Trophic ecology of the family Artedidraconidae (Pisces:Osteichthyes) and its impact on the eastern Weddell Sea benthic system

Abstract

The family Artedidraconidae comprises small, endemic Antarctic fishes, known as plunderfish, mostly distributed in the High Antarctic region. To study the diet of these specialised benthic feeders, stomach contents of the 11 most abundant species in the eastern Weddell Sea were examined. Prey composition was identified to the lowest taxonomic level for peracand crustaceans and polychaetes. Half of the food volume compr~sed 36 crustacean taxa (26 of which were amphipods). The other half was made up of 7 polychaete taxa and 8 other zoological groups. The diet of plunderfishes < 20 cm long was found to include about 70 % peracarid crustaceans, 50 % of which were amphipods. mainly garnrnarids; the rest of their diet was mostly sessile and motile polychaetes. Individuals larger than 15 cm began to prey on other fishes, although garnmands were stdl a part of their diet. The size of prey ranged from 5 to 32 mm. The mean size of prey increased with predator size. Selective predation effects were observed. small prey (copepods, cumaceans, ostracods, the gamrnarid family Eusiridae s.1. and the polychaete family Phyllodocidae) were found more frequently in small predators, whereas large prey (Epimeriidae, Lysianassidae s.1.. Cirolanidae, Arcturidae, Crangonidae. Euphausiidae. Pycnogonida) appeared in the stomachs of predators larger than a certain size. Plunderfish prey are generally abundant in the area, but the high diversity of the diet found in the genus Artedidraco, compared with the genera Dolloidraco and Pogonophryne, was surprising. The present analysis is based on data concerning the distribution and abundance of predators, as well as biological knowledge regarding the most characteristic types of prey. The specialised d e t s of plunderfishes from different habitats and of different sizes are also compared, in order to more closely examine the feedmg strategy of the family Artedidraconidae, and roughly quantify its impact on the benthic trophic web.