<table cellspacing="0" cellpadding="0" border="0" ><tr><td valign="top" style="font: inherit;"><H1 id=article-title-1><EM>PNAS<SPAN class=slug-pub-date> August 18, 2009 </SPAN><SPAN class=slug-vol>vol. 106 </SPAN><SPAN class=slug-issue>no. 33 </SPAN><SPAN class=slug-pages>13865-13869 </SPAN></EM></H1>
<H1>The influence of depth on mercury levels in pelagic fishes and their prey</H1>
<DIV class=contributors>
<OL id=contrib-group-1 class=contributor-list jQuery1252472281584="64">
<LI id=contrib-1><SPAN class=name><A class=name-search href="http://www.pnas.org/search?author1=C.+Anela+Choy&sortspec=date&submit=Submit">C. Anela Choy</A></SPAN><A id=xref-aff-1-1 class=xref-aff href="http://www.pnas.org/content/106/33/13865.abstract#aff-1" jQuery1252472281584="66"><SUP>a</SUP></A><SPAN class=xref-sep>,</SPAN><A id=xref-corresp-1-1 class=xref-corresp href="http://www.pnas.org/content/106/33/13865.abstract#corresp-1"><SUP>1</SUP></A>, </LI>
<LI id=contrib-2><SPAN class=name><A class=name-search href="http://www.pnas.org/search?author1=Brian+N.+Popp&sortspec=date&submit=Submit">Brian N. Popp</A></SPAN><A id=xref-aff-2-1 class=xref-aff href="http://www.pnas.org/content/106/33/13865.abstract#aff-2" jQuery1252472281584="67"><SUP>b</SUP></A>, </LI>
<LI id=contrib-3><SPAN class=name><A class=name-search href="http://www.pnas.org/search?author1=J.+John+Kaneko&sortspec=date&submit=Submit">J. John Kaneko</A></SPAN><A id=xref-aff-3-1 class=xref-aff href="http://www.pnas.org/content/106/33/13865.abstract#aff-3" jQuery1252472281584="68"><SUP>c</SUP></A> and </LI>
<LI id=contrib-4><SPAN class=name><A class=name-search href="http://www.pnas.org/search?author1=Jeffrey+C.+Drazen&sortspec=date&submit=Submit">Jeffrey C. Drazen</A></SPAN><A id=xref-aff-1-2 class=xref-aff href="http://www.pnas.org/content/106/33/13865.abstract#aff-1" jQuery1252472281584="69"><SUP>a</SUP></A></LI></OL>
<P class=affiliation-list-reveal><A class=view-more href="http://www.pnas.org/content/106/33/13865.abstract#" jQuery1252472281584="65">-</A> Author Affiliations</DIV>
<OL class="affiliation-list showaffil" jQuery1252472281584="63">
<LI class=aff><A id=aff-1 name=aff-1></A>
<ADDRESS><SUP>a</SUP>Department of Oceanography, University of Hawaii, 1000 Pope Road, Honolulu, HI 96822; </ADDRESS></LI>
<LI class=aff><A id=aff-2 name=aff-2></A>
<ADDRESS><SUP>b</SUP>Department of Geology and Geophysics, University of Hawaii, 1680 East-West Road, Honolulu, HI 96822; and </ADDRESS></LI>
<LI class=aff><A id=aff-3 name=aff-3></A>
<ADDRESS><SUP>c</SUP>PacMar Inc., 3615 Harding Avenue, Suite 409, Honolulu, HI 96816 </ADDRESS></LI></OL></DIV>
<DIV id=abstract-1 class="section abstract">
<H2>Abstract</H2>
<P id=p-3>Mercury distribution in the oceans is controlled by complex biogeochemical cycles, resulting in retention of trace amounts of this metal in plants and animals. Inter- and intra-specific variations in mercury levels of predatory pelagic fish have been previously linked to size, age, trophic position, physical and chemical environmental parameters, and location of capture; however, considerable variation remains unexplained. In this paper, we focus on differences in ecology, depth of occurrence, and total mercury levels in 9 species of commercially important pelagic fish (<EM>Thunnus obesus</EM>, <EM>T. albacares</EM>, <EM>Katsuwonus pelamis</EM>, <EM>Xiphias gladius</EM>, <EM>Lampris guttatus</EM>, <EM>Coryphaena hippurus</EM>, <EM>Taractichthys steindachneri</EM>, <EM>Tetrapturus audax</EM>, and <EM>Lepidocybium flavobrunneum</EM>) and in numerous representatives (fishes, squids, and crustaceans) of their lower trophic level prey sampled from
the central North Pacific Ocean. Results indicate that total mercury levels of predatory pelagic fishes and their prey increase with median depth of occurrence in the water column and mimic concentrations of dissolved organic mercury in seawater. Stomach content analysis results from this study and others indicate a greater occurrence of higher-mercury containing deeper-water prey organisms in the diets of the deeper-ranging predators, <EM>X. gladius</EM>, <EM>T. obesus</EM>, and <EM>L. guttatus</EM>. While present in trace amounts, dissolved organic mercury increases with depth in the water column suggesting that the mesopelagic habitat is a major entry point for mercury into marine food webs. These data suggest that a major determinant of mercury levels in oceanic predators is their depth of forage. </DIV></DIV>
<UL class=kwd-group>
<LI class=kwd><SPAN><A class=kwd-search href="http://www.pnas.org/search?fulltext=depth+of+forage&sortspec=date&submit=Submit&andorexactfulltext=phrase">depth of forage</A></SPAN></LI>
<LI class=kwd><SPAN><A class=kwd-search href="http://www.pnas.org/search?fulltext=marine+pelagic+predators&sortspec=date&submit=Submit&andorexactfulltext=phrase">marine pelagic predators</A></SPAN></LI>
<LI class=kwd><SPAN><A class=kwd-search href="http://www.pnas.org/search?fulltext=North+Pacific+Ocean&sortspec=date&submit=Submit&andorexactfulltext=phrase">North Pacific Ocean</A></SPAN></LI>
<LI class=kwd><SPAN><A class=kwd-search href="http://www.pnas.org/search?fulltext=mercury+bioaccumulation&sortspec=date&submit=Submit&andorexactfulltext=phrase">mercury bioaccumulation</A></SPAN></LI>
<LI class=kwd><SPAN><A class=kwd-search href="http://www.pnas.org/search?fulltext=mesopelagic+zone&sortspec=date&submit=Submit&andorexactfulltext=phrase">mesopelagic zone</A></SPAN></LI></UL>
<DIV id=fn-group-1 class="section fn-group">
<H2>Footnotes</H2>
<UL>
<LI id=corresp-1 class=corresp><SPAN class=corresp-label></SPAN><SUP>1</SUP>To whom correspondence should be addressed. E-mail: <A href="mailto:cachoy@hawaii.edu">cachoy@hawaii.edu</A></LI></UL></DIV></td></tr></table><br>