{"id":1,"date":"2014-08-04T15:30:41","date_gmt":"2014-08-04T06:30:41","guid":{"rendered":"http:\/\/localhost\/alexsjwyatt\/?p=1"},"modified":"2016-04-26T15:17:24","modified_gmt":"2016-04-26T06:17:24","slug":"hello-world","status":"publish","type":"post","link":"https:\/\/www.oceanecol.com\/?p=1","title":{"rendered":"Isotope discrimination in captive whale sharks @ IsoEcol 2014 (Dr Wyatt)"},"content":{"rendered":"

Isotope Discrimination in Planktivorous Elasmobranchs Focusing on the World\u2019s Largest Fish, Captive Whale Sharks Rhincodon typus<\/em><\/h2>\n

Alex S.J. WYATT1*<\/sup> Rui Matsumoto2<\/sup> Yoshito Chikaraishi3<\/sup> Keiichi Sato2<\/sup> Nao Ohkouchi3<\/sup> Toshi Nagata1<\/sup><\/p>\n

1<\/sup>Marine Biogeochemistry Laboratory, Department of Chemical Oceanography, Atmosphere & Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba, JAPAN.<\/em>
\n 2<\/sup>Okinawa Churaumi Aquarium, Motobu, Okinawa, JAPAN.<\/em>
\n 3<\/sup>Japan Agency for Marine-Earth Science and Technology, Yokosuka, JAPAN<\/em>
\n*<\/sup>Presenting author<\/p>\n

Accurate diet-tissue discrimination factors (DTDF) are essential for quantifying diets and trophic positions (TP) using stable isotope analyses (SIA), with potential variation between diets, tissues, organisms and environments arguing against untested application of meta-analysis averages (e.g. 3.4 \u2030 for bulk nitrogen (\u039415<\/sup>Nbulk<\/sub>), ~0.5 \u2030 for bulk carbon (\u039413<\/sup>Cbulk<\/sub>), and 7.6 \u2030 and 0.4 \u2030 for nitrogen of glutamic acid (\u039415<\/sup>Nglu<\/sub>) and phenylalanine (\u039415<\/sup>Nphe<\/sub>), respectively). Experimental derivations of DTDF in elasmobranchs (sharks and rays) are scarce, with large-bodied organisms difficult to maintain in captivity and non-lethal multi-tissue sampling problematic for both captive and wild individuals. SIA of captive whale sharks Rhincodon typus<\/em>, one male (8.5 m in length) and two females (7.1 and 7.2 m), fed a mixed diet composed mainly (~ 48 % each) of Antarctic krill Euphausia superba<\/em> (\u03b415<\/sup>N = 3.45 \u2030, \u03b413<\/sup>C = -26.3 \u2030) and North Pacific krill E. pacifica<\/em> (\u03b415<\/sup>N = 5.88 \u2030, \u03b413<\/sup>C = -21.6 \u2030), provide an opportunity to examine DTDF in the world\u2019s largest fish and one of three planktivorous sharks. DTDFs estimated based on temporally averaged diets for easily sampled but slow turnover fin tissue were close to previous observations, but varied between individuals, perhaps reflecting differing growth rates with size or physiological differences between the sexes: \u039415<\/sup>Nbulk<\/sub> (2.6, 3.3, 3.1 \u2030), \u039413<\/sup>Cbulk<\/sub> (3.9, 4.5, 5.9 \u2030), \u039415<\/sup>Nglu<\/sub> (7.6, 6.5, n.d. \u2030) and \u039415<\/sup>Nphe<\/sub>\u00a0(0.3, 0.2, n.d. \u2030). Short turnover tissues, such as liver or blood, may be difficult or impossible to obtain for these species, requiring non-lethal isotopic proxies to examine diet and TP at higher temporal resolution. For instance, SIA of faecal material was highly variable but reflected day-to-day variation in minor (<3 %) components of the sharks\u2019 diets. DTDF will be discussed in the context of sampling constraints related to multi-tissue SIA and recent radioisotope approaches for understanding feeding and aggregations of planktivorous elasmobranchs, including recent application to a wild caught (4.4 m) specimen of the smallest planktivorous shark, the rare megamouth shark Megachasma pelagios<\/em>.<\/p><\/blockquote>\n","protected":false},"excerpt":{"rendered":"

Isotope Discrimination in Planktivorous Elasmobranchs Focusing on the World\u2019s Largest Fish, Captive Whale Sharks Rhincodon typus Alex S.J. WYATT1* Rui Matsumoto2 Yoshito Chikaraishi3 Keiichi Sato2 Nao Ohkouchi3 Toshi Nagata1 1Marine Biogeochemistry Laboratory, Department of Chemical Oceanography, Atmosphere & Ocean Research Institute, The University of Tokyo, | Click for More \u2192<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4,15,3],"tags":[28,33,32,35,31,77,75,45,76,30],"class_list":["post-1","post","type-post","status-publish","format-standard","hentry","category-conferences","category-news","category-presentations","tag-conference","tag-csia","tag-fractionation","tag-isoecol","tag-isotope","tag-megamouth","tag-radiocarbon","tag-stable-isotope-analyses","tag-trophic-discrimination","tag-whale-shark"],"_links":{"self":[{"href":"https:\/\/www.oceanecol.com\/index.php?rest_route=\/wp\/v2\/posts\/1","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.oceanecol.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.oceanecol.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.oceanecol.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.oceanecol.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1"}],"version-history":[{"count":11,"href":"https:\/\/www.oceanecol.com\/index.php?rest_route=\/wp\/v2\/posts\/1\/revisions"}],"predecessor-version":[{"id":385,"href":"https:\/\/www.oceanecol.com\/index.php?rest_route=\/wp\/v2\/posts\/1\/revisions\/385"}],"wp:attachment":[{"href":"https:\/\/www.oceanecol.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.oceanecol.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.oceanecol.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}