bluuebunny/crossref_metadata_2025 huggingface dataset:
Soilpak: a successful decision support system for managing the structure of Vertisols under irrigated cotton
Authors: Daniells I , Larsen DL , Mckenzie DC , Anthony DTW
Published: April 2005

We describe a successful way of presenting knowledge of soil management to Australian cotton growers. Previous soil management methods were costly, and often involved unnecessary tillage that further damaged soil structure. Other growers did not correct serious subsoil compaction. Poor control of paddock traffic was a widespread problem. We gathered available information on soil management from researchers, agronomists, and leading growers to present in a format that is easy to follow. We produced guidelines and 'rules of thumb' on best practices and published a manual called 'SOILpak, a Soil Management Package for Cotton Production on Cracking Clay Soils'. The manual was promoted at workshops on practical soil management. Assessments of yield trends and a recent survey of SOILpak clients showed that the manual had improved farming practices. By helping growers to make soil management decisions, the manual assisted the industry's trend towards adopting minimum tillage, permanent beds, and controlled traffic.
Soil nitrogen availability in the cereal zone of South Australia .1. Soil organic carbon, total nitrogen, and nitrogen mineralisation rates
Authors: Xu ZH , Ladd JN , Elliott DE
Published: April 2005

Assessments of soil nitrogen (N) availability were undertaken using soils sampled at 0-10 and 10-20 cm depths from 123 experimental sites where the responses of cereal crops to N fertilisers were tested, throughout the cereal zone of South Australia. Rates of N mineralisation and percentage N mineralisation, as determined by a laboratory aerobic incubation method, were related to soil properties. Mineralisable N (N mineralised during a Li-week incubation) of 0-10 cm soil varied from 14 to 121 kg N/ha with a median of 50 kg N/ha, and that of 10-20 cm soil, from 5 to 42 kg N/ha (median 19 kg N/ha). Mineralisable N in 0-10 cm soil accounted for 90% of total mineralisable N in 0-20 cm soil. The percentages of N mineralised were generally higher in 0-10 cm soil (0.8-12.5%, median 3.4%) than in 10-20 cm soil (0.4-8.3%, median 2.3%). Soil organic carbon (OC) and total N could be well estimated from each other, and fron! soil pH, bulk density, and held capacity, with coefficients of determination (R2) ranging from 0.64 to 0.78. Overall, either mineralisable N or percentage N mineralisation rate in the surface soils could be well estimated from soil OC, total N, C to N ratio, bulk density, field capacity, and pH (R2, 0.78-0.86 for mineralisable N, and 0.67-0.91 for percentage N mineralisation rate).
The temporal organisation of the feeding behaviour of four species of wallaby: examining chronobiological and homeostatic influences
Authors: Lentle R. G. , Hume I. D. , Stafford K. J. , Kennedy M. , Springett B. P. , Haslett S.
Published: April 2005

We studied the temporal distribution of feeding events of tammar wallabies, parma wallabies, brush-tailed rock-wallabies and swamp wallabies by infrared video-recording of captive animals maintained in a 12 : 12 light : dark cycle with constant temperature, and by radio-microphone surveillance of free-ranging animals on Kawau Island, New Zealand. Analyses of mean time spent feeding per 20-min period for tammar and parma wallabies showed significant circadian variation in both captive and free-ranging animals but not in captive or free-ranging brush-tailed rock wallabies or swamp wallabies. While there was no significant difference in the extent of circadian variation of feeding rate between tammar and parma wallabies there were significant differences according to the type of food being fed. Thus, circadian variation in feeding rate was greater in both species when standing sward was fed. None of the survivorship curves of the interfeed intervals of either captive or free-ranging animals showed a discontinuity suggestive of organisation of feed events into meals. There were bicrepuscular peaks of feed-event density in both captive and free-ranging tammar and parma wallabies. There was a similar bicrepuscular distribution of feed-event density in free-ranging brush-tailed rock-wallabies but a more uniform temporal distribution of this parameter in captive specimens. There was a more uniform circadian distribution of feed-event density in a single captive and a single free-ranging swamp wallaby. Thus the circadian incidence of the feeding events of tammar and parma wallabies were more resistant to changes in the incidence of stochastic environmental variables such as predation whereas those of bush-tailed rock-wallabies and swamp wallabies were more susceptible to changes in these stimuli.
(G–H)
•
–C and G–(C–H)
•
radicals derived from the guanine·cytosine base pair cause DNA subunit lesions
Authors: Bera Partha Pratim , Schaefer Henry F.
Published: April 2005

