Data from: Quantifying the ecological role of crocodiles: A 50-year review of metabolic requirements and nutrient contributions in Northern Australia
Data files
Feb 11, 2025 version files 45.40 KB
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Crocodile_recovery_impacts_PRSB_2024_summary_bioenergetics.csv
41.49 KB
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README.md
3.91 KB
Abstract
The ecological roles of large predators are well recognised, but quantifying their functional impacts remains an active area of research. In this study, we examined the metabolic requirements and nutrient outputs of the estuarine crocodile population (Crocodylus porosus) in northern Australia over a 50-year period, during which the population increased from a few thousand to over 100,000 individuals. Bioenergetic modelling showed that during this period, the crocodile population’s annual prey consumption increased from < 20 kg km-2 in 1979 to ~180 kg km-2 in 2019. Further, the prey consumption increase was accompanied by a significant dietary shift from predominantly aquatic prey (~65% in 1979) to a terrestrial-based diet (~70% in 2019). A substantial portion of these terrestrial-derived nutrients was excreted into the water, significantly increasing the input rates of nitrogen (186-fold) and phosphorus (56-fold). The study shows that despite being ectothermic, the high biomass of crocodiles within the environment generated nutrient inputs comparable to terrestrial endothermic predator populations. Apex ectotherm predators are generally considered not to affect ecosystems in the same manner as endothermic predators. Still, in northern Australia’s oligotrophic freshwater environments, the high rates of prey consumption by dense crocodile populations are likely causing top-down and bottom-up effects.
https://doi.org/10.5061/dryad.3n5tb2rt9
Description of the data and file structure
GENERAL INFORMATION
1. Title of Dataset: Data supporting "Crocodile recovery impacts nutrient transfers in tropical freshwater ecosystems”.
2. Corresponding Author Information: This information has been removed for the manuscript review to comply with the Journal's double anonymous peer review standard.
3. Date of data collection (single date, range, approximate date): 1971-2022
4. Geographic location of data collection: North-western areas of the Northern Territory, Australia.
5. Information about funding sources that supported the data collection: This information has been removed for the manuscript review to comply with the Journal's double anonymous peer review standard.
SHARING/ACCESS INFORMATION
1. Licenses/restrictions placed on the data: None
2. Links to publications that cite or use the data: NA
3. Links to other publicly accessible locations of the data: NA
4. Links/relationships to ancillary data sets: NA
5. Was data derived from another source? Yes
A. If yes, list source(s): Crocodile survey data belongs to the Northern Territory Government (Department of Environment, Parks and Water Security.
6. Recommended citation for this dataset: This information has been removed for the manuscript review to comply with the Journal's double anonymous peer review standard.
DATA & FILE OVERVIEW
1. File List:
File 1: Tabular data [Crocodile recovery impacts_PRSB_2024_summary_bioenergetics.csv]
File 2: R script [Crocodile recovery impacts_PRSB_2024_summary_bioenergetics.R]
2. Relationship between files, if important: NA
3. Additional related data collected that was not included in the current data package:
Other data sets used in the study (as per R code):
A. DOI 10.1007/s00360-012-0732-1 (Table 1)
B. DOI 10.1126/science.1162302 (Supplementary Material)
C. DOI 10.1098/rsbl.2021.0676
D. DOI 10.1371/journal.pone.0200983
4. Are there multiple versions of the dataset? No
DATA-SPECIFIC INFORMATION FOR: [Crocodile recovery impacts_PRSB_2024_summary_bioenergetics.csv]
1. Number of variables: 6
2. Number of cases/rows: 681
3. Variable List:
Mean variables were modelled per km of river per year surveyed. Values are mean from 10000 replicates of the bioenergetics model per crocodile size class per year.
NA denotes missing values and represents size classes not detected by the crocodile survey in that respective year.
- Year: Year (correspondent to NT crocodile survey conducted by the NT Government)
- size_class: crocodile size class in meters
- mean.ingested.kg.km.year: mean modelled protein ingested by crocodiles (kg/km/year).
- mean.biomass.km.year: mean modelled crocodile biomass (kg/km/year).
- mean.indiv_MR.km.year: mean modelled crocodile metabolic rate (MR: ml/min).
- mean.growth_MR.km.year: mean modelled crocodile growth metabolic rate (MR: ml/min).
- mean.maint_MR.km.year: mean modelled crocodile maintenance metabolic rate (MR: ml/min).
4. Missing data codes: NA
5. Specialised formats or other abbreviations used: NA
Code/Software
DATA-SPECIFIC INFORMATION FOR: [Crocodile recovery impacts_PRSB_2024_summary_bioenergetics.R]
File 2 Description: This R script was used to analyse the data for the manuscript "Quantifying the ecological role of crocodiles: A 50-year review of metabolic requirements and nutrient contributions in northern Australia", published in the Proceedings of the Royal Society B. This R script includes data preprocessing and statistical analyses. The required packages are listed in the script. The file was designed for R version 4.2.0 or later.
Analysis was conducted in R 4.2.0