Daily Activity Cycle Research Articles

Diel periodicity in both sei whale vocalization rates and the vertical migration of their copepod prey observed from ocean gliders

The daily activity cycles of marine predators may be dictated in large part by the timing of prey availability. For example, recent studies have observed diel periodicity in baleen whale vocalization rates that are thought to be governed by the diel vertical migration of their zooplanktonic prey. We addressed this hypothesis by studying associations between sei whale (Balaenoptera borealis) vocalization rates, oceanographic conditions, and the vertical distribution of the whales' prey, the calanoid copepod Calanus finmarchicus, during May 2005 in the southwestern Gulf of Maine using an array of autonomous ocean gliders. Each of the four gliders was equipped with sensors to measure temperature, salinity, and chlorophyll fluorescence. Three of the four gliders carried a digital acoustic recorder and the fourth carried a 1‐MHz acoustic Doppler current profiler. We observed strong diel periodicity in the acoustic backscatter measured by the current profiler that we attribute (based on a corroborating shipboard study) to the diel vertical migration of C. finmarchicus. Sei whale vocalization rates also exhibited diel periodicity, with more calls detected during the daytime when C. finmarchicus was observed at depth. We found no evidence to suggest that the observed patterns in sei whale calling rates were attributable to diel periodicity in background noise or acoustic propagation conditions. Sei whales are adept at foraging on nearsurface aggregations of C. finmarchicus; therefore we expect that the whales were feeding at night. We hypothesize that calling rates are reduced at night while the whales are feeding, but increase with social activity during the day when copepods are either more difficult or less efficient to capture at depth. The gliders' persistence during adverse weather conditions experienced during the study allowed continuous collocated observations of whale vocalization behavior and oceanographic conditions that have not been previously possible with traditional shipboard techniques.

Species identification and measurement of activity in odontocete species of Palmyra Atoll by acoustic monitoring

Acoustic monitoring has been used to study odontocete presence at Palmyra Atoll, a remote island in the Northern Line Islands chain. Long-term recordings of high-frequency, broadband acoustic data have become possible with recent technological advances. A High-frequency Autonomous Recording Package (HARP) has been developed which samples at 200 kHz with a duty cycle of 1/4 for up to seven months. This instrument has recorded since October 2006 at Palmyra Atoll. Visual and acoustic surveys were conducted around Palmyra Atoll using a four-element towed hydrophone array sampling real-time at 200 kHz to obtain species-specific acoustic data. These data are used as reference for automatic detection algorithms applied on the long-term recordings. To date, acoustically and visually detected odontocetes include bottlenose dolphins (Tursiops truncatus), spinner dolphins (Stenella longirostris), melon-headed whales (Peponocephala electra) and beaked whales of the genus Mesoplodon. The long-term HARP data reveal acoustic activity primarily at night time and predominantely odontocete clicks. Both the beaked as well as the melon-headed whales are present year round and show a distinct daily acoustic activity cycle.

Behavioral testing and preliminary analysis of the hamster visual system

The dependence of visual orienting ability in hamsters on the axonal projections from retina to midbrain tectum provides experimenters with a good model for assessing the functional regeneration of this central nervous system axonal pathway. For reliable testing of this behavior, male animals at least 10-12 weeks old are prepared by regular pretesting, with all procedures carried out during the less active portion of the daily activity cycle. Using a sunflower seed attached to a small black ball held at the end of a stiff wire, and avoiding whisker contact, turning movements toward visual stimuli are video recorded from above. Because at the eye level, the nasal-most 30 degrees of the visual field can be seen by both the eyes, this part of the field is avoided in assessments of a single side. Daily sessions consist of ten presentations per side. Measures are frequency of responding and detailed turning trajectories. Complete assessment of the functional return of behavior in this testing paradigm takes 3-6 months to complete.

