Associational defense reduces grazing and deforestation in a kelp forest ecosystem: implications for restoration

This repository supports a research project investigating whether the chemically and structurally defended brown alga Desmarestia herbacea can function as an associational defense to reduce sea urchin grazing on juvenile bull kelp (Nereocystis luetkeana). Using a combination of field surveys, field manipulations, and laboratory feeding assays, this project evaluates whether co-occurrence with Desmarestia can improve kelp survival and inform restoration strategies in urchin-dominated systems.

This repository contains the data and, if applicable, the code required to reproduce the results presented in the associated journal article:

Wiley, B. W., E. M. Carrasco, M. Sedeño, and P. E. Bourdeau. (2026) "Associational defense reduces grazing and deforestation in a kelp forest ecosystem: implications for restoration" Journal of Applied Ecology

All figures and tables in the paper should be reproducible by running the scripts provided in this repository.

• Data collected by: Brayden Wiley (Cal Poly Humboldt), in collaboration with the Cher-Ae Heights Indian Community of the Trinidad Rancheria and the Bourdeau Lab
• Date of data collection: [2024-05-10] to [2025-09-10], using the YYYY-MM-DD standard
• Geographic location: Nearshore kelp forests along the northern California coast, including sites near Trinidad (Humboldt County) and Van Damme State Beach (Mendocino County) CA, USA
• Data files:

Excel File RCode Description Format feedingassay2024.xlsx understory_feeding_assay.R Laboratory feeding assay data measuring sea urchin consumption rates across treatment types after 24 hrs .xlsx feeding_assay_2025.xlsx feedingassy2025szn.R Laboratory feeding assay data measuring sea urchin consumption rates across treatment types for 1 month .xlsx Des Master_s Field Expirement Summer 2024.xlsx Wiley_Summer_2024_December (2).R And GLMM_models_wileyfield2024.R Resultrs from in situ grazing experiments testing kelp survival over a 24 hr time frame with different barrieris .xlsx desmarestia_removal_exp_2025_thesis.xlsx densities2025_withfigure.R And

des_removal_exp2025.R Results from in situ grazing experiments testing kelp survival with and without Desmarestia .xlsx