Sea‐ice loss boosts visual search: fish foraging and changing pelagic interactions in polar oceans

Light is a central driver of biological processes and systems. Receding sea ice changes the lightscape of high‐latitude oceans and more light will penetrate into the sea. This affects bottom‐up control through primary productivity and top‐down control through vision‐based foraging. We model effects...

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Bibliographic Details
Published in:Global change biology 2017-12, Vol.23 (12), p.5318-5330
Main Authors: Langbehn, Tom J., Varpe, Øystein
Format: Article
Language:English
Subjects:
Ablation
Animals
Aquatic ecosystems
Arctic Regions
Biogeography
Biological activity
Capacity
Climate
Control
Detection
Ecology
Ecosystem
Ecosystems
Environmental changes
Feeding Behavior
Fish
Fishes - physiology
Forage
Foraging
Ice Cover
Interactions
Interspecific relationships
Lakes
Latitude
Light
Mathematical models
Migratory species
Models, Biological
Oceans
Oceans and Seas
photoperiod
Photoperiods
Polar environments
Predator prey relations
Predator-prey interactions
Predators
predator–prey interaction
Predictive control
Prey
Primary production
Range extension
range shift
Sea ice
Searching
Seasonal variations
Seasonality
Shading
Sunlight
tipping points
visual ecology
Visual perception
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Summary:Light is a central driver of biological processes and systems. Receding sea ice changes the lightscape of high‐latitude oceans and more light will penetrate into the sea. This affects bottom‐up control through primary productivity and top‐down control through vision‐based foraging. We model effects of sea‐ice shading on visual search to develop a mechanistic understanding of how climate‐driven sea‐ice retreat affects predator–prey interactions. We adapt a prey encounter model for ice‐covered waters, where prey‐detection performance of planktivorous fish depends on the light cycle. We use hindcast sea‐ice concentrations (past 35 years) and compare with a future no‐ice scenario to project visual range along two south–north transects with different sea‐ice distributions and seasonality, one through the Bering Sea and one through the Barents Sea. The transect approach captures the transition from sub‐Arctic to Arctic ecosystems and allows for comparison of latitudinal differences between longitudes. We find that past sea‐ice retreat has increased visual search at a rate of 2.7% to 4.2% per decade from the long‐term mean; and for high latitudes, we predict a 16‐fold increase in clearance rate. Top‐down control is therefore predicted to intensify. Ecological and evolutionary consequences for polar marine communities and energy flows would follow, possibly also as tipping points and regime shifts. We expect species distributions to track the receding ice‐edge, and in particular expect species with large migratory capacity to make foraging forays into high‐latitude oceans. However, the extreme seasonality in photoperiod of high‐latitude oceans may counteract such shifts and rather act as a zoogeographical filter limiting poleward range expansion. The provided mechanistic insights are relevant for pelagic ecosystems globally, including lakes where shifted distributions are seldom possible but where predator–prey consequences would be much related. As part of the discussion on photoperiodic implications for high‐latitude range shifts, we provide a short review of studies linking physical drivers to latitudinal extent. We explore how climate‐driven sea‐ice decline restructures visual search, and thereby predator–prey interactions and distribution of pelagic fish, in a future Arctic Ocean. Less sea ice means increased light, which results in a nonlinear change of visual predation performance. We find that earlier melt dates and longer ice‐free periods during summer mo
ISSN:1354-1013
1365-2486
DOI:10.1111/gcb.13797