The radicals generated by the homolytic cleavage of an X–H bond from the guanine·cytosine (G·C) base pair were studied by using carefully calibrated theoretical methods. The gradient-corrected density functional B3LYP was applied in conjunction with double-ζ plus polarization and diffuse function basis sets. Optimized geometries, energies, and vibrational frequencies were obtained for all of the radicals considered. Structural perturbations along with energy relaxation due to radical formation were investigated. Dissociation energies of the G·C base pair and all of the radicals are predicted and compared with the dissociation energy of neutral G·C. The three lowest-energy base pair radicals all involve removal of an H atom from one of the N atoms in G·C. The lowest-energy base pair radical has the hydrogen atom removed from the guanine nitrogen atom used for the sugar phosphate linkage in DNA. This (G–H)
•
–C radical has a dissociation energy (to G–H
•
+ C) of 30 kcal/mol, which may be compared with 27 kcal/mol for G·C. All of the radicals that are possible outcomes of direct ionizing radiation or oxidizing species were investigated for the presence of local minima with significant structural changes. Major structural deformations cause strain in the interstrand hydrogen bonding in the DNA double helix. Severe geometry changes were observed when the hydrogen was abstracted from interstrand hydrogen bonding sites, along with sizeable energy changes, indicating the potentially serious consequences to the G·C base pair.
The true costs of scholarly journal publishing
Authors: Morris Sally
Published: April 2005

There has been much debate recently about whether publishers' prices are too high, and what publishing a journal article really costs. Publication of the article in a journal is only one part of the cost of research communication; first of all there are the costs of research and writing, then the costs of peer review, editing and publication, and finally the costs of acquisition by the library, management, storage, reading by the end user and long‐term preservation. Several studies have been conducted of these different costs; the results are summarized and the potential impact, both on costs and on sources of funds, of moving to an alternative, ‘author‐funded’ open access model is considered.
Open access — the impact of legislative developments
Authors: Waltham Mary
Published: April 2005

An account is given of the development of the idea of open access for the results of STM research over the period 1999–2005 with particular attention to PubMed Central and to the initiatives of the legislatures in the US and UK in 2004. Stakeholder responses to open access are briefly reviewed and possible future developments are outlined.
Tracking the Interactions of rRNA Processing Proteins during Nucleolar Assembly in Living Cells
Authors: Angelier Nicole , Tramier Marc , Louvet Emilie , Coppey-Moisan Maïté , Savino Tula M. , De Mey Jan R. , Hernandez-Verdun Danièle
Published: April 2005

Reorganization of the nuclear machinery after mitosis is a fundamental but poorly understood process. Here, we investigate the recruitment of the nucleolar processing proteins in the nucleolus of living cells at the time of nucleus formation. We question the role of the prenucleolar bodies (PNBs), during migration of the processing proteins from the chromosome periphery to sites of rDNA transcription. Surprisingly, early and late processing proteins pass through the same PNBs as demonstrated by rapid two-color four-dimensional imaging and quantification, whereas a different order of processing protein recruitment into nucleoli is supported by differential sorting. Protein interactions along the recruitment pathway were investigated using a promising time-lapse analysis of fluorescence resonance energy transfer. For the first time, it was possible to detect in living cells the interactions between proteins of the same rRNA processing machinery in nucleoli. Interestingly interactions between such proteins also occur in PNBs but not at the chromosome periphery. The dynamics of these interactions suggests that PNBs are preassembly platforms for rRNA processing complexes.
Role for the SCFCDC4Ubiquitin Ligase inCandida albicansMorphogenesis
Authors: Atir-Lande Avigail , Gildor Tsvia , Kornitzer Daniel
Published: April 2005

The ability of Candida albicans, a major fungal pathogen, to switch between a yeast form, and a hyphal (mold) form is recognized as being important for the ability of the organism to invade the host and cause disease. We found that a C. albicans mutant deleted for CaCDC4, a homologue of the Saccharomyces cerevisiae F-box protein component of the SCFCDC4ubiquitin ligase, is viable and displays constitutive filamentous, mostly hyphal, growth. The phenotype of the Cacdc4–/– mutant suggests that ubiquitin-mediated protein degradation is involved in the regulation of the dimorphic switch of C. albicans and that one or more regulators of the yeast-to-mold switch are among the substrates of SCFCaCDC4. Epistasis analysis indicates that the Cacdc4–/– phenotype is largely independent of the filamentation-inducing transcription factors Efg1 and Cph1. We identify C. albicans Far1 and Sol1, homologues of the S. cerevisiae SCFCDC4substrates Far1 and Sic1, and show that Sol1 is a substrate of C. albicans Cdc4. Neither protein is essential for the hyphal phenotype of the Cacdc4–/– mutant. However, ectopic expression and deletion of SOL1 indicate a role for this gene in C. albicans morphogenesis.
The extraction of uranium from groundwaters on iron surfaces
Authors: Scott Thomas B , Allen Geoffrey C , Heard Peter J , Lewis Andrew C , Lee Darren F
Published: April 2005

The observation of uranium remediation from groundwater onto mild-steel surfaces is reported. Mechanisms for uranium immobilization are proposed.
Tracking butterfly flight paths across the landscape with harmonic radar
Authors: Cant E.T , Smith A.D , Reynolds D.R , Osborne J.L
Published: April 2005

