MEPS 194:143-158 (2000)  -  doi:10.3354/meps194143

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

Ignacio Olaso1,*, Martin Rauschert2, Claude De Broyer3

1Instituto Español de Oceanografía, Laboratorio Oceanográfico de Santander, Apartado 240, 39080 Santander, Spain
2AWI Potsdam, Institut für spezielle Zoologie Berlin, Invalidenstr. 43, 10115 Berlin, Germany
3Institut Royal des Sciences Naturelles de Belgique, Rue Vautier 29, 1000 Bruxelles, Belgium

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 peracarid crustaceans and polychaetes. Half of the food volume comprised 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 gammarids; the rest of their diet was mostly sessile and motile polychaetes. Individuals larger than 15 cm began to prey on other fishes, although gammarids were still 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 gammarid family Eusiridae s.l. and the polychaete family Phyllodocidae) were found more frequently in small predators, whereas large prey (Epimeriidae, Lysianassidae s.l., 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 diets of plunderfishes from different habitats and of different sizes are also compared, in order to more closely examine the feeding strategy of the family Artedidraconidae, and roughly quantify its impact on the benthic trophic web.

KEY WORDS: Benthic feeders · Artedidraconids · Trophic relationships · Amphipods · Polychaetes · Weddell Sea

Full text in pdf format