On the physiological-biochemical state of kilka Clupeonella cultriventris (Clupeidae, Clupeiformes) in Rybinsk Reservoir (Russia)

The results of studies into lipid total content and fractional composition in the tissue and wholebody levels in kilka (Clupeonella cultriventris) are given. The fish studied belonged to various size-age groups and were sampled in Rybinsk Reservoir during active feeding periods in 2002 and 2005. A trend was revealed of deterioration of the physiological-biochemical state in adult specimens of this invasive species. This was especially true of the modal (in terms of their proportion in population) two-year-old fish. This was evidenced by a decrease in contents of total and reserve (triacylglycerol) lipids in fish muscles during the whole study period. It is shown that, in young kilka caught in all reservoir stretches in autumn, the values of these parameters depend on the time and rate of the reservoir water level decrease during the active feeding period. Probable reasons for changes in the physiological-biochemical state in adult and young specimens in the kilka population are discussed. The discussion is in view of the recent state of the Rybinsk Reservoir ecosystem which undergoes successional modification of the pelagic zooplankton community both at the level of large taxa and of some dominant species.     

Influences of the feeding ecology on body mass and possible implications for reproduction in the edible dormouse (<Emphasis Type="Italic">Glis glis</Emphasis>)

The edible dormouse (Glis glis) is a small rodent and an obligate hibernator. Dormice undergo strong fluctuations of reproductive output during years that seem to be timed to coincide with future food supply. This behaviour enables them to avoid producing young that will starve with a high probability due to food shortage, and to increase their lifetime reproductive success. Aims of this study were to elucidate the extent to which feeding ecology in the edible dormouse has an impact on body mass and the fatty acid (FA) pattern of the white adipose tissue (WAT) before and after hibernation, which in turn might influence reproductive status in spring. Dormice show strong seasonal fluctuations of the body mass, which is reduced by one third during hibernation. Body mass and its changes depend on autumnal food availability as well as on the dietary FA pattern. During the pre-hibernation fattening period, dormice eat lipid rich food with a high content of linoleic acid. During hibernation, linoleic acid content is slightly but significantly reduced and body mass loss during winter is negatively correlated with the pre-hibernation linoleic acid content in the WAT. No relation between reproductive status and body mass, body condition or the FAs pattern of the WAT could be detected. However, in a year of high reproduction, dormice commence the shift to seed eating earlier than in a year of low reproduction. These seeds could be either a predictor for future food supply in autumn, or represent a high-energy food compensating high energetic costs of sexual activity in male edible dormice.     

The diurnal modulation of the circatidal activity rhythm by feeding in the isopod eurydice pulchra

The diurnal modulation of circatidal activity was studied in freshly caught Eurydice pulchra of different feeding states. Apparently fully fed specimens displayed definite circadian modulation, with greatest tidal activity at the time of expected night‐time high tides, and apparently starved animals showed no circadian variation. Circatidal activity was also entrained in the laboratory using cycles of artificial agitation and the subsequent pattern of free‐running rhythmicity was studied. Animals fed prior to entrainment displayed definite diurnal modulation of the pattern of ciractidal swimming activity. Those fed after the entrainment regime, or not at all, displayed no apparent diurnal inequality of tidal activity peaks. No relationship between diurnal inequality and phototactic behaviour of freshly collected specimens was detected.     

On the diurnal rhythm and feeding electivity in kilka (<Emphasis Type="Italic">Clupeonella cultriventris</Emphasis>) in Rybinsk Reservoir

Diurnal rhythms, feeding electivity, and feeding resources were studied for the new for Rybinsk Reservoir fish species, kilka (Clupeonella cultriventris). It is revealed that, in Rybinsk Reservoir, kilka actively feeds during day time. Selective feeding is a characteristic of this fish. Yearlings prefer small Cyclopoida and their young specimens dominating in zooplankton. Two-year-old fish actively select innumerous but large crustaceans of genera Heterocope, Bythotrephes, Leptodora, and Cyclops. Possible factors determining selection of food items by kilka are discussed. These factors are as follows: zooplankters’ biomasses, the extent of plankters’ aggregations, body size, and visibility of some prey species for kilka (as determined by movement pattern, transparency and cuticle color, presence of eggs, or large eye).     

