bluuebunny/crossref_metadata_2025 huggingface dataset:
Determinants of territory size of the dusky gregory
Authors: Jan R.‐Q. , Ho C.‐T. , Shiah F.‐K.
Published: December 2003

To test the effect of food abundance and intruder pressure as determinants of territory size, the dusky gregoryStegastesnigricanswere used as subjects on a coral reef in southern Taiwan during November to December 2000. Adults were used as intruders to provoke aggressiveness in a conspecific territory owner. The owner's maximum distance of attack (MDA) was used to delineate the territory size. While the owner of a territory appeared to defend a single boundary against different conspecifics, size variations among territories were evident. The effect of an intruder's identity on territory‐size regulation was not clear because for each territory examined, the MDA was found to be neither linked to the body size of the intruder nor to the amount of algae in the intruder's territory. Moreover, no significant differences were found between the MDAs that the owner maintained against neighbours and non‐neighbours even though, when conspecifics intruded in pairs, the probability was significantly higher for the first attack to be launched on a neighbour than on a non‐neighbour. Also when a neighbour and a non‐neighbour appeared simultaneously near the territory, the bite rate against the neighbour was also significantly higher. An inverse relationship between the amount of algae in the defended territory and the MDA of the owner indicates that food abundance might account for variations among territories. By contrast, territory size was not linked to the body size of the owner.
Alimentary tract morphology and diet in three coral reef fish families
Authors: Elliott J. P. , Bellwood D. R.
Published: December 2003

Alimentary tract morphology and its relationship with diet was examined in three coral reef fish families: Labridae, Chaetodontidae and Pomacentridae. Convergent patterns of dietary‐related morphological variation were evident across the three families, with corallivores possessing long and narrow intestines, carnivores relatively short and wide intestines and herbivores relatively long and wide intestines. Between‐family differences were also evident: chaetodontids typically possessed long and narrow intestines, pomacentrids long and wide intestines and labrids generally possessed short and wide intestines. Overall, intestinal length variation was most strongly attributable to diet, whilst intestinal diameter varied most widely among families. Relative intestinal length appears as a useful predictor of dietary variation, particularly within families. Relative intestinal diameter appears as a less reliable measure, but rather, a useful adjunct to intestinal length comparisons.
Diet segregation between two sympatric ‘small’Barbus spp: an experimental study of mechanisms
Authors: Dejen E. , Sibbing F. A.
Published: December 2003

Gut contents of two co‐occurring species of ‘small’ diploid barbs (<10 LF cm) in Lake Tana revealed that zooplankton is the major diet component for B. tanapelagius(75% based on volume), but less prominent in B. humilis(40%). Functional response experiments in the laboratory were conducted to elucidate the mechanisms causing this difference. The type of functional response by the two ‘small’ barbs under different microcrustacean zooplankton densities (10, 20, 40, 60 and 80 ind.l−1) was examined. The functional response of B. tanapelagius to increasing prey densities corroborates with Holling Type II model, whereas B. humilis exhibits a Type III functional response. Predation rate is higher for B. tanapelagius at low zooplankton density (<40 ind.l−1) and equals the level of B. humilis at higher densities (>40 ind.l−1). This suggests that at lower zooplankton densities B. humilis is a less efficient forager on zooplankton prey items than B. tanapelagius. In Lake Tana average zooplankton density is relatively low (<35 ind.l−1). Under these food conditions, B. humilis is forced to feed on other food items (e.g. benthic invertebrates), whereas B. tanapelagius primarily feeds on zooplankton. The feeding potentials of the two ‘small’ barbs, as deduced from their morphology explain their different performances and their segregation in space and food resources.
Familiarity confers anti‐predator and foraging advantages on juvenile brown trout
Authors: Griffiths S. , Höjesjö J. , Johnsson J.
Published: December 2003

Many fish species preferentially associate with familiar conspecifics rather than unfamiliar individuals with whom they have no previous experience. The function of discriminatory ability, however, is not well documented. In territorial fish, observations of lower aggression levels among pairs of familiar neighbours lead to two predictions. First, that increased time available for vigilance among familiar fish will allow a faster response to a predator attack, and second that after an attack familiar fish resume foraging more quickly than unfamiliar fish. We conducted an experiment to test these hypotheses using wild juvenile brown trout from Sweden. Our results confirm hypothesis one by demonstrating that familiar brown trout juveniles respond 16% more quickly to a model predator than individuals held in unfamiliar groups. Hypothesis two, that familiar fish resume feeding more quickly after a simulated predator attack was not supported. Nevertheless familiar fish consume a greater number of food items than fish in unfamiliar groups. To the best of our knowledge our results provide the first evidence that familiarity confers advantages through the direct fitness benefits afforded by faster predator evasion responses, and through the long‐term benefits provided by increased feeding opportunities. We discuss the possibility that these advantages promote the formation of stable association patterns and improve growth and survival in wild populations.
Improving anti‐predator responses of hatchery reared salmonids by social learning
Authors: Hirvonen H. , Vilhunen S. , Brown C. , Lintunen V. , Laland K. N.
Published: December 2003