New Host and Geographical Distribution for the Pearlfish Carapus Mourlani (carapidae) with a Discussion on its Biology

Specimens of the pearlfish Carapus mourlani (Carapidae) were observed for the first time in association with the sea cucumber Isostichopus fuscus (Holothuroidea: Echinodermata) along the coast of Ecuador. Out of 4345 sea cucumbers collected from various depths between 5 and 60 m, 12 harbored a pearlfish either in the coelomic cavity, the respiratory tree, or the digestive tract, yielding a prevalence of ca. 0.0028. The presence of C. mourlani appeared to be detrimental to the holothurian host in some cases. Side effects resulting from coelomic cavity infections included less advanced gonad maturity (reduced gonadal tubule diameter and length, lower ratio of mature oocytes) and a significant proportion of necrotic and shriveled gonadal tubules, devoid of gametes. Aside from discussing this evidence, the present paper briefly describes the biology of the pearlfish, its relationship with the host, and its daily activity cycle.

Rhynchophorus palmarum

<i>Rhynchophorus palmarum</i>

Biology, Habitat Preference, and Larval Description of Cicindela cursitans Leconte (Coleoptera: Carabidae: Cicindelinae)

Cicindela cursitans LeConte is a small, flightless tiger beetle with a widely scattered distribution in the Great Plains, the Ohio Valley, and the north-central Gulf Coast region. Many aspects of the life history of C. cursitans are poorly known, and the larval stages have remained undescribed until now. We designed experiments to determine specific habitat preference, female oviposition preference, and daily activity cycles of the adults. In addition, we describe the entire pre-adult life history. Adults are most numerous on moist clay soils with sparse to patchy vegetation, but they may also occur in tall-grass prairies. Females oviposit strictly in moist soils consisting of fine particles. Adults are both diurnal and crepuscular, and presumably spend the nighttime hours hiding among vegetation. Larvae occur in the same habitats as the adults and are typically clustered near the bases of plants. The larvae are the smallest of any tiger beetle species described in North America (body length of first instars ¼ 2.6‐3.2 mm, second instars ¼ 5.4‐6.7 mm, third instars ¼ 8.4‐10.1 mm) and most similar in morphology to Cicindela debilis Bates. Knowledge of the life history and habitats used by this species will allow a better understanding of its distribution and abundance, and its association with prairie habitats. This information as well as low dispersal rates may make this species useful for assessment of habitat quality and restoration success. Cicindela cursitans LeConte is a small flightless tiger beetle. At less than 1 cm in length, adults are among the smallest species in North America (Graves and Brzoska 1991). It is also among the more poorly known species, despite having been first described by LeConte in 1857 (LeConte 1857). The species is associated with bunchgrass prairies near rivers (Tinerella and Rider 2000; M. L. Brust, pers. obs.); however, its pre-adult life history remains very poorly known. It is a summer-active species in the adult stage and is most numerous in June and July (Graves and Pearson 1973; Knisley et al. 1987; Larochelle and Lariviere 2001). Because of its small size and general resemblance to ants it is easily overlooked (Graves and Brzoska 1991), and its North American distribution is probably underestimated (Graves and Pearson 1973; Graves

Morphological and behavioral adaptations in Bolitoglossa colonnea (Caudata, Plethodontidae) in relation to habitat use and daily activity cycle

Bolitoglossa colonnea is a member of the Bolitoglossa striatula group (sensu Wake and Lynch 1976) that inhabits low to intermediate elevations on the Caribbean slope of Costa Rica and Panama, and the Golfo Dulce area in southwestern Costa Rica and extreme western Panama. Due to their secretive habits and the low density in which these tropical salamanders generally occur, observations are rare and their natural history remains poorly known. Here we present data from field observations and a behavioral experiment that extend our understanding of the biology of this tropical salamander. Both Dunn (1926) and Taylor (1952) reported observing specimens of B. colonnea at night crawling on fallen logs and on low vegetation near a small fast-flowing stream. Bruce (1997) invariably found these salamanders close to the forest floor, either on the upper surfaces of broad-leaved herbaceous plants, on a pinnatifid fern, or on the vertical stem of a small plant. A single individual was observed crawling on leaf litter on the forest floor. The latter author remarked upon not being able to locate any salamanders during the