For the first time, the flight paths of five butterfly species were successfully tracked using harmonic radar within an agricultural landscape. Until now, butterfly mobility has been predominantly studied using visual observations and mark–recapture experiments. Attachment of a light-weight radar transponder to the butterfly's thorax did not significantly affect behaviour or mobility. Tracks were analysed for straightness, duration, displacement, ground speed, foraging and the influence of linear landscape features on flight direction. Two main styles of track were identified: (A) fast linear flight and (B) slower nonlinear flights involving a period of foraging and/or looped sections of flight. These loops potentially perform an orientation function, and were often associated with areas of forage. In the absence of forage, linear features did not provide a guiding effect on flight direction, and only dense treelines were perceived as barriers. The results provide tentative support for non-random dispersal and a perceptual range of 100–200 m for these species. This study has demonstrated a methodology of significant value for future investigation of butterfly mobility and dispersal.
Life‐history variation of a neotropical thrush challenges food limitation theory
Authors: Ferretti Valentina , Llambías Paulo E , Martin Thomas E
Published: April 2005

Since David Lack first proposed that birds rear as many young as they can nourish, food limitation has been accepted as the primary explanation for variation in clutch size and other life‐history traits in birds. The importance of food limitation in life-history variation, however, was recently questioned on theoretical grounds. Here, we show that clutch size differences between two populations of a neotropical thrush were contrary to expectations under Lack's food limitation hypothesis. Larger clutch sizes were found in a population with higher nestling starvation rate (i.e. greater food limitation). We experimentally equalized clutches between populations to verify this difference in food limitation. Our experiment confirmed greater food limitation in the population with larger mean clutch size. In addition, incubation bout length and nestling growth rate were also contrary to predictions of food limitation theory. Our results demonstrate the inability of food limitation to explain differences in several life-history traits: clutch size, incubation behaviour, parental feeding rate and nestling growth rate. These life-history traits were better explained by inter‐population differences in nest predation rates. Food limitation may be less important to life history evolution in birds than suggested by traditional theory.
Forecasting changes in amphibian biodiversity: aiming at a moving target
Authors: Collins James P , Halliday Tim
Published: April 2005

Amphibian population declines and sudden species' extinctions began to be noted at the beginning of the 1980s. Understanding the causes of the losses is hampered by our poor knowledge of the amphibian fauna in many parts of the world. Amphibian taxa are still being described at a high rate, especially in the tropics, which means that even quantifying species lost as a percentage of the current fauna can be a misleading statistic in some parts of the globe. The number of species that have gone missing is only one measure of the loss of biodiversity. Long-term studies of single-species populations are needed, but this approach has its limits. Amphibian populations often show great annual variation in population size making it difficult, if not impossible, to use short-term studies as a basis for deciding if a population is increasing or decreasing in the long term. Aggregating single studies into databases and searching for patterns of variation is a way of overcoming this limitation. Several databases on species and population time series are available or in development. These records show that declines are continuing worldwide with some species and populations, especially in the tropics and at higher elevations, at greater risk of extinction than others. Unfortunately, amphibian databases with population time series have much less information for the tropics compared to the temperate zone, and less for Africa and Asia compared with Europe and North America. Focusing limited resources using comprehensive statistical designs is a way to maximize the efficiency and effectiveness of monitoring efforts. It is clear that, in the first decades of the twenty-first century, the regions of the globe with the highest diversity of amphibian species will experience the greatest rates of decrease of forests and increase in human population size, fertilizer use, agricultural production, creation of new croplands and irrigation. Many of these changes are likely negatively to affect amphibian species diversity, and their influence must be understood before concluding, at least for amphibians, that the 2010 millennium assessment goal of significantly reversing the rate of loss of Earth's biodiversity can be met.
Measuring coral reef decline through meta-analyses
Authors: Côté I.M , Gill J.A , Gardner T.A , Watkinson A.R
Published: April 2005

Coral reef ecosystems are in decline worldwide, owing to a variety of anthropogenic and natural causes. One of the most obvious signals of reef degradation is a reduction in live coral cover. Past and current rates of loss of coral are known for many individual reefs; however, until recently, no large-scale estimate was available. In this paper, we show how meta-analysis can be used to integrate existing small-scale estimates of change in coral and macroalgal cover, derived fromin situsurveys of reefs, to generate a robust assessment of long-term patterns of large-scale ecological change. Using a large dataset from Caribbean reefs, we examine the possible biases inherent in meta-analytical studies and the sensitivity of the method to patchiness in data availability. Despite the fact that our meta-analysis included studies that used a variety of sampling methods, the regional estimate of change in coral cover we obtained is similar to that generated by a standardized survey programme that was implemented in 1991 in the Caribbean. We argue that for habitat types that are regularly and reasonably well surveyed in the course of ecological or conservation research, meta-analysis offers a cost-effective and rapid method for generating robust estimates of past and current states.
The 2010 challenge: data availability, information needs and extraterrestrial insights
Authors: Balmford Andrew , Crane Peter , Dobson Andy , Green Rhys E , Mace Georgina M
Published: April 2005

