Philip M. Riekenberg, Bradley D. Eyre, Marcel T. J. van der Meer, Joanne M. Oakes
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Four treatment applications were applied: (1) algal dissolved organic matter (DOM), (2) amino acid mixture, (3) glucose and <span></span><math>\n <mrow>\n <msubsup>\n <mi>NH</mi>\n <mn>4</mn>\n <mo>+</mo>\n </msubsup>\n </mrow></math>, and (4) NaHCO<sub>3</sub> and <span></span><math>\n <mrow>\n <msubsup>\n <mi>NH</mi>\n <mn>4</mn>\n <mo>+</mo>\n </msubsup>\n </mrow></math> to assess bioavailability effects on processing (1 vs. 2) and short-term processing for OM fixed via microphytobenthos only (pennate diatom dominated) (4) vs. material taken up by the entire microbial community (3) across 24 h. <sup>13</sup>C from algal-DOM was preferentially used by the microbial community vs. <sup>15</sup>N. At 24 h more <sup>13</sup>C from algal-DOM remained in microbial biomass indicating use of labeled precursor molecules to form biomass. Conversely, <sup>13</sup>C from the amino acid treatment was not incorporated into biomass and was either rapidly respired to DIC or discarded as the in situ microbial community preferentially used and retained <sup>15</sup>N from amino acids. Short-term export of <sup>13</sup>C as CO<sub>2</sub> from glucose was lower than from microphytobenthos-C, while retention of <sup>15</sup>N from <span></span><math>\n <mrow>\n <msubsup>\n <mi>NH</mi>\n <mn>4</mn>\n <mo>+</mo>\n </msubsup>\n </mrow></math> was similar between treatments (3 and 4) despite doubling the application N concentration, suggesting potentially higher glucose-stimulated <sup>15</sup>N export via nitrification–denitrification that was not confirmed via flux measurements in this study. Despite careful site selection for similar tidal exposure and sediment types among the three estuaries, the uptake and processing of labeled substrate varied substantially between replicates and sites which challenged traditional statistical analysis. Disproportionate processing of substrates occurring in sediment hotspots of microbial activity can cause variability spanning orders of magnitude which was found to be widespread through comparison of our results against 19 previous studies in intertidal settings. Development of robust analytical techniques to handle variability from abiotic and biotic factors will allow greater clarity surrounding in situ biogeochemical processing in intertidal environments.</p>","PeriodicalId":18143,"journal":{"name":"Limnology and Oceanography","volume":"69 10","pages":"2243-2262"},"PeriodicalIF":3.8000,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Hot spots drive uptake and short-term processing of organic and inorganic carbon and nitrogen in intertidal sediments\",\"authors\":\"Philip M. Riekenberg, Bradley D. Eyre, Marcel T. J. van der Meer, Joanne M. Oakes\",\"doi\":\"10.1002/lno.12670\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p>This study uses dual-labeled (<sup>13</sup>C and <sup>15</sup>N) stable isotope applications to examine microbial uptake and short-term processing of carbon (C) and nitrogen (N) from organic and inorganic compounds in subtropical intertidal sediment. Four treatment applications were applied: (1) algal dissolved organic matter (DOM), (2) amino acid mixture, (3) glucose and <span></span><math>\\n <mrow>\\n <msubsup>\\n <mi>NH</mi>\\n <mn>4</mn>\\n <mo>+</mo>\\n </msubsup>\\n </mrow></math>, and (4) NaHCO<sub>3</sub> and <span></span><math>\\n <mrow>\\n <msubsup>\\n <mi>NH</mi>\\n <mn>4</mn>\\n <mo>+</mo>\\n </msubsup>\\n </mrow></math> to assess bioavailability effects on processing (1 vs. 2) and short-term processing for OM fixed via microphytobenthos only (pennate diatom dominated) (4) vs. material taken up by the entire microbial community (3) across 24 h. <sup>13</sup>C from algal-DOM was preferentially used by the microbial community vs. <sup>15</sup>N. At 24 h more <sup>13</sup>C from algal-DOM remained in microbial biomass indicating use of labeled precursor molecules to form biomass. Conversely, <sup>13</sup>C from the amino acid treatment was not incorporated into biomass and was either rapidly respired to DIC or discarded as the in situ microbial community preferentially used and retained <sup>15</sup>N from amino acids. Short-term export of <sup>13</sup>C as CO<sub>2</sub> from glucose was lower than from microphytobenthos-C, while retention of <sup>15</sup>N from <span></span><math>\\n <mrow>\\n <msubsup>\\n <mi>NH</mi>\\n <mn>4</mn>\\n <mo>+</mo>\\n </msubsup>\\n </mrow></math> was similar between treatments (3 and 4) despite doubling the application N concentration, suggesting potentially higher glucose-stimulated <sup>15</sup>N export via nitrification–denitrification that was not confirmed via flux measurements in this study. Despite careful site selection for similar tidal exposure and sediment types among the three estuaries, the uptake and processing of labeled substrate varied substantially between replicates and sites which challenged traditional statistical analysis. Disproportionate processing of substrates occurring in sediment hotspots of microbial activity can cause variability spanning orders of magnitude which was found to be widespread through comparison of our results against 19 previous studies in intertidal settings. Development of robust analytical techniques to handle variability from abiotic and biotic factors will allow greater clarity surrounding in situ biogeochemical processing in intertidal environments.</p>\",\"PeriodicalId\":18143,\"journal\":{\"name\":\"Limnology and Oceanography\",\"volume\":\"69 10\",\"pages\":\"2243-2262\"},\"PeriodicalIF\":3.8000,\"publicationDate\":\"2024-09-26\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Limnology and Oceanography\",\"FirstCategoryId\":\"89\",\"ListUrlMain\":\"https://onlinelibrary.wiley.com/doi/10.1002/lno.12670\",\"RegionNum\":1,\"RegionCategory\":\"地球科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"LIMNOLOGY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Limnology and Oceanography","FirstCategoryId":"89","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1002/lno.12670","RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"LIMNOLOGY","Score":null,"Total":0}
Hot spots drive uptake and short-term processing of organic and inorganic carbon and nitrogen in intertidal sediments
This study uses dual-labeled (13C and 15N) stable isotope applications to examine microbial uptake and short-term processing of carbon (C) and nitrogen (N) from organic and inorganic compounds in subtropical intertidal sediment. Four treatment applications were applied: (1) algal dissolved organic matter (DOM), (2) amino acid mixture, (3) glucose and , and (4) NaHCO3 and to assess bioavailability effects on processing (1 vs. 2) and short-term processing for OM fixed via microphytobenthos only (pennate diatom dominated) (4) vs. material taken up by the entire microbial community (3) across 24 h. 13C from algal-DOM was preferentially used by the microbial community vs. 15N. At 24 h more 13C from algal-DOM remained in microbial biomass indicating use of labeled precursor molecules to form biomass. Conversely, 13C from the amino acid treatment was not incorporated into biomass and was either rapidly respired to DIC or discarded as the in situ microbial community preferentially used and retained 15N from amino acids. Short-term export of 13C as CO2 from glucose was lower than from microphytobenthos-C, while retention of 15N from was similar between treatments (3 and 4) despite doubling the application N concentration, suggesting potentially higher glucose-stimulated 15N export via nitrification–denitrification that was not confirmed via flux measurements in this study. Despite careful site selection for similar tidal exposure and sediment types among the three estuaries, the uptake and processing of labeled substrate varied substantially between replicates and sites which challenged traditional statistical analysis. Disproportionate processing of substrates occurring in sediment hotspots of microbial activity can cause variability spanning orders of magnitude which was found to be widespread through comparison of our results against 19 previous studies in intertidal settings. Development of robust analytical techniques to handle variability from abiotic and biotic factors will allow greater clarity surrounding in situ biogeochemical processing in intertidal environments.
期刊介绍:
Limnology and Oceanography (L&O; print ISSN 0024-3590, online ISSN 1939-5590) publishes original articles, including scholarly reviews, about all aspects of limnology and oceanography. The journal''s unifying theme is the understanding of aquatic systems. Submissions are judged on the originality of their data, interpretations, and ideas, and on the degree to which they can be generalized beyond the particular aquatic system examined. Laboratory and modeling studies must demonstrate relevance to field environments; typically this means that they are bolstered by substantial "real-world" data. Few purely theoretical or purely empirical papers are accepted for review.