Seasonal and daily activity patterns of Vipera latastei in northern Portugal

AbstractThe annual and daily activity cycles of Vipera latastei were investigated in northern Portugal from 1999 to 2001, based on field observations, radio-tracking data and road killed snakes. Annual activity was extended from early March to late October, although some snakes were active during winter. Two annual peaks of activity were observed, a minor one in March-May and a major one in September-October. The daily activity pattern of vipers in spring and autumn was unimodal, whereas in summer they expanded their activity from early morning to late afternoon, and were also active at night. Activity and body exposure of adult males were correlated with meteorological variables. Females had shedding periods in June and July, whereas males shed their skin more frequently in June and August. Sperm was detected in the vas deferens of males in October to December. Females ovulated in June and new-born vipers were found from early August. Mating season is apparently restricted to autumn, and spring mating is either absent or very reduced.

Up All Night

Fear of aging keeps some people awake at night, and growing old doesn't help matters. As we age, the internal clock that coordinates our physiology with the 24-hour day falters. New research provides the first glimpse at molecular changes that underlie the mistiming. The results suggest that aging disrupts the connection between the brain's central clock and timekeepers elsewhere in the body. Sleep problems, which commonly trouble the elderly, aren't just an annoyance. Lack of sleep can impair memory, disrupt metabolism, and perhaps even hasten death. In addition, disjointed internal clocks prompt many Alzheimer's patients to do things at inappropriate times, "like making breakfast at 3:00 in the morning," says molecular biologist Christopher Driver of the National Ageing Research Institute in Melbourne, Australia. Scientists have identified a network of clock proteins whose concentrations wax and wane over the course of the day. The proteins tick away in the brain's central clock, known as the suprachiasmatic nucleus (SCN), and in tissues throughout the body. But how aging alters their oscillations has mystified scientists. To investigate this issue, Yamazaki and colleagues scrutinized rats that carry an artificial DNA segment consisting of a gene that encodes a light-producing enzyme linked to a control region from a clock gene called Period . This system allows the researchers to gauge Period 's output by measuring the amount of light beaming from the animals' tissues. The team extracted various tissues from young and withering rats and grew them in culture. Over the course of a week, Period turned on and off normally in most tissues from young and old animals, including the SCN. Further experiments showed that the SCN's cycle was shorter in older animals than in controls and that it matched up with aged rats' daily cycle of activity and rest. Aging also altered Period waves in other tissues, but in different ways. For instance, the kidney and the pineal gland--a brain structure that releases the hormone melatonin and is inhibited by light--exhibited Period oscillations that were out of synch with the SCN. And the gene's output didn't ebb and flow at all in the lung and the retrochiasmatic area: a brain region that receives information about external light intensity from the eye. The researchers conclude that aging doesn't impede Period waves in the central clock, but it might disrupt the clock's capability to synchronize tissues throughout the body. Other researchers agree. "There seems to be a failure of the connections between the clocks with age," says Driver, although he adds that scientists don't understand how the clocks link up or how they control behavior. This is one of the few papers to analyze age-related molecular changes in circadian clocks, according to Driver. "The genius of this particular publication is that they keep a tissue alive and look at the rise and fall of a particular protein just by visualizing it," he says, making it a robust method for monitoring circadian cycling. Tracking other components of circadian clocks and deciphering how they break down in elderly animals could awaken researchers to the cause of old-age sleeplessness. --R. John Davenport S. Yamazaki, M. Straume, H. Tei, Y. Sakaki, M. Menaker, G. D. Block, Effects of aging on central and peripheral mammalian clocks. Proc. Natl. Acad. Sci. U.S.A. , 29 July 2002 [e-pub ahead of print]. [Abstract] [Full Text]

