Data from: Quantifying the ecological role of crocodiles: A 50-year review of metabolic requirements and nutrient contributions in Northern Australia

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.