Learning to recognize novel predators under weakly acidic conditions: the effects of reduced pH on acquired predator recognition by juvenile rainbow trout

Summary. Recent studies have demonstrated that under weakly acidic conditions (pH 6.0), many prey fishes, including juvenile rainbow trout (Onchorhynchus mykiss), do not exhibit overt antipredator responses to conspecific chemical alarm cues. In laboratory trials, we investigated the potential effects of reduced pH on the ability of hatchery reared, predator naïve juvenile rainbow trout to acquire the recognition of a novel predator (yellow perch, Perca flavenscens). Initially, we exposed trout to the odour of a predatory yellow perch, buffered to pH 6.0 (weakly acidic) or pH 7.0 (neutral) paired with conspecific skin extracts (also buffered to pH 6.0 or 7.0) or a distilled water control. Juvenile trout exhibited significant increase in antipredator behaviour when exposed to neutral skin extract (pH 7.0). When retested 48 hours later to perch odour alone (pH 7.0), only trout initially conditioned with neutral skin extracts (pairs with either neutral or acidic perch odour) exhibited a learned recognition of perch odour as a predator risk. Those initially exposed to weakly acidic skin extract or the distilled water control did not show a learned response to predator odour. These results demonstrate that the ability to acquire the recognition of novel predators is impaired under weakly acidic conditions, as would occur in natural waterways affected by acidic precipitation.     

Land-use dynamics in a southern Illinois (USA) watershed

The Cache River of southernmost Illinois is used as a case study for developing and demonstrating an approach to quantitatively link (1) national agricultural policy and global agricultural markets, (2) landowner's decisions on land use, (3) spatial patterns of land use at a watershed scale, and (4) hydrologic impacts, thus providing a basis to predict, under a certain set of circumstances, the environmental consequences of economic and political decisions made at larger spatial scales. The heart of the analysis is an estimation, using logistic regression, of the affect of crop prices and Conservation Reserve Program (CRP) rental rates on farmland owner's decisions whether to reenroll in the CRP or return to crop production. This analysis shows that reasonable ranges for crop prices (80%–150% of 1985–1995 values) and CRP rental rates (0–125% of 1985–1995 rates) result in a range of 3%–92% of CRP lands being returned to crop production, with crop prices having a slightly greater effect than CRP rental rates. Four crop price/CRP rental rate scenarios are used to display resulting land-use patterns, and their effect on sediment loads, a critical environmental quality parameter in this case, using the agricultural non point source (AGNPS) model. These scenarios demonstrate the importance of spatial pattern of land uses on hydrological and ecological processes within watersheds. The approach developed can be adapted for use by local governments and watershed associations whose goals are to improve watershed resources and environmental quality.     

Proactive Management of Air Quality

Traditional air resource management systems have difficulty in addressing global issues, sustainable development, direct citizen participation, and integration with broad economic interests. As reactive management systems, they tend to be compliance-driven, static, and rigid. In contrast, proactive management systems are principle-driven, innovative, and flexible. Bridge scientists play a key role in supporting the transformation of raw data into wise action. Decision-makers need to integrate social values with knowledge about emissions, atmospheric processes, and potential environmental effects using the primary tools of measurements, monitoring, and modeling. The Alberta Clean Air Strategic Alliance, a unique partnership of governments, industry, and public interest groups formed in 1994, operates a comprehensive air management system that is capable of addressing air issues of greater complexity and uncertainty. Its success is measured by the satisfaction of its diverse stakeholders and by the number and scope of its initiatives.     

Cultural ecology of Whitethroat (Sylvia communis) habitat management by farmers: winter in farmland trees and shrubs in Senegambia

The presence of Whitethroats and their potential invertebrate prey in farmland trees and shrubs was investigated. The management of this vegetation by farmers, and their motivation for that management, was explored using participatory techniques. Whitethroats were associated with Guiera senegalensis, the shrub species which supports most caterpillars and spiders. Farmers reported declines in trees and shrubs since the 1950s, loss of fallow areas, declines in soil fertility and crop yields, and increases in the use of fire for clearing fields. Trees are valued by people for their cultural and medicinal uses and some species used by Whitethroats and other birds have potential for restoring soil fertility, although this was not recognised by farmers. More sustainable use of savanna farmland could have both agronomic and wider conservation benefits, and the provision of information that accommodates farmers' cultural and economic incentives could benefit both farmers and wildlife.     

复合菌种发酵酒糟菌体生长量和COD去除率的研究

在１００ｍＬ混合酒精培养液中接种优质复合菌种８５０３和８５０５,在接种量为体积浓度１０％,温度为３０．０℃,转速为１７０ｒ／ｍｉｎ的条件下,经摇床培养４８ｈ后,绝于菌体质量最高可收获１．４６９３ｇ,ＣＯＤ去除率高达６７．７４％,即ＣＯＤ由发酵前的３２６８０ｍｇ／Ｌ,降为发酵后的１０５４４ｍｇ／Ｌ。     

Human Population Numbers as a Function of Food Supply

Human population growth has typically been seen as the primary causative factor of other ecologically destructive phenomena. Current human disease epidemics are explored as a function of population size. That human population growth is itself a phenomenon with clearly identifiable ecological/biological causes has been overlooked. Here, human population growth is discussed as being subject to the same dynamic processes as the population growth of other species. Contrary to the widely held belief that food production must be increased to feed the growing population, experimental and correlational data indicate that human population growth varies as a function of food availability. By increasing food production for humans, at the expense of other species, the biologically determined effect has been, and continues to be, an increase in the human population. Understanding the relationship between food increases and population increases is proposed as a necessary first step in addressing this global problem. Resistance to this perspective is briefly discussed in terms of cultural bias in science.     