Circadian modulation of starvation-induced hypothermia in sheep and goats

Prolonged food deprivation is known to cause a fall in the core body temperature of homeotherms. In various species of small birds and mammals (body mass up to 2–3 kg), it has been shown that starvation-induced hypothermia is modulated by the circadian system, in the sense that hypothermia is observed primarily during the inactive phase of the daily activity cycle (i.e., during the night for diurnal animals and during the day for nocturnal animals), whereas relatively normal temperatures are recorded during the active phase. To investigate whether this modulation occurs also in larger animals, we investigated the effects of 4d food deprivation on the body temperature rhythm of goats and sheep (body mass 30–40 kg). In goats, the body temperature rhythm was found to have a mean level of 39.0°C with a mean daily range of excursion of 0.42°C. The daily oscillation in body temperature persisted during the first day of fasting, but the rhythm was drastically damped, if not eliminated, over the next 3 d as body temperature descended from the baseline level of 39.0 to 38.2°C. In sheep, the rhythm was found to have a mean level of 39.3°C with a mean daily range of excursion of 0.34°C. The daily oscillation in body temperature persisted through the 4 d of food deprivation, even though the mean level of body temperature gradually fell. Temperature fell more during the third and fourth nights than during the third and fourth days. Thus, circadian modulation of starvation-induced hypothermia was observed in sheep but not in goats.

Reduced ground beetle activity following ice damage in maple stands of southwestern Quebec

The 1998 ice storm led to significant tree crown loss in the deciduous forests of southwestern Quebec. Increased irradiation in the understory may alter edaphic parameters of affected forests, such as temperature and humidity. We examined effects such a disturbance might have on the epigeal fauna of sugar maple stands during the summers of 1998 and 1999. Dry pitfall traps were set in the deciduous forest of Mont-Saint-Bruno Provincial Park, 20 km southeast of Montreal, Quebec under three different post-ice storm conditions (light tree crown loss, severe loss, and gaps) from mid-July to mid-August. We captured significantly fewer total Coleoptera and Carabidae at sites damaged by the ice storm. Species diversity of Coleoptera was also lower at damaged sites. However, the daily activity cycle of the insects did not change following heavy crown loss. Synhuchus impunctatus (Say), the dominant forest species, proved to be very sensitive to the disturbance. Observed decreases in insect abundance may be related to environmental changes resulting from heavy crown loss; these effects were probably both direct (on metabolism) and indirect (on nutritional resources). Key words: Carabidae, crown loss, disturbance, ice storm, maple stands, Synuchus impunctatus

Periodic fluctuations in the pulmonary surfactant system in Gould's wattled bat (Chalinolobus gouldii).

Pulmonary surfactant is a mixture of phospholipids, neutral lipids, and proteins that controls the surface tension of the fluid lining the lung. Surfactant amounts and composition are influenced by such physiological parameters as metabolic rate, activity, body temperature, and ventilation. Microchiropteran bats experience fluctuations in these parameters throughout their natural daily cycle of activity and torpor. The activity cycle of the microchiropteran bat Chalinolobus gouldii was studied over a 24-h period. Bats were maintained in a room at constant ambient temperature (24 degrees C) on an 8L : 16D cycle. Diurnal changes in the amount and composition of surfactant were measured at 4-h intervals throughout a 24-h period. The C. gouldii were most active at 2 a.m. and were torpid at 2 p.m. Alveolar surfactant increased 1.5-fold immediately after arousal. The proportion of disaturated phospholipid remained constant, while surfactant cholesterol levels increased 1.5-fold during torpor. Alveolar cholesterol in C. gouldii was six times lower than in other mammals. Cholesterol appears to function in maintaining surfactant fluidity during torpor in this species of bat.

