Responses of Arctic Grayling (Thymallus arcticus) to Acute and Prolonged Exposure to Yukon Placer Mining Sediment

1987 ◽  
Vol 44 (3) ◽  
pp. 658-673 ◽  
Author(s):  
D. J. McLeay ◽  
I. K. Birtwell ◽  
G. F. Hartman ◽  
G. L. Ennis
Keyword(s):  
Stress Responses ◽  
Prolonged Exposure ◽  
Feeding Activity ◽  
River System ◽  
Mining Area ◽  
Yukon Territory ◽  
Short Exposure ◽  
Arctic Grayling ◽  
Organic Sediment ◽  
Thymallus Arcticus

Underyearling Arctic grayling (Thymallus arcticus) from the Yukon River system were expsed for 4 d to suspensions of fine inorganic (≤ 250 g∙L−1) and organic (≤ 50 g∙L−1) sediment and for 6 wk to inorganic sediment (≤ 1000 mg∙L−1) under laboratory conditions. The test sediments were collected from an active placer mining area near Mayo, Yukon Territory. The exposures evoked sublethal responses but did not cause gill damage. Mortalities (10 and 20%) occurred only in experiments at 5 °C with inorganic sediment concentrations ≤ 20 g∙L−1. Six weeks of exposure to sediment concentrations > 100 mg∙L−1 impaired feeding activity, reduced growth rates, caused downstream displacement, colour changes, and decreased resistance to the reference toxicant pentachlorophenol, but did not impair respiratory capabilities. Stress responses (elevated and/or more varied blood sugar levels, depressed leucocrit values) were recorded after short exposure (1–4 d) to organic sediment concentrations as low as 50 mg∙L−1. Inorganic sediment strengths ≥ 10 g∙L−1 caused fish to surface. The lethal and sublethal responses of Arctic grayling to pentachlorophenol were similar to those determined for other healthy salmonid fishes.

Late Pleistocene fish fossils of Coregonus, Stenodus, Thymallus, Catostomus, Lota, and Cottus from the Old Crow basin, northern Yukon, Canada

1981 ◽  
Vol 18 (11) ◽  
pp. 1740-1754 ◽  
Author(s):  
Stephen L. Cumbaa ◽  
Don E. McAllister ◽  
Richard E. Morlan
Keyword(s):  
North America ◽  
Geographic Variation ◽  
Glacial Refugia ◽  
Yukon Territory ◽  
The Arctic ◽  
Arctic Grayling ◽  
Thymallus Arcticus ◽  
Freshwater Sculpin ◽  
Longnose Sucker ◽  
First Time

Fossils of the broad whitefish, Coregonus nasus; the inconnu, Stenodus leucichthys; the longnose sucker, Catostomus catostomus; and the burbot, Lota lota, are reported for the first time from North America and a freshwater sculpin, Cottus, for the first time from Yukon Territory. The known fossil occurrence of the Arctic grayling, Thymallus arcticus, in North America is extended from 32 000 to about 60 000 years BP. These six fossils represent about one sixth of the present-day Yukon freshwater ichthyofauna of 35 species.These fossils provide a major test for the method of determining glacial refugia based on geographic variation of morphological or protein characters. They confirm that these taxa were present prior to and presumably survived the Wisconsinan glaciation in a Beringian refugium.The occurrence of these fossils, all subarctic or subarctic–boreal species known at present in the same area, does not suggest a paleoenvironment greatly different from the present one.

Hunger and the Capture of Grayling and Char

1974 ◽  
Vol 31 (12) ◽  
pp. 1945-1948 ◽  
Author(s):  
J. E. Bryan
Keyword(s):  
Sex Ratio ◽  
Salvelinus Alpinus ◽  
Yukon Territory ◽  
Arctic Char ◽  
Remote Areas ◽  
Size Selection ◽  
Arctic Grayling ◽  
Thymallus Arcticus

Arctic grayling, Thymallus arcticus, and Arctic char, Salvelinus alpinus, were collected by angling and seining in remote areas of northern Yukon Territory. Stomach samples were observed to test the hypothesis that fish caught by angling had eaten less food than those caught by seining. The hypothesis was supported by the data for grayling. The data for char were consistent with the hypothesis, but the results were not statistically significant. There was no difference in the sex ratio of fish caught by the two methods. Angling selected larger char than did seining, but there was no evidence of size selection in grayling.

