Non-trophic interactions amplify kelp harvest-induced biomass oscillations and biomass changes in a kelp forest ecological network model
Cite this dataset
Perala, Tommi; Pesari, Susanna (2023). Non-trophic interactions amplify kelp harvest-induced biomass oscillations and biomass changes in a kelp forest ecological network model [Dataset]. Dryad. https://doi.org/10.5061/dryad.dv41ns23c
Abstract
Kelp forests are important marine ecosystems providing habitat for numerous species. Despite over 50 years of mechanical harvesting in the Northeast Atlantic, the indirect impacts of kelp harvesting and associated habitat loss on faunal species within kelp forests remain poorly understood. We investigated the consequences of kelp harvesting by developing an allometric trophic network model for a subtidal Northeast Atlantic kelp forest (dominated by Laminaria hyperborea). Additionally, we designed a novel mechanistic model to explore the non-trophic interactions between kelp and age class 0 Atlantic cod (Gadus morhua) and kelp and European lobster (Homarus gammarus), specifically focusing on the increased survival benefits provided by the kelp habitat. Simulations were conducted over a 50-year period, incorporating harvesting cycles of 2, 5, and 9 years, as well as low and high harvesting intensities. Our findings reveal the complex dynamics resulting from kelp harvesting. The recovery of kelp biomass was observed with 5- and 9-year harvesting cycles, whereas a decline was observed with a 2-year cycle. Furthermore, the non-trophic interaction facilitated a higher pre-harvest biomass for both the European lobster and the Atlantic cod compared to scenarios without this interaction. These results highlight the multitrophic effects of kelp harvesting and emphasize that the recovery of kelp-associated species may not necessarily align with kelp recovery, depending on harvesting intensity and recovery periods. Importantly, our study contributes to a better understanding of the ecological consequences of kelp harvesting and underscores the need for sustainable management practices to mitigate habitat loss in kelp ecosystems.
README: Perälä et al. (2023) Non-trophic interactions amplify kelp harvest-induced biomass oscillations and biomass changes in a kelp forest food web model
Authors and correspondence:
Tommi Perälä, tommi.a.perala@jyu.fi, https://orcid.org/0000-0002-4995-5997
Susanna Pesari, susannapesari@hotmail.com
Contents:
Data:
Simulation outputs
Software:
Simulator software and codes for running the simulations and producing the figures in the manuscript.
Data
This section consists of the following files and directories
"README.md" - This readme file
"Results.mat" - MATLAB formatted binary file containing simulation outputs and input variables
In MATLAB, Results.mat can be loaded using the load command. In R, loading of a mat-file is done using the readMat function from the R.matlab package.
The Results.mat file contains the following variables:
Name Size Bytes Class
Data 1x1 385678 struct
DefaultOptions 1x1 5280 struct
OPTIONS 1x8 9008 struct
RESULTS 1x8 712764288 struct
Data is a structure array containing the necessary input information about the species and their interactions in the food web.
"Data"
"B0" - Half-saturation density parameters of the functional response [mugC/m3]
"d" - Intraspecific consumer interference parameters of the functional response [m3/mugC]
"y" - Maximum consumption rate scaling factor parameters
"q" - Hill's exponent parameters of the functional response
"e" - Assimilation efficiency parameters
"Guilds" - 1x123 Structure array containing guild specific information with fields:
"label" - Guild label
"name" - Guild name
"type" - Guild type (Detritus/Producer/Consumer/Fish/Kelp)
"igr" - Intrisict growth rate 1/day
"mbr" - Mass-specific metabolic rate 1/day
"binit" - Initial biomass [mugC/m3]
"age" - Age of fish age class
"f_m" - Maintenance respiration coefficient
"c" - Intraspecific producer competition coefficient
"s" - Fraction of exudation (Producers only)
"diss_rate" - Dissolution rate of POC to DOC [1/day]
"f_a" - Activity respiration coefficient (Consumers and Fish only)
"invest" - Strength of reproductive investment (Fish only)
"Pmat" - Proportion of mature biomass (Fish only)
"bodymass" - Individual body mass mugC/individual
"lambda" - Kelp utilization multiplier (Kelp habitat users only)
"adjacencyMatrix" - Food web link structure
"DefaultOptions" structure array contains the default options for the simulation that are overwritten by the scenario-specific options when needed. Contains the following nested structure
"DefaultOptions"
"Model" - Submodel options
"Kelp" - Kelp habitat effect and harvest model options
"alpha" - Kelp habitat user transfer rate to kelp habitat
"Harvest" - Kelp harvest model options
"cycle" - Length of the kelp harvest cycle [year]
"rate" - Kelp harvest rate [1/year]
"Simulation" - Simulation options
"nGrowthDays" - Number of days in a growth season [day]
"periodHarvestingL" - Length of the harvesting period [year]
"periodRecoveryL" - Length of the recovery period after harvesting [year]
"burninL" - Length of the burn in period [year]
"startHarvest" - The start year of harvesting
"endHarvest" - The end year of harvesting
"nYears" - Total number of years in the simulation [year]
"OPTIONS" is a 18 cell array containing the name of the scenario and the scenario-specific options in structure arrays for each of the 8 different scenarios (see "DefaultOptions" above).
"RESULTS" is a 1x8 struct array containing the simulation outputs for each of the 8 different scenarios specified in the OPTIONS cell array of structure arrays.
RESULTS =
18 struct array with fields:
"B" - Biomasses at the end of each simulation year [mugC/m3]
"allbiomasses" - Biomasses at the end of each simulation day [mugC/m3]
"GF" - Reproductive output of each fish guild for each simulation year [mugC/m3]
Code/Software
This section consists of the zip-file called Perala_et_al_2023_MarEcolProgSer.zip containing the simulator software. The contents of the zip-file are:
"atnODE.m" - Gradient function of the model describing the dynamics during the growth season
"compileOdeData.m" - Utility function for optimizing the model for the ODE solver
"Figure2.m" - Generate Figure 2 of the manuscript
"Figure3.m" - Generate Figure 3 of the manuscript
"Figure4.m" - Generate Figure 4 of the manuscript
"Figure5.m" - Generate Figure 5 of the manuscript
"KelpForest.mat" - MATLAB formatted binary file containing the simulation input variable "Data" as described above
"main.m" - Runs simulations, plots figures and creates tables
"parseOptions.m" - Overwrites defaultOptions with scenario specific options
"reproductionAndAging.m" - Age class transfer and reproduction of fish species
"setScenarioOptions.m" - Specifies scenario-specific options
"Table2.m" - Generates Table 2 of the manuscript
"updateGuildInfo.m" - Utility function for indexing and size information of matrices
"webDriver.m" - Main simulation script
Funding
Academy of Finland, Award: 317495
Academy of Finland, Award: 350392
European Research Council, Award: 770884
Emil Aaltosen Säätiö