A fully coupled ecosystem model to predict the foraging ecology of apex predators in the California Current

Results from a fully coupled end-to-end ecosystem model for the California Current Large Marine Ecosystem are used to describe the impact of environmental variability and prey availability on the foraging ecology of its most abundant apex predator, the California sea lion Zalophus californianus. The ecosystem model consists of a biogeochemical submodel embedded in a regional ocean circulation submodel, both coupled with a multi-species individual-based submodel for forage fish (sardine and anchovy) and California sea lions. Sardine and anchovy are explicitly represented in the model as they are commonly found in the diet of sea lions and exhibit significant interannual and decadal variability in population abundances that reflect variations in their environment and lower trophic level prey. Output from a 20 yr run (1989-2008) of the model demonstrates how different physical and biological processes control habitat utilization and foraging success of California sea lions on interannual time scales, with the dominant modes of variability linked to sardine abundance and coastal upwelling intensity. The results also illustrate how variability in environmental conditions, forage fish distribution, and prey assemblage affect sea lion feeding success. While specifically focusing on the foraging ecology of sea lions, the modeling framework has the ability to provide a more complete understanding of the physical and biological mechanisms impacting trophic interactions in the California Current, or other regions where similar fully coupled ecosystem models may be implemented

A fully coupled ecosystem model to predict the foraging ecology of apex predators in the California Current

Results from a fully coupled end-to-end ecosystem model for the California Current Large Marine Ecosystem are used to describe the impact of environmental variability and prey availability on the foraging ecology of its most abundant apex predator, the California sea lion Zalophus californianus. The ecosystem model consists of a biogeochemical submodel embedded in a regional ocean circulation submodel, both coupled with a multi-species individual-based submodel for forage fish (sardine and anchovy) and California sea lions. Sardine and anchovy are explicitly represented in the model as they are commonly found in the diet of sea lions and exhibit significant interannual and decadal variability in population abundances that reflect variations in their environment and lower trophic level prey. Output from a 20 yr run (1989-2008) of the model demonstrates how different physical and biological processes control habitat utilization and foraging success of California sea lions on interannual time scales, with the dominant modes of variability linked to sardine abundance and coastal upwelling intensity. The results also illustrate how variability in environmental conditions, forage fish distribution, and prey assemblage affect sea lion feeding success. While specifically focusing on the foraging ecology of sea lions, the modeling framework has the ability to provide a more complete understanding of the physical and biological mechanisms impacting trophic interactions in the California Current, or other regions where similar fully coupled ecosystem models may be implemented

Influence of hunting strategy on foraging efficiency in Galapagos sea lions

The endangered Galapagos sea lion (GSL, Zalophus wollebaeki) exhibits a range of foraging strategies utilising various dive types including benthic, epipelagic and mesopelagic dives. In the present study, potential prey captures (PPC), prey energy consumption and energy expenditure in lactating adult female GSLs (n = 9) were examined to determine their foraging efficiency relative to the foraging strategy used. Individuals displayed four dive types: (a) epipelagic (<100 m; EP); or (b) mesopelagic (>100 m; MP) with a characteristic V-shape or U-shape diving profile; and (c) shallow benthic (<100 m; SB) or (d) deep benthic (>100 m; DB) with square or flat-bottom dive profiles. These dive types varied in the number of PPC, assumed prey types, and the energy expended. Prey items and their energetic value were assumed from previous GSL diet studies in combination with common habitat and depth ranges of the prey. In comparison to pelagic dives occurring at similar depths, when diving benthically, GSLs had both higher prey energy consumption and foraging energy expenditure whereas PPC rate was lower. Foraging efficiency varied across dive types, with benthic dives being more profitable than pelagic dives. Three foraging trip strategies were identified and varied relative to prey energy consumed, energy expended, and dive behaviour. Foraging efficiency did not significantly vary among the foraging trip strategies suggesting that, while individuals may diverge into different foraging habitats, they are optimal within them. These findings indicate that these three strategies will have different sensitivities to habitat-specific fluctuations due to environmental change

Cover Image, Volume 176A, Number 5, May 2018

The cover image, by Paul Kruszka et al., is based on the Original Article Williams‐Beuren Syndrome in Diverse Populations, DOI: 10.1002/ajmg.a.3867