Spawning, embryo development and growth of the American sand lance Ammodytes americanus in the laboratory

Smigielski, Alphonse S.; Halavik, Thomas A.; Buckley, LJ; Drew, S. M.; Laurence, Geoffrey C.

doi:10.3354/meps014287

Cited by 35 publications

(34 citation statements)

References 10 publications

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“…Lipid reserves of prey also gradually become depleted through the winter, and individual prey captures are thus less energetically rewarding (Smigielski et al. ; Robards et al. ; Comeau et al.…”

Section: Discussionmentioning

confidence: 99%

Behavioral signature of intraspecific competition and density dependence in colony‐breeding marine predators

Breed

Bowen

Leonard

2013

Ecology and Evolution

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In populations of colony-breeding marine animals, foraging around colonies can lead to intraspecific competition. This competition affects individual foraging behavior and can cause density-dependent population growth. Where behavioral data are available, it may be possible to infer the mechanism of intraspecific competition. If these mechanics are understood, they can be used to predict the population-level functional response resulting from the competition. Using satellite relocation and dive data, we studied the use of space and foraging behavior of juvenile and adult gray seals (Halichoerus grypus) from a large (over 200,000) and growing population breeding at Sable Island, Nova Scotia (44.0 oN 60.0 oW). These data were first analyzed using a behaviorally switching state-space model to infer foraging areas followed by randomization analysis of foraging region overlap of competing age classes. Patterns of habitat use and behavioral time budgets indicate that young-of-year juveniles (YOY) were likely displaced from foraging areas near (<10 km) the breeding colony by adult females. This displacement was most pronounced in the summer. Additionally, our data suggest that YOY are less capable divers than adults and this limits the habitat available to them. However, other segregating mechanisms cannot be ruled out, and we discuss several alternate hypotheses. Mark–resight data indicate juveniles born between 1998 and 2002 have much reduced survivorship compared with cohorts born in the late 1980s, while adult survivorship has remained steady. Combined with behavioral observations, our data suggest YOY are losing an intraspecific competition between adults and juveniles, resulting in the currently observed decelerating logistic population growth. Competition theory predicts that intraspecific competition resulting in a clear losing competitor should cause compensatory population regulation. This functional response produces a smooth logistic growth curve as carrying capacity is approached, and is consistent with census data collected from this population over the past 50 years. The competitive mechanism causing compensatory regulation likely stems from the capital-breeding life-history strategy employed by gray seals. This strategy decouples reproductive success from resources available around breeding colonies and prevents females from competing with each other while young are dependent.

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Section: Discussionmentioning

confidence: 99%

Behavioral signature of intraspecific competition and density dependence in colony‐breeding marine predators

Breed

Bowen

Leonard

2013

Ecology and Evolution

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“…Our working hypotheses were that if all other factors were equal, then starvation would only be found in small larvae that are learning to feed o n planktonic prey; that a greater proportion of first-feeding herring would be diagnosed as starving than first-feeding sand lance hecause sand lance are adapted to growing and surviving on dilute concentrations of prey (Buckley et al, 1987;Sherman et al, 1984;Smigielski et al, 1984;Yamashita and Aoyama, 1986); and that starvation would be more prevalent at a well-mixed site than at a stratified site because prey are more aggregated in stratified environments. …”

Section: Introductionmentioning

confidence: 99%

RNA–DNA ratio of herring and sand lance larvae from Port Moller, Alaska: Comparison with prey concentration and temperature

McGurk¹,

Warburton²,

Galbraith

et al. 1992

Fisheries Oceanography

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A key assumption of hypotheses that link the production of prey for larval fish with year‐class strength of fish is that larval growth and condition is food‐limited. We tested this assumption by comparing whole‐body RNA‐DNA ratios of individual Pacific herring, Clupea pallasi, larvae and Pacific sand lance, Ammodytes hex‐apterus, larvae from Port Moller, a subarctic Alaskan estuary, with prey concentration and temperature. RNA‐DNA ratios were correlated with larval length, but not with prey concentration or temperature. Ratios were not significantly different between a warm, well‐mixed station with low prey concentrations and a colder, stratified station with higher prey concentrations. Using RNA‐DNA ratios, we classified as starving 11 to 23% of first‐feeding (< 13 mm long) herring larvae and 45% of first‐feeding (< 7 mm long) sand lance larvae. However, starvation could not have been caused by low concentrations of prey because micro‐zooplankton prey concentrations were high enough (16 to 84 prey L_l) to support relatively high rates of growth. Therefore, starving larvae were either abnormal or they were stIII learning to forage. We conclude that the magnitude of starvation among first‐feeding herring and sand lance larvae, and, therefore, the total contribution of starvation to year‐class strength, is dependent not only on prey concentration, but on the proportion of a population of larvae that can feed effectively.

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“…Prey species also show pronounced annual cycles in energy density, becoming lipid rich in the summer prior to spawning and losing condition through the winter. Thus, the same prey items in winter will have less energy than they do in the summer (Smigielski et al 1984, Comeau et al 2002, Beck et al 2007). In addition to changes in energy density and depth distribution, some prey such as sandlance, a major component of the diet, spend more time hidden in sand (Smigielski et al 1984), requiring predators to switch foraging tactics.…”

Section: Annual Foraging Routinesmentioning

confidence: 99%

Development of foraging strategies with age in a long-lived marine predator

Breed¹,

Bowen²,

Leonard³

2011

Mar. Ecol. Prog. Ser.

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The development of foraging strategies as animals mature depends upon experience, stage-specific physiology, the onset of reproductive maturity and the reproductive costs incurred by each sex. To understand the ontogeny of foraging behaviour, we compared movement behaviour of 24 young-of-year (YOY) juveniles (12 male, 12 female) with 6 subadult (4 male, 2 female) and 81 adult (43 male, 38 female) grey seals Halichoerus grypus. We used a behaviour discriminating state-space model followed by a series of mixed-effects models to examine trip structure and habitat use in these age classes. In foraging trips, tortuosity and speed of outbound travel were not different in YOY, subadults and adults, suggesting that YOY navigate as well as older animals. On average, however, YOY trips lasted 1.2 to 3.5 d longer and required up to twice as much transit time to reach foraging areas that were 1.5 to 3 times farther from haul-out sites than those of subadults and adults. This suggests an overall apparent higher foraging effort for YOY. Differences, however, were highly seasonally dependent. In all groups, apparent foraging effort decreased in the summer and increased in the winter, which is consistent with seasonal changes in prey distribution and energy content. Adult foraging patterns showed complex seasonal patterns influenced by both reproductive cycles and seasonal environmental variation, whereas annual foraging patterns of YOY and subadults, neither of which invest in reproduction, were simpler and appeared more closely tied to seasonal changes in prey availability and condition. Although foraging in the same habitats, male and female YOY showed small but significant differences in movement behaviour and trip structure. These differences are unlikely to be due to size difference, which is minimal at this age, and suggest that sex-related differences in foraging develop early before sexual size dimorphism is significantly expressed.

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Spawning, embryo development and growth of the American sand lance Ammodytes americanus in the laboratory

Cited by 35 publications

References 10 publications

Behavioral signature of intraspecific competition and density dependence in colony‐breeding marine predators

Behavioral signature of intraspecific competition and density dependence in colony‐breeding marine predators

RNA–DNA ratio of herring and sand lance larvae from Port Moller, Alaska: Comparison with prey concentration and temperature

Development of foraging strategies with age in a long-lived marine predator

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