title: Intraspecific differences in lipid content of calanoid copepods across fine-scale depth ranges within the photic layer.
abstract: Copepods are among the most abundant and diverse groups of mesozooplankton in the world's oceans. Each species has a certain depth range within which different individuals (of the same life stage and sex) are found. Lipids are accumulated in many calanoid copepods for energy storage and reproduction. Lipid content in some species increases with depth, however studies so far focused mostly on temperate and high-latitude seasonal vertically migrating copepods and compared lipid contents among individuals either from coarse layers or between diapausing, deep-dwelling copepods and individuals found in the photic, near-surface layer. Here we examined whether lipid contents of individual calanoid copepods of the same species, life stage/sex differ between finer depth layers within the upper water column of subtropical and Arctic seas. A total of 6 calanoid species were collected from samples taken at precise depths within the photic layer in both cold eutrophic and warm oligotrophic environments using SCUBA diving, MOCNESS and Multinet. Measurements of lipid content were obtained from digitized photographs of the collected individuals. The results revealed significant differences in lipid content across depth differences as small as 12-15 meters for Mecynocera clausi C5 and Ctenocalanus vanus C5 (Red Sea), Clausocalanus furcatus males and two clausocalanid C5s (Mediterranean Sea), and Calanus glacialis C5 (Arctic). We suggest two possible explanations for the differences in lipid content with depth on such a fine scale: predator avoidance and buoyancy.
authors.affiliation: The Interuniversity Institute for Marine Sciences, Eilat, Israel; Department of Ecology, Evolution and Behavior, Silberman Institute of Life Sciences, the Hebrew University of Jerusalem, Jerusalem, Israel.
authors.forename: Margarita
authors.initials: M
authors.lastname: Zarubin
authors.affiliation: The Interuniversity Institute for Marine Sciences, Eilat, Israel.
authors.forename: Viviana
authors.initials: V
authors.lastname: Farstey
authors.affiliation: Akvaplan-niva, Fram Centre, Tromsø, Norway.
authors.forename: Anette
authors.initials: A
authors.lastname: Wold
authors.affiliation: Akvaplan-niva, Fram Centre, Tromsø, Norway; Department of Arctic and Marine Biology, Faculty of Biosciences, Fisheries and Economics, University of Tromsø, Tromsø, Norway; Norwegian Polar Institute, Tromsø, Norway.
authors.forename: Stig
authors.initials: S
authors.lastname: Falk-Petersen
authors.affiliation: The Interuniversity Institute for Marine Sciences, Eilat, Israel; Department of Ecology, Evolution and Behavior, Silberman Institute of Life Sciences, the Hebrew University of Jerusalem, Jerusalem, Israel.
authors.forename: Amatzia
authors.initials: A
authors.lastname: Genin
mesh_terms: D000818:Animals; D001110:Arctic Regions; D033342:Copepoda / Q000254:growth & development / Q000378:metabolism*; D005260:Female; D008018:Life Cycle Stages; D050356:Lipid Metabolism; D008297:Male; D009791:Oceanography; D011156:Population Density; D012623:Seawater; D012737:Sex Factors; D013696:Temperature; D014329:Tropical Climate