Aspects of krill growth and condition during late winter-early spring off East Antarctica (110-130°E)
Antarctickrill, Euphausiasuperba, isakeystonespeciesintheSouthernOcean.However,informationongrowth,dietandconditionduringwinterandearlyspringislimited,hamperingourunderstandingofthese fundamentalbiologicalparametersatthisimportantperiodintheirlifecycle.Ourstudyassesseddiet andconditionoflarvalandpos...
Published in: | Deep Sea Research Part II: Topical Studies in Oceanography |
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Main Authors: | , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Pergamon-Elsevier Science Ltd
2011
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Subjects: | |
Online Access: | https://doi.org/10.1016/j.dsr2.2010.11.001 http://ecite.utas.edu.au/76369 |
Summary: | Antarctickrill, Euphausiasuperba, isakeystonespeciesintheSouthernOcean.However,informationongrowth,dietandconditionduringwinterandearlyspringislimited,hamperingourunderstandingofthese fundamentalbiologicalparametersatthisimportantperiodintheirlifecycle.Ourstudyassesseddiet andconditionoflarvalandpostlarvalkrillcollectedfromopenwaterandbelowtheiceoffEastAntarctica(110130% oE) inSeptember/October2007.Conditionwasassessedusinglipidcontent,growthratesanddigestiveglandsize;feedinghistorywasassessedusingfattyacidprofilesandstomachcontentanalysis;anda207-daystarvationstudyinvestigatedtheresponseofkrilltolong-termfooddeprivation.Potentialfooditems(Calanuspropinquus and sea-icebiota)wereanalysedforlipidandfattyacidcompositiontocomparewithkrillsamples.Krillwerefoundtobeingoodcondition,withmeangrowthrate of0.95%permoultforpostlarvaeand14.79%forlarvae,andmeanlipidcontentof24.1%forpostlarvaeand 6.6%forlarvae.Fattyacidprofilesandstomachcontentanalysisrevealedtwomainfeedingstrategies- krillbelowtheicewerefeedingmostlyonsea-icediatoms,whilethoseinopenwaterwereingestingcopepodsanddetritus.Krillbelowtheicehadlargerdigestiveglandsthanthoseinopenwater.Furciliaefatty acidprofilesindicatedadietofheterotrophicflagellatesand/ordetritus.Postlarvalkrillsurvived207days offooddeprivationbyusingbodyproteinandlipidreservesforenergy.Incontrast,krillfurciliaewere severelydepletedafterjust5daysoffooddeprivation,indicatingthattheymustfeedcontinuallyatthis timeofyear.Krill,copepodsandsea-icebiotawerealllowinpolyunsaturatedfattyacids,indicatingthat krillmustrelyonlaterspringphytoplanktonbloomstoobtaintheseessentialnutrientsrequiredforreproduction. |
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