Feeding chronology of Atlantic salmon parr in subarctic rivers: consistency of nocturnal feeding

During the ice-free season in three subarctic rivers in northern Norway and Finland, Atlantic salmon parr Salmo salar exhibited significant diel fluctuations in stomach content weights in August and September, the largest weights being recorded consistently at 0300 hours. Accordingly, the feeding rate of the parr was highest during the night and lowest in daytime, whereas during the other periods of the ice-free season, no pronounced diel fluctuations in food intake occurred. The consistent nocturnal feeding periodicity in early autumn in subarctic rivers may be associated with benthic feeding and an increased availability of benthic prey at night.     

Circadian and ultradian activity rhythms in male long‐evans rats: Relationship to feeding

Abstract

Rats exhibit ultradian as well as circadian rhythms in activity. Short‐term activity rhythms appear to result from bouts of feeding‐related behavior interspersed with periods of quiescence. We examined the relationship of activity to feeding in 12 male Long‐Evans derived rats during ad lib and restricted feeding (RF) conditions to determine the effect of RF on both circadian and ultradian activity rhythms. By the end of 20 days of RF all animals exhibited an ultradian periodicity of approximately 12 hours. A twenty‐four hour rhythm in feeding persisted, apparently due to the rats adapting to the diurnal feeding period. General findings were that RF resulted in anticipatory activity prior to feeding and that short‐term activity fluctuations and investigations of the food bin continued during RF even though overall nocturnal activity decreased. The results suggest that male rats of this strain exhibit ultradian activity rhythms that appear to be strongly related to feeding.     

Diel feeding rhythms and daily food consumption of juvenile Atlantic salmon in the River Alta, northern Norway

Atlantic salmon fry (0+) sampled from the River Alta exhibited only minor differences in stomach content weights and feeding rates throughout diel periods, but feeding rates were generally lowest at night. In contrast, salmon parr (1+ to 3+) had large diel fluctuations in stomach content weight, with the largest weights usually being recorded during the night and early morning. Accordingly, their feeding rates were highest at night. This nocturnal feeding pattern was consistent throughout all sampling occasions, and appeared to reflect a persistent feeding periodicity in the salmon parr. The daily food consumption rates of both fry and parr were highest during midsummer and decreased towards autumn.     

Diurnal variation in the feeding pattern of rabbits

Laboratory rabbits maintained under controlled lighting and fed $\text{ad libitum}$ exhibit a weak but consistent diurnal fluctuation in feed intake. There are two major periods of eating; at the beginning and the end of the light period. This results in similar feed consumption for the light and dark periods. Water intake shows a similar diurnal variation to that of feed intake. If the normal lighting cycle is retarded by 6 hours, the animals adjust their diurnal rhythm of feeding behaviour to the new lighting cycle within 8 to 15 days. Comparative studies on rats are included.     

Formation and development of the Black Sea-Caspian kilka Clupeonella cultriventris (Clupeidae) in the Rybinsk reservoir

We studied the state and development of the population of the Black Sea-Caspian kilka Clupeonella cultriventris in the Rybinsk reservoir from 1994 to 2010. The population dynamics, the rate of growth of the kilka, as well as its food relationships with other fish species of the pelagial community, were analyzed. It was found that the period of exponential increase in the numbers was replaced by the period of interannual fluctuations. With the development of the population, tendencies for a decrease in the rate of growth of the kilka and aggravation of its food relationships with other species are revealed, which is determined by changes in the structure of pelagic aggregations of fish. One of the most significant environmental factors determining dynamics of the numbers and state of the kilka population in the northernmost part of its modern range is water temperature.     

Short communication. Food availability and diel feeding rhythms in the marine copepods Acartia grani and Centropages typicus

The effects of food availability on the daily feeding pattern of planktonic copepods was studied for two species: Acartia grani (cultured and wild specimens) and Centropages typicus (wild specimens). Both species showed clear diel feeding rhythms at high food concentrations, with significantly higher clearance rates during night hours. However, at limiting food conditions, while C.typicus maintained its daily feeding pattern, A.grani fed continuously, with similar day and night clearance rates. These results could be explained in relation to differences in predation risks and probability of experiencing starvation episodes in their respective habitats, as well as their capacity for dampening food fluctuations. On the other hand, the maintenance (although with less intensity) of the diel feeding rhythm in A.grani, when cultured in the laboratory for long periods of time (>10 generations) and in the absence of predators, suggests the importance of the endogenous control of copepod feeding patterns.      

