Description Usage Arguments Details Value Author(s) References See Also Examples
View source: R/meanTLCommunity.R
This function calculates the Mean Trophic Level of the community weighted by biomass for j areas and i years.
meanTLCommunity(X, TL.table, metric = "BIOMASS", years)
A dataframe of fishery independent data derived from research vessel
survey data or model output, with columns
A dataframe with columns
A character string indicating which column in
A vector of years for which to calculate indicator.
Mean trophic level (TL):
TL = Σ (TL_i*B_i)/Σ B_i
TL_i is trophic level of species i, and B_i is the biomass of species i.
This indicator is based on trophic levels of all species with available biomass time series, weighted by annual species-specific biomass, to reflect the structure of the community (Christensen, 1998).
Returns a dataframe with 3 columns.
If there is no data for spatial scale j in year i, indicator
value is assigned
Danielle Dempsey Danielle.Dempsey@dfo-mpo.gc.ca, Adam Cook, Catalina Gomez, Alida Bundy
Bundy A, Gomez C, Cook AM. 2017. Guidance framework for the selection and evaluation of ecological indicators. Can. Tech. Rep. Fish. Aquat. Sci. 3232: xii + 212 p.
Christensen V. 1998. Fishery-induced changes in a marine ecosystem: insight from models of the Gulf of Thailand. J. Fish Bio. 53:128-142. Article No. jb980809
Shannon L, Coll M, Bundy A, Gascuel D, Heymans JJ, Kleisner K, Lynam CP, Piroddi C, Tam J, Travers-Trolet M, Shin Y. 2014. Trophic level-based indicators to track fishing impacts across marine ecosystems. Mar. Ecol. Prog. Ser. 512, 115–140.
Other ecosystem structure and function indicators:
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# Compile data data(X) data(species.info) # Calculate indicator meanTLCommunity(X, TL.table = species.info, metric = "BIOMASS", years = c(2014:2019))
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