Predation shortly after release is the main source of mortality among hatchery‐reared fish used to restore or enhance endangered salmonid populations. We found, that hatchery‐reared salmonid young originating from endangered stocks have weak innate responses to their natural fish predators. The ability to avoid predation in fish can be improved through social learning from experienced to naïve individuals. Huge benefits would be achieved, if social learning processes could be successfully applied on a large scale to enhance viability of hatchery fish prior to release into the wild. By using model predators together with chemical cues from real predators we tested if social learning could be used to train hatchery‐reared salmonid young to avoid fish predators. As there are clear differences in social behaviour among the salmonid species, we first examined whether these differences affect the probability and efficiency of learning anti‐predator skills from trained demonstrators. We compared anti‐predator responses of observers (fish trained by using experienced fish as demonstrators) with those of control fish, which had been ‘trained’ by untrained naïve conspecifics. We also examined how the efficiency of social learning depends on the ratio of experienced to naïve fish involved in social transmission trials. The results of these experiments will give guidelines how social learning could be utilized in developing hatchery scale training protocols.
Tidal stream mediation of metapopulation structure in North Sea plaice
Authors: Hunter E. , Metcalfe J. D. , Arnold G. P. , Reynolds J. D.
Published: December 2003

Migration is widespread among marine fishes, yet little is known about variation in the migration of individuals within localities. We tested the hypothesis that variation in the migratory behaviour among plaice (Pleuronectes platessa) in the North Sea could be explained by large‐scale differences in the speed and directions of the tidal streams, which the fish use as a transport mechanism. Towards this end, 752 mature female plaice tagged with electronic data storage tags were released at eight locations with contrasting tidal flow properties, between December 1993 and September 1999. The experiment yielded 20 403 days of data from 145 plaice. The position of each fish was determined at intervals throughout the liberty period using the tidal location method. The results show 3 geographically discrete feeding aggregations during the summer, which dispersed over the southern North Sea and Eastern English Channel to spawn during winter. Our results re‐affirmed the major role of the tidal streams in the southern North Sea in structuring plaice dispersion, both by providing transport and guidance, and by delimiting the extent of distribution due to thermal stratification during the summer. These results confirm the prediction that large‐scale variation in migration behaviour can be explained in part by the tidal guidance and transport mechanisms available. They have revealed features of spatial dynamics not previously observed from a century of conventional tagging experiments and illustrate how the study of individual fish can successfully define the migratory characteristics of populations.
Reproductive investment in relation to survival risk in a livebearing fish
Authors: Lindström K. , St Mary C. , Gunnels B. , Hale R. , Osenberg C. , Stevens S. , Vonesh J. , Wilson J.
Published: December 2003

Animals are expected to change their allocation of resources into offspring depending on their future survival probabilities. Under environmental conditions where survival probabilities are low, we expect to see an increased investment in current reproduction. Fish show an exceptionally wide range of reproductive modes, including systems where parents can be expected to have extensive control of investment in their offspring. In the least killifish, Heterandria formosa, a small livebearing fish, fertilization is internal and females extensively provision developing embryos. Hence females are likely to have control over parturition time and size of their offspring. Our expectation was that under predator threat females should produce offspring at a higher rate than in control situations. Females were given visual and chemical exposure to mosquito fish and sunfish predators. The time until the birth of the first brood was longer in the presence of predators than in the control. However, subsequent birth intervals showed the opposite pattern. In the presence of predators ensuing brood intervals were shorter than in the control treatment. The effect of mosquito fish and sunfish was similar. Despite the decrease in pregnancy interval, newborn offspring were still larger in the presence of sunfish. Our results suggest that the initial response of refraining from reproduction later changes to an increased reproductive output. This increase, however, did not manifest itself as a quality vs. number trade‐off as offspring were also bigger in the sunfish treatment. This suggests that reproductive investment increases in the presence of predators and this may represent terminal investment.
Yellow belly as honest signal of female quality in Knipowitschia panizzae(Gobiidae)
Authors: Mazzoldi C. , Massironi M. , Rasotto M. B.
Published: December 2003

Sexually dimorphic traits are common in fish species, and examples from both males and females have been described. The function of these traits has been widely investigated in males. On the contrary, female ornaments have been studied mainly in sex role reversed species, such as pipefish, while their role in species with ‘conventional’ sex roles remain to be investigated.

