Intermittent breeding in the absence of a large cost of reproduction: evidence for a non‐migratory, iteroparous salmonid

Morbey, Yolanda E.; Shuter, Brian J.

doi:10.1890/es13-00259.1

Cited by 16 publications

(15 citation statements)

References 42 publications

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“…Further reductions in access to littoral regions with future warming could prevent lake trout from accumulating sufficient energy to spawn in the fall (27), potentially increasing the frequency of skip-spawning (32,33). The prospective smaller postadult body size with warming could also lead to reductions in fecundity, which is positively correlated with body size (34).…”

Section: Discussionmentioning

confidence: 99%

Behavioral responses to annual temperature variation alter the dominant energy pathway, growth, and condition of a cold-water predator

Guzzo

Blanchfield

Rennie

2017

Proc. Natl. Acad. Sci. U.S.A.

119

152

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There is a pressing need to understand how ecosystems will respond to climate change. To date, no long-term empirical studies have confirmed that fish populations exhibit adaptive foraging behavior in response to temperature variation and the potential implications this has on fitness. Here, we use an unparalleled 11-y acoustic telemetry, stable isotope, and mark-recapture dataset to test if a population of lake trout (Salvelinus namaycush), a coldwater stenotherm, adjusted its use of habitat and energy sources in response to annual variations in lake temperatures during the open-water season and how these changes translated to the growth and condition of individual fish. We found that climate influenced access to littoral regions in spring (data from telemetry), which in turn influenced energy acquisition (data from isotopes), and growth (mark-recapture data). In more stressful years, those with shorter springs and longer summers, lake trout had reduced access to littoral habitat and assimilated less littoral energy, resulting in reduced growth and condition. Annual variation in prey abundance influenced lake trout foraging tactics (i.e., the balance of the number and duration of forays) but not the overall time spent in littoral regions. Lake trout greatly reduced their use of littoral habitat and occupied deep pelagic waters during the summer. Together, our results provide clear evidence that climate-mediated behavior can influence the dominant energy pathways of top predators, with implications ranging from individual fitness to food web stability.food web | climate change | habitat coupling | lake trout | north-temperate lake T here is growing urgency to understand how ecosystems are responding to climate change (1, 2). Recent work, using latitudinal gradients as proxies to warming, has argued that the behavioral responses of mobile top predators to changing temperatures can drive fundamental shifts in aquatic food webs by altering the coupling of major energy pathways (3, 4). Although this work is intriguing, no one has yet examined long-term empirical data that have explicitly tested if populations of top predators can shift their foraging behavior in response to annual changes in temperature or has evaluated what implications this might have for individual fitness. Temporal studies are critically important in this context because they control for the ecosystemspecific adaptations that can confound latitudinal studies and instead focus on the active responses to changing conditions that are highly relevant to understanding the impacts of climate change.Mobile top predators display adaptive foraging behavior by moving across spatially disparate habitats in response to changing conditions, most notably prey densities. For example, birds feed on both terrestrial and aquatic prey, effectively coupling these ecosystems (5). Habitat coupling can also occur within ecosystems and has been well described in freshwater lakes, where predatory fish feed upon prey supported by dissimilar energy sources, such as offsho...

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Section: Discussionmentioning

confidence: 99%

Behavioral responses to annual temperature variation alter the dominant energy pathway, growth, and condition of a cold-water predator

Guzzo

Blanchfield

Rennie

2017

Proc. Natl. Acad. Sci. U.S.A.

119

152

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“…We chose midsummer as our study period in all lakes: this covers a significant portion of the intense feeding period that supports the gonadal development (Morbey & Shuter, ; Plumb, Blanchfield, & Abrahams, ) essential for successful reproduction, but is sufficiently separated from the October spawning period (Weatherley, Kaseloo, Gare, Gunndr, & Llpicnik, ) so that the observed behaviour should only reflect foraging. To compare lakes under relatively similar environmental conditions, we focused our analysis on data collected during the 20‐day period in each lake when (a) average epilimnetic water temperatures reached their seasonal maximum, (b) all lakes were fully stratified, and (c) the temperature difference between epilimnion and hypolimnion always exceeded 10°C (Appendix S4).…”

Section: Methodsmentioning

confidence: 99%

Life at the top: Lake ecotype influences the foraging pattern, metabolic costs and life history of an apex fish predator