At the 2002 Johannesburg World Summit on Sustainable Development, 190 countries endorsed a commitment to achieve, by 2010, a significant reduction of the current rate of biodiversity loss at the global, regional and national levels. A wide range of approaches is available to the monitoring of progress towards this objective. The strengths and weaknesses of many of these approaches are considered, with special attention being given to the proposed and existing indicators described in the other papers in this issue. Recommendations are made about the development of indicators. Most existing and proposed indicators use data collected for other purposes, which may be unrepresentative. In the short term, much remains to be done in expanding the databases and improving the statistical techniques that underpin these indicators to minimize potential biases. In the longer term, indicators based on unrepresentative data should be replaced with equivalents based on carefully designed sampling programmes. Many proposed and existing indicators do not connect clearly with human welfare and they are unlikely to engage the interest of governments, businesses and the public until they do so. The extent to which the indicators already proposed by parties to the Convention on Biological Diversity are sufficient is explored by reference to the advice an imaginary scientific consultant from another planet might give. This exercise reveals that the range of taxa and biomes covered by existing indicators is incomplete compared with the knowledge we need to protect our interests. More fundamentally, our understanding of the mechanisms linking together the status of biodiversity, Earth system processes, human decisions and actions, and ecosystem services impacting human welfare is still too crude to allow us to infer reliably that actions taken to conserve biodiversity and protect ecosystem services are well chosen and effectively implemented. The involvement of social and Earth system scientists, as well as biologists, in collaborative research programmes to build and parameterize models of the Earth system to elucidate these mechanisms is a high priority.
Turning science into policy: challenges and experiences from the science–policy interface
Authors: Watson Robert T
Published: April 2005

This paper discusses key issues in the science–policy interface. It stresses the importance of linking the conservation and sustainable use of biodiversity to the Millennium Development Goals and to issues of immediate concern to policy-makers such as the economy, security and human health. It briefly discusses the process of decision-making and how the scientific and policy communities have successfully worked together on global environmental issues such as stratospheric ozone depletion and climate change, and the critical role of international assessments in providing the scientific basis for informed policy at the national and international level. The paper also discusses the drivers of global environmental change, the importance of constructing plausible futures, indicators of change, the biodiversity 2010 target and how environmental issues such as loss of biodiversity, stratospheric ozone depletion, land degradation, water pollution and climate change cannot be addressed in isolation because they are strongly interconnected and there are synergies and trade-offs among the policies, practices and technologies that are used to address these issues individually.
The impact of altered precipitation on spatial stratification and activity‐densities of springtails (Collembola) and spiders (Araneae)
Authors: Lensing Janet R. , Todd Sara , Wise David H.
Published: April 2005

Abstract. 1. A field experiment was conducted to determine how short‐term changes in moisture can alter activity‐densities of spiders and springtails.

2. In a Kentucky forest 10 unfenced 4‐m2plots were divided into two rainfall treatments. A clear roof over five plots excluded rainfall to simulate severe drought conditions (droughttreatment). Water was sprayed on the five uncovered plots at a rate equal to two times the long‐term mean in order to establish thehigh‐rainfalltreatment. Activity‐densities of Collembola and spiders were measured using pitfall traps designed to sample the top, middle, and bottom layers of leaf litter. The experiment ran from 20 July to 23 September 2001.

3. Overall (i.e. litter layers pooled) activity‐density (mean number trapped each sampling date) of Collembola was ≈ 60% lower in drought plots than in plots receiving increased precipitation. Surprisingly, overall spider activity‐density was ≈ 1.6 times greater in the drought plots.

4. Differences in rainfall affected the spatial stratification of Collembola and spiders in strikingly different ways. Activity‐densities of neither group differed between drought and high‐rainfall treatments in the bottom litter layer. Collembola activity‐density was three times greater in the top and middle litter layers in high‐rainfall plots than in drought plots. In contrast, spider activity‐density did not differ between treatments in the top layer, but activity‐density was decreased by 50% in the middle layer of high‐rainfall plots compared with drought plots.

5. Three Collembola families (Sminthuridae, Tomoceridae, and Entomobryidae) accounted for most of the Collembola pattern. The spider response was due to altered activity‐density of one family of wandering spider, the Gnaphosidae.
Asymmetrical competition between Neotropical dung beetles and its consequences for assemblage structure
Authors: Horgan Finbarr G. , Fuentes René C.
Published: April 2005

Abstract.  1. This study combines the results of laboratory experiments using representative assemblage components and pitfall trapping over a large geographical area to examine the hypothesis that ongoing interspecific competition structures Neotropical dung beetle assemblages.

2. From Guatemala to Panama assemblages of large to medium‐sized, fast‐tunnelling dung beetles include a single large, nocturnal dichotomiine species, Dichotomius annae (Kohlmann & Solís, 1997). In competition experiments, this species out‐competed the medium‐sized coprine species, Copris lugubris Boheman and Phanaeus demon Laporte‐Castelnau, for dung and nesting space, in spite of earlier colonisation by the diurnal species, P. demon.

3. Differences in the abundance of D. annae at Central American sites did not affect total fast‐tunnelling dung beetle assemblage richness over the rainy season. However, D. annae rank order was directly related to the probability of interspecific encounters (Hurlbert's Δ1) among species. These trends were also observed when species lists from published and unpublished studies of other large allopatric dichotomiine species, with a more northerly distribution, were included in the analyses.

