Importance of the large copepod Paraeuchaeta antarctica (Giesbrecht, 1902) in coastal waters and the diet of seabirds at Kerguelen, Southern Ocean

• Published in: Journal of Plankton Research
• Main Authors: Bocher, P., Cherel, Y., Alonzo, F., Razouls, S., Labat, J. P., Mayzaud, P., Jouventin, P.
• Format: Text
• Language: English
• Published: Oxford University Press 2002
• Subjects: ORIGINAL ARTICLES; Southern Ocean; Kerguelen; Kerguelen Islands; Golfe du Morbihan; Antarc*; Antarctica
• Online Access: http://plankt.oxfordjournals.org/cgi/content/short/24/12/1317; https://doi.org/10.1093/plankt/24.12.1317

The importance of the euchaetid copepod Paraeuchaeta antarctica in the subantarctic pelagic ecosystem was quantified in the coastal waters of the Golfe du Morbihan at Kerguelen Islands by comparing food samples from two diving seabirds with concurrent net samples taken within the predator foraging area. Paraeuchaeta antarctica occurred in very high densities (up to 30 individuals m−3 and 96 mg dry weight m−3) in the water column, being more abundant in the deepest part of the gulf than in shallow waters or at the more offshore shelf stations. The common diving petrel feeds almost exclusively on crustaceans, its diet being dominated by the amphipod Themisto gaudichaudii (52% by number and 84% by reconstituted mass) and P. antarctica (33% and 16%, respectively). Rockhopper penguins preyed upon crustaceans and fish, with four taxa being important, namely T. gaudichaudii (37% and 23%, respectively), Euphausia vallentini (24% and 41%), postlarval fish (10% and 24%), and P. antarctica (13% and 3%). Paraeuchaeta antarctica dominated numerically in 21% of the diving-petrel food samples and in 12% of penguin samples. The two bird species segregated by preying upon different developmental stages of P. antarctica, diving petrels fed equally on CV of both sexes and CVI♀, while penguins fed on CVI♀ only. Comparison of P. antarctica found in net and food samples indicated no prey selection by common diving petrels that caught the different copepod stages in proportion to their availability in the water column. On the other hand, the diving performance of penguins, which is better than that of the petrels (mean maximum dive depths 69 m for penguins versus 32 m in petrels), allows them to catch CVI♀ in deeper waters, probably near the bottom. Our study shows that P. antarctica is a major component of the coastal macrozooplankton community and a significant prey for two species of diving seabirds inhabiting Kerguelen. This is also the first record of a copepod species as a prey for penguin, and the first to highlight P. ...