Cruz‐Font

Shuter

Blanchfield

et al. 2019

Journal of Animal Ecology

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We used acoustic telemetry and acceleration sensors to compare population‐specific measures of the metabolic costs of an apex fish predator living in four separate lakes. We chose our study species and populations to provide a strong test of recent theoretical predictions that optimal foraging by an apex fish predator in a typical aquatic environment would be consistent with feeding to satiation rather than continuous feeding. We chose four populations where the primary prey type differed along a body size gradient (from small invertebrates to large planktivorous fish) and along a thermal accessibility gradient (from easily accessible cold‐water pelagic prey to less accessible warm‐water epilimnetic and littoral prey). We expected that these gradients in prey type would evoke distinctly different activity gradients depending on whether predators fed to satiation (e.g., less frequent “rest” detections where primary prey are smaller/less accessible) or fed continuously (e.g., fixed level of “rest” detections under all prey conditions). Our study organism was a fall spawning, cold‐water visual apex predator (lake trout). Therefore, we focused our study on diel (early night, dawn, day, dusk, late night) changes in metabolic costs associated with summer feeding behaviour. The duration (~20 days) and fine temporal scale (~30 min) of our behavioural data provided a uniquely detailed picture of intra‐ and inter‐population differences in activity patterns over a critical period in the annual growing season. In all populations, diel shifts in activity were qualitatively consistent with that expected of a visual predator (e.g., resting state detections were most frequent at night). Between‐lake differences in daytime thermal experience were qualitatively consistent with between‐lake differences in the location of primary prey (e.g., excursions to warm habitats were common in lakes with epilimnetic/littoral fish as primary prey and relatively rare in lakes with pelagic cold‐water invertebrates/fish as primary prey). Daytime activity patterns were more consistent with the feeding pattern expected from feeding to satiation rather than continuous feeding: (a) individuals in all four populations exhibited clearly delineated bouts of resting behaviour and active behaviour; (b) the frequency of resting bouts and the resultant overall cost of daily activity were strongly associated with the size and accessibility of prey—in lakes with smaller and/or less accessible prey, predators rested less frequently, exhibited marginally higher costs when active and had higher overall daytime activity costs. Within each lake, similar changes in activity occurred concurrently with diel changes in prey accessibility/relative density.

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“…In contrast, demonstrating the indirect impact of predation risk on the decision to skip breeding has proven to be challenging under natural conditions, for both conceptual and practical reasons. First, the strategy of intermittent breeding requires substantial accessory costs of reproduction to evolve (Morbey and Shuter 2013) and also that reliable predictive cues about predation risk are available to breeders prior to the onset of breeding (Reed et al 2015). Second, detection of non-breeders is difficult and sometimes even impossible because non-breeders are simply not present at the breeding grounds (Gimenez et al 2008;Desprez et al 2011).…”

Section: Introductionmentioning

confidence: 99%

To breed or not to breed: drivers of intermittent breeding in a seabird under increasing predation risk and male bias

et al. 2018

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Intermittent breeding may be adaptive for long-lived species subjected to large accessory reproductive costs, but it may also reflect reduced adaptation to the environment, reducing population growth. Nevertheless, environmental influences on breeding propensity, particularly that of predation risk, remain poorly understood and difficult to study, because non-breeders are typically not identified. Female eiders Somateria mollissima from the Baltic Sea provide an excellent testbed, because nesting females have been exposed to intensifying predation and growing male bias that may increase female harassment. We based our study on long-term data (14 years) on females captured and marked at the nest, and females individually identified at sea irrespective of capture status. We hypothesized that breeding propensity decreases with increasing predation risk and male bias, and increases with breeder age. Consistent with our hypotheses, females nesting on islands with higher nest predation risk were more likely to skip breeding, and breeding probability increased with age. In contrast, the steep temporal decline in breeding propensity could not be reliably attributed to annual adult sex ratio or to the abundance of white-tailed sea eagles (Haliaeetus albicilla), the main predator on females, at the nearby Hanko Bird Observatory. Breeding probability showed significant consistent individual variation. Our results demonstrate that spatiotemporal variation in predation risk affects the decision to breed and high incidence of non-breeding was associated with low fledging success. The increased frequency of intermittent breeding in this declining population should be explicitly considered in demographic models, and emphasis placed on understanding the preconditions for successful reproduction.

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Intermittent breeding in the absence of a large cost of reproduction: evidence for a non‐migratory, iteroparous salmonid

Cited by 16 publications

References 42 publications

Behavioral responses to annual temperature variation alter the dominant energy pathway, growth, and condition of a cold-water predator

Behavioral responses to annual temperature variation alter the dominant energy pathway, growth, and condition of a cold-water predator

Life at the top: Lake ecotype influences the foraging pattern, metabolic costs and life history of an apex fish predator

To breed or not to breed: drivers of intermittent breeding in a seabird under increasing predation risk and male bias

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