State-dependent vertical distribution of the carnivore copepod Pareuchaeta norvegica

We explored the impact of body condition on vertical distributionof the carnivore copepod Pareuchaeta norvegica. Individualssampled in the upper part of the water column had lower dryweight and slightly shorter prosome than individuals sampleddeeper. Non-ovigerous females occurred higher in the water columnthan ovigerous females. Our results suggest that ovigerous femalesand individuals with large energy reserves to a large extentprioritize predator avoidance in deep water versus feeding inthe upper part of the water column compared to non-ovigerousfemales and individuals with low energy reserves. Adult femalescollected closest to the surface were less pigmented than thosefound deeper. This, however, proved to be a quickly adjustabletrait depending on prevailing light conditions.     

Lymphocyte antioxidant response and H2O2 production after a swimming session: gender differences

This study evaluated the gender differences in response to intense exercise on lymphocyte hydrogen peroxide production, nitric oxide handling and mitochondrial superoxide dismutase (MnSOD) activity and gene expression. Fifteen males and nine females participated voluntarily in the study and performed a swimming session at 75-80% of the maximal capacity. In basal conditions females presented higher lymphocyte MnSOD activity compared to males (p<0.05). Exercise increased MnSOD activity in males (p<0.05) reaching similar values to females. MnSOD gene expression was also increased in males after exercise (p<0.05) but not in females. Nitrite concentration and iNOS gene expression significantly increased only in males after swimming (p<0.01). The exercise decreased UCP-3 gene expression in both genders (p<0.05). Lymphocyte H(2)O(2) production significantly increased in males after exercise in non-stimulated and in PMA-stimulated cells (p<0.01). In conclusion, females seem to be more protected against oxidative stress induced by a swimming session. Hydrogen peroxide is mainly produced in males and this subsequently leads to increases in MnSOD gene expression and activity.     

Transition from precopulatory to copulatory behaviour in male rats with lesions in medial preoptic area: dependence on precopulatory pattern of female

In the present study, both the precopulatory behaviour and the copulatory readiness of male rats following the bilateral medial preoptic area lesions was compared with their intact states. In behavioural testing, the intensity of female precopulatory behaviour was used as an experimental variable. The results showed that the natural threshold of copulatory readiness of males was increased in the lesioned state, the animals were more dependent on the soliciting patterns of the female. However, all the males exhibited conspicuous precopulatory behaviour towards the stimulus females used. Apparently, further brain structures participate in the regulation of sexual behaviour of males, above all, in activation or maintenance of precopulatory activity.     

Behavioural responses of female Neogobius melanostomus to odours of conspecifics

The behavioural responses of reproductive and non‐reproductive female round gobies Neogobius melanostomus to water conditioned by reproductive and non‐reproductive males and females were tested. The behavioural responses of reproductive female round gobies exposed to odour of reproductive males included increased time spent near the source of the odour, elevated swimming velocities and directed movement to and around the odour source when compared with their responses to control water. These results suggested that pheromones released from reproductive males may induce spawning behaviour in reproductive females. Non‐reproductive females exposed to reproductive female odour spent significantly more time near the odour source of reproductive females compared with control water. Non‐reproductive females also showed directed movement towards and around the odour source when exposed to reproductive female odour. These results suggested that round gobies use inter‐sexual and intra‐sexual pheromones and that both sex and reproductive status are important in the detection and release of these pheromones.     