This study focused on the presence, function, and possible role as indicator of female quality of a sexually dimorphic nuptial trait in the lagoon goby, Knipowitschia panizzae. In this species, that present conventional sex roles, females show a yellow spot on the belly. Aquarium spawning experiments demonstrated that the coloration on the belly is due to dermal pigments, is displayed only when female is ready to spawn and is switched off within few minutes from the end of egg deposition. This sexual trait presents variability in size among females and indicates female fecundity relatively to her own body size. As a consequence, female yellow belly appears to be an honest signal of female quality. Field data on natural nests highlighted that males perform parental cares mostly only on one egg batch at a time and the modality of egg deposition suggested that males are limited in their potential reproductive rates by environmental factors. Male limitation in egg care could constitute the basis for a female biased operational sex ratio, favouring male choosiness and the evolution of female nuptial displays.
Operational sex ratio and resource defence as predictors of the mating system in European bitterling
Authors: Mills S. C. , Reynolds J. D.
Published: December 2003

Operational sex ratio (OSR), the ratio of sexually active males to fertilizable females in a population, plays a central role in the theory of mating systems by predicting that the intensity of male–male competition and the degree of sexual selection increases as the OSR becomes increasingly male biased. At high values of OSR, however, resource defence theory predicts the breakdown of territoriality and a shift towards scramble competition with a decrease in sexual selection. The direction that correlations between OSR and resource competition and variance in mating success will take depends on the biology of the species of interest. We investigated the effects of male population density and male‐biased operational sex ratio on male mating tactics shown by a freshwater fish, the European bitterling, Rhodeus sericeus. This species spawns inside living unioneid mussels. Large males defended territories, were aggressive towards conspecifics under equal sex ratios and monopolized pair spawnings with females. The mating tactic, however, changed at high male density where large males ceased to be territorial and instead competed with groups of smaller males to release sperm when females spawned. This change in male behaviour from pair to group spawning has two ramifications for sexual selection. The intensity of sexual selection and variance in male mating success decrease, and the form of sexual competition changes from resource‐ to sperm competition. Thus, the use of alternative mating tactics renders the OSR unable to predict the direction of resource competition and variance in male mating success at high densities.
Components of care: are they honest signals of parental care quality?
Authors: St Mary C. M. , Lindström K.
Published: December 2003

It has been argued that male parental care provides direct benefits to females and therefore should be under sexual selection. Given this, we expect signals that honestly indicate the quality of care to be favoured by selection. One such potential signal is care itself. Fish have several features that make them excellent model systems for studying the evolution and dynamics of parental care. We use the flagfish, Jordanella floridae, as a model to evaluate these general ideas. Males of this species guard, clean and fan empty nests and then eggs. Females prefer males that fan more (1) before spawning and (2) when eggs are newly received. When single males and females were paired, males that fanned and visited their nests more prior to spawning were more likely to be mated. Furthermore, among successful males, rates of fanning in the first day after spawning were correlated with the number of eggs received in the future (but not current egg numbers). We then considered whether these two putative signals were correlated and whether males that fan more in these contexts actually have higher egg survivorship. We found no correlation between nest fanning rates before and after spawning and neither ‘signal’ was predictive of variation in egg survivorship among mated males. We further considered whether pre‐spawning fanning rates were predictive of hatching success in an experiment in which single males were allowed to establish nests and provided eggs. We found little evidence that fanning is an honest signal of care quality and discuss alternative explanations. In particular, we discuss patterns of care elaboration in light of our results.
Countergradient variation in behaviour, growth and lipid storage in Atlantic cod; environmental and genetic effects
Authors: Salvanes A. G. V. , Skjæraasen J. E. , Nilsen T.
Published: December 2003

We housed offspring from northern (70° N) and southern (60° N) coastal cod (Gadus morhua) together in a ‘common garden’ rearing experiment at a temperature and light regime representative of the southern population. Through a more active feeding behaviour and a higher success, the northern cod achieved a larger food share and a higher growth rate and condition than their southern conspecifics. This is contrary to what was demonstrated by field data of fish from their natural habitats. The northern cod also allocated more energy to the liver throughout the experiment. Our results agree with the theory of countergradient variation, suggesting that genetic influences on growth and condition have been opposed by environmental constraints in their natural habitat. The observation that the offspring from these populations differ in behavior and growth when housed together support the idea that the growth response to selection would be through a behavioral response.

The field data suggest that density‐dependent population process and high juvenile density relative to prey limit the growth and condition in the wild and not necessarily the length of the growth season per se as assumed in the literature. The topographic distance (over 2000 km) limit mixing of early life stages of cod from the northern and southern population, and the different environmental stimuli (seasonality, temperature, food‐web interactions and habitat heterogeneity) in north and south are likely to evolve genetic differences.
Does behaviour explain the larval dispersal of coral reef fishes better than oceanography?– An individual based model simulation approach
Authors: Simpson S. D. , Dytham C. , Meekan M. G.
Published: December 2003

Until recently, oceanographic models have been used, with limited success, to predict the larval dispersal of coral reef fishes. Settlement‐stage larvae have been shown to be capable swimmers and have highly developed sensory organs. We built two simulation individual based models (IBMs) of larval dispersal in the Dampier Archipelago, Western Australia. One followed an oceanographic model, while the other was driven by behavioural constraints. We compare predictions of these models with an extensive dataset from a light‐trapping programme in an attempt to elucidate the overriding mechanism of larval coral reef fish dispersal.
The evolution of cooperation and advanced social behaviour
Authors: Taborsky M.
Published: December 2003

