Correlation between Degree of Herbivory and Gut Morphology in 8 Notothenioids

MOREIRA, EUGENIA; NOVILLO, MANUEL; EASTMAN, JOSEPH; BARRERA-ORO, ESTEBAN

Davos

Congreso; POLAR2018 Open Science Conference; 2018

Scientific Comitte of Antarctic Science

Although many notothenioid fishes are primarily carnivorous, some species consistently feed on macroalgae and are therefore omnivorous. The degree of herbivory is reflected in the morphology of the digestive tract especially intestine length. We examined a large number of juvenile and adult specimens of eight sympatric notothenioid species collected at Potter Cove during eight consecutive seasons. We compare, in most cases for first time for an ontogenetic series, the distinct proportions of algae and animal prey in their diets (W %), and provide their relative intestine lengths [RIL= (IL/SL)*100]. Based on this correlation a ?ranking? or degree of herbivory is established for the fish species analysed, and this was found to be related to their distinct feedingtypes and strategies. The benthos feeders Gobionotothen gibberifrons, Notothenia coriiceps, N. rossii and Trematomus bernacchii were the most herbivorous with higher RILs (> 70%). Conversely, Lepidonotothen nudifrons, T. newnesi and Harpagifer antarcticus were predominantly carnivorous, with lower and intermediate RILs values (< 43-52%). Our results are discussed in context of gut morphology, trophic ecology and buoyancy as aspects of their divergence into to the trophic web of the Antarctic ecosystem.