Behavioural approaches to demonstrate the ecological significance of exposure of juvenile Pacific salmon (genus Oncorhynchus) to the antisapstain fungicide TCMTB

Simulated stream conditions were used to expose underyearling Pacific salmon (genus Oncorhynchus) to sublethal doses of TCMTB (2-thiocyanomethylthio) benzothiazole; a fungicide used by the lumber industry to protect against discolouration by sapstain fungi. Observed changes in schooling, swimming, and respiration were studied in more detail utilizing progressively more complex and ecologically relevant experimental designs. Laboratory troughs (600 litre) were used to quantify innate shelter-seeking behaviour and susceptibility to predation during salinity stress. Swimming speed, schooling behaviour and responses to salinity and hypoxia were studied in a 4500-litre Water Column Simulator under vertically stratified conditions (fresh water overlying sea water). Finally a similarly stratified 15,500-litre outdoor tank was designed to compare susceptibility to predation during a volitional salinity challenge. Relative to controls, TCMTB-exposed underyearling salmon exhibited a reduction in cover response, were slower to seek shelter from bright light, were more erratic in their swimming behaviour and more likely to be eaten by marine predators. Videotape analyses confirmed that TCMTB reduced exploratory behaviour and swimming speed under both normoxic and hypoxic conditions in the WCS. The ecological consequences of these overt behavioural changes were experimentally linked to a clear increase in risk from predation by yellowtail rockfish (Sebastes flavidus) inhabiting the marine zone below the halocline of the 15,500-litre tank. These techniques illustrate our most recent efforts to correlate cumulative sublethal physiological stress with ecologically meaningful behavioural dysfunction.     

Factors Affecting Swimming Speed in the Rotifer <Emphasis Type="Italic">Brachionus plicatilis</Emphasis>

This study examines the swimming speed in amictic females of Brachionus plicatilis in laboratory cultures. Five different stages were examined: recently hatched females, juveniles, adult non-ovigerous females, ovigerous females with 1 attached egg and ovigerous females with 2 attached eggs. We tested the speed at two temperatures, 15 °C and 25 °C, and two feeding conditions, presence and absence of microalgal cells. An automated motion analysis system was used to measure speed which was then video recorded. Swimming speed (μm s⁻¹) increased with increasing body size. There was a slight decrease in the speed of adult females as the number of attached eggs increased. Swimming activity was higher at 25 °C than at 15 °C and in the absence of food than if microalgae were present. Average values under the different experimental conditions ranged between 500 μm s⁻¹ for the recently hatched and fed females and 1500 μm s⁻¹ for the adult non-ovigerous females in the absence of microalgae. Mass-specific swimming speed decreased with body mass increase.     

Lymphocyte antioxidant response and H2O2 production after a swimming session: Gender differences

This study evaluated the gender differences in response to intense exercise on lymphocyte hydrogen peroxide production, nitric oxide handling and mitochondrial superoxide dismutase (MnSOD) activity and gene expression. Fifteen males and nine females participated voluntarily in the study and performed a swimming session at 75–80% of the maximal capacity. In basal conditions females presented higher lymphocyte MnSOD activity compared to males (p<0.05). Exercise increased MnSOD activity in males (p<0.05) reaching similar values to females. MnSOD gene expression was also increased in males after exercise (p<0.05) but not in females. Nitrite concentration and iNOS gene expression significantly increased only in males after swimming (p<0.01). The exercise decreased UCP-3 gene expression in both genders (p<0.05). Lymphocyte H₂O₂ production significantly increased in males after exercise in non-stimulated and in PMA-stimulated cells (p<0.01). In conclusion, females seem to be more protected against oxidative stress induced by a swimming session. Hydrogen peroxide is mainly produced in males and this subsequently leads to increases in MnSOD gene expression and activity.     

The behavior of tamarin monkeys during the learning and realization of instrumental food habits in a competitive situation

Special features of competitive behavioural organization have been revealed during formation and realization of simple feeding and instrumental reflexes elaborated simultaneously in family pairs of marmoset monkeys. In contrast to other anthropoid species, male and female marmosets performed feeding reactions of different levels of complexity with equal efficiency. The differences between male and female marmosets concern the structure of competitive behaviour: males showed more active forms of competition under equal number of the given reinforcement, whereas passive forms of behaviour were more typical in females. The latter produced intensive vocalization in comparison with males. Stabilization of competitive activity was accompanied by the decrease of active forms of competition and by standardization of individual behaviour. The increase in the number of behavioural strategies was observed in family groups under sophisticated experimental conditions.     