Different components contribute to the evolution of advanced sociality. These include the existence of non‐depreciable resources, ecological constraints, relatedness patterns, direct fitness effects of group living, demography and phylogenetic inertia. Several of these components are usually responsible for the origin and stability of highly organized groups in which conspecifics cooperate in reproduction. Therefore, all these levels should be considered when we aim to understand such complex social patterns. This is usually difficult for practical reasons. In cooperatively breeding cichlids, however, it is possible to study the importance of these components with observational and experimental approaches. With help of this paradigm I aim to illustrate the potential significance of these extrinsic and intrinsic causes of social evolution, and their functional relationships.
Behavioural interactions between native smokey dace and introduced yellowfin shiner: implications from habitat selection theory for an ongoing invasion
Authors: Wagner C. M. , Grossman G. D.
Published: December 2003

The occupation of adjacent, non‐overlapping positions along environmental gradients by closely related and ecologically similar species has drawn considerable attention from ecologists over the past decades. Condition‐specific competition, wherein competitive superiority varies with the abiotic environmental gradient, has been proposed as the major structuring force behind such distributions. These concepts, however, are generally applied to explain the contemporary distribution of organisms that share an evolutionary history. Our aim was to apply these concepts to the naive interactions between native and introduced fishes. In 1990 yellowfin shiner (Notropis lutipinnis) were introduced into the headwaters of the Little Tennessee River of western North Carolina, U.S.A. where it exhibits microhabitat preferences that overlap significantly with those of a threatened native minnow, the smokey dace (Clinostomus funduloides raneyi). Previous research has established that these drift‐feeding minnows: (1) differ in their average ability to intercept drifting prey as a function of water velocity; (2) generally occupy focal‐point velocities that maximize the rate of prey capture; and, (3) occasionally defend the forward positions in foraging aggregations that form in high quality patches. We present the results of a series of experiments designed to: (1) evaluate the role of aggression in the establishment and maintenance of preferred foraging positions in drift‐feeding minnows; (2) test the effects of prey availability, group size, and velocity on dominance rank, spatial position in groups, and feeding rates of individuals; and, (3) evaluate the potential for condition‐specific competition to establish competitive refugia for the native within the natural heterogeneity of mountain streams.
The effects of habitat‐ and diet‐based cues on association preferences in the three‐spined stickleback (Gasterosteus aculeatus)
Authors: Ward A. J. W. , Krause J. , Hart P. J. B.
Published: December 2003

A number of recent papers have investigated the potential of familiarity to organize the distributions of free‐ranging animals. It is not clear, however, to which extent individual recognition or a more general recognition of a group odour is responsible for familiarity preferences. First, we tested the sensory basis of the recognition of familiars in three‐spined stickleback (Gasterosteus aculeatus). When allowed to choose between a familiar and an unfamiliar stimulus shoal on the basis of both visual and chemical communication, visual communication only and chemical communication only, the preference of focal fish for familiars was shown to be dependent on the presence of chemical cues. We subsequently investigated the mechanisms underlying such association preferences, specifically the effects of recent habitat and diet on preferences. Experimental fish were divided into four treatment groups consisting of two environment treatments (saline and freshwater) and two diet treatments (Daphnia spp. and chironimid larvae). Focal fish subsequently showed significant association preferences for groups of unfamiliar fish that had undergone the same environment or diet treatment as themselves, suggesting self‐referent matching. These data indicate that individual recognition is not a pre‐requisite for the expression of familiarity preferences.
Effects of light intensity and spectrum on fish behaviour in laboratory aquaria
Authors: Barber I. , Young J. , Morrison‐Smith E. , Matthews E.
Published: December 2003

Teleost fish are commonly used as model species in laboratory studies of behaviour and ecology. In comparison to other groups of vertebrates used routinely in such studies, however, relatively little attention has been paid to their environmental requirements from a welfare perspective. Fish naturally inhabit a wide variety of aquatic habitats that differ enormously in the range of light environments they provide, and light regime has enormous potential to affect behaviour. Yet the level and quality of illumination (in terms of intensity and wavelength spectrum) provided in experimental studies of fish behaviour is generally designed to maximize ease of recording by the observer. In addition, display or home aquaria provide illumination that maximizes the ‘viewing pleasure’ of the observer, and specialist lighting tubes are available to stimulate rapid plant growth and to ‘show off’ the colours of fish, rather than to provide ‘natural’ light environments. Here we present the results of three studies designed to examine the effects of light intensity, wavelength spectrum and their interactions on the behaviour of a model species commonly used in behavioural studies, the three‐spined stickleback Gasterosteus aculeatus. Our aims are to determine whether unnatural light environments, generated by manipulating light intensity and wavelength spectrum, affect behaviour in ways that may lead to concern for the welfare of fish as research animals or pets.
Synchrony between parasite development and host behaviour change
Authors: Barber I. , Svensson P. A.
Published: December 2003

