Data for: Global Thresholds in properties emerging from Cumulative Curves of Marine Ecosystems

Published: 22 April 2019| Version 1 | DOI: 10.17632/mrg6j4nbf9.1
Contributor:
simone libralato

Description

This dataset contains the curve parameters estimated from the Cum-B curve of landings time series. We used landings data for 62 Large Marine Ecosystems (LMEs) obtained from the Sea Around Us Project (SAUP) database (http://www.seaaroundus.org/). Each taxa was associated with a trophic level (TL) as obtained from Fishbase (www.fishbase.org) and Sealifebase (www.sealifebase.org); for a few species, TL were assigned according to literature and available ecosystem model oputputs (Stergiou and Karpouzi, 2002). Landings by TL were than determined for each LME. The catch data for each LME and each year were ordered by increasing TL and a cumulative curve of catches vs TL was generated (i.e. the cumB-TL curve, c.f. Link et al., 2015). The cumB vs TL data resemble a S-shape curve, consistent with prior theory and observations (Pranovi et al., 2014; Link et al., 2015). For each LME and each year the data were fit independently to an S-shaped curve using a 5-parameter logistic nonlinear regression model(Ricketts and Head, 1999), i.e., using the ‘drc’ package (Ritz et al., 2015) for R (v3.5.2; R Core Team 2018). The main curve parameters (see Figure 1), i.e., the steepness (Steep), TL Inflection point (TL_Infl), and the Biomass at inflection (B_Infl) were estimated through a fitting process. This was executed on an annual basis for each LME, resulting in 3782 (61 years x 62 LMEs) fitted curves each represented by the values of the three estimated parameters (Steep, TL_Infl, B_infl). More details on the method for fitting and estimating the parameters can be found in another paper (c.f. Pranovi et al. 2014; Pranovi unpubl. data). See maintext of the paper: "Global Thresholds in properties emerging from Cumulative Curves of Marine Ecosystems"

Files

Categories

Ecosystem Change, Curve Modeling

License