Direct and correlated responses to selection for post-weaning weight gain on ad libitum or restricted feeding in mice

Summary Selection for post-weaning weight gain in mice from 21 to 42 days, on either a full or restricted feeding level during this period was carried out for seven generations. Control lines were maintained for each feeding level. The rate of selection response was higher on full feeding due to a higher heritability and a larger phenotypic variance. Realised heritabilities of 0.29±0.05 and 0.19±0.04 for selection on full and restricted feeding respectively, were in close agreement with base population estimates.Selection on full feeding led to positive correlated responses in 21 day weight, 42 day weight, food intake and efficiency between 21 and 42 days, and 42 day tail length, but with little change in reproductive performance.Correlated responses to selection on restricted feeding were reduced 21 day weight, but an increase in 42 day weight and increased efficiency from 21 to 42 days. However, overall reproductive performance fell.     

Temporal pattern of feeding activity in the firebug Pyrrhocoris apterus and its relation to sex, wing dimorphism and physiological state of adults

Abstract.  The present study tested whether the pattern of feeding activity in the firebug Pyrrhocoris apterus (L.) is sex- and wing morph-related, diurnal or nocturnal, as well as whether the feeding rhythm persists in constant darkness. Temporal patterns of feeding activity are analysed in macropterous and brachypterous adults reared under long-day (LD 18 : 6 h) and short-day (LD 12 : 12 h) photoperiods, and in adults transferred to constant darkness. In females, the total feeding activity is highest in long-day reproductively active brachypters, intermediate in short-day diapausing brachypters, and lowest in macropters; the differences among males are substantially smaller. Although the total feeding activity of macropterous males is higher than in macropterous females, no sex-related differences are found in feeding activity of diapausing and reproductively active brachypters. The frequency of feeding exhibits sex-related differences, with obviously higher values in males. Mean feeding periods of macropterous and reproductively active brachypterous males are shorter than in females of the same wing morph. Mean interfeeding periods are longest in macropters, intermediate in diapausing brachypters, and shortest in reproductively active brachypters, and always lower in males than in females. The study shows that the feeding activity of P. apterus adults is age-, sex- and wing morph-related, and exhibits a diurnal pattern, except in reproductively active brachypterous females. The latter do not express a clear diurnal rhythm of feeding, presumably because of interactions with cycles of egg development and oviposition. The persistence of diurnal rhythm of feeding activity in short-day brachypterous females transferred to constant darkness indicates an endogeneity of this rhythm in P. apterus .     

Seasonal Variation of Diurnal and Ultradian Rhythms in Red Deer

To describe the normal rhythmic behavioural patterns and to test procedures for the detection of short-time disturbances, 4 red deer were studied in 2 quasi-natural enclosures. Activity and feeding were recorded by means of the storage-telemetrysystem ETHOSYS®. Daily and monthly mean values, power spectra and 'Degrees of Functional Coupling' (DFC) were calculated. DFC were applied to measure stability and harmonic synchronisation between ultradian rhythms and the 24-hours period. The general patterns of activity and feeding were nearly identical in all animals and closely related to photoperiod change. Levels of total activity and feeding were lowest in winter and highest in summer. In winter highest activity was generally observed in daylight hours and shifted gradually to dark hours in summer. Spectral analysis of activity and feeding revealed a time pattern in which ultradian components, between 4.8 and 12 hrs in period length, mostly exceeded the diurnal rhythm power. Compared to winter higher frequencies were found in activity and feeding in spring, summer and autumn. During such periods up to 8 strong bouts of activity per day (3-hrs rhythm) were observed. These rhythmic patterns are discussed in the context of red deer feeding strategy. Short-term disturbances by humans and changing feeding conditions resulted in lowered DFCs. Time pattern analysis of long-term and continuously measured behavioural parameters proved to be an appropriate approach for observing general living conditions and for detecting disturbances.     