Many parasites rely on the predation of one host by another to be transmitted. Such parasites are expected to have evolved strategies of host manipulation that alter the susceptibility of current hosts to predation by suitable predators, and many examples of altered behaviour exist. For many parasites, however, a period of growth and development in each host is essential before they are ready to be transmitted. If changes in host behaviour are truly parasite adaptations, rather than side‐effects of infection, then host behaviour change should only be predicted when the parasite is infective to the next host. This study documents the behaviour of individual three spined sticklebacks Gasterosteus aculeatus over a 16‐week period following experimental infection with the common cestode parasite Schistocephalus solidus, which requires infected fish to be ingested by birds before it can attain sexual maturity. In addition to regularly monitoring shelter use and escape response behaviour of infected fish, we also used non‐invasive morphometric techniques to estimate parasite size, and thus were able to link behaviour changes to the growth of the parasite in individual fish. The behaviour of experimentally infected sticklebacks deviated significantly from that of controls (sham‐exposed) fish when the parasites they harboured approached an estimated weight of 100 mg. The results are discussed in the light of a further study, examining the relationship between parasite size and ultimate fecundity in the bird host.
Effects of substrate embeddedness on juvenile brown trout (Salmo trutta L.) growth and behaviour
Authors: Bolliet V. , Bardonnet A. , Vignes J.‐C.
Published: December 2003

Young salmonids may use substratum as hiding stations and/or shelter and they depend on invertebrates, which develop on substratum, for their feeding. For several decades, human activities have contributed to increase siltation in streams, and negative consequences on trout production have sometimes been highlighted. In the research devoted to the understanding of that negative effect, most studies have focused on embryo‐larval survival, and consequences of substrate embeddedness on later stages have rarely been investigated. In the present work we attempt at studying the impact of embeddedness on brown trout juveniles. In an experimental channel, trout growth was compared in embedded and non‐embedded sections. Growth was reduced with embeddedness due to change in trophic conditions and/or in habitat. To investigate the direct role of substratum for fish, trouts behaviour was observed from an under water observation room in two cages offering embedded and non‐embedded substrate conditions but similar trophic conditions. Competition appeared heavier in the embedded cage where dominated fishes stayed almost motionless. The effect of substratum quality on intra‐specific competition is discussed in relation with visual isolation and territory size.
The relationship between dominance rank and feed intake following the introduction of novel feeds to African catfish
Authors: Carter C. G. , Abdel‐Warith A‐W. A. , Davies S. J.
Published: December 2003

The experiment aimed to examine the effect of changing feeds on individual feed intake and feeding and dominance ranks in groups of African catfish. Following feeding on a commercial control feed (Con.) groups (n = 3) of 6 catfish were either fed fish meal (FM42) or maize gluten (MG32) based feeds for five days before being switched to the other feed for five days. Feed intake was significantly lower on FM42 than on Con. or MG32 and occurred whether FM42 was fed first or second after Con. Thus, the effect of changing the feed was feed specific. Stability (Kendall's coefficient of concordance) of feeding rank was higher in 5 out of the 6 groups when they were fed MG35 than when fed FM42. Six types of agonistic behaviours were identified and used to assign dominance rank, there were no correlations between dominance and feeding ranks in groups. This was probably due to non‐linear hierarchies with one dominant fish in each group. There were significant correlations between dominance and feeding ranks for combined data over the initial period (r = −0·51, P < 0·005, n = 36) and when analyzed for the two feeds. Correlations were stronger for MG35 (r = −0·41, P < 0·01) than for FM42 (r = −0·33, P < 0·05). The experiment demonstrated that the introduction of a novel feed can, but does not necessarily, alter feed intake. Of greater significance is the indication that when feed intake decreased the feeding hierarchy and its relationship to dominance rank became less stable.
Telemetering sub aqua video photography to boat‐ and shore‐bases: a new approach
Authors: Davies R. , Humphries S.
Published: December 2003

The use of video photography normally involves sub‐aqua recording via a camcorder device. The problem is that the scientist needs to be directly involved in the recording underwater or else viewing the results of the footage after the event. The system we have developed enables real time images to be relayed to a boat, satellite of shore‐based recorder. With a two‐way audio communication system, it is possible for the scientist/team to direct the camera work of the divers, remotely. The configuration of this system are discussed, and a wide range of scientific applications suggested.
Morphometric recognition of two morphs in sterlet (Acipenser ruthenus) population induced by different reproductive behaviour
Authors: Lenhardt M. , Cakic P. , Kolarevic J. , Gacic Z.
Published: December 2003

Four species of sturgeons appear in the Yugoslav part of the Danube River. Among them three are anadromous, beluga (Huso huso), Russian sturgeon (Acipenser gueldenstaedtii) and stellate sturgeon (Acipenser stellatus) and migrate to Danube from the Black Sea to spawn. Only sterlet (Acipenser ruthenus) is exclusively freshwater. There are obvious differences between vernal and winter races of anadromous sturgeons, due to their different migratory patterns. Russian ichthyologist Berg (1934) claimed that there are two races (morphs) in the starlet population as well. This stimulated long discussion in Russian and Yugoslav literature, and it was the starting point for our research on sterlet in the Yugoslav part of the Danube River.

