Southern Elephant Seals Replenish Their Lipid Reserves at Different Rates According to Foraging Habitat

Richard, Gaëtan; Cox, Samantha L.; Picard, Baptiste; Vacquié‐Garcia, Jade; Guinet, Christophe

doi:10.1371/journal.pone.0166747

Cited by 18 publications

(21 citation statements)

References 44 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Here, PrCA rates were typically reduced (Figure and Supporting Information ). While confounding processes (e.g., temporal changes in foraging success and/or prey quality) suggest increased PrCA rates are not necessarily directly linked to better foraging (Orgeret et al, ; Richard et al, ), combined with increased survival rates these patterns suggest foraging habitats associated with increased SSTs and TKE estimates are more suitable for southern elephant seals during this time in their development.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

High mortality rates in a juvenile free‐ranging marine predator and links to dive and forage ability

Cox

Authier

Orgeret

et al. 2019

Ecology and Evolution

Self Cite

View full text Add to dashboard Cite

1. High juvenile mortality rates are typical of many long-lived marine vertebrate predators. Insufficient development in dive and forage ability is considered a key driver of this. However, direct links to survival outcome are sparse, particularly in free-ranging marine animals that may not return to land.2. In this study, we conduct exploratory investigations toward early mortality in juvenile southern elephant seals Mirounga leonina. Twenty postweaning pups were equipped with (a) a new-generation satellite relay data tag, capable of remotely transmitting fine-scale behavioral movements from accelerometers, and (b) a location transmitting only tag (so that mortality events could be distinguished from device failures). Individuals were followed during their first trip at sea (until mortality or return to land). Two analyses were conducted. First, the behavioral movements and encountered environmental conditions of nonsurviving pups were individually compared to temporally concurrent observations from grouped survivors. Second, common causes of mortality were investigated using Cox's proportional hazard regression and penalized shrinkage techniques.3. Nine individuals died (two females and seven males) and 11 survived (eight females and three males). All but one individual died before the return phase of their first trip at sea, and all but one were negatively buoyant. Causes of death were variable, although common factors included increased horizontal travel speeds and distances, decreased development in dive and forage ability, and habitat type visited (lower sea surface temperatures and decreased total [eddy] kinetic energy).4. For long-lived marine vertebrate predators, such as the southern elephant seal, the first few months of life following independence represent a critical period, when small deviations in behavior from the norm appear sufficient to increase mortality risk. Survival rates may subsequently be particularly vulnerable to changes in climate and environment, which will have concomitant consequences on the demography and dynamics of populations. | 411COX et al.

show abstract

Section: Discussionmentioning

confidence: 99%

“…Information on fine‐scale biophysical habitats encountered by each individual, which may impact prey availability/quality (Abrahms et al, ; Richard, Cox, Picard, Vacquie‐Garcia, & Guinet, ), was also obtained. For each individual for each day, SST was taken from the DSA tag as the mean temperature of all measurements of that day.…”

Section: Methodsmentioning

confidence: 99%

High mortality rates in a juvenile free‐ranging marine predator and links to dive and forage ability

Cox

Authier

Orgeret

et al. 2019

Ecology and Evolution

Self Cite

View full text Add to dashboard Cite

show abstract

“…In particular, changes in descent swimming speeds and ascent swimming efforts (Biuw et al, 2003;Richard et al, 2014) can be used as a proxy for body condition, and compared to indices of foraging effort (i.e. time spent in PrCA behaviours) to assess foraging performance (Richard, Cox, Picard, Vacquie-Garcia, & Guinet, 2016). The methods explored in this study are applicable to a diversity of other species including pinnipeds, cetaceans, seabirds (e.g.…”

Section: Discussionmentioning

confidence: 99%

Processing of acceleration and dive data on‐board satellite relay tags to investigate diving and foraging behaviour in free‐ranging marine predators