Flight ability and reproductive development in newly‐emerged pine weevil Hylobius abietis and the potential effects of climate change

• 1 Adult pine weevils Hylobius abietis emerge from conifer root‐stumps, on which larvae develop, over an extended period during summer and autumn. Newly‐emerged weevils were tested for their ability to fly and assessed for wing muscle and reproductive development. In addition, the effect of summer–autumn maturation feeding on reproductive development was assessed in field bioassays.
• 2 There was considerable variation in development between newly‐emerged weevils that was related to the timing of emergence. The first weevils, emerging in early July, weighed less than later‐emerging ones, had undeveloped flight muscles and did not fly. Over the emergence period, wing muscle size and flight ability increased markedly, with 50–60% flying by mid‐September. Differences between emerging adults are likely to have been affected by temporal changes in the quality of the bark on which the larvae feed.
• 3 Reproductive development lagged behind that of wing muscles but, in early August, there was a rapid increase in the proportion of weevils with immature eggs and a corresponding increase in oocyte size. However, although wing muscles were fully formed in later‐emerging weevils, immature eggs were only approximately 10% of the volume of mature eggs.
• 4 In field bioassays of summer–autumn maturation feeding, eggs continued to develop and some weevils laid mature eggs. Feeding and development during the pre‐overwinter period is likely to influence winter survival and also dispersal and reproduction in the following spring.
• 5 The potential effects of climate change on the weevil life cycle are briefly discussed. Weevils are likely to benefit from the higher temperatures and later autumns predicted under climate change, resulting in an increase in damage to transplants.

     

Influence of diurnal rhythms of feeding during intestine total amylolytic activity and activity of alkaline phosphatase in juvenile fish

The total amylolytic activity and activity of alkaline phosphatase in the intestine mucosa of larvae and fries of roach, blue bream, and perch change both during the process of individual development and during the day. Maximal intensities of juvenile feeding was observed primarily in the morning and evening hours. The pattern of diurnal alkaline phosphatase activity correlates to a greater extent to intensity of juvenile feeding, in comparison to the pattern of total amylolytic activity. In planktivorous blue bream, such regularity is more pronounced than in benthivorous roach. The total amylolytic activity in fries of roach, blue bream and perch correlates to fish type of feeding.     

Modelling the effects of climate change on the potential feeding activity of Thaumetopoea pityocampa (Den. & Schiff.) (Lep., Notodontidae) in France

Aim We investigated whether climate change has affected the potential feeding activity of a winter active larva, the pine processionary moth (PPM), Thaumetopoea pityocampa L., and whether it may explain its range expansion. Location The study area is France and, at a smaller scale, the Paris Basin. Methods We used a statistical model derived from Huchon and Démolin [1970 Revue Forestière Française (special issue: La lutte biologique en forêt), 220–234] to test whether their model, updated with climate change, could explain the observed range expansion. Since Battisti and colleagues have recently shown that climate could affect survival of the PPM through its effect on feeding activity, we also developed a mechanistic model based on larval feeding requirements (night air temperature above 0 °C and temperature inside the nest above 9 °C on the preceding day). We reconstructed the geographical distribution of feeding activity and we compared the resulting change with the PPM range expansion. Results The statistical model did not successfully predict the observed expansion but the mechanistic model showed considerable change in the feeding activity of the PPM. In the Paris Basin, the PPM border coincided with a zone unfavourable for feeding activity in the period 1992–96. Feeding conditions became more favourable in the period 2001–04, and the PPM succeeded in crossing this zone. Over larger temporal and spatial scales improved feeding conditions in the north‐western part of France were forecast by the mechanistic model. Main conclusions (1) The range distribution of the PPM in the Paris Basin is no longer limited by unfavourable feeding conditions. (2) The pattern of range expansion of the PPM is now governed mainly by its dispersal capabilities and host tree distribution. (3) At the country scale, this approach gives an approximate prediction of the potential distribution of the PPM, though the model may not be reliable in mountainous regions.     

Daily feeding rhythms in Atlantic salmon II: size-related variation in feeding patterns of post-smolts under constant environmental conditions

Previous studies of feeding rhythms in post-smolt Atlantic salmon Salmo salar have produced variable results. Therefore, the present study was performed to clarify the source of these differences and to examine size-related variation in daily feeding patterns. A small group of hatchery reared post-smolts was kept in an indoor seawater tank under conditions of constant photoperiod and light intensity, and negligible diurnal variation in water temperature. Feeding responses were monitored by video camera throughout the day. The resultant feeding pattern for the population mirrored an earlier study, with the highest levels of feeding activity in the early morning and late evening. Differences between this and other studies may be due to variation in climate, season or life-history stage. Daily feeding patterns were size-dependent. The largest fish fed at a relatively constant level through the day, medium-sized fish fed in a pattern similar to that described above for the population and small fish fed most at first and last light. These differences were due probably to the effect of competitive interactions upon fish of different sizes.     