Morphometric analysis was preformed on 159 individuals caught in Danube River among 1123 and 1173 km, on four localities during September and October 2002. Analysis included 24 morphological and 3 meristic characters. K‐means cluster analysis indicated existence of two different clusters (groups), one with 95 (59·75%) and other with 64 (40·25%) samples. Significant differences were found for preorbital, preoral and prebarbel length. Mean values (in % of head length) for first group were 50·13 ± 1·71, 57·61 ± 1·87, 39·74 ± 2·20 and for second group 53·50 ± 2·46, 62·07 ± 2·20 and 43·30 ± 2·08 respectively. Findings were confirmed by Principal Components & Classification Analysis. These results speak in favour of existence of two morphs in sterlet population, one with long and pointed rostrum (vernal) and other with short rostrum (winter). According to the literature that is probably influenced by different reproductive behaviour (time separation in spawning).
Effect of light intensity on the shoaling behaviour of the guppy (Poecilia reticulata)
Authors: O'Connor E. , Krause J.
Published: December 2003

It has been shown that the tendency of fish to shoal decreases as night falls. Much is known about shoaling in the daytime, however, little is known about the social behaviour of fish at night. Although the nocturnal disintegration of shoal structure is the conventional expectation for most diurnal marine fish, it has not yet been investigated for diurnal freshwater fish. This possibility has been investigated using guppies (Poecilia reticulata), collected from the wild, as an experimental model.

Three preference tanks were used, one of which permitted only visual cues, another only olfactory cues and the other both visual and olfactory cues. Shoaling tendency was observed at four different light intensities (8 wt/m, 0·05 wt/m, 0·025 wt/m, 0·003 wt/m). These light intensities were chosen to mimic daylight, dawn/dusk, clear night and cloudy night conditions, respectively. Trials were carried out on randomly selected male guppies. Results indicated that with both modalities present fish significantly preferred the stimulus shoal at all light intensities. However with only one modality to indicate the presence of the shoal, fish showed no significant shoaling tendency at any of the diminished light intensities. A test of shoal cohesion at the four different light intensities was carried out on freely interacting fish. This test condition was chosen to mimic the situation of guppies in the wild. The results to date suggest that guppies continue to shoal during dusk (at low light intensities) but not during the night. These findings make an important contribution to our understanding of the social behaviour of fish at night and deserve further investigation.
Female preferences based on olfactory cues in the guppy (Poecilia reticulata)
Authors: Watt P. J. , Shohet A. J.
Published: December 2003

Guppies are highly sexually dimorphic and females have been shown to mate preferentially with males with various visible traits. Guppies, however, have been shown to respond behaviourally to odour cues from conspecifics. Using a specially designed olfactory choice tank, we tested whether females (1) could detect other guppies on the basis of their olfactory cues alone, (2) preferred to associate with males or with females and (3) could distinguish between different males. Female guppies were found to associate preferentially with other guppies when given a choice between water containing cues from another fish and water containing no cues. When females were presented with olfactory cues from a male or a female, they preferred the female initially but most then reversed their decision and swam to the male. Females associated preferentially with certain males based upon olfactory cues alone. Males, however, preferred on the basis of olfactory cues were the least preferred for visual cues.
Nasal retention of budesonide and fluticasone in man: Formation of airway mucosal budesonide‐esters in vivo
Authors: Petersen Hannes , Kullberg Annika , Edsbäcker Staffan , Greiff Lennart
Published: December 2003

Aims  The efficacy of topical glucocorticosteroids in rhinitis and asthma is likely to depend on drug retention in the airway mucosa. With fluticasone propionate, retention may be achieved exclusively by lipophilicity, whereas for budesonide an additional possibility may be provided by its ability to form fatty acid esters in the airway mucosa that release the active drug. The aim of the present study was to determine the nasal mucosal retention of budesonide and fluticasone propionate, and the occurrence of budesonide‐esters (budesonide‐oleate, budesonide‐palmitate) in the nasal mucosa.

Methods  In the present study, involving 24 healthy subjects, we have examined nasal mucosal drug retention of single doses of topical budesonide (256 µg) and fluticasone propionate (200 µg). Treatments were given consecutively and the administration sequence was randomised. Subjects were randomised into four parallel groups and two nasal biopsies were taken from each subject, i.e. before and at 2 h, at 2 and 6 h, at 6 and 24 h, or before and at 24 h after drug administration, resulting in 12 biopsies/time point. The measurement of unesterified budesonide, budesonide‐oleate, budesonide‐palmitate, and fluticasone propionate was based on microwave extraction procedures combined with liquid‐chromatography/tandem mass‐spectrometry.

