Pathways of blue carbon export from kelp and seagrass beds along the Atlantic coast of Nova Scotia
Data files
Jun 16, 2025 version files 27.94 GB
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Krumhansl_etal_DOC_sumulation_outputs_code.zip
20.08 GB
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Krumhansl_etal_POC_simulation_outputs_code.zip
7.86 GB
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README.md
5.08 KB
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Shelfbreak.mat
3.87 KB
Abstract
Coastal vegetated ecosystems are recognized for their role in cycling and storing carbon in the world’s oceans (i.e., blue carbon); however, high uncertainty in carbon sequestration rates are driven in part by an absence of studies directly estimating carbon export to the deep sea. We modeled export from nearshore kelp forests and seagrass beds, showing that export varies by orders of magnitude across spatial scales (5 – 100s km), kelp and seagrass species, seasons, and forms of carbon, raising caution in using generalized export rates in blue carbon accounting. Our results are also the first to show rapid (within 20-30 days) and extensive export of neutrally buoyant dissolved organic carbon to the shelf break (up to 44% within 90 days), contrasting sinking particulate organic carbon particles that remained within 100 m water depth in the near shore. These results improve estimates of carbon sequestration by nearshore vegetated ecosystems and reveal contrasting patterns of export relative to other regions of the globe.
Dataset DOI: 10.5061/dryad.wpzgmsc0w
Description of the data and file structure
Files are particle positions during dispersal from Lagrangian Particle Track Modelling of carbon particles released from kelp forests and seagrass beds on the Atlantic Coast of Nova Scotia, Canada.
Files and variables
File: Krumhansl_etal_POC_simulation_outputs_code.zip
Description: Simulation outputs from modeling experiments of kelp and seagrass particulate organic carbon (POC) dispersal.
File: Krumhansl_etal_DOC_sumulation_outputs_code.zip
Description: Simulation outputs from modelling experiments of kelp and seagrass dissolved organic carbon (DOC) dispersal
File naming convention and data description
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Names of files show Genus_species_carbontype_subregion_season_duration_variable.txt
Genus_species: Kelps: Laminaria digitata, Saccharina latissima; seagrass: Zostera marina
Carbon type: Particulate Organic Carbon (POC) or Dissolved Organic Carbon (DOC)
Subregion: Particles were released from eastern and western subregions, defined in Krumhansl et al.
Season: Winter, Spring, Summer, Fall - release dates and times in Krumhansl et al.
Duration: In days
Variable: Latitude (lat), Longitude (lon), and depth (z) of particles along their dispersal trajectory.
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Rows are particles, columns are time steps. Each time step for the model output is 3600 seconds.
Model description and simulation details are in Krumhansl et al.
Code/software
MATLAB files used to process output files are included in the publication. DOC files are processed using the same code from kelp and seagrass species, and POC files are processed using different codes for each species group. MATLAB R2020a was used for processing with no additional toolboxes.
File: dist_from_shelf.m
The file is code for a function used to calculate the distance of particles from the shelf break, defined with a data file showing the position of the shelf break (Shelfbreak.mat) encompassing the Scotian Shelf only. This code is a modification of the dist_from_coast.m function written by Dan Chavas at Princeton University (http://www.princeton.edu/~dchavas/). Further authorship details of the original function are included in the .m file (present in https://doi.org/10.5281/zenodo.15657822). Shelfbreak.mat contains 2 columns of data, Latitude and Longitude. Each point in this data file represents a position along the Scotian Shelf Break.
File: DOC_processing.m (located in Krumhansl_etal_DOC_sumulation_outputs_code.zip)
The file is used to process output files from simulations of the dispersal of DOC released from kelp and seagrass beds. This includes loading in output files, calculating the distance of each particle from the shelf break using the dist_from_shelf function (defined above), and plotting the number of particles at the shelf break for each day of the simulation. Note, to reproduce the analysis, users need to read in the provided .txt files instead of running the .nc loading and cleaning steps. This can be done after the code lines annotated %write variables into .txt files.
File: KelpPOC_processing.m (located in Krumhansl_etal_POC_simulation_outputs_code.zip)
The file is used to process output files from simulations of the dispersal of POC released from kelp beds. The code demonstrates how simulations were read in and cleaned. The file also calculates degradation times of particles based on temperature-dependent decay rates in the literature, plots the temperatures experienced by particles along their tracks, corrects particle tracks to stop where bottom velocities are below a specific threshold, freezes particles when they reach the model boundaries, and plots final particle positions and depth distributions. Note, to reproduce the analysis, users need to read in the provided .txt files instead of running the .nc loading and cleaning steps. This can be done after the code lines annotated %write variables into .txt files.
File: ZosteraPOC_processing.m (located in Krumhansl_etal_POC_simulation_outputs_code.zip)
The file is used to process output files from simulations of the dispersal of POC released from seagrass beds. The code demonstrates how floating and sinking simulations were combined and cleaned. The file also calculates degradation times of particles based on temperature-dependent decay rates in the literature, plots the temperatures experienced by particles along their tracks, corrects particle tracks to stop where bottom velocities are below a specific threshold, freezes particles when they reach the model boundaries, and plots final particle positions and depth distributions. Note, to reproduce the analysis, users need to read in the provided .txt files instead of running the .nc loading and cleaning steps. This can be done after the code lines annotated %write variables into .txt files.