4. The results obtained suggest that where large dichotomiine species are abundant, their efficient pre‐emption of a considerable proportion of available resources drives all, or most, other fast‐tunnelling species to a lower population density, thereby decreasing assemblage diversity.
The effect of food supply and larval cannibalism on adult size and biomass of the grazing caddis‐flyMelampophylax mucoreus(Limnephilidae)
Authors: Spänhoff Bernd , Kock Christian , Meyer Alexander , Meyer Elisabeth I.
Published: April 2005

Abstract. 1. Larvae of the grazing caddis‐flyMelampophylax mucoreuswere reared in a laboratory experiment investigating the effect of food availability on different substrates and cannibalism on the size and biomass of emergent adults. All experiments were performed in stream‐water filled, aerated aquaria under controlled temperature and light conditions. Larvae (fourth and fifth instar) were reared in aquaria (50 larvae in each) with three substrate scenarios: (i) limestone (LS), (ii) limestone and leaf litter (LS + L), and (iii) silicate stone (SS).

2. Cannibalism among the larvae in the LS scenario led to the highest adult dry masses (male = 5.13 ± 0.25 mg, female = 7.64 ± 0.63 mg) and to the highest mortality rate (88.7%). The SS scenario displayed the most unfavourable condition for larval growth indicated by the lowest adult dry masses (males = 3.12 ± 0.15 mg, females = 4.69 ± 0.25 mg) and a high mortality rate (81.7%). The limestone supplemented with leaf litter (ii) offered the most balanced nutrients to complete larval development and enough shelter to avoid excessive encounter rates of larvae within the aquaria, indicated by the lowest mortality rate (43.6%). Adults from the LS + L scenario showed biomasses (male = 3.94 ± 0.12 mg, female = 6.48 ± 0.24 mg) intermediate between the two other scenarios.

3. The results implied that cannibalism among larvae can lead to higher adult biomasses and therefore to increased fitness, if cannibalism supplements larval feeding requirements. Larvae developing under insufficient food availability can not compensate for this by cannibalism. Additionally, leaf litter not only provided a complementary food source for developing larvae, but also provided shelter, which reduced encounter rates.

4. Increased stress induced by high larval encounter rates (resulting in enhanced cannibalism) in the LS scenario and low food availability in the SS scenario could be indicated by premature emergence times compared with the LS + L scenario.
Computer‐generated null models as an approach to detect perceptual range in mark–re‐sight studies – an example with grasshoppers
Authors: Hein Silke , Poethke Hans‐Joachim , Hovestadt Thomas
Published: April 2005

Abstract. 1. Dispersal and habitat detection are key factors for the colonisation of habitat fragments in heterogeneous landscapes. The ability to recognise a habitat from a certain distance should increase the survival chances of a dispersing individual; however, due to methodological problems there is little information on the perceptual range of most species.

2. In a field experiment, 44 individually marked grasshoppers of the speciesOedipoda caerulescens(Orthoptera: Acrididae: Locustinae) were released into an unfamiliar, hostile environment at various distances from a patch of preferred habitat.

3. Whether individuals reached the habitat or not was measured, as well as the daily movement distances. The number of individuals that reached the habitat was tested against computer‐generated predictions based on different underlying rules for the movement behaviour of individuals but not accounting for the ability to detect habitat from distance.

4. On the first day a significantly higher proportion of grasshoppers arrived in the habitat than predicted by any of the null models.

5. It was concluded that individuals ofO. caerulescensare able to detect their preferred habitat from a distance.

6. Edge permeability was very low as none of the individuals left the habitat once they had reached it.

7. Additional analyses showed that individuals changed movement behaviour from a directed walk with great daily distances in unsuitable habitat to a walk with significantly shorter daily distances within the preferred habitat.

8. The problems that arose in the field experiment are discussed and recommendations are given for further studies.
Geographic differences in flash intervals and pre‐mating isolation between populations of the Genji firefly, Luciola cruciata
Authors: Tamura Masayoshi , Yokoyama Jun , Ohba Nobuyoshi , Kawata Masakado
Published: April 2005

Abstract.  1. Two types of Genji firefly, Luciola cruciata, have been recognised on the basis of the inter‐flash interval.

2. The fast‐flash and slow‐flash type fireflies, distributed in the western and eastern parts of Japan, exhibit a 2‐ and 4‐s interval of bioluminescence flash, respectively. In addition, an intermediate‐flash type is found on the boundary between these two regions.

3. The differences in the responses of the males of four field populations to different intervals of artificial flashes were examined.

4. The results revealed that in the Aomori and Sendai populations (slow‐flash type), a significantly larger number of males approached the 4‐ and 5‐s flash intervals than approached the 2‐ and 3‐s intervals of artificial flashes. On the other hand, in the Ohtsu population (fast‐flash type), a significantly larger number of males approached the 2‐ and 3‐s flash intervals than the 4‐ and 5‐s intervals of artificial flashes. The Inuyama population (intermediate‐flash type) did not show any particular preferences to flash intervals.