Results  Neither of the analytes was detected in samples taken before glucocorticosteroid administration. After administration, unesterified budesonide, budesonide‐esters, and fluticasone propionate were detected in the tissue from 23, 20, and 19 subjects, respectively. The mean tissue levels of budesonide at 2 and 6 h were 1051 and 176 pmol g−1; the mean levels of fluticasone propionate at these time points were 237 and 10 pmol g−1. The dose‐corrected budesonide/fluticasone propionate tissue concentration ratios were 3.5 (P = 0.07) and 13.7 (P < 0.0002), respectively. At 24 h, budesonide and fluticasone propionate were detected in 8/12 and 3/12 of the biopsies, respectively.

Conclusions  The present study demonstrates the formation of budesonide‐esters in the human nasal mucosa in vivo, and that budesonide is retained in the nasal mucosa to a greater extent than fluticasone propionate. It is suggested that the formation of budesonide‐esters and their subsequent release of budesonide contributes to an extended retention of budesonide in the airway mucosa.
Biomarkers for the effects of antipsychotic drugs in healthy volunteers
Authors: De Visser S. J. , Van Der Post J. , Pieters M. S. M. , Cohen A. F. , Van Gerven J. M. A.
Published: December 2003

Studies of novel antipsychotics in healthy volunteers are traditionally concerned with kinetics and tolerability, but useful information may also be obtained from biomarkers of clinical endpoints. A useful biomarker should meet the following requirements: a consistent response across studies and antipsychotics; a clear response of the biomarker to a therapeutic dose; a dose–response relationship; a plausible relationship between biomarker, pharmacology and pathogenesis. In the current review, all individual tests found in studies of neuroleptics in healthy volunteers since 1966 were progressively evaluated for compliance with these requirements. A MedLine search yielded 65 different studies, investigating the effects of 23 different neuroleptics on 101 different (variants of) neuropsychological tests, which could be clustered into seven neuropsychological domains. Subjective and objective measures of alertness, and of visual‐visuomotor‐auditory and motor skills were most sensitive to antipsychotics, although over half of all the studies failed to show statistically significant differences from placebo. The most consistent effects were observed using prolactin response and saccadic eye movements, where 96% and 83% of all studies resp. showed statistically significant effects. The prolactin inducing dose equivalencies relative to haloperidol of 19 different antipsychotic agents correlated with the lowest recommended daily maintenance dose (r2 = 0.52). This relationship could reflect the clinical practice of aiming for maximum tolerated levels, or it could represent a common basis behind prolactin release and antipsychotic activity (probably D2‐receptor antagonism). The number of tests used in human psychopharmacology appears to be excessive. Future studies should look for the most specific and sensitive test within each of the domains that are most susceptible to neuroleptics.
Pharmacokinetics of sabeluzole and dextromethorphan oxidation capacity in patients with severe hepatic dysfunction and healthy volunteers
Authors: Pageaux G. P. , Micallef J. , Nataf M. Barugola , Levron J. C. , Lacarelle B. , Le Moing J. P. , Bouhours P. , Blin O.
Published: December 2003

Aims  The primary objective of this study was to determine how the pharmacokinetics of sabeluzole, an investigational drug with specific effects on memory and learning abilities, are affected by chronic liver disease. Since sabeluzole is metabolised by CYP2D6, a secondary objective was to study the correlation between CYP2D6 activity (as assessed by the dextromethorphan dextrorphan metabolic ratio) and hepatic dysfunction.

Methods  The single‐dose pharmacokinetics of sabeluzole (10 mg) was compared in 10 healthy Caucasian subjects and 10 patients with severe hepatic dysfunction. The urinary dextromethorphan/dextrorphan (DMP/DRP) metabolic ratio was determined after intake of 20 mg dextromethorphan (NODEX® capsules).

Results  The terminal half‐life of sabeluzole was significantly prolonged in subjects with severe hepatic dysfunction vs healthy subjects (respectively 39.3 ± 11.5 h; 17.5 ± 10.2 h (mean ± s.d.)). The areas under the curve (AUC) were significantly higher in subjects with severe hepatic dysfunction than in healthy volunteers (681 ± 200 ng ml −1h vs 331 ± 282 ng ml −1h). There was a significant correlation between the AUC(0,∞) and the DMP/DRP metabolic ratio in healthy volunteers and subjects with severe hepatic dysfunction. AUC was greater and elimination of sabeluzole slower in poor metabolizers compared with extensive metabolizers.