Differences in feeding activity between females and males of Temora longicornis

We have studied experimentally in the laboratory the behavioural responses of females and males of the calanoid copepodTemora longicornis and their encounter probability with the alga Rhodomonas. Both sexes of this calanoid copepod adapted their motion velocity and style of swimming in reaction to the presence of prey. Their mean velocity, as well as the probability of high velocity values, increased in the presence of the algae. Moreover, the time spent in swimming activity increased, reflecting a possible adaptation in order to facilitate encounter with prey. Females were more sensitive to the presence of food: mean velocities showed a 40 % increase for males, from control to food conditions, whereas for females the increase was 240 %. This result was confirmed using several indicators: net-to-gross displacement ratio, probability density functions, and symbolic dynamics. This may indicate that female T. longicornis are more attracted by food than males.     

Locomotor activity pattern in pairs of the subsocial desert isopod Hemilepistus reaumurii

Locomotor activity rhythm of fresh adult of H. reaumurii was recorded in pairs with ovigerous and with non-ovigerous females. According to double-plotted actograms and waveform curves, results showed the presence of different locomotor patterns. In fact, locomotor profiles of pairs with ovigerous females were mainly bimodal whatever the recording conditions, whereas locomotor patterns were trimodal in pairs with non-ovigerous females. Results showed also that locomotor activity rhythm was more stable in the presence of the synchronizer (nLD cycle) than in constant darkness whatever the recording type. Moreover, the most important stability of the locomotor rhythm was observed under constant darkness and individuals were more active in pairs with ovigerous females than in pairs with non-ovigerous females.     

Influence of time of mating and paced copulation on induction of pseudopregnancy in cyclic female rats

The present experiment was designed to examine whether changes occur during the course of behavioural oestrus in the sensitivity of the female to copulatory stimulation and in patterns of sexual behaviour which might influence the likelihood of luteal maintenance. Cyclic female rats were mated on the evening of pro-oestrus (21:00 h) or early on the morning of oestrus (05:00 h) and received either 5 or 10 intromissions from males under conditions which allowed or did not allow pacing of contacts with males to occur. During mating, the levels of sexual receptivity, the timing of sexual mounts from males, and pacing behaviours were measured. The occurrence of pseudopregnancy or pregnancy in each animal was determined by examining vaginal smears for 14 days after mating and by examining the uterus for the presence of fetuses at the end of the experiment. At both mating times, pacing of copulation with males increased the likelihood of prolonged luteal activity. However, females were more likely to become pseudopregnant following non-paced mating at 05:00 h than at 21:00 h the previous evening. Of those females receiving an ejaculation during mating, no difference were seen between groups in the incidence of pregnancy. This change in sensitivity to cervical-vaginal stimulation during oestrus was not associated with changes in sexual receptivity or pacing behaviour. The ability of cervical-vaginal stimulation to induce pseudopregnancy therefore increases toward the end of the period of oestrus, but the behavioural mechanisms which regulate receipt of such stimulation remain constant during that time.     

Changes in the swimming behavior of Pseudodiaptomus annandalei (Copepoda,Calanoida) adults exposed to the diatom toxin 2-trans, 4-trans decadienal

