DOI: 10.5061/dryad.44j0zpcsb
title: Data from: A path towards appropriate degradation experiments for assessing carbon sequestration potential of macroalgae

description: The biodiversity and climate crises have increased the urgency to
 understand turnover rates and drivers of marine carbon sequestration.
 Efforts have concentrated on measuring degradation of macroalgae, to
 quantify how much of their carbon might be sequestered. We systematically
 reviewed literature on macroalgal degradation, compiling 364 measurements
 of exponential decay constant k. To date, most degradation
 experiments (1) are carried out in aquaria or shallow environments, (2)
 span short timescales, (3) use dried or frozen material, or (4) rarely
 incorporate environmental gradients driving degradation. Decay constants
 were higher in intertidal vs. subtidal habitats, for pre-treated algal
 tissue compared to fresh, and when refractory material was present rather
 than absent. These patterns have implications for estimates of export
 efficiency of macroalgal carbon to the deep ocean. Synthesis: We
 recommend that future studies of macroalgal degradation (1) adopt
 standardized approaches, such as using fresh material and litter bag mesh
 size of 10mm, to make studies more comparative, (2) measure degradation
 with sufficient frequency to robustly estimate decay constants and/or
 refractory material, and (3) incorporate environmental gradients,
 including depth, light and oxygen availability, to improve estimates of
 macroalgal carbon remineralisation rates during transport to deeper
 water. 
description: # Data from: A path towards appropriate degradation experiments for
 assessing carbon sequestration potential of macroalgae Dataset DOI:
 [10.5061/dryad.44j0zpcsb](10.5061/dryad.44j0zpcsb) ## Description of the
 data and file structure 49 variables were extracted from 71 peer reviewed
 studies, either directly from text and tables or from figures using
 metadigitise in R. This dataset is used to perform analyses and generate
 all output such as summaries and visualizations in the accompanying R
 scripts and manuscript.  The files representing the entry point for the
 data extraction process (figures and excel files from published papers)
 are not included here, due to potential copywright infringement.  The
 scripts used to extract data, however, are included for reference in R
 scripts 1-3, with a detailed description of the extraction process.  ###
 Files and variables #### File: degredation_database_white_2025.xls
 **Description:** This file has 5 sheets:  *database* - All the records
 found to be relevant for the study following systematic review of the
 literature, includes 71 peer reviewed studies and 49 variables extracted
 from each study *database_variables* - Description of each of the variable
 listed within the database  *search_terms* - Search terms used in Web of
 Science (WOS) *WOS_savedrecs* - List of records exported from WOS
 following literature search  *final_records_following_review* - List of
 relevant records included within the study following evaluation #####
 Variables * 49 different variables are explained and described in
 the *database_variables* sheet  #### File: degradation_meta-main.zip
 **Description:**  Scripts containing details on data extraction, data
 processing, model fitting, analysis and figures  ## Code/software Data
 extraction, analysis, and figures were made using R (version 4.5.0).  The
 project contains 7 scripts located in the `script` directory in
 degradation_meta-main.zip : `1_dataextract_functions.R` includes functions
 to fit single phase exponential decay curve models to each data set of
 biomass or carbon loss over time, separate functions fit models with and
 without a refractory term, and use a range of starting values or
 self-starting functions. `2_dataextract_k.R` collates all published data
 on macroalgal degradation rates, explains how datasets were extracted from
 figures downloaded from published articles using metaDigitise and fits
 single phase exponential decay curve models to each dataset
 `3_dataextract_temperature.R` collates published data on temperature,
 light and oxygen from degradation experiments when averages were not
 reported in the study `4_analysis_upsetplot.R` synthesises data at the
 study and experiment level, summarising experiment duration, depth,
 sampling frequency, habitat etc and creates figure 3
 `5_analysis_k_exploration.R` explores how degradation constant k varies
 with different biological, environmental and experimental variables
 `6_analysis_k_exploration_browns.R` explores how degradation constant k of
 brown forest forming macroalgae varies with different biological,
 environmental and experimental variables, and sensitivity of carbon export
 models to k and created figure 4
 `7_supplementary_temperature_k_regressions.R` explores how degradation
 constant k varies with temperature and latitude and creates figure S2 and
 S3 in supplementary info ## Access information Data was derived from the
 following sources: * List of 71 published records included within the
 study following systematic evaluation are included in the data files, see
 sheet *final_records_following_review*