Conclusions  These results suggest that a) sabeluzole dose should be reduced in patients with severe hepatic dysfunction and b) the AUC of sabeluzole is linked to individual CYP2D6 activity.
Journal impact factors: a ‘bioequivalence’ issue?
Authors: Rostami‐Hodjegan A. , Tucker G.T.
Published: December 2003

Aims  Journal impact factors (IMFs) are used increasingly by institutions as performance indicators of the quality of ‘individual research output’. Although the need for discretion when using the numbers has been emphasized, there has been little formal analysis of the issues. We therefore investigated citation profiles for three clinical pharmacology journals to assess the validity of using IMF as a measure of ‘individual research’.

Methods  We compared the pattern of individual citations for random samples of 120 papers published in Clin Pharmacol Ther (CPT), Br J Clin Pharmacol (BCP) and Eur J Clin Pharmacol (EJCP) in 1981, 1991, 1995 and 1996. Using an analogy between citation‐time profiles of papers and concentration‐time profiles of drugs, it was possible to define ‘lag‐time’, Cmax, tmax, t½ and AUC(t), and to investigate ‘bioequivalence’.

Results  Citation distributions for individual publications were widely variable and skewed (skewness = 1.47, 2.16 and 1.37 for CPT, BCP and EJCP, respectively). The 90% CI values for the IMF of a publication in each journal (i.e. 90% CI for an observation as opposed to 90% CI for the mean) were 0.24–16.94, 0.08–10.3 and 0.09–5.68.

Conclusions  IMF does not represent the impact of an individual paper. Furthermore, if the comparison of journals is treated as a bioequivalence issue, the citation data should be log transformed prior to calculating IMF such that they represent the likelihood of citation for the median article. After such transformation, absolute differences between the IMF of clinical pharmacology journals become much smaller.
The effects of lacidipine on the steady/state plasma concentrations of simvastatin in healthy subjects
Authors: Ziviani Luigi , Da Ros Lucio , Squassante Lisa , Milleri Stefano , Cugola Mauro , Iavarone Laura E.
Published: December 2003

Aims Lacidipine, a long acting 2, 4‐dihydropyridine calcium channel antagonist is frequently administered with cholesterol lowering agents, particularly in elderly populations. The effects of lacidipine on the pharmacokinetics of simvastatin were investigated, since they share the CYP3A4 pathway for metabolism.

Methods The study was an open, randomised, two‐way crossover design, with at least 7 days washout. Eighteen healthy subjects received simvastatin, 40 mg once daily, alone and together with lacidipine, 4 mg once daily, for 8 days. The pharmacokinetics of simvastatin were studied on the eighth day. Analysis was made of total simvastatin acid concentrations (naive simvastatin acid plus that derived from alkaline hydrolysis of the lactone).

Results Lacidipine increased the maximum concentration of simvastatin (Cmax) by approximately 70% (P=0.016) and the area under the plasma concentration‐time curve AUC(0,24 h) by approximately 35% (P=0.001). The mean Cmax and AUC(0,24 h) of simvastatin (95% confidence interval) when given alone were 8.76 (6.72–11.41) ng ml−1 and 60.36 (47.15–77.28) ng ml−1 h. During treatment with lacidipine they were, respectively, 14.89 (10.77–20.58) ng ml−1 and 80.96 (64.62–101.44) ng ml−1 h. No significant differences were observed in either time to peak concentration (tmax was 1.0 h for simvastatin alone and 1.5 h for the combination) or in the half‐life (t1/2,z was 8.5 h in both cases). The combination was safe and well tolerated.

Conclusions The observed increased exposure to simvastatin 40 mg following coadministration of lacidipine is unlikely to be of clinical relevance.
Targeted psychosocial interventions for bipolar disorder
Authors: Zaretsky Ari
Published: December 2003

Abstract:  Pharmacotherapy is the foundation of treatment for bipolar disorder, but research suggests that adjunctive psychosocial interventions that are manualized, reproducible, time‐limited, empirically supported, and strategically target a number of critical domains, can efficiently provide additional benefits. Psychoeducation as an adjunct of pharmacotherapy may be beneficial, but questions remain about the utility of this treatment for patients who are already compliant with medication treatment. Family educational interventions have demonstrated encouraging results in relapse prevention, but follow‐up data are limited and application to patients who have limited social networks may be problematic. Reports on interpersonal and social rhythm therapy in patients with bipolar disorder are scarce, and what is available shows no differential effect on time to remission or relapse, but a significant impact on subsyndromal symptoms. Follow‐up data suggest that patients receiving cognitive behavior therapy have significantly fewer bipolar episodes, shorter episodes, fewer hospitalizations, and less subsyndromal mood symptoms. It is unclear, however, if cognitive behavior therapy is superior to other active psychosocial treatments and whether its mechanism in patients with bipolar disorder is through changing dysfunctional cognitions or simply enhancing early symptom detection. Psychotherapies should be considered early in the course of illness to improve medication compliance and to help patients identify prodromes of relapse in order to take steps for prevention. In addition, some strategies may have a beneficial effect on residual symptoms, particularly symptoms of depression, and thus help move patients toward a more comprehensive functional recovery.