Spatially dynamic maternal control of migratory fish recruitment pulses triggered by shifting seasonal cues
Authored by Valery E Forbes, Martin J Hamel, Jeremy J Hammen, Matthew L Rugg, Mark A Pegg, Daisuke Goto
Date Published: 2018
DOI: 10.1071/mf17082
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Abstract
Environmental regimes set the timing and location of early life-history
events of migratory species with synchronised reproduction. However,
modified habitats in human-dominated landscapes may amplify uncertainty
in predicting recruitment pulses, impeding efforts to restore habitats
invaluable to endemic species. The present study assessed how
environmental and spawner influences modulate recruitment variability
and persistence of the Missouri River shovelnose sturgeon
(Scaphirhynchus platorynchus) under modified seasonal spawning and
nursery habitat conditions. Using a spatially explicit individual-based
biophysical model, spawning cycle, early life-history processes
(dispersal, energetics and survival) and prey production were simulated
under incrementally perturbed flow (from -10 to -30\%) and temperature
(+1 and +2 degrees C) regimes over 50 years. Simulated flow reduction
and warming synergistically contracted spring spawning habitats (by up
to 51\%) and periods (by 19\%). Under these conditions, fewer mature
females entered a reproductive cycle, and more females skipped spawning,
reducing spawning biomass by 20-50\%. Many spawners migrated further to
avoid increasingly unfavourable habitats, intensifying local density
dependence in larval stages and, in turn, increasing size-dependent
predation mortality. Diminished egg production (by 20-97\%) and weakened
recruitment pulses (by 46-95\%) ultimately reduced population size by
21-74\%. These simulations illustrate that environmentally amplified
maternal influences on early life histories can lower sturgeon
population stability and resilience to ever-increasing perturbations.
Tags
Agent-based model
Climate change
Spatially explicit model
Simulation-model
Climate-change
Life-history
Shovelnose sturgeon
Pallid sturgeon
Phenology
Marine populations
Acipenser-transmontanus
Fresh-water fish
Altered flow regimes
Endangered species
Missouri river