Diatoms are broadly present in marine habitats and often dominate seasonal phytoplankton blooms in polar and temperate latitudes. Certain species produce polyunsaturated aldehydes upon mechanical wounding caused by mesozooplankton grazing. Ample evidence is available on toxin-induced reproductive failure in copepods, yet their behavioral effects remain unclear. Here we present results of laboratory experiments in which we investigated the immediate effects of the diatom-derived aldehyde 2-trans, 4-trans decadienal on the three-dimensional swimming behavior of the calanoid copepod Pseudodiaptomus annandalei. Short-term direct exposure to the toxin at 3 μM, 6 μM and 12 μM induced hyperactivity in the three adult states, as evidenced by a marked and dose-dependent increase in the number of trajectories. It also caused a higher proportion of vertical movements. In males and ovigerous females exposed to decadienal at 3 μM and 6 μM, hyperactivity came with an equally specific dose-dependent decrease in swimming speed. Males and ovigerous females swam faster at 12 μM than at 6 μM, suggesting a complex mode of action of the toxin. In non-ovigerous females, decadienal had little effects on swimming speed, supporting the assumption that female copepods are less affected by certain environmental stressors. Multifractal analysis revealed differences in the statistical properties of the swimming behavior between experimental conditions. The moment structure function of the displacement appeared to be moderately multifractal in the three adult states swimming in control water. Ethanol as carrier solvent at 200 ppm caused an increase in swimming speed and a switch toward a more ballistic motion in males and ovigerous females. On the opposite, exposure to the toxin reduced or cancelled the effects of ethanol and resulted in a more Brownian motion for high moment values. Decadienal had little effects on the behavior of non-ovigerous females except at the highest concentration. Our results demonstrate that decadienal, a model diatom aldehyde, impairs the behavior of adult copepods. They provide further information on the interaction between diatoms and their main predator.     

Time-budgeting and foraging strategy of the stoplight parrotfish Sparisoma viride Bonnaterre,in Jamaica

Quantitative data on the ways in which the different phases of the stoplight parrotfish (Sparisomaviride Bonnaterre) distribute their time among various activities in different habitats are presented. Individuals spent from 84–97% of their diurnal time swimming, feeding, and hovering. Additionally, large adults spent a significant amount of time sheltering among crevices. Phase-related differences in these activities are statistically significant, as are differences in duration and rates of change of the activities. Large individuals spent more time swimming, while small individuals spent more time hovering. In addition, large individuals performed longer bouts of activity and switched activities less frequently than small individuals. Adult males and females spent approximately equal proportions of time in each of the activity states. Stochastic analyses of behavioural sequences show second order Markov chain dependencies, suggesting that preceding activity states affect subsequent behaviour. Possible relationships between behavioural sequencing and the species foraging strategy are discussed, and it is suggested that the sequence of behavioural activities can provide an estimation of the distribution of food resources in the environment.     

Can sunbleak Leucaspius delineatus or topmouth gudgeon Pseudorasbora parva disperse through saline waters?

In order to determine the potential for the invasive fishes sunbleak Leucaspius delineatus and topmouth gudgeon Pseudorasbora parva to disperse through saline waters their behaviour and physiology were investigated during exposure to salinities of 10·0 and 12·5. Increased salinity caused an increase in whole body cortisol in both species, but sunbleak and topmouth gudgeon showed very different metabolic and behavioural responses to the salinity stress. Sunbleak displayed increased swimming activity in brackish water, which may be important for dispersal through saline waters in the wild, although there were increased metabolic costs associated with this behaviour. Conversely, topmouth gudgeon showed a reduction in both swimming activity and metabolic rate in brackish waters. A pronounced depression in food intake (70–80%) was shown by both species during the salinity exposures. Both sunbleak and topmouth gudgeon, however, showed a full recovery of food intake within 24 h following return to fresh water. Despite the fact that exposure to saline waters is stressful, and affects both physiology and behaviour, rapid recovery of appetite after return to fresh water suggests that short-term use of brackish waters is a feasible dispersal route for sunbleak and topmouth gudgeon in the wild.     

