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Maturation, fecundity, and intertidal spawning of Pacific sand lance in the northern Gulf of Alaska (1999)

Robards, M. D. ; Piatt, J. F. ; Rose, G. A.

Oxford, UK : Blackwell Publishing Ltd

Journal of fish biology 54 (1999), S. 0

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ISSN: 1095-8649

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology

Notes: Pacific sand lance Ammodytes hexapterus in Kachemak Bay, Alaska, showed no sexual dimorphism in length-to-weight (gonad-free) ratio or length-at-age relationship. Most matured in their second year, males earlier in the season than females, but females (31%) attained a higher gonadosomatic index than males (21%). Sand lance spawned intertidally once each year in late September and October on fine gravel or sandy beaches soon after the seasonal peak in water temperatures. Sand lance in Cook Inlet and Prince William Sound displayed similar maturation schedules. Schools were dominated 2: 1 by males as they approached the intertidal zone at a site where spawning has taken place for decades. Sand lance spawned vigorously in dense formations, leaving scoured pits in beach sediments. Fecundity of females (93–199 mm) was proportional to length, ranging from 1468 to 16 081 ova per female. About half of the overall spawning school fecundity was derived from age group 1 females (55% of the school by number). Spawned eggs were 1·02 mm in diameter, demersal, slightly adhesive, and deposited in the intertidal just below the waterline. Sand lance embryos developed over 67 days through periods of intertidal exposure and sub-freezing air temperatures.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1095-8649.1999.tb00857.x

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The adrenocortical stress-response of Black-legged Kittiwake chicks in relation to dietary restrictions (1999)

Kitaysky, A. S. ; Piatt, J. F. ; Wingfield, J. C. ; [et al.]

Springer

Journal of comparative physiology 169 (1999), S. 303-310

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ISSN: 1432-136X

Keywords: Key words Corticosterone ; Testosterone ; Food-stress ; Nest-bound chicks

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Medicine

Notes: Abstract In this study we examined hormonal responses of Black-legged Kittiwake (Rissatridactyla) chicks to experimental variations in energy content and nutritional quality (low or high lipid to protein ratio, LPR) of their food. Starting at the age of 10 days, chicks were fed either high or low LPR fish at 30, 50, 70 and 100% of ad libitum energy intake. After 20 days of treatment, chicks were exposed to a standardized acute handling and restraint stress protocol, where a baseline sample was taken immediately after taking a chick from the nest, and three additional blood samples were taken at intervals up to 50 min. Testosterone and corticosterone titres in plasma were measured via radioimmunoassay. We found that baseline testosterone levels were not significantly affected by the experimental treatments. Food-restricted chicks had elevated baseline and acute stress-induced levels of corticosterone compared to chicks fed ad libitum. An elevation of circulating levels of corticosterone in energetically stressed individuals was further magnified by low nutritional quality of food. Baseline and acute stress-induced corticosterone levels of chicks were negatively correlated with their fat reserves. We conclude that the physiological condition of Black-legged Kittiwake chicks can be assessed reliably by measuring circulating levels of corticosterone. We discuss short- and long-term effects of elevated corticosterone secretion in food-stressed nest-bound chicks.