{"id":4713,"date":"2015-05-28T10:29:04","date_gmt":"2015-05-28T14:29:04","guid":{"rendered":"http:\/\/ncseagrant.ncsu.edu\/coastwatch\/?page_id=4713"},"modified":"2024-08-28T14:06:47","modified_gmt":"2024-08-28T18:06:47","slug":"sea-science-it-runs-through-riversfinding-the-chemical-signature-of-a-waterbody","status":"publish","type":"post","link":"https:\/\/ncseagrant.ncsu.edu\/coastwatch\/sea-science-it-runs-through-riversfinding-the-chemical-signature-of-a-waterbody\/","title":{"rendered":"SEA SCIENCE: IT RUNS THROUGH RIVERS:Finding the Chemical Signature of a Waterbody"},"content":{"rendered":"\n\n\n\n\n
Read the PDF here<\/a>.<\/strong><\/p>\n\n\n\n For years, North Carolina scientists and resource managers have carefully extracted surveillance data on fish movements through an onboard tracking device, so to speak. It allows researchers to learn where the fish went and what they had been doing.<\/p>\n\n\n\n By examining the rings in fish ear bones, also known as otoliths, scientists can identify important spawning habitat and migration patterns of anadromous fish \u2014 those that migrate between rivers, estuaries and the ocean to spawn and feed. Fish form annual rings within their bones, much like growth rings in trees. The rings show the age of the fish, as well as record chemical signatures, absorbed from surrounding waterbodies, that can determine where the fish has been.<\/p>\n\n\n\n Coley Hughes, a doctoral candidate in Coastal Resources Management at East Carolina University, is stepping back from the fish and looking at the water itself. She is hoping to find enough variation among the rivers feeding the Albemarle Sound to be able to identify water and its chemical signatures from each of these tributaries.<\/p>\n\n\n\n Also, until recently, most researchers have simply assumed that the elemental makeup of the water stays consistent enough over time for comparison with the otolith. Her work will be the first to fully test these suppositions.<\/p>\n\n\n\n \u201cWe\u2019ve always been basing our assumptions on other estuaries that aren\u2019t as well-mixed as the Albemarle,\u201d Hughes says, noting that many of the presuppositions made about water chemistry are based on studies done in the Chesapeake Bay, which is very different from the North Carolina sounds.<\/p>\n\n\n\n Her research is supported by the N.C. Fishery Resource Grant Program administered by North Carolina Sea Grant<\/a>. The studies build upon efforts initiated through the N.C. Division of Marine Fisheries\u2019 Coastal Recreational Fishing License Grants Program<\/a>.<\/p>\n\n\n\n ECU biologist Roger Rulifson has been using otolith analysis techniques to help identify key habitat areas for species such as striped bass and river herring for many years, including for several Sea Grant-funded projects.<\/p>\n\n\n\n \u201cIn our early work on fish otoliths, we were able to separate fish collected from different watersheds, but we did not know anything about the water chemistry itself,\u201d he says.<\/p>\n\n\n\n Rulifson could tell if fish had spent time in the same watershed, but he could not name the particular location. \u201cStriped bass collected from Albemarle Sound did not have identifiable element signatures. The ability to determine if a fish was from the Albemarle Sound was like flipping a coin,\u201d he adds.<\/p>\n\n\n\n The chemical signature of a waterbody can be affected by environmental factors, such as the source of freshwater input, proximity to the ocean or the chemical makeup of the surrounding soil. It also can be influenced by pollutants, such as pesticides or heavy metals. Theoretically, each habitat area should have a unique chemical signature that can be identified in the otolith.<\/p>\n\n\n\nREADING THE BONES<\/h2>\n\n\n\n