Temporally sustained dietary niche partitioning in two mesopelagic copepod species and their mouthpart morphology

Abstract

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 518:51-67 (2015) - DOI: https://doi.org/10.3354/meps11045 Temporally sustained dietary niche partitioning in two mesopelagic copepod species and their mouthpart morphology Masayoshi Sano1,*, Yuichiro Nishibe1, Yuji Tanaka2, Shuhei Nishida1 1Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8564, Japan 2Tokyo University of Marine Science and Technology, 4-5-7 Konan, Minato, Tokyo 108-8477, Japan *Corresponding author: sano@aori.u-tokyo.ac.jp ABSTRACT: We compared seasonal feeding habit patterns, mouthpart structures, body sizes and vertical distributions of the aetideid copepods Undeuchaeta major and Chirundina streetsii in Sagami Bay, Japan. We focused on niche partitioning as one of the mechanisms sustaining co-existence of these mesopelagic copepods, by integrative application of stable-isotope analysis, microscopic observation and elemental analysis of the gut contents. While the body sizes and vertical distribution of both species were similar, they showed marked differences in their feeding habits throughout the year, i.e. carnivory in U. major and omnivory in C. streetsii, suggesting that food niche partitioning was a mechanism enabling their co-existence. Of particular interest was the consistently lower δ15N values in U. major, attributable to its selective feeding on oncaeid copepods. Previous reports of low δ15N in oncaeids, whose major food source has been assumed to be nanoplankton attached to appendicularian houses, suggest that the size of the primary producer is important in δ15N analyses of pelagic food webs. Comparison of mouthparts of the 2 species indicated slight differences in the maxilliped morphology. The relationship between feeding habit and maxilliped morphology was examined for the species above, other omnivorous aetideids and the Euchaetidae, a carnivorous sister family of the Aetideidae. The results suggest that carnivores have a broad basis and long unguiform setae, while omnivores have a narrower basis and shorter, more slender setae. The feeding habits of Aetideidae, which have so far been considered as exclusively omnivorous, comprise omnivory and carnivory, and can be distinguished by their maxilliped morphology. KEY WORDS: Aetideidae · Vertical distribution · Food chain · Marine snow · Feeding · Stable isotope · Elemental analysis Full text in pdf format Supplementary material PreviousNextCite this article as: Sano M, Nishibe Y, Tanaka Y, Nishida S (2015) Temporally sustained dietary niche partitioning in two mesopelagic copepod species and their mouthpart morphology. Mar Ecol Prog Ser 518:51-67. https://doi.org/10.3354/meps11045 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 518. Online publication date: January 07, 2015 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2015 Inter-Research.