5. This study shows that in firefly populations, geographic variation in flash pattern can cause some degree of pre‐mating isolation between populations.
Foraging behaviour influences the outcome of predator–predator interactions
Authors: Björkman Christer , Liman Anna‐Sara
Published: April 2005

Abstract.  1. Interactions among predators may influence the total efficiency of a predator complex. The effect of intra‐ and interspecific interactions of the generalist predators Orthotylus marginalis (Heteroptera: Miridae) and Anthocoris nemorum (Heteroptera: Anthocoridae) was investigated in a laboratory experiment. Outcomes of the interactions were determined by comparing predation rates on eggs and larvae of the blue willow beetle Phratora vulgatissima of single individuals with those of two individuals of the same or different species.

2. A non‐additive, antagonistic effect on predation rates due to intraspecific interactions was found between individuals of A. nemorum. No such effect was found in O. marginalis. These results are as expected as a consequence of differences in behaviour of the two predator species: A. nemorum is a much more active and mobile predator than O. marginalis.

3. Contrary to expectation, interspecific interactions between A. nemorum and O. marginalis did not affect the total predation rate.

4. An observation from the field corroborated the results obtained in the laboratory study; there was no negative relationship between the densities of the two predator species, indicating that the two species do not interact negatively in the field at their natural densities.

5. It is concluded that the additive effect of multiple predator species is of potential value in biological control.
Larval interspecific competition in two flea species parasitic on the same rodent host
Authors: Krasnov Boris R. , Burdelova Nadezhda V. , Khokhlova Irina S. , Shenbrot Geogry I. , Degen Allan
Published: April 2005

Abstract.  1. The fleas Xenopsylla conformis and Xenopsylla ramesis exploit the same rodent host, Meriones crassus, and replace each other between two different habitats situated at the opposite sides of a steep precipitation gradient. It was hypothesised that the reason for this paratopic distribution is competition between larvae of the two species for food resources.

2. This hypothesis was tested by studying the performance of larvae of the two species in terms of their developmental success in mixed‐species and single‐species treatments under different air temperatures, relative humidities, substrate textures, and food abundance.

3. The number of individuals of X. conformis that survived until emergence depended significantly on the presence of competing species, being, in general, lower in mixed‐species compared with single‐species treatments. The decrease in developmental success of X. conformis in mixed‐species treatments was found mainly during food shortage. In contrast, presence of the competitor did not affect the number of X. ramesis that survived until emergence. No effect of the presence of the competitor on duration of development or sex ratio was found in either species.

4. The results of this study, together with the results of our previous studies, provide an explanation for the paratopic distribution of X. conformis and X. ramesis that exploit the same host species.
Factors influencing the seasonal life history of the pitcher‐plant mosquito, Wyeomyia smithii
Authors: Bergland Alan O. , Agotsch Marci , Mathias Derrick , Bradshaw William E. , Holzapfel Christina M.
Published: April 2005

Abstract.  1. The effects of resource levels, thermal microclimate, and seasonal oviposition patterns on fecundity and survivorship in the pitcher‐plant mosquito, Wyeomyia smithii (Coq.), were examined at a northern Wisconsin bog over the course of 2 years. Wyeomyia smithii are bivoltine at this locality, thereby enabling the study of summer and overwintering generations separately.

2. Nutrient resources of W. smithii were not limiting and there was no indication of density‐dependent survivorship or fecundity.

3. Oviposition rates were highest in young, large pitchers and individual mosquitoes appeared to allocate only a few eggs to any one leaf.

4. Winter was the harsh season, and the principal manifestation of seasonal harshness was reduced survivorship.

5. Overwintering W. smithii that had been oviposited later in the summer had a higher odds of survival than those oviposited earlier in the summer.

6. It was concluded that dispersal of eggs among many pitchers serves to spread the risk of encountering lethal winter temperatures among spatially unpredictable patches.
Dropping behaviour of larvae of aphidophagous ladybirds and its effects on incidence of intraguild predation: interactions between the intraguild prey, Adalia bipunctata (L.) and Coccinella septempunctata (L.), and the intraguild predator, Harmonia axyridis Pallas
Authors: Sato Satoru , Yasuda Hironori , Evans Edward W.
Published: April 2005

Abstract.  1. Two experiments were performed in the laboratory to assess the behaviour of dropping from a host plant as a defence against intraguild predation in aphidophagous ladybird larvae.

2. In the first experiment, encounters were observed on bean plants between fourth instars of the intraguild predator species, Harmonia axyridis, and first instars of two other ladybird species, Adalia bipunctata (L.) and Coccinella septempunctata (L.). The percentages of first instars of the latter two species that dropped from the plant in response to attack differed dramatically, with 47.5% of C. septempunctata first instars dropping vs. 0% of A. bipunctata.

3. In the second experiment, first instars of A. bipunctata or C. septempunctata and a fourth instar of H. axyridis were allowed to forage together on bean plants for 3 h. During this time, 44.3% of C. septempunctata larvae dropped from the plant, but less than 2% of A. bipunctata larvae did so. In contrast, 95.0% of A. bipunctata larvae fell victim to intraguild predation by H. axyridis vs. only 54.5% of C. septempunctata larvae.

