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Ecological Intelligence

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Ecological Intelligence / Subject

Food webs

Peer-reviewed Transregional

Arid streams in a rainfall gradient produced more secondary biomass than wetter ones

Evidence
Peer-reviewed
Geography
Nine rivers across a natural precipitation gradient
System
Freshwater food webs; riverine secondary production

WHAT THE EVIDENCE SAYS

Across nine rivers over three years, researchers compared invertebrate and vertebrate secondary production. Wetter streams had food-web energy concentrated in detritivorous invertebrates; arid streams showed more vertebrate herbivory and approximately twice the secondary production and biomass turnover.

WHY IT MATTERS / OUR READ

A changing rainfall regime can reorganize an aquatic food web even when the river still appears to flow; production depends on which trophic pathways carry energy.

CAVEATS / UNCERTAINTY

Site contrasts along a rainfall gradient are not a controlled climate-change experiment; geology, productivity and local biota may also differ. Reported production ratios are context-bound.

SOURCE

Ecology — primary comparative multi-river study
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Nine rivers tracked for three years shifted from detritivore-heavy food webs in wetter settings toward vertebrate herbivory in drier settings.

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Peer-reviewed Antarctic

Antarctic amphipods clustered where ocean currents met near Elephant Island

Evidence
Peer-reviewed
Geography
South Shetland Islands and Elephant Island, Southern Ocean
System
Pelagic food webs; polar currents and zooplankton

WHAT THE EVIDENCE SAYS

Researchers examined 75 stations sampled during the 2018 Polarstern PS112 expedition and recorded 1,347 Themisto gaudichaudii. Abundance peaked near Elephant Island under the Antarctic Circumpolar Current's influence; the sample was juvenile-heavy, and body length was related to chlorophyll a but not significantly to temperature or salinity in the sampled range.

WHY IT MATTERS / OUR READ

Monitoring alternative prey in changing polar food webs needs attention to water masses, timing and life stages as well as species presence.

CAVEATS / UNCERTAINTY

These samples were from one March–May 2018 expedition, not a trend in abundance through 2026. No krill replacement or predator dietary switch was established.

SOURCE

Polar Biology — primary expedition-based field study
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A newly published analysis of 2018 sampling found concentrated Themisto amphipods in warmer current-influenced waters, with many juveniles.

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Peer-reviewed Europe

Large pike connected littoral and pelagic food webs by changing diets through life

Evidence
Peer-reviewed
Geography
Lake Bourget, France
System
Large lake littoral and pelagic food webs

WHAT THE EVIDENCE SAYS

Sequential stable-isotope measurements from eye lenses of 17 large pike reconstructed lifetime resource use. Every fish showed a major littoral-to-pelagic dietary shift, but the timing and extent differed among individuals; median lifetime littoral reliance was 52.5%.

WHY IT MATTERS / OUR READ

Food-web coupling can be generated by ontogeny rather than by a species occupying the same trophic role throughout life. Population models that average individuals may hide when and how top predators move energy between habitats.

CAVEATS / UNCERTAINTY

The study is retrospective and based on 17 large pike from one lake. Eye-lens isotope trajectories infer resource pathways rather than directly tracking movement, and results should not be generalized to all pike populations or lake types.

SOURCE

Freshwater Biology
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EvidencePeer-reviewedGeographyLake Bourget, FranceSystemLarge lake littoral and pelagic food webs WHAT THE EVIDENCE SAYS Sequential stable-isotope measurements from eye lenses of 17 large pike reconstructed lifetime resource use. Every

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Peer-reviewed Global

Coastal browning changed plankton succession, then grazing erased much of the early signal

Evidence
Peer-reviewed
Geography
Controlled coastal mesocosm experiment
System
Coastal plankton food web

WHAT THE EVIDENCE SAYS

A 22-day mesocosm experiment manipulating colored dissolved organic matter and iron availability initially increased small phytoplankton despite lower light, but later treatment differences weakened after phytoplankton and microzooplankton declined under mesozooplankton grazing.

WHY IT MATTERS / OUR READ

Browning and micronutrient chemistry can alter early plankton succession without determining the final community trajectory; food-web interactions can override a strong bottom-up signal.

CAVEATS / UNCERTAINTY

This was a short controlled mesocosm experiment. The treatment chemistry simplifies natural catchment inputs, and the inferred food-web mechanism needs field validation across seasons and coastal systems.

SOURCE

Microbial Ecology
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EvidencePeer-reviewedGeographyControlled coastal mesocosm experimentSystemCoastal plankton food web WHAT THE EVIDENCE SAYS A 22-day mesocosm experiment manipulating colored dissolved organic matter and iron availability initially increased small phytoplankton despite

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