et al. 2017

Self Cite

View full text Add to dashboard Cite

Biologging technologies are changing the way in which the marine environment is observed and monitored. However, because device retrieval is typically required to access the high‐resolution data they collect, their use is generally restricted to those animals that predictably return to land. Data abstraction and transmission techniques aim to address this, although currently these are limited in scope and do not incorporate, for example, acceleration measurements which can quantify animal behaviours and movement patterns over fine‐scales.In this study, we present a new method for the collection, abstraction and transmission of accelerometer data from free‐ranging marine predators via the Argos satellite system. We test run the technique on 20 juvenile southern elephant seals Mirounga leonina from the Kerguelen Islands during their first months at sea following weaning. Using retrieved archival data from nine individuals that returned to the colony, we compare and validate abstracted transmissions against outputs from established accelerometer processing procedures.Abstracted transmissions included estimates, across five segments of a dive profile, of time spent in prey catch attempt (PrCA) behaviours, swimming effort and pitch. These were then summarised and compared to archival outputs across three dive phases: descent, bottom and ascent. Correlations between the two datasets were variable but generally good (dependent on dive phase, marginal R 2 values of between .45 and .6 to >.9) and consistent between individuals. Transmitted estimates of PrCA behaviours and swimming effort were positively biased to those from archival processing.Data from this study represent some of the first remotely transmitted quantifications from accelerometers. The methods presented and analysed can be used to provide novel insight towards the behaviours and movements of free‐ranging marine predators, such as juvenile southern elephant seals, from whom logger retrieval is challenging. Future applications could however benefit from some adaption, particularly to reduce positive bias in transmitted PrCA behaviours and swimming effort, for which this study provides useful insight.

show abstract

“…A recently developed method to observe the feeding attempts of marine mammals using accelerometers on the jaw or the head of seals has made it possible to estimate putative feeding rates (hereafter, feeding rates) dive by dive covering the entire period of migration (Adachi et al., ; Jouma'a et al., ; Naito et al., ; Richard, Cox, Picard, Vacquié‐Garcia, & Guinet, ). These results have raised the hypotheses that elephant seals forage on small mesopelagic prey (10–20 g) on average during migration (Guinet et al., ; Naito et al., ), which accord with stable isotope studies (Cherel et al., ), and that they fine‐tune their diving behavior by adjusting their swimming effort in relation to prey patch depth and density and according to changes in buoyancy (Adachi et al., ; Jouma'a et al., ; Richard et al., ). Despite these recent studies, the entirety of their dietary choice, characterized within the mesopelagic zone and particularly in the OMZ, remains largely unknown.…”

Section: Introductionmentioning

confidence: 99%

Oxygen minimum zone: An important oceanographic habitat for deep‐diving northern elephant seals,Mirounga angustirostris

Naito

Costa

Adachi

et al. 2017

Ecology and Evolution

View full text Add to dashboard Cite

Little is known about the foraging behavior of top predators in the deep mesopelagic ocean. Elephant seals dive to the deep biota‐poor oxygen minimum zone (OMZ) (>800 m depth) despite high diving costs in terms of energy and time, but how they successfully forage in the OMZ remains largely unknown. Assessment of their feeding rate is the key to understanding their foraging behavior, but this has been challenging. Here, we assessed the feeding rate of 14 female northern elephant seals determined by jaw motion events (JME) and dive cycle time to examine how feeding rates varied with dive depth, particularly in the OMZ. We also obtained video footage from seal‐mounted videos to understand their feeding in the OMZ. While the diel vertical migration pattern was apparent for most depths of the JME, some very deep dives, beyond the normal diel depth ranges, occurred episodically during daylight hours. The midmesopelagic zone was the main foraging zone for all seals. Larger seals tended to show smaller numbers of JME and lower feeding rates than smaller seals during migration, suggesting that larger seals tended to feed on larger prey to satisfy their metabolic needs. Larger seals also dived frequently to the deep OMZ, possibly because of a greater diving ability than smaller seals, suggesting their dependency on food in the deeper depth zones. Video observations showed that seals encountered the rarely reported ragfish (Icosteus aenigmaticus) in the depths of the OMZ, which failed to show an escape response from the seals, suggesting that low oxygen concentrations might reduce prey mobility. Less mobile prey in OMZ would enhance the efficiency of foraging in this zone, especially for large seals that can dive deeper and longer. We suggest that the OMZ plays an important role in structuring the mesopelagic ecosystem and for the survival and evolution of elephant seals.

show abstract

Southern Elephant Seals Replenish Their Lipid Reserves at Different Rates According to Foraging Habitat

Cited by 18 publications

References 44 publications

High mortality rates in a juvenile free‐ranging marine predator and links to dive and forage ability

High mortality rates in a juvenile free‐ranging marine predator and links to dive and forage ability

Processing of acceleration and dive data on‐board satellite relay tags to investigate diving and foraging behaviour in free‐ranging marine predators

Oxygen minimum zone: An important oceanographic habitat for deep‐diving northern elephant seals,Mirounga angustirostris

Contact Info

Product

Resources

About