Seasonality in foreign exchange volatility

The paper reports further empirical evidence on seasonality in foreign exchange volatility using high-frequency data. Using a basis of the signal plus noise framework, the approach decomposes tick-by-tick Reuters FXFX quotes into a random walk and a stationary component, termed the efficient price and the pricing error, respectively. The efficient price is not directly observable and is an approximation of the ‘true’ value. The pricing error captures the deviation between the observed indicative quote and the efficient price. Under the proposed model, daily and intraday volatilities of the efficient price are estimated. A pronounced pattern of volatility is uncovered and appears related to the daily activity cycle of major organized stock exchanges. It is argued that seasonality in volatility is a symptom of foreign exchange markets. Results confirm Andersen and Bollerslev's findings that significant seasonal effects are one important determinant of overall volatility at high frequencies.

Circadian rhythm of nitrogenase gene expression in the diazotrophic filamentous nonheterocystous cyanobacterium Trichodesmium sp. strain IMS 101.

Recent studies suggested that the daily cycle of nitrogen fixation activity in the marine filamentous nonheterocystous cyanobacterium Trichodesmium sp. is controlled by a circadian rhythm. In this study, we evaluated the rhythm of nitrogen fixation in Trichodesmium sp. strain IMS 101 by using the three criteria for an endogenous rhythm. Nitrogenase transcript abundance oscillated with a period of approximately 24 h, and the cycle was maintained even under constant light conditions. The cyclic pattern of transcript abundance was maintained when the culture was grown at 24 and 28.5 degrees C, although the period was slightly longer (26 h) at the higher temperature. The cycle of gene expression could be entrained with light-dark cues. Results of inhibitor experiments indicated that transcript abundance was regulated primarily by transcription initiation, rather than by degradation. The circadian rhythm, the first conclusively demonstrated endogenous rhythm in a filamentous cyanobacterium, was also reflected in nitrogenase MoFe protein abundance and patterns of Fe protein posttranslational modification-demodification.

Interleukin-1β Reduces Daily Activity Level in Male Lizards,Sceloporus occidentalis

In mammals, interleukin-1 (IL-1) mediates many of the behavioral consequences of pathogen infection. Other vertebrates show behavioral changes when infected, but the neuroendocrine bases of these changes are seldom known. Here we report that IL-1β alters the daily activity cycle of lizards (Sceloporus occidentalis) similar to that seen in lizards infected with malaria. To our knowledge, this is the first report of behavioral effects of interleukin in lower vertebrates. Male lizards were injected with human IL-1β (10 ng/g animal), saline, or nothing (control) and the activity level (proportion of lizards above ground) was monitored for 48 h. IL-1β-injected lizards showed a decrease in activity compared to saline-injected and control lizards within 2 h after treatment. Activity levels were equivalent among treatment groups during the middle of the day (1200–1600 h), but IL-1-treated animals were significantly less active in the morning (0800–1200 h) and evening (1600–2200 h). This decrease in activity is similar that seen in free-ranging lizards infected with malaria, supporting the hypothesis that IL-1 mediates the pathogen-induced alterations to activity behavior under natural conditions.

The Genetics of Timekeeping

inks between single genes and behavior in the fruit flyDrosophila melanogaster have been studied since the 1970s, but scientists have only recently begun making such connections in mammals by studying the genes that control the circadian clock, the body's daily sleep and activity cycle. The investigators are concentrating on these genes because the clock's cellular actions take place in a well-understood region of the mammalian brain and because genes with similar functions have been characterized for

Amino Acid Cycling in Colonies of the Planktonic Marine Cyanobacterium Trichodesmium thiebautii

