Diel pattern of emergence in grayling (Thymallus thymallus Linnaeus, 1758)

The emergence rhythm of grayling fry (Thymallus thymallus) was studied under semi-natural rearing conditions, using special traps buried in the gravel. The diel pattern of emergence proved to be mainly diurnal, with a maximum just after sunrise. The discussion emphasizes the fact that this distinguishes the grayling from other salmonids, and since eggs are buried at a reduced depth, proposes the hypothesis that light conditions during development influence the daily pattern of emergence.

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The diel pattern in harbour porpoise clicking behaviour is not a response to prey activity

Scientific Reports ◽

10.1038/s41598-020-71957-0 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Anna N. Osiecka ◽

Owen Jones ◽

Magnus Wahlberg

Keyword(s):

Behaviour Pattern ◽

Ambient Light ◽

Light Conditions ◽

Phocoena Phocoena ◽

Diel Pattern ◽

Acoustic Activity ◽

Clear Peak ◽

Similar Temperature ◽

Free Ranging ◽

Diel Behaviour

Abstract Wild harbour porpoises (Phocoena phocoena) mainly forage during the night and, because they rely on echolocation to detect their prey, this is also when they are most acoustically active. It has been hypothesised that this activity pattern is a response to the diel behaviour of their major prey species. To test this hypothesis, we monitored the acoustic activity of two captive harbour porpoises held in a net pen continuously during a full year and fed by their human keepers during daylight hours, thus removing the influence of prey activity. The porpoises were exposed to similar temperature and ambient light conditions as free-ranging animals living in the same region. Throughout the year, there was a pronounced diel pattern in acoustic activity of the porpoises, with significantly greater activity at night, and a clear peak around sunrise and sunset throughout the year. Clicking activity was not dependent on lunar illumination or water level. Because the porpoises in the pen are fed and trained during daylight hours, the results indicate that factors other than fish behaviour are strongly influencing the diel clicking behaviour pattern of the species.

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Influence of Daily Variations of Light and Temperature on the Emergence Rhythm of Grayling Fry (Thymallus thymallus)

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f91-141 ◽

1991 ◽

Vol 48 (7) ◽

pp. 1176-1180 ◽

Cited By ~ 13

Author(s):

Agnès Bardonnet ◽

Philippe Gaudin

Keyword(s):

Constant Temperature ◽

Early Morning ◽

Thymallus Thymallus ◽

Temperature Variations ◽

Emergence Pattern ◽

Daily Variations ◽

Emergence Rhythm ◽

Dim Light

The emergence rhythm of grayling fry (Thymallus thymallus) was studied in four aquaria fitted with traps under four different conditions of light and temperature. Both light and temperature induced an emergence rhythm characterized by a 24-h period. Under ambient Sight and constant temperature, emergence peaked at the end of the night before the onset of dawn. Under constant dim light and varying temperature, emergence peaked in early morning during the coldest hours. When both light and temperature fluctuated daily the emergence pattern was equivalent to the "sum" of these previous two regimes and was similar to that described in the field in a previous report. In the absence of light and temperature variations, no emergence rhythm was observed.

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Shedding new light upon circadian emergence rhythmicity in the mountain pine beetle (Coleoptera: Curculionidae: Scolytinae)

The Canadian Entomologist ◽

10.4039/tce.2019.18 ◽

2019 ◽

Vol 151 (3) ◽

pp. 273-277 ◽

Cited By ~ 1

Author(s):

Debra L. Wertman ◽

Katherine P. Bleiker

Keyword(s):

Circadian Clock ◽

Mountain Pine Beetle ◽

Historical Data ◽

Life Stages ◽

Light Conditions ◽

Dark Cycle ◽

Long Wavelength ◽

Mountain Pine ◽

Pine Beetle ◽

Emergence Rhythm

AbstractThe phenological behaviours of temperate insects can be highly controlled by photoperiod. Some foundational studies of the mountain pine beetle, Dendroctonus ponderosae (Hopkins) (Coleoptera: Curculionidae), documented a diurnal emergence rhythm that was asynchronous with maximum daily temperatures in the field and persisted under constant temperature and light conditions. In the 1970s, researchers hypothesised that this emergence rhythm was regulated by an endogenous circadian mechanism. Reflecting upon these historical data, we consider that a diurnal pattern of D. ponderosae emergence may result from photoperiodic entrainment of the circadian clock during the immature stages. Mechanistically, we suggest that the long-wavelength-sensitive opsin that we previously found to be expressed across D. ponderosae life stages could mediate, from beneath the bark, the input of light–dark cycle cues that are usually required for entrainment of the insect circadian clock.

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