{"323081":{"#nid":"323081","#data":{"type":"news","title":"Sharks in Acidic Waters Avoid Smell of Food","body":[{"value":"\u003Cp\u003EThe increasing acidification of ocean waters caused by rising atmospheric carbon dioxide levels could rob sharks of their ability to sense the smell of food, a new study suggests.\u003C\/p\u003E\u003Cp\u003EElevated carbon dioxide levels impaired the odor-tracking behavior of the smooth dogfish, a shark whose range includes the Atlantic Ocean off the eastern United States. Adult sharks significantly avoided squid odor after swimming in a pool of water treated with carbon dioxide. The carbon dioxide concentrations tested are consistent with climate forecasts for midcentury and 2100. The study suggests that predator-prey interactions in nature could be influenced by elevated carbon dioxide concentrations of ocean waters.\u003C\/p\u003E\u003Cp\u003E\u201cThe sharks\u2019 tracking behavior and attacking behavior were significantly reduced,\u201d said\u0026nbsp;\u003Ca href=\u0022http:\/\/www.biology.gatech.edu\/people\/danielle-dixson\u0022\u003EDanielle Dixson\u003C\/a\u003E, an assistant professor in the School of Biology at the Georgia Institute of Technology in Atlanta.\u003Cstrong\u003E\u0026nbsp;\u201c\u003C\/strong\u003ESharks are like swimming noses, so chemical cues are really important for them in terms of finding food.\u201d\u003C\/p\u003E\u003Cp\u003EThe study is the first time that sharks\u2019 ability to sense the odor of their food has been tested under conditions that simulate the acidity levels expected in the oceans by the turn of the century. The work supports\u0026nbsp;\u003Ca href=\u0022http:\/\/scholar.google.com\/citations?user=p9RD2kYAAAAJ\u0026amp;hl=en\u0026amp;oi=sra\u0022\u003Erecent research from Dixson\u003C\/a\u003E\u0026nbsp;and other research groups showing that ocean acidification impairs sensory functions and alters the behavior of aquatic organisms.\u003C\/p\u003E\u003Cp\u003EThe study was published August 11 the journal\u0026nbsp;\u003Cem\u003E\u003Ca href=\u0022http:\/\/onlinelibrary.wiley.com\/doi\/10.1111\/gcb.12678\/full\u0022\u003EGlobal Change Biology\u003C\/a\u003E\u003C\/em\u003E\u0026nbsp;and was sponsored by the National Science Foundation (NSF).\u003C\/p\u003E\u003Cp\u003ECarbon dioxide released into the atmosphere is absorbed into ocean waters, where it dissolves and lowers the pH of the water. Acidic waters affect fish behavior by disrupting a specific receptor in the nervous system, called GABA\u003Csub\u003EA\u003C\/sub\u003E, which is present in most marine organisms with a nervous system. When GABA\u003Csub\u003EA\u003C\/sub\u003E\u0026nbsp;stops working, neurons stop firing properly.\u003C\/p\u003E\u003Cp\u003EDixson\u2019s previous research has shown that fish living on coral reefs where carbon dioxide seeps from the ocean floor were\u0026nbsp;\u003Ca href=\u0022http:\/\/www.news.gatech.edu\/2014\/04\/14\/fish-acidic-ocean-waters-less-able-smell-predators\u0022\u003Eless able to detect predator odor\u003C\/a\u003E\u0026nbsp;than fish from normal coral reefs. Study co-author Philip Munday, from James Cook University in Australia, has shown in previous work that a tiny coral reef predator fish, the dottyback,also loses interest in food in waters that simulate ocean acidification conditions forecast for the future.\u003C\/p\u003E\u003Cp\u003EIn the experimental part of the new study, conducted at Woods Hole Oceanographic Institute in Cape Cod, Massachusetts, 24 sharks from local waters were studied in a 10-meter-long flume. The flume resembled two lanes of a swimming pool. Odor from a squid was pumped down one lane of the flume, while normal seawater was pumped down the other side.\u003C\/p\u003E\u003Cp\u003ESharks tend to prefer one side of a tank over the other, so researchers first assessed each sharks\u2019 side preference. Then the research team ran control experiments under normal ocean conditions to ensure that the sharks were tracking the food cue. Under present-day water conditions, sharks adjusted their position in the flume to spend a greater amount of time on the side containing the squid odor plume, regardless of the individual shark\u2019s natural side preference.