Evidence map›Paper›PMID 41605549›Full record

ArticleEcological applications : a publication of the Ecological Society of America2026

Demography and dynamics of giant kelp cohorts across four decades: Lessons for conservation and resilience planning.

P Edward Parnell, Cleridy E Lennert-Cody, Lydia B Ladah, Kristin L Riser, Brenna Bulach, James J Leichter, Ami K Latker, Stephen C Schroeter, Paul K Dayton

Abstract read
PubMed Full text at PMC Publisher
In one paragraph

Article in Ecological applications : a publication of the Ecological Society of America, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 1 paper.

0numbers the graph read from it
0cells of the map it votes in
1citing papers in PubMed
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

1 citing paper in PubMed.

  1. Demography and dynamics of giant kelp cohorts across four decades: Lessons for conservation and resilience planning.Ecological applications : a publication of the Ecological Society of America · 2026
    Article
4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

9 authors.

P Edward ParnellIntegrative Oceanography Division, Scripps Institution of Oceanography, University of California, San Diego, San Diego, California, USA.
Cleridy E Lennert-CodyIntegrative Oceanography Division, Scripps Institution of Oceanography, University of California, San Diego, San Diego, California, USA.
Lydia B LadahIntegrative Oceanography Division, Scripps Institution of Oceanography, University of California, San Diego, San Diego, California, USA.
Kristin L RiserIntegrative Oceanography Division, Scripps Institution of Oceanography, University of California, San Diego, San Diego, California, USA.
Brenna BulachIntegrative Oceanography Division, Scripps Institution of Oceanography, University of California, San Diego, San Diego, California, USA.
James J LeichterIntegrative Oceanography Division, Scripps Institution of Oceanography, University of California, San Diego, San Diego, California, USA.
Ami K LatkerCity of San Diego Public Utilities Department, San Diego, California, USA.
Stephen C SchroeterUniversity of California Santa Barbara, Marine Science Institute, Santa Barbara, California, USA.
Paul K DaytonIntegrative Oceanography Division, Scripps Institution of Oceanography, University of California, San Diego, San Diego, California, USA.

Funding

California Sea Grant, University of California, San DiegoCity of San Diego, Public Works DepartmentNational Science Foundation
6 · The paper itself

Abstract

Kelp forests throughout many temperate zones are in decline due to various human stressors, chiefly marine warming. Conservation measures including restoration are presently of great interest and focus on both historical and novel methodologies. Of paramount importance for these efforts is an understanding of the mechanics of kelp decline to identify the factors and triggers leading to stepwise declines and thus support the development and spatial prioritization of strategic intervention to facilitate resilience. Here, we utilized a unique dataset documenting the demographic dynamics of giant kelp, Macrocystis pyrifera, in response to multiple disturbances across >40 years off San Diego (California, USA). The recruitment and life history of >14,000 individuals were used to evaluate cohort structure, size, and longevity forced by algal community structure and disturbance. Cohort dynamics varied spatially by depth and study subregion, thus aiding identification of areas to prioritize intervention to foster resilience. Five algal assemblages were characterized providing context for cohort dynamics in response to physical disturbances and sea urchin grazing. A trend of decreasing cohort size and resilience was observed over time accentuated by the marine heat wave of 2014-2015 (MHW) after which competition with understory canopies increasingly interfered with giant kelp cohort development and plant size structure. Cohort recruitment ranged on a continuum from discrete ("pulsed") to more gradual ("trickled") episodes. Pulsed cohorts mainly produced single cohort-dominated age stands punctuated by major disturbances. Pulsed events were more common than trickled recruitment, especially at deeper sites. Trickled cohorts resulted in relatively mixed age stands, especially when individual cohorts overlapped within sites. Trickled recruitment increased over time as understory dominance increased. Cohort longevity was highly variable among sites and among cohorts within a site, with high first-year mortality mostly due to warming, waves, or their combination. Longevity was inversely related to temperature and sea urchin density, and was greatest at deeper sites, especially after the MHW. The downward trend of single cohort dominance and individual plant size over time and its step downward after the MHW suggest that deeper areas should be prioritized for restoration. Regardless, understory canopies will increasingly dominate Southern California with continued warming.

Indexed as

Conservation of Natural ResourcesKelpMacrocystisAnimalsCaliforniaPopulation DynamicsSea Urchinsclimate changecohortconservationdemographykelplong‐term ecological researchMacrocystis pyriferamanagementmarine heat wavesmonitoringsea urchinssouthern Californiaunderstory

Identifiers

PMID41605549
PMCPMC12851851

What OpenQuestion holds

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LicenceCC BY
Read underepoch 390

Registered trials

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.