Seasonal variation in the feeding ecology of the grey-cheeked mangabey (Lophocebus albigena) in Cameroon

Seasonal fluctuations in resource abundance often cause primates to change their feeding behavior and ecology. The objective of this study was to examine the response of a largely frugivorous monkey, the grey-cheeked mangabey (Lophocebus albigena), to seasonal variations in fruit abundance. We used 15-min scan sampling to quantify feeding, activity, and habitat use by monkeys between February and December 1998 in the Dja Reserve, Cameroon. L. albigena were found to have omnivorous feeding habits, consuming the fruits, seeds, leaves, and flowers of 132 plant species. Although monkeys fed from many plant species, only five plant species accounted for 45% of all feeding records. The number of feeding observations on a plant species was significantly correlated with its fruit production. L. albigena responded to fruit-lean periods by shifting from a diet dominated by fruit to one dominated by seeds, flowers, and young leaves. This diet shift coincided with greater use of swamp habitat and higher dietary diversity. L. albigena spent the greatest percentage of scan samples feeding and traveling, but activities varied significantly over the day. Individuals spent a significantly higher percentage of scan samples feeding during the fruit-rich season than in the fruit-lean season. Comparing our results to those of studies in Gabon and Uganda, we found that L. albigena differ across regions in the number of plant species they consume and time spent feeding. These differences may be a result of variations in tree diversity or the strength of seasonal fluctuations in resource abundance among sites.     

Effect of restricted feeding schedule on seasonal shifting of daily demand-feeding pattern and food anticipatory activity in European sea bass (Dicentrarchus labrax L.)

The effect of restricted feeding schedule was investigated on the seasonal shifting of daily demand-feeding pattern and food anticipatory activity in European sea bass (Dicentrarchus labrax) held under natural environmental conditions in an outdoor laboratory. To that end, demand-feeding behavior was continuously monitored for approximately one year in four groups of 15 fish each exposed to natural fluctuations of water temperature (from 13.2 degrees C to 27.4 degrees C) and photophase (from 9.5 h to 14.5 h of light). When the animals were subjected to a time-restricted feeding schedule, the demand-feeding rhythm rapidly synchronized to the three periods of food availability: the first meal (FM) from 08:00 to 09:00 h, the second meal (SM) from 16:00 to 17:00 h, and the third meal (TM) from 00:00 to 01:00 h. The occurrence of demand-feeding activity into the three periods of food availability displayed a double seasonal shift: fish that self-fed mostly during the daytime periods of feeding availability (FM and SM) in summer and autumn changed to nocturnal feeding (TM) from December to April, returning to diurnal preferences in April. Food-demands appeared to be predominantly associated with feed availability, reaching its maximum levels during the hours of reward. In addition, feeding anticipatory activity (FAA) was observed. A relationship was detected between the duration of FAA and feeding-time, with shortest FAA (30-60 min) when mealtime occurred just after sunrise (FM) or sunset (TM). These findings demonstrate the ability of sea bass to self-feed under time-restricted schedules, and show a seasonal-phase inversion in demand-feeding activity in spite of the restrictions in their feeding availability. Sea bass can use external signals as reference to anticipate the time of feed availability. This information may be useful for designing new feeding strategies for European sea bass fish farming.     

Feeding biology of sunfishes: patterns of variation in the feeding mechanism

Fishes are generally believed to differ in their ability to alter (modulate) their feeding behaviour in response to different prey. We investigated modulation quantitatively in four species of sunfishes (Centrarchidae) by evaluating the variation in 11 electromyographic variables measured from recordings of electrical activity in head muscles during feeding on three prey types. The experimental design used allowed us to partition variation between species, among individuals within species, among prey types, and among feedings. Duration of activity of the sternohyoideus muscle was the only variable significantly different among the four species. All variables showed significant differences among individuals within species. The overall range of activity of each muscle activity variable was about the same for all four sunfishes. However, three species showed a significant ability to modulate most muscle variables while a fourth did not change its feeding response with respect to prey type. The results indicate that: (1) intraspecific variation is an important source of variability in functional attributes that should be accounted for in comparisons between species; (2) the ability of some species to modulate appears to be independent of the potential variability in muscle activity possessed by each species; (3) closely related species can differ considerably in their ability to alter muscle electrical activity patterns during feeding; and (4) a quantitative assessment of variation in electromyographic patterns is a powerful approach for asking questions about differences in feeding behaviour.