DOI: 10.5061/dryad.wpzgmsc0w
title: Pathways of blue carbon export from kelp and seagrass beds along the Atlantic coast of Nova Scotia

description: 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.
description: # Pathways of blue carbon export from kelp and seagrass beds along the
 Atlantic coast of Nova Scotia Dataset DOI:
 [10.5061/dryad.wpzgmsc0w](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 * 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. * 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/](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.