Pleistocene grayling, Thymallus, from Yukon, Canada

1969 ◽  
Vol 6 (5) ◽  
pp. 1185-1190 ◽  
Author(s):  
D. E. McAllister ◽  
C. R. Harington
Keyword(s):  
North America ◽  
Yukon Territory ◽  
The Arctic ◽  
Fish Scales ◽  
Arctic Grayling ◽  
Thymallus Arcticus ◽  
Fossil Records ◽  
Pleistocene Deposit

Eleven cycloid fish scales or scale fragments with scalloped anterior margins were obtained from a Pleistocene deposit in the Old Crow area, Yukon Territory. Shells from the same horizon as the scales were radiocarbon dated at 32 400 ± 770 yr B.P. The scales are from the Arctic grayling, Thymallus arcticus, providing the first fossil records of the genus and of the subfamily Thymallinae for North America.

New Complexities in Zoogeography and Taxonomy of the Pygmy Whitefish (Prosopium coulteri)

1972 ◽  
Vol 29 (12) ◽  
pp. 1772-1775 ◽  
Author(s):  
C. C. Lindsey ◽  
W. G. Franzin
Keyword(s):  
River System ◽  
Yukon Territory ◽  
Hudson Bay ◽  
The South ◽  
Bristol Bay ◽  
River Drainage ◽  
Bay Area ◽  
First Time ◽  
Mackenzie River

Pygmy whitefish (Prosopium coulteri) are recorded for the first time from the Peel–Mackenzie river drainage (Elliott Lake, Yukon Territory) and from the Hudson Bay drainage (Waterton Lakes, Alberta, in the South Saskatchewan–Nelson river system). The morphology of specimens from both localities contradicts the previously known pattern of a southeastern "low-rakered" and a northwestern "high-rakered" form (with the two forms occurring sympatrically in some lakes of the Bristol Bay area). Specimens from Elliott Lake, the most northerly known locality, resemble the southeastern form and those from Waterton Lakes the northwestern form. Both Waterton and Elliott lakes lie close to unglaciated refugia, suggesting that the species may have survived Wisconsin glaciation and diverged in several different watersheds.

Light-induced suppression of the rat circadian system

1995 ◽  
Vol 268 (5) ◽  
pp. R1111-R1116 ◽  
Author(s):  
P. Depres-Brummer ◽  
F. Levi ◽  
G. Metzger ◽  
Y. Touitou
Keyword(s):  
Locomotor Activity ◽  
Body Temperature ◽  
Circadian Rhythms ◽  
Prolonged Exposure ◽  
Light Exposure ◽  
Continuous Light ◽  
Circadian System ◽  
Short Exposure ◽  
Complete Suppression ◽  
Continuous Darkness

In a constant environment, circadian rhythms persist with slightly altered period lengths. Results of studies with continuous light exposure are less clear, because of short exposure durations and single-variable monitoring. This study sought to characterize properties of the oscillator(s) controlling the rat's circadian system by monitoring both body temperature and locomotor activity. We observed that prolonged exposure of male Sprague-Dawley rats to continuous light (LL) systematically induced complete suppression of body temperature and locomotor activity circadian rhythms and their replacement by ultradian rhythms. This was preceded by a transient loss of coupling between both functions. Continuous darkness (DD) restored circadian synchronization of temperature and activity circadian rhythms within 1 wk. The absence of circadian rhythms in LL coincided with a mean sixfold decrease in plasma melatonin and a marked dampening but no abolition of its circadian rhythmicity. Restoration of temperature and activity circadian rhythms in DD was associated with normalization of melatonin rhythm. These results demonstrated a transient internal desynchronization of two simultaneously monitored functions in the rat and suggested the existence of two or more circadian oscillators. Such a hypothesis was further strengthened by the observation of a circadian rhythm in melatonin, despite complete suppression of body temperature and locomotor activity rhythms. This rat model should be useful for investigating the physiology of the circadian timing system as well as to identify agents and schedules having specific pharmacological actions on this system.

Time variation in transfer amounts of mercury by a river system near an artisanal and small-scale gold mining area in West Java, Indonesia

2019 ◽  
Vol 78 (24) ◽  
Author(s):  
Takashi Tomiyasu ◽  
Yuriko Kono Hamada ◽  
Christine Baransano ◽  
Nuril Hidayati ◽  
Joeni Setijo Rahajoe
Keyword(s):  
Time Variation ◽  
Gold Mining ◽  
River System ◽  
Mining Area ◽  
Small Scale ◽  
West Java

Energetic status and bioelectrical impedance modeling of Arctic grayling Thymallus arcticus in interior Alaska Rivers

2019 ◽  
Vol 102 (11) ◽  
pp. 1337-1349
Author(s):  
Jeffrey A. Falke ◽  
Lauren T. Bailey ◽  
Kevin M. Fraley ◽  
Michael J. Lunde ◽  
Andrew D. Gryska
Keyword(s):  
Bioelectrical Impedance ◽  
Arctic Grayling ◽  
Interior Alaska ◽  
Impedance Modeling ◽  
Thymallus Arcticus
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