4. The significance of dropping behaviour of ladybird larvae as a defence against intraguild predation, and the relationship of dropping behaviour to species‐specific habitat affinity of ladybirds, is discussed.
Diel feeding patterns and daily ration of cyprinid species in the wild determined using an iterative method, MAXIMS
Authors: De Silva S. S. , Amarasinghe U. S. , Wijegoonawardena N. D. N. S.
Published: April 2005

Diel feeding patterns and daily food rations of five cyprinids Amblypharyngodon melettinus, Barbus chola, B. dorsalis, B. filamentosus and Rasbora daniconius in two Sri Lankan reservoirs were studied based on diel surveys using an iterative method, MAXIMS. A. melettinus and B. chola had single peaks of feeding whereas diel feeding patterns with two peaks occurred in the other three species. Daily food rations varied seasonally and with size of fish. The iterative technique used is reliably applicable for quantifying daily rations, and provides a means of linking trophic levels in natural populations of fish.
Nuclear DNA content in Salmo fibvenl in Lake Posta Fibreno, Italy
Authors: Alfei L. , Cavallo D. , Eleuteri P. , Grollino M. G. , Colombari P. T. , Ferri A. , Onali A. , Vita R. De
Published: April 2005

The nuclear DNA content of Salmo fibreni, endemic to Lake Posta Fibreno, and of the sympatric Salmo trutta macrostigma, was evaluated using flow cytometric (FCM) analysis. The DNA content was 6‐29 pg/nucleus for male and significantly greater at 6‐41 pg/nucleus for female S, fibreni; and 6‐37 pg/nucleus for male S, trutta macrostigma.
The reproductive tactics of dace in central Siberia: evidence for temperature regulation of the spatio‐temporal variability of its life history
Authors: Lobón‐Cerviá J. , Dgebuadze Y. , Utrilla C. G. , Rincón P. A. , Granado‐Lorencio C.
Published: April 2005

Major life history characteristics of dace Leuciscus leuciscus from the R. Yenisei at Mirnoye (66° N, Central Siberia, Russia) were determined in June 1993 and were compared with those available throughout the distribution range of the species. Differences between populations located 25° further south and 8000 km away are smaller than those described for other freshwater fishes, whose distributions fall within that of dace. For all the populations, the growth rates (K) are inversely correlated with latitude but these rates for the actual growing season are faster in northern dace. The latitudinal (spatial) variations in the growth rates resemble the temporal variation described for the R. Frome (U.K.). Also, the variations in fecundity between populations are comparable to the temporal variations reported for this British river. Fecundity of the Yenisei dace was correlated with female length [log F=– 3–6284+4–0424 x log L] but these females spawned lower numbers of eggs than other populations; and the size of their eggs, like those of the Siberian Ust'Ilim dace, did not vary with female length. We hypothesize that a similar spatio‐temporal response to low water temperature, coupled with limitations of energy for reproduction, may result in a constant egg size in Siberian dace. The effects of other selective forces cannot, however, be excluded.
Seasonal changes in food consumption and growth of Arctic charr exposed to either simulated natural or a 12:12 LD photoperiod at constant water temperature
Authors: Sæther B.‐S. , Johnsen H. K. , Jobling M.
Published: April 2005

Immature male and female and maturing male Arctic charr Salvelinus alpinus were held at constant temperature (4° C) under either simulated natural photoperiod (nLD) or constant photoperiod (12:12 LD) conditions, and feed intake and growth were monitored at monthly intervals over 13 months. Food was supplied in excess during a 5‐h period each day, and daily consumption was determined using X‐radiography. Food consumption and growth of both immature and maturing fish showed distinct seasonal cycles irrespective of photoperiod treatment. Feed intake and growth rates were highest in mid‐summer and lowest in autumn. The fact that seasonal cycles persisted under constant photoperiod (12:12 LD) and temperature conditions suggests that circannual rhythms of food consumption and growth exist in the absence of seasonal changes in these environmental cues. The data support the view that seasonal changes in food consumption and growth in the Arctic charr are driven by endogenous rhythms. Reductions in feeding and growth in autumn occurred about 1 month earlier in the maturing males than in the immature fish. Males that matured under the 12:12 LD regime displayed a growth cycle that was delayed in comparison with that shown by the maturing males held under nLD.
Upp er lethal temperature tolerance of fingerling black crapp ie
Authors: Baker S. C. , Heidinger R. C.
Published: April 2005

Upper lethal temperature tolerance was determined for 26–81 mm, age 0 black crappie Pomoxis nigromaculatus of three size classes using both a rapid transfer and slow heating protocol. Rapid transfer protocols determined 24 LT50 values of 33–8, 35–1 and 31–5° C for size classes with mean total lengths of 30–2, 45–6 and 74–9 mm. A predictive model was generated from the slow heating protocols that relates lethal temperature to acclimation temperature, total length, and condition factor (K) as predictors.
Survival and growth rates of the anemonefish Amphiprion ocellanris: a transfer experiment
Authors: Nelson J. S. , Phang V. P. E. , Chou L. M.
Published: April 2005