We examined diel trends in internal pools and net efflux of free amino acids in colonies of the nonheterocystous, diazotrophic cyanobacterium Trichodesmium thiebautii, freshly collected from waters of the Caribbean and the Bahamas. The kinetics of glutamate uptake by whole colonies were also examined. While intracolonial pools of most free amino acids were relatively constant through the day, pools of glutamate and glutamine varied over the diel cycle, with maxima during the early afternoon. This paralleled the daily cycle of nitrogenase activity. We also observed a large net release of these two amino acids from intact colonies. Glutamate release was typically 100 pmol of N colony h. This is about one-fourth the concurrent rate of N(2) fixation during the day. However, while nitrogenase activity only occurs during the day, net release of glutamate and glutamine persisted into the night and may therefore account for a greater loss of recently fixed N on a daily basis. This release may be an important route of new N input into tropical, oligotrophic waters. Whole colonies also displayed saturation kinetics with respect to glutamate uptake. The K(s) for whole colonies varied from 1.6 to 3.2 muM, or about 100-fold greater than typical ambient concentrations. Thus, uptake systems appear to be adapted to the higher concentrations of glutamate found within the intracellular spaces of the colonies. This suggests that glutamate may be a vehicle for N exchange among trichomes in the colony.

Life in Extreme Dryness and Heat: A Telemetric Study of the Behaviour of the Diamond DoveGeopelia cuneatain its Natural Habitat

Summary: Daily activity cycle and thermoregulatory behaviour of free-ranging Diamond Doves Geopelia cuneata were recorded in the Hamersley Range National Park in north-west Western Australia. Birds were equipped with miniature HF-transmitters (mass approx. 1.6 g, representing 4-5% of body mass) and radio-tracked from sunrise to sunset over a period of 30 days. Transmitters glued onto the tails of the doves did not cause any obvious alteration in the birds' behaviour. For comparison, the behaviour of Spinifex Pigeons, Zebra Finches and various raptors was observed simultaneously. The observations were interpreted with reference to the results of previous laboratory studies. Dia

Mental and Physical Triggers of Silent Myocardial Ischemia: Ambulatory Studies Using Self-Monitoring Diary Methodology

Abstract The ability to monitor the electrocardiogram (ECG) during daily life, together with refinements in self-monitoring diary techniques have increased scientific understanding of the effects of physical and mental stress on the heart. During daily life, myocardial ischemia—an important functional measure of the activity of coronary disease—occurs frequently in coronary artery disease (CAD) patients during a wide variety of activities and exhibits characteristic features: it is more frequently asymptomatic or silent; it is triggered at relatively low heart rate elevations compared to controlled exercise testing; and it exhibits a circa-dian rhythm, being more likely in the morning. This article reviews recent ambulatory monitoring studies employing structured diaries, suggesting that behavioral factors, including mental stress, may contribute to these features of out-of-hospital ischemia. Mental stress is shown to be a potent trigger of daily-life ischemia, and silent versus symptomatic episodes have a different profile of physical and mental triggers. Daily activity cycles also appear to contribute to the morning increase in ischemia. Methodological issues in ambulatory ECG/diary studies are considered, especially concerning the reliability and validity of diary reports and problems associated with the analysis of data involving many repeated observations on large numbers of subjects.

Diurnal rhythms of activity in three species of sunfishes(Lepomis spp., Centrarchidae)

Abstract The daily activity cycles of three species of sunfishes (Lepomis macrochirus, L. cyanellum, L. gibbosus) were compared by measuring hourly activity under a 12:12 light/dark cycle with half‐hour dawn and dusk periods. Two different feeding times were also tested. Time‐series analyses showed a strong 24 hour component in the activity cycles of all three species, although an analysis of ARIMA models indicated that green sunfish activity was less predictable from hour to hour than was that of the other two species. The distribution of activity over the light/dark cycle was similar for pumpkinseed and green sunfish, both species exhibiting generally diurnal activity cycles with a tendency toward crepuscular peaks. Overall activity was higher for bluegill sunfish than for green or pumpkinseed sunfish, and bluegills exhibited a higher level of activity during the dark portion of the cycle than did the other two species.