北京市大气甲醛浓度研究

分别于2006年7, 9, 12月和2007年3月采用2, 4-二硝基苯肼(DNPH)高效液相色谱法测定了北京市大气中的φ(甲醛).结果表明:在观测期间,春、夏、秋、冬各季φ(甲醛)的平均值分别为7.56×10-9, 12.70×10-9和 7.24×10-9,3.34×10-9;夏季φ(甲醛)明显高于其他3个季节, 春、秋φ(甲醛)平均值非常接近, 冬季φ(甲醛)最低;夏季φ(甲醛)与 φ(O₃), 温度,UVB的日变化表现出良好的一致性,均在12:00—15:00出现高值;夏季φ(甲醛)主要受光化学氧化过程的控制和影响; 降水对大气甲醛有明显的清除作用.      

Social transmission of food handling in the context of triadic interactions between adults and young canaries (<Emphasis Type="Italic">Serinus canaria</Emphasis>)

We studied the factors that enhance food recognition and consumption in young canaries when confronted with adults. In contrast to previous studies on canaries, in which social transmission of food habits was studied in the context of dyadic interactions (one juvenile–one adult), we proposed a more realistic framework in which young canaries were studied in the context of triadic interactions, free or not, with adults of both sexes. We found that during free interactions, the young bird only eats with a familiar male and that this association enhances the social transmission of seed handling. When the juvenile was separated from the adults by a transparent partition, it only learned to husk seed if it was present at the feeder at the same time as a familiar adult acting as a demonstrator. The presence of adults that are familiar but do not act as demonstrators does not facilitate social transmission of handling. However, the presence of a familiar, demonstrating female had also no effect on this transmission. Coordination of the actions of the experienced bird and of the naive subject is required for social transmission to occur. Action coordination does not depend solely on the level of familiarity between partners but also on the role played by the demonstrator (here, the adult male) that looks after the juvenile during its transition towards independence.     

Patterns of host switching in the fish ectoparasite <Emphasis Type="Italic">Argulus coregoni</Emphasis>

Mating is essential for sexually reproducing species to pass on their genes. For sexual parasites, this implies a need to switch the host in the search for a mate when potential partners are not available on the same host, although host switching includes risks like starvation and predation. Studies of mate-searching behavior predict that commonly only one sex searches for mating partners while the other remains stationary. In the present work, we experimentally infected rainbow trout (Oncorhynchus mykiss) with the fish ectoparasite Argulus coregoni and determined whether the sex, age and the presence of mating partners influenced the host switching activity. Our results show that increased host switching by A. coregoni occurred only after the parasite reached the adult stage and a difference between the sexes was also recorded. Host switching by mature males was enhanced when no mating partners were present on the same host, whereas females remained mainly stationary on their host regardless of male presence or absence. Our data therefore support the hypothesis that there is a strategic difference in reproductive behavior between males and females; males invest energy in mate searching while females are rather stationary and invest into body size and hence increased fecundity. Our data also showed that leaving the host to find a mate is potentially costly in terms of predation since a substantial number of free-swimming parasites were eaten by fish.     

Correlated changes in breeding status and polyunsaturated cuticular hydrocarbons: the chemical basis of nestmate recognition in the burying beetle <Emphasis Type="Italic">Nicrophorus vespilloides</Emphasis>?

Nestmate recognition in eusocial insects has received a lot of attention in the last decades. Recognition in subsocial species, in contrast, has been ignored almost completely and consequently, and little is known about proximate mechanisms of recognition in subsocial systems. We studied one subsocial species, the biparental brood caring burying beetle Nicrophorus vespilloides, an interesting model organism for studies of recognition because of its ability to discriminate between breeding partners and conspecific competitors. Recognition appears to be based on a chemical cue closely linked to the breeding status of individuals. Breeding and non-breeding beetles consistently differ in their relative proportions of polyunsaturated cuticular hydrocarbons. To investigate the function of these polyenes in the burying beetles’ recognition system, we quantified their concentration on the cuticle during the early state of a breeding attempt and tested the response of breeding beetles in corresponding behavioural experiments. We observed a rapid increase in the proportion of polyunsaturated hydrocarbons of both males and females after they were provided with a carcass suitable for reproduction. Furthermore, we found that the relative amount of polyenes on an individual’s surface was closely correlated with its chance of being accepted as breeding partner. Our results support the idea that polyunsaturated hydrocarbons are involved in breeding partner recognition in N. vespilloides, functioning as a signal that conveys information about the individual’s breeding status. Breeding females have greater amount of polyenes than breeding males, and females ingest more carrion during the first days on the carcass, which supports our hypothesis that precursors for the respective polyenes are derived from ingested carrion.