Cephalopods of the Sargasso Sea - Distribution patterns in relation to hydrographic conditions

Lischka, Alexandra (2015) Cephalopods of the Sargasso Sea - Distribution patterns in relation to hydrographic conditions (Master thesis), Christian-Albrechts-Universität Kiel, Kiel, Germany, 112 pp

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A comprehensive collection of mainly early life cephalopods that were sampled during two research cruises to the Sargasso Sea with the FRV Walther Herwig III in April 2014, and the RV Maria S Merian in April 2015, is analysed in this work. In 2014, 714 specimens were collected by a pelagic midwater trawl, and further 1,349 specimens by an Isaacs-Kidd Midwater Trawl (IKMT). A total of 2,487 cephalopods were caught during the cruise in 2015. They belonged to 36 species (20 families). The most abundant family was represented by the Flying squids (Ommastrephidae). Identification of cephalopods was supported by DNA barcoding based on partial COI sequences. The subtropical convergence zone
(STCZ) was found at approximately 27°N. This frontal system is characterised by a sharp near-surface temperature gradient and divides the Sargasso Sea into a northern and a southern area. This distinction was also reflected in the
cephalopod community composition. For example, the cranchiid Leachia lemur prevailed in the northern part, while the cirrate octopod, Japetella diaphana was mainly distributed in the southern part of the study area. PCA and RDA
analyses detected a significant correlation between species occurrence and sea surface temperature. Ordination analysis (MDS) showed significant differences in the cephalopod assemblages between day and night with midwater species (Enoploteuthidae, Pyroteuthidae) dominating the night catches, probably due
to their upward migration into the top 200 m during the night.

Document Type: Thesis (Master thesis)
Thesis Advisors: Hartl, G., Hanel, Reinhold and Piatkowski, Uwe
Keywords: MSM41 ; R.V. Maria S. Merian; R. V. Walther Herwig; WH373
Research affiliation: OceanRep > GEOMAR > FB3 Marine Ecology > FB3-EV Evolutionary Ecology of Marine Fishes
OceanRep > Leibniz Institute of Marine Sciences
Date Deposited: 04 Mar 2016 13:46
Last Modified: 04 Mar 2016 14:04
URI: http://eprints.uni-kiel.de/id/eprint/31706

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