Fish diet composition in floodplain lagoons of an Australian dryland river in relation to an extended dry period following flooding

• Published in: Environmental biology of fishes Vol. 97; no. 7; pp. 797 - 812
• Main Authors: Medeiros, Elvio S. F., Arthington, Angela H.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.07.2014; Springer; Springer Nature B.V
• Subjects: Agnatha. Pisces; Ambassis; Animal and plant ecology; Animal populations; Animal Systematics/Taxonomy/Biogeography; Animal, plant and microbial ecology; Animals; Arid zones; Autoecology; Biological and medical sciences; Biomedical and Life Sciences; Diet; Dry season; Drying; Environment; Fish; Fish diets; Flooding; Floodplains; Food resources; Foraging behavior; Fresh water ecosystems; Freshwater & Marine Ecology; Fundamental and applied biological sciences. Psychology; General aspects; Lagoons; Leiopotherapon unicolor; Life Sciences; Nature Conservation; Nematalosa erebi; Rivers; Synecology; Vertebrata; Vertebrates: general zoology, morphology, phylogeny, systematics, cytogenetics, geographical distribution; Zoology; Australia; Oceania; Invertebrate prey; Foraging strategy; Fish trophic position; Dietary variability; Feeding behavior; Arid environment; Foraging behavior; Coastal lagoon; Feeding; Freshwater environment; Dry out; Prey; Vertebrata; Flood plain; Temporary water; Flood; Diet; Food intake; Trophic level; Pisces; Stream; Invertebrata; Dryland
• ISSN: 0378-1909; 1573-5133
• DOI: 10.1007/s10641-013-0180-0

Floodplain rivers worldwide are threatened by loss of connectivity to their floodplains and hence reduced benefits from floodplain energy subsidies. Dryland rivers with ‘boom and bust’ ecological responses to flooding and extended dry periods may be particularly vulnerable. This paper describes variations in dietary composition of three fish species of contrasting trophic position in dryland floodplain lagoons with variable flood inundation and drying histories. The study species were Ambassis agassizii - a microphagic carnivore, Leiopotherapon unicolor - a carnivore/omnivore, and Nematalosa erebi - an algivore/detritivor. Despite the range of food items recorded in fish guts, each species fed mostly on relatively few food categories and few food items within each category. Most of the spatial (i.e. among lagoons) and temporal dietary variation was associated with different proportional contributions of these food items. Given the absence or low magnitude of flooding during the study period, temporal changes in diets of the three species are probably the result of successional changes in composition of invertebrate prey as the dry season progressed. The focus of each fish species on relatively few food categories and a few reliable food items within each category may be the most profitable foraging strategy when food resources are limiting in progressively drying floodplain lagoons.