\u003C\/p\u003E\u003Cp\u003ENext, sharks spent five days in holding pools of three different carbon dioxide concentrations: local water concentration today (405 \u00b1 26microatmospheres\u003Cstrong\u003E\u0026nbsp;(\u003C\/strong\u003E\u00b5atms) CO\u003Csub\u003E2\u003C\/sub\u003E), projected midcentury concentration (741 \u00b1 22 \u00b5atms CO\u003Csub\u003E2\u003C\/sub\u003E),projected concentration for 2100 (1,064 \u00b1 17 \u00b5atms CO\u003Csub\u003E2\u003C\/sub\u003E). Sharks were not fed while in the holding pools to ensure they were motivated to track a food odor. The sharks were then released into the flume and their tracking behavior was observed.\u003C\/p\u003E\u003Cp\u003ESharks from the normal seawater pool and mid-level carbon dioxide pool spent more than 60 percent of their time in the water stream containing the food stimulus. Sharks from the high carbon dioxide pool spent less than 15 percent of their time in the water stream containing the food stimulus. These sharks avoided the odor plume even when it was on the side of the flume that the sharks\u2019 naturally prefer.\u003C\/p\u003E\u003Cp\u003EThe food odor stream was pumped through bricks to make the plume flow better and to give the sharks a target to attack. Sharks treated under mid and high CO\u003Csub\u003E2\u003C\/sub\u003E\u0026nbsp;conditions also reduced their attack behavior.\u003C\/p\u003E\u003Cp\u003E\u201cThey significantly reduced their bumps and bites on the bricks compared to the control group,\u201d Dixson said. \u201cIt\u2019s like they\u2019re uninterested in their food.\u201d\u003C\/p\u003E\u003Cp\u003EExposure to carbon dioxide did not significantly affect the sharks\u2019 overall activity levels. The gill rate of the sharks \u2013 an indicator of heart rate \u2013 held in different water conditions was not significantly different, suggesting that differences in stress to the sharks was not likely affecting the experimental results.\u003C\/p\u003E\u003Cp\u003EDixson noted that the study was carried out under laboratory conditions and thus does not allow for the full evaluation of the potential effects of ocean acidification on predatory abilities of the smooth dogfish.\u003C\/p\u003E\u003Cp\u003ELive food was not used as the odor cue because sharks can detect prey with their other senses, such as hearing and their ability to detect electrical impulses. By using an odor cue, the researchers were focusing on only the chemical sensing of sharks. Dixson\u2019s future work will explore how sharks\u2019 other senses might be affected by ocean acidification.\u003C\/p\u003E\u003Cp\u003ESharks are an ancient species, and in the past have adapted to ocean acidification conditions projected for the future. But they\u2019ve never had to adapt to changes happening as quickly as they are today.\u003C\/p\u003E\u003Cp\u003E\u201cIt\u2019s the rate of change that\u2019s happening that\u2019s concerning. Sharks have never had to deal with it this fast,\u201d Dixson said.\u003C\/p\u003E\u003Cp\u003E\u003Cem\u003EThis research is supported by the National Science Foundation (NSF) under award number NSF-IOS-0843440. Any conclusions or opinions are those of the authors and do not necessarily represent the official views of the sponsoring agency.\u003C\/em\u003E\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003ECITATION\u003C\/strong\u003E: Danielle L. Dixson, et al., \u201cOdor tracking in sharks is reduced under future ocean acidification conditions.