Distribution and habitat preferences of two grapsid crab species in Mar Chiquita Lagoon (Province of Buenos Aires,Argentina)

Cyrtograpsus angulatus andChasmagnathus granulata (Grapsidae) are the two dominant decapod crustacean species in the outer parts of Mar Chiquita Lagoon, the southernmost in a series of coastal lagoons that occur along the temperate Atlantic coasts of South America. Distribution and habitat preferences (water and sediment type) in these crab species were studied in late spring. There is evidence of ontogenetic changes in habitat selection of both species. Recruitment ofC. angulatus takes place mainly in crevices of tube-building polychaete (Ficopomatus enigmaticus) “reefs” and, to a lesser extent, also in other protected microhabitats (under stones). In the latter, mostly somewhat larger juveniles were found, suggesting that these are used as a refuge for growing individuals. Adults are most frequently found on unprotected muddy and sandy beaches.C. angulatus was found in all parts of Mar Chiquita Lagoon, including freshwater, brackish, and marine habitats.C. granulata, in contrast, was restricted to the lower parts of the lagoon, where brackish water predominates and freshwater or marine conditions occur only exceptionally. It showed highest population density on “dry mud” flats and inSpartina densiflora grassland, where it can build stable burrows and where high contents of organic matter occur in the sediment. Such habitats are characterized by mixed populations of juveniles (including newly settled recruits) and adults, males and females (including a high percentage of ovigerous). Unstable “wet mud” as well as stony sand were found to be inhabited by chiefly adult populations, with only few ovigerous females. In “dry mud” flats, the proportion of males increased vertically with increasing level in the intertidal zone, showing a significantly increasing trend also in their average body size. These observations may be explained by higher resistance of males, in particular of large individuals, to desiccation, salinity, and temperature stress occurring in the upper intertidal. However, an opposite, or no such, tendency was found in the distribution of ovigerous and non-ovigerous females, respectively. With increasing distance from the water edge, salinity increased and pH decreased significantly inC. granulata burrows, whereas temperature showed no consistent tendency within the intertidal gradient. A highly significant linear relationship (r=−0.794; P<0.001) between salinity and pH in water from crab burrows is described. This regression line is significantly different from one that had been observed in water from the lagoon, indicating consistently lower pH values at any salinity level in burrow water. This is interpreted as a result of crab and/or microbial respiration.     

Sex and reproductive stage differences in the growth,metabolism, feed,fecal production,excretion and energy budget of the Amazon River prawn (Macrobrachium amazonicum)

The aim of this study was to evaluate differences in various physiological measures (growth, fecal production, feed intake, nitrogenous excretion, oxygen consumption, energy substrate used, and energy budget) among males, ovigerous females and non-ovigerous females of the freshwater prawn Macrobrachium amazonicum. This species exhibits pronounced sexual dimorphism and different male morphotypes and has the potential for use in aquaculture. Males and non-ovigerous females were studied for 30?days. Ovigerous females were studied for 10?days. Prawns were fed commercial prawn food, and all males were of the Translucent Claw (TC) morphotype. The results demonstrate physiological differences both between males and females and between females of different reproductive stages. Males had higher rates of ingestion, growth and oxygen consumption and less fecal loss than females. We postulate that in the absence of other morphotypes, TC males may exhibit increased growth rates. Males and females used protein as an energy substrate. Males channeled approximately 9% of their energy budget into growth, whereas non-ovigerous and ovigerous females channeled only 1.4?±?0.4 and 0.07?±?0.07%, respectively. Whereas males and non-ovigerous females channeled 9.0?±?9.74 and 61.8?±?3.0%, respectively, of the energy ingested into metabolism, ovigerous females channeled 97.7?±?4.7% into metabolism, likely due to the frequent beating of their pleopods, which oxygenates and cleans the eggs. As reported for marine prawns, males and non-ovigerous females of M. amazonicum lost approximately 5% of their ingested energy in exuviae. The physiological differences observed between the sexes and between females of different reproductive stages might reflect corresponding differences in patterns of activity, growth, and reproduction.     

