. These samples were processed into workable media prior to treatment in bioreactors. Soil moisture content in the bioreactors was adjusted to 30 percent, 40 percent, 50 percent (control), and 60 percent, dry‐weight basis, and nutrient levels were adjusted by applying fertilizer, yielding carbon (C) to nitrogen (N) ratios of 20:1, 10:1, and 5:1, versus a control C:N ratio of 140:1. Temperature, pH, viable bacterial plate counts, contaminant degradation rate, and microbial respiration were monitored. Concentrations of three selected branched alkanes in the aviation fuel contaminant, measured by gas chromatography, decreased for most treatments. The greatest degradation occurred with a moisture content of 40 percent and C:N ratio of 5:1. Increased contaminant degradation was consistent with increased microbial activity measured by respiration. There was poorer correlation between contaminant degradation and viable plate counts, which suggests that respirometry is a better measure of activity of the microbial population responsible for contaminant degradation. General plate counts, which enumerate only a fraction of the total population, may not be a reliable quantitative indicator of the actual microorganism population that is responsible for degradation. © 2003 Wiley Periodicals, Inc.     

Length of index and ring fingers differentially influence sexual attractiveness of men’s and women’s hands

Humans show intra- and intersexual variation in second (2D) relative to fourth (4D) finger length, men having smaller 2D:4D ratio, possibly because of differential exposure to sex hormones during fetal life. The relations between 2D:4D and phenotypic traits including fitness components reported by several studies may originate from the organizational effects that sex hormones have on diverse organs and their concomitant effect on 2D:4D. Evolutionary theory posits that sexual preferences are adaptations whereby choosy individuals obtain direct or genetic indirect benefits by choosing a particular mate. Since sex hormones influence both fitness and 2D:4D, hand sexual attractiveness should depend on 2D:4D, a hypothesis tested only in one correlational study so far. We first presented hand computer images to undergraduates and found that opposite-sex hands with long 2D and 4D were considered more sexually attractive. When we experimentally manipulated hand images by increasing or decreasing 2D and/or 4D length, women preferred opposite-sex hands that had been masculinized by elongating 4D, whereas men avoided masculinized opposite-sex right hands with shortened 2D. Hence, consensus exists about which hands are attractive among different opposite-sex judges. Finger length may signal desirable sex hormone-dependent traits or genetic quality of potential mates. Psychological mechanisms mediating hand attractiveness judgments may thus reflect adaptations functioning to provide direct or indirect benefits to choosy individuals. Because the genetic mechanisms that link digit development to sex hormones may be mediated by Hox genes which are conserved in vertebrates, present results have broad implications for sexual selection studies also in nonhuman taxa.     

Nestling rearing is antioxidant demanding in female barn swallows (Hirundo rustica)

Reproduction is a demanding activity, since organisms must produce and, in some cases, protect and provision their progeny. Hence, a central tenet of life-history theory predicts that parents have to trade parental care against body maintenance. One physiological cost thought to be particularly important as a modulator of such trade-offs is oxidative stress. However, evidence in favour of the hypothesis of an oxidative cost of reproduction is contradictory. In this study, we manipulated the brood size of wild barn swallows Hirundo rustica soon after hatching of their nestlings to test whether an increase in nestling rearing effort translates into an increased oxidative damage and a decreased antioxidant protection at the end of the nestling rearing period. We found that, while plasma oxidative damage was unaffected by brood size enlargement, females rearing enlarged broods showed a decrease in plasma non-enzymatic antioxidants during the nestling rearing period. This was not the case among females rearing reduced broods and among males assigned to either treatment. Moreover, individuals with higher plasma oxidative damage soon after the brood size manipulation had lower plasma non-enzymatic antioxidants at the end of the nestling rearing period, suggesting that non-enzymatic antioxidants were depleted to buffer the negative effects of high oxidative damage. Our findings point to antioxidant depletion as a potential mechanism mediating the cost of reproduction among female birds.