\u201d (\u003Cem\u003EGlobal Change Biology\u003C\/em\u003E, August 2014)\u0026nbsp;\u003Ca href=\u0022http:\/\/onlinelibrary.wiley.com\/doi\/10.1111\/gcb.12678\/full\u0022\u003Ehttp:\/\/onlinelibrary.wiley.com\/doi\/10.1111\/gcb.12678\/full\u003C\/a\u003E\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EResearch News\u003Cbr \/\u003EGeorgia Institute of Technology\u003Cbr \/\u003E177 North Avenue\u003Cbr \/\u003EAtlanta, Georgia\u0026nbsp; 30332-0181\u0026nbsp; USA\u003Cbr \/\u003E\u003C\/strong\u003E\u003Ca href=\u0022https:\/\/twitter.com\/GTResearchNews\u0022\u003E\u003Cstrong\u003E@GTResearchNews\u003C\/strong\u003E\u003C\/a\u003E\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EMedia Relations Contacts\u003C\/strong\u003E: Brett Israel (\u003Ca href=\u0022https:\/\/twitter.com\/btiatl\u0022\u003E@btiatl\u003C\/a\u003E) (404-385-1933) (\u003Ca href=\u0022mailto:brett.israel@comm.gatech.edu\u0022\u003Ebrett.israel@comm.gatech.edu\u003C\/a\u003E) or John Toon (404-894-6986) (\u003Ca href=\u0022mailto:jtoon@gatech.edu\u0022\u003Ejtoon@gatech.edu\u003C\/a\u003E)\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EWriter\u003C\/strong\u003E: Brett Israel\u0026nbsp;\u003C\/p\u003E","summary":null,"format":"limited_html"}],"field_subtitle":"","field_summary":"","field_summary_sentence":[{"value":"The increasing acidification of ocean waters caused by rising atmospheric carbon dioxide levels could rob sharks of their ability to sense the smell of food, a new study suggests."}],"uid":"27902","created_gmt":"2014-09-09 09:15:20","changed_gmt":"2016-10-08 03:17:04","author":"Brett Israel","boilerplate_text":"","field_publication":"","field_article_url":"","dateline":{"date":"2014-09-09T00:00:00-04:00","iso_date":"2014-09-09T00:00:00-04:00","tz":"America\/New_York"},"extras":[],"hg_media":{"323041":{"id":"323041","type":"image","title":"Smooth dogfish shark","body":null,"created":"1449245025","gmt_created":"2015-12-04 16:03:45","changed":"1475895034","gmt_changed":"2016-10-08 02:50:34","alt":"Smooth dogfish shark","file":{"fid":"201794","name":"smooth_dogfish_shark.jpg","image_path":"\/sites\/default\/files\/images\/smooth_dogfish_shark.jpg","image_full_path":"http:\/\/www.tlwarc.hg.gatech.edu\/\/sites\/default\/files\/images\/smooth_dogfish_shark.jpg","mime":"image\/jpeg","size":1236460,"path_740":"http:\/\/www.tlwarc.hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/smooth_dogfish_shark.jpg?itok=ehhEwpzD"}},"323051":{"id":"323051","type":"image","title":"Shark mouth","body":null,"created":"1449245025","gmt_created":"2015-12-04 16:03:45","changed":"1475895034","gmt_changed":"2016-10-08 02:50:34","alt":"Shark mouth","file":{"fid":"201795","name":"shark_mouth_view.jpg","image_path":"\/sites\/default\/files\/images\/shark_mouth_view.jpg","image_full_path":"http:\/\/www.tlwarc.hg.gatech.edu\/\/sites\/default\/files\/images\/shark_mouth_view.jpg","mime":"image\/jpeg","size":1793660,"path_740":"http:\/\/www.tlwarc.hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/shark_mouth_view.jpg?itok=g_0l7yyt"}},"323061":{"id":"323061","type":"image","title":"Shark flume","body":null,"created":"1449245025","gmt_created":"2015-12-04 16:03:45","changed":"1475895034","gmt_changed":"2016-10-08 02:50:34","alt":"Shark flume","file":{"fid":"201796","name":"shark_flume.jpg","image_path":"\/sites\/default\/files\/images\/shark_flume.jpg","image_full_path":"http:\/\/www.tlwarc.hg.gatech.edu\/\/sites\/default\/files\/images\/shark_flume.jpg","mime":"image\/jpeg","size":953577,"path_740":"http:\/\/www.tlwarc.hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/shark_flume.jpg?itok=-5U68mup"}}},"media_ids":["323041","323051","323061"],"groups":[{"id":"1188","name":"Research Horizons"}],"categories":[{"id":"154","name":"Environment"},{"id":"146","name":"Life Sciences and Biology"}],"keywords":[{"id":"102501","name":"cape code"},{"id":"831","name":"climate change"},{"id":"79191","name":"Danielle Dixson"},{"id":"4320","name":"ecology"},{"id":"169672","name":"shark feeding"},{"id":"169673","name":"Sharks"},{"id":"169674","name":"smooth dogfish"},{"id":"169675","name":"squids"},{"id":"102491","name":"woods hole"}],"core_research_areas":[{"id":"39441","name":"Bioengineering and Bioscience"}],"news_room_topics":[{"id":"71911","name":"Earth and Environment"}],"event_categories":[],"invited_audience":[],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[{"value":"\u003Cp\u003EBrett Israel\u003C\/p\u003E\u003Cp\u003E404-385-1933\u003C\/p\u003E\u003Cp\u003E\u003Ca href=\u0022http:\/\/www.twitter.com\/btiatl\u0022\u003E@btiatl\u003C\/a\u003E\u003C\/p\u003E","format":"limited_html"}],"email":["brett.israel@comm.gatech.edu"],"slides":[],"orientation":[],"userdata":""}}}