Prey amino acid composition affects rates of protein synthesis and N wastage of a freshwater carnivore Academic Article uri icon

abstract

  • Humans modify prey communities and hence alter the availability of nutrients to wild carnivores. Such changes in amino acid ‘landscapes’ are likely to affect the growth of individuals, and potentially the success of populations. This study aimed to determine whether amino acid composition of animal prey alone affects protein synthesis efficiency and N wastage of a freshwater carnivore. River blackfish (Gadopsis marmoratus) were fed two diets differing only in amino acid composition: the first diet was formulated to match the composition of the fish themselves, representing a balanced ‘ideal protein’, whereas the second diet was produced to match the composition of a prey item, namely the shrimp Macrobrachium australiense. By measuring the postprandial increase in metabolic rate (specific dynamic action) and ammonia excretion, it was found that the amino acid composition of the fish diet was associated with an increase in protein synthesis, whereas the shrimp diet doubled the amount of dietary amino acids directed to pathways of catabolic energy production and N wastage. This study adds to the stoichiometric ecology literature by showing that changes in the amino acid composition of food webs could affect carnivore growth and nutrient cycling.

publication date

  • 2019