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On November 30, 2022 at 6:28:39 PM UTC, Gravatar patdavid:
  • Updated description of Stable isotope values in tissues of live and stranded dolphins and manatees from the northern Gulf of Mexico from

    ### Abstract Stable isotope analysis (SIA) provides ecological data that can be safely and efficiently collected on endangered, threatened, and cryptic species. Marine mammals are an ecologically important group for which economical and logistical constraints can make data collection challenging. Stranded marine mammals are often used in research, but the causes of strandings and subsequent tissue decomposition could affect SIA. We conducted a three-part study to test the validity of using δ<sup>13</sup> C and δ15 N values from tissues of stranded bottlenose dolphins (Tursiops truncatus) and West Indian manatees (Trichechus manatus) for ecological studies. First, we quantified isotopic overlap using ellipses based on 95% of the data to compare isotope values in skin between stranded and live-captured animals. Second, we compared stable isotope values from liver, skin, and muscle from animals that had stranded and were sampled at different decomposition stages. Third, we experimentally exposed each tissue to environmental conditions and sampled tissues as they decomposed. For both dolphins and manatees, isotopic ellipses from skin of stranded carcasses were similar to live-captured individuals. Among individuals recovered at different decomposition stages, more advanced decomposition affected δ13 C values in dolphin liver and skin but not in manatee tissues and had no effect on δ15 N values in any tissue for either species. In the experimental manipulation, decomposition resulted in depleted δ13 C values, enriched δ15 N values, and increased C:N in liver for both species. Skin and muscle from stranded dolphins and manatees are representative of their corresponding live populations and can be used for SIA with appropriate caution. To facilitate the use of tissues from stranded animals, tissues should be dried or frozen for storage as soon as possible after sampling. We recommend liver from stranded animals only be used for SIA when researchers need tissues with short turnover times and can access fresh samples. Without consideration of decomposition effects on isotope values, ecologists may make inaccurate inferences about habitat use, diet, and community structure. Careful use of SIA on tissues from stranded animals can help researchers provide better quality information for managers and policymakers. ### Purpose This file contains two datasheets. The first sheet, titled read.me, contains column title information for the second sheet. The second sheet, title Data, contains data on stable isotope values from live and dead stranded dolphins and manatees as well as the tissue sampled (liver, skin, muscle), the condition code specifying whether the sample was from a live or dead animal and, if dead, the decomposition code at time of sampling. This sheet also contains information on the year of sampling, the total amount of carbon and nitrogen in the sample. Samples from live dolphins were from Mobile Bay, AL during 2019 and 2020. Samples from stranded animals were from 2011-2019 from coastal Alabama waters. Samples from live manatees were taken from animals between 2009-2017. Samples from stranded manatees were taken between 2008-2017. These data were used to test the first two objectives in the study outlined above. **DOI: ** [10.57778/9xbe-kr37](https://doi.org/10.57778/9xbe-kr37) ### Suggested Citation Cloyed, C., Carmichael, R., Clance, L., & Bouveroux, T. (2022). Stable isotope values of live and stranded dolphins and manatees from the northern Gulf of Mexico [Data set]. Dauphin Island Sea Lab. https://doi.org/10.57778/9XBE-KR37 ### Related Publication Citation Cloyed, C.S., Johnson, C., DaCosta, K.P., Clance, L.R., Russell, M.L., Díaz Clark, C., Hieb, E.E., Carmichael, R.H. (2023). Effects of tissue decomposition on stable isotope ratios and implications for use of stranded animals in research. Ecosphere
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    ### Abstract The dataset includes stable carbon and nitrogen isotope ratios in tissues from bottlenose dolphins in coastal Alabama waters and manatees in the northern Gulf of Mexico, separated into two datasets: 1) Decomposition field study (workbook 1), which includes data from live sampled (skin) and dead stranded (liver, skin, and muscle) individuals relative to the decomposition stage of each individual. Isotope data from live dolphins were obtained using dart biopsy methods on dolphins within Mobile Bay. Isotope data from live manatees were obtained during health assessments and capture events in Alabama waters. Samples from live dolphins were from Mobile Bay, AL during 2019 and 2020. Samples from stranded dolphins were from 2011-2019 from coastal Alabama waters. Samples from live manatees were taken from animals between 2009-2017 and from stranded manatees between 2008-2017. This dataset contains the stable isotope values from live and dead stranded dolphins and manatees as well as the tissue sampled (liver, skin, muscle), the condition code specifying whether the sample was from a live or dead animal and, if dead, the decomposition code at time of sampling. This workbook also contains information on the year of sampling and the total amount of carbon and nitrogen in the sample. 2) Decomposition experiment (workbook 2), which includes stable carbon and nitrogen isotope values in liver, skin, and muscle of one dolphin and one manatee where the samples were left in natural conditions while being sampled for isotope values as they decomposed for 10 days. Subsamples were taken on days 0 (before any experimental decomposition), 1, 3, 6, and 10 to capture potential isotopic changes during decomposition. The dolphin and manatee stranded in coastal Alabama waters in 2019 (dolphin) and 2021 (manatee). This workbook contains stable carbon and nitrogen isotope values, total amount of carbon and nitrogen, tissue type, species, day sampled, and accumulated degree days (ADD), which is the sum of daily temperatures. ### Purpose These data are part of a study to test the validity of using  13 C and  15 N values from tissues of stranded bottlenose dolphins (Tursiops truncatus) and West Indian manatees (Trichechus manatus) for ecological studies. Using a combination of quantifying overlap between stranded and live-captured animals, comparing isotope values from different stages of decomposition, and sampling tissues as they experimentally decomposed, we determined that isotope values between live and dead stranded overlapped in skin but there were greater effects of decomposition occurred in tissues that decompose more quickly, such as liver. Muscle was much less affected by decomposition across the time frame we examined. These effects occurred primarily in stable carbon isotopes and stable nitrogen was less affected. Our results on the decomposition effects on stable isotope values have important implications in the use and interpretation of stable isotopes from stranded individuals. **DOI: ** [10.57778/9xbe-kr37](https://doi.org/10.57778/9xbe-kr37) ### Suggested Citation Cloyed, C., Carmichael, R., Clance, L., & Bouveroux, T. (2022). Stable isotope values of live and stranded dolphins and manatees from the northern Gulf of Mexico [Data set]. Dauphin Island Sea Lab. https://doi.org/10.57778/9XBE-KR37 ### Related Publication Citation Cloyed, C.S., Johnson, C., DaCosta, K.P., Clance, L.R., Russell, M.L., Díaz Clark, C., Hieb, E.E., Carmichael, R.H. (2023). Effects of tissue decomposition on stable isotope ratios and implications for use of stranded animals in research. Ecosphere


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