DOI: 10.5061/dryad.kprr4xhhn
title: Warming strengthens food web effects of predator phenotypic variation

description: Intraspecific variation modifies ecological processes and ecosystem
 functioning. Still, we know relatively little of how the nature and
 strength of ecosystem effects caused by intraspecific variation may
 interact with climate change. We conducted a mesocosm experiment to test
 if, and to what extent, ocean warming modifies the ecological impacts of
 intraspecific variation in a predatory fish. The mesocosms consisted of a
 simplified coastal food web with threespine stickleback (Gasterosteus
 aculeatus) as the top predator, from a population where two stickleback
 phenotypes with either complete or incomplete lateral armour plating
 coexist and display differentiated predation behavior: The completely
 plated phenotype often feeds more on invertebrate herbivores compared to
 the incompletely plated phenotype. Presence of stickleback reduced biomass
 of arthropod shredders (crustaceans, insect larvae). Warming (+4 °C)
 strengthened this predation, releasing benthic primary producers (diatoms)
 from top-down control, causing a trophic cascade. This trophic cascade was
 attributed to one of the plate phenotypes: the completely plated
 stickleback increased their predation on shredders under warming, while
 the incompletely plated stickleback instead decreased their predation.
 Diatom biomass responded accordingly: warming increased diatom biomass in
 the presence of completely plated stickleback but not when incompletely
 plated stickleback were present. Our results suggest that different plate
 phenotypes of threespine stickleback differentially affect lower trophic
 levels, and that warming may exacerbate these cascading effects. These
 trait-dependent effects on trophic cascades highlight the consequences of
 intraspecific variation on ecosystem functioning.
description: # Warming strengthens food web effects of predator phenotypic variation
 Dataset DOI: https://doi.org/10.5061/dryad.kprr4xhhn
 Salo_et_al_predation.csv Salo_et_al_plate_phenotypes.csv
 Salo_et_al_stomach_contents.csv Contact information:
 [tiina.salo@helsinki.fi](mailto:tiina.salo@helsinki.fi) Data for
 Salo_et_al_predation.csv include: temperature: temperature treatment in
 the study (ambient, high) predation: presence or absence of top predators
 in the mesocosm (fish, no fish) plate_phenotypes: three-spine stickleback
 plate phenotype (completely plated, incompletely plated, both, no_fish)
 waterbath: waterbath id for nested analyses shredder_biomass: the biomass
 (g dw) of shredders in the mesocosm shredder_survival: the survival of
 shredders in the mesocosm shredder_recruitment: the recruitment of
 shredders to the mesocosm gastropod_biomass: the biomass (g dw) of
 gastropods in the mesocosm theodoxus_eggs: the biomass (g dw) of Theodoxus
 fluviatilis eggs in the mesocosm diatom_biomass: the biomass (g dw) of
 diatoms in the mesocosm epiphyte_biomass: the biomass (g dw) epiphytic
 macroalgae in the mesocosm turbidity: turbidity in the mesocosm Data for
 Salo_et_al_plate_phenotypes.csv include: temperature: temperature
 treatment in the study (ambient, high) plate_phenotypes: three-spine
 stickleback plate phenotype (completely plated, incompletely plated, both,
 none) waterbath: waterbath id for nested analyses shredder_biomass: the
 biomass (g dw) of shredders in the mesocosm shredder_survival: the
 survival of shredders in the mesocosm shredder_recruitment: the
 recruitment of shredders to the mesocosm gastropod_biomass: the biomass (g
 dw) of gastropods in the mesocosm theodoxus_eggs: the biomass (g dw) of
 Theodoxus fluviatilis eggs in the mesocosm diatom_biomass: the biomass (g
 dw) of diatoms in the mesocosm epiphyte_biomass: the biomass (g dw)
 epiphytic macroalgae in the mesocosm turbidity: turbidity in the mesocosm
 Data for Salo_et_al_stomach contents.csv include: temperature: temperature
 treatment in the study (ambient, high) phenotype_teatment: three-spine
 stickleback plate phenotypes in the mesocosm (completely plated,
 incompletely plated, both) plate_phenotype: plate phenotype of the fish
 (completely plated, incompletely plated) mesocosm_code: mesocosm id for
 any nasted analyses waterbath: waterbath id for any nested analyses
 shredders: biomass (g dw) of shredders in the stomach