Post-mating changes in the behaviour and activity of the female anobiid bread beetle, Stegobium paniceum

ABSTRACT. In an investigation of the effect of mating on the behaviour and activity of female Stegobium paniceum (L.) the following factors were examined: initiation of oviposition, amount of walking activity, refractory behaviour, and tendency to fly. 2–3 min in copula were sufficient to induce initiation of oviposition, increase the amount of walking activity and produce refractory behaviour. Mating was also shown to increase the occurrence of female flight behaviour. The number of females flying increased after oviposition had started and decreased when oviposition was complete. The greatest behavioural changes were found in females allowed to separate from males in their own time after a mean period in copula of 63 min. The significance of these changes and possible causative stimuli are discussed.     

Influence of gonadal hormones and social housing conditions on agonistic,copulatory, and related socio-sexual behaviour in the Mongolian gerbil (Meriones unguiculatus)

The Mongolian gerbil is colonial, but its social organization within its colonies is not known. Pair formation has been suggested by breeders and has been observed under semi-natural conditions. Family units remain stable under such conditions. In the solitary-living hamster (Cricetus auratus), agonistic behaviour decreases in male-female encounters during female heat. This report concerns the influence of female and male gonadal hormones on agonistic behaviour in gerbils studied in cagemate and non-cagemate encounters. Further, the occurrence of mating, marking, and drumming was studied in the same situations. No effects were found of either the female or the male endocrine condition on the low amount of agonistic behaviour between cagemates. A reduction in the high amount of agonistic responses in encounters between non-cagemates was indicated. It was related to the castrated-male and induced-oestrous female conditions. Copulatory behaviour was not influenced by social maintenance conditions. Marking and drumming were most frequent in females in oestrous and intact males. The occurences in the females were influenced by the individual's endocrine condition, but not by the opponent's. Intact males in encounters with non-cagemates marked more frequently when the females were in anoestrous. Drumming in the intact males increased in tests with oestrous versus anoestrous females but occurred more frequently in encounters with non-cagemates than in those with cagemates. The behaviour of castrated males was not influenced by the endocrine or by social housing conditions. The limited variation in agonistic behaviour relative to the endocrine conditions may reflect a non-solitary social organization.     

Influence of gonadal hormones on the behaviour of pair-living Mongolian gerbils (Meriones Unguiculatus) towards the cagemate versus a non-cagemate in a social choice test

Laboratory, semi-natural and field observations indicate that the Mongolian gerbil may naturally live in pairs or family groups. Endocrine influence on behaviour towards cagemates and non-cagemates was investigated. The males tested were intact or castrated. The hormonal condition of the females was controlled by gonadectomy and oestrogen and progesterone replacement treatment. The duration and number of visits to the incentive animals were recorded in a choice test, which allowed restricted contact between the experimental and incentive animals. Anoestrous females approached the intact cagemates more than the non-cagemates, while the intact males approached the non-cagemates more often. A comparison of the female behaviour under the different female endocrine conditions tested showed that females significantly increased their response in oestrus towards the strange intact males but not towards their cagemates. Experimental intact males analogously increased their response towards the strange oestrus female but not towards the cagemate. In tests which involved castrated males either as experimentals or incentives, no behavioural change was seen relative to the endocrine condition of the female. The hormonal effects seen were thus connected with the social relationship, as the hormone-induced changes were seen only in behaviour towards a strange animal.     

Swimming behaviour in Monoporeia affinis (Crustacea: Amphipoda) - dependence on temperature and population density

Swimming speed and swimming activity of the nocturnally active benthic amphipod Monoporeia affinis were measured in water temperatures from 3 to 18 degrees C and different population densities in the laboratory. Swimming speed increased with increasing temperature. Increasing water temperature reduced the percentage of active animals in the population, as measured by a "freeze frame" technique. At 7 and 10 degrees C a higher percentage of the population was active in higher animal densities. In all tested conditions swimming activity was highest at about 1 h after light-off and lowest shortly before the predicted time of light-on. The consequences of the documented behavioural responses to environmental stimuli are discussed in relation to population dynamics.