Amphiprion ocellaris individuals were removed from their host anemones on three coral reefs and transferred to a recipient site lacking anemonefish. Return surveys were conducted around 7 days and 330 days after transfer. Survival rates 1 week after transfer were high. The fish surviving 330 days after transfer were those that were shorter. This contrasted with the control fish where survivors had significantly longer initial lengths than non‐survivors. Relative length gain of transferred fish increased with decreasing total length, also contrasting with the control individuals. Percent survival rates were significantly lower in largest transferred fish, relative to the largest control individuals. Relative length gains of transferred fish were highest in the smaller fish contrasting with the growth of the control fish.
Ovarian development and serum sex steroid and vitellogenin profiles in the female cultured sturgeon hybrid, the bester
Authors: Mojazi Amiri B. , Maebayashi M. , Hara A. , Adachi S. , Yamauchi K.
Published: April 2005

Changes in serum levels of estradiol‐17/J (E2), testosterone (T), 17,20β‐dihydroxy‐4‐pregnen‐3‐one (17,20β‐P) and vitellogenin (VTG), in cultured adult female bester were examined in relation to ovarian development during a 1‐year sampling period. Considerable variations in oocyte development were found among fish. Oocytes at previtellogenic stage (≥0–6mm in diameter) generally started to develop concomitantly with the degeneration of the first batch of oocytes. In vitellogenic individuals, ovaries were comprised of more advanced oocytes with diameter ranging from 0–6 to 2–6 mm and in the post‐vitellogenic class, oocytes attained their largest size (>2–6mm) while the germinal vesicle was migrating towards the animal pole. Oocytes with a migrating nucleus were maintained during the winter period and massive degeneration started in April–May without germinal vesicle breakdown (GVBD) or ovulation occurring. Seasonal changes in E2, T and VTG levels were well correlated with the advancement of oogenesis. Their levels increased during vitellogenesis, whereas in the post‐vitellogenic (migratory nucleus) stage the levels of E2 declined from 2–4 ng ml −1± to 1–2 ng ml −1 and VTG from 4–10 mg ml −1 to 0.–0.5 mg ml −1 while T levels remained high (50–60 ng ml −1). In contrast, serum levels of 17,20†‐P were constantly low (less than 0.2 ng ml−L) throughout the reproductive cycle. These results indicate that the time appropriate for induction of artificial reproduction would be from October–November to April–May when the oocytes are in the late Stages of the development.
The physiological effects of salmon lice infection on post‐smolt of Atlantic salmon
Authors: Grimnes A. , Jakobsen P.J.
Published: April 2005

The physiological effects of salmon lice infections on post‐smolt of Atlantic salmon were examined by experimentally infecting hatchery reared post‐smolts with infective copepodids. Even at high infection intensities, ranging from 30–250 lice per fish, early chalimus stages did not have severe, physiological effects on the fish. There was a sudden increase in fish mortality after the appearance of preadult I stages. Infected fish were then suffering due to lesions and osmoregulatory failure. Plasma chloride level increased significantly and total protein, albumin and haematocrit decreased significantly in infected compared to uninfected fish. All infected fish became moribund before adult lice appeared. Infection intensities above 30 salmon lice larvae per fish thus appear to cause death of Atlantic salmon post‐smolt soon after the lice reach their pre‐adult stage.
Environmental effects on primary increment formation in the otoliths of newlyhatched Arctic charr
Authors: Radtke R. , Fey D. P.
Published: April 2005

Otolith microincrements were investigated in Arctic charr Salvelinus alpinus, reared from hatching under various temperatures (1, 3, 5, 7° C) and feeding conditions (starved, fed every third day, fed daily). Larval charr otoliths were marked with oxytetracycline and alizarin complexone. Alizarin complexone was found to be 100 per cent successful in marking otoliths while oxytetracycline marks could be seen in <10 per cent of the otoliths viewed. Otolith microincrements were viewed by light and scanning electron microscopy to investigate the daily nature of increment deposition. Low temperatures (1 and 3° C) and starvation depressed daily increment formation. Increment deposition was found to be daily among the larvae reared at warmer temperatures (5 and 7° C) and fed at least every third day. Scanning electron microscopic analysis allowed us to confirm the results of light microscope increment counts from all temperatures except 1 ° C, where the number of increments enumerated were higher than the number obtained during light microscopy analyses. Increased feeding and warmer temperatures also resulted in increased increment width. The difference in increment number and width seems to be dependent upon fish growth rate which we have found to be affected by both temperature and feeding conditions.
Detection of allelic variation within the growth hormone gene in common bream using heteroduplex analysis*
Authors: Gross R. , Schlee P‐ , Stein H. , Rottmann O.
Published: April 2005

A novel method, heteroduplex analysis, was applied for detecting variation in an amplified growth hormone (GH) gene segment of common bream Abramis brama. Two‐allele polymorphism was detected within a 262 bp restriction fragment. The frequency of the variant haplotype in the Main River was 0–50 and in the Danube River 0–32, but the difference was Statistically not significant.