{"title":"In situ benthic community response to a phytodetritus pulse in the Cabo Verde Abyssal Basin (tropical NE Atlantic)","authors":"","doi":"10.1016/j.pocean.2024.103340","DOIUrl":null,"url":null,"abstract":"<div><p>Ecosystem functioning, i.e. the transfer of material through a system, supports the ecosystem services deep-sea sediments provide, including carbon sequestration, nutrient regeneration, and climate regulation. To date, seven studies globally have researched <em>in situ</em> how various benthic groups contribute to organic matter degradation in abyssal sediments through stable isotope tracer experiments, of which only one in the Atlantic (at the Porcupine Abyssal Plain or PAP). To expand the limited knowledge base on abyssal ecosystem functioning, we performed <em>in situ</em> stable isotope experiments in the Cabo Verde Abyssal Basin (CVAB, tropical North-East Atlantic). The Cabo Verde marine region is an oceanographically interesting region with complex currents, resulting in strong gradients of productivity and unique ecological characteristics. We conducted 2-day <em>in situ</em> incubations with organic substrate (lyophilised diatom culture) labelled with <sup>13</sup>C and <sup>15</sup>N stable isotopes through five benthic lander deployments to 4,200 m in an area presumed mesotrophic. We assessed sediment community oxygen consumption (SCOC), dissolved inorganic carbon (DI<sup>13</sup>C) production, nutrient fluxes, and label incorporation into bacteria, large Foraminifera (>300 μm), meiobenthos, and macrofauna. Results were specifically compared across the Atlantic basin to the eutrophic PAP for which all the same system components were reported (<span><span>Witte et al. 2003</span></span>). At CVAB, bacteria and meiobenthos dominated phytodetritus processing (91% and 8%, respectively), in contrast to PAP where macrofauna dominated (98%). Phytodetritus remineralisation was two to three times lower at CVAB compared to PAP, most likely due to the low abundance of fast responding macrofauna. However, overall phytodetritus processing efficiency at CVAB was four times greater compared to PAP. Our results support a mesotrophic regime at the CVAB lander site, and provide a unique first insight into ecosystem functioning of tropical (low-latitude) abyssal systems in the Atlantic Ocean. A better understanding of abyssal ecosystem functioning in various ocean regions, to which this study contributes, provides insight into main regulators of abyssal communities and thus may have implications for our understanding of abyssal systems under future climate scenarios.</p></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":null,"pages":null},"PeriodicalIF":3.8000,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0079661124001460/pdfft?md5=05eafde81c0c66ed00e5ceefe336e1f6&pid=1-s2.0-S0079661124001460-main.pdf","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Progress in Oceanography","FirstCategoryId":"89","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0079661124001460","RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"OCEANOGRAPHY","Score":null,"Total":0}
引用次数: 0
Abstract
Ecosystem functioning, i.e. the transfer of material through a system, supports the ecosystem services deep-sea sediments provide, including carbon sequestration, nutrient regeneration, and climate regulation. To date, seven studies globally have researched in situ how various benthic groups contribute to organic matter degradation in abyssal sediments through stable isotope tracer experiments, of which only one in the Atlantic (at the Porcupine Abyssal Plain or PAP). To expand the limited knowledge base on abyssal ecosystem functioning, we performed in situ stable isotope experiments in the Cabo Verde Abyssal Basin (CVAB, tropical North-East Atlantic). The Cabo Verde marine region is an oceanographically interesting region with complex currents, resulting in strong gradients of productivity and unique ecological characteristics. We conducted 2-day in situ incubations with organic substrate (lyophilised diatom culture) labelled with 13C and 15N stable isotopes through five benthic lander deployments to 4,200 m in an area presumed mesotrophic. We assessed sediment community oxygen consumption (SCOC), dissolved inorganic carbon (DI13C) production, nutrient fluxes, and label incorporation into bacteria, large Foraminifera (>300 μm), meiobenthos, and macrofauna. Results were specifically compared across the Atlantic basin to the eutrophic PAP for which all the same system components were reported (Witte et al. 2003). At CVAB, bacteria and meiobenthos dominated phytodetritus processing (91% and 8%, respectively), in contrast to PAP where macrofauna dominated (98%). Phytodetritus remineralisation was two to three times lower at CVAB compared to PAP, most likely due to the low abundance of fast responding macrofauna. However, overall phytodetritus processing efficiency at CVAB was four times greater compared to PAP. Our results support a mesotrophic regime at the CVAB lander site, and provide a unique first insight into ecosystem functioning of tropical (low-latitude) abyssal systems in the Atlantic Ocean. A better understanding of abyssal ecosystem functioning in various ocean regions, to which this study contributes, provides insight into main regulators of abyssal communities and thus may have implications for our understanding of abyssal systems under future climate scenarios.
期刊介绍:
Progress in Oceanography publishes the longer, more comprehensive papers that most oceanographers feel are necessary, on occasion, to do justice to their work. Contributions are generally either a review of an aspect of oceanography or a treatise on an expanding oceanographic subject. The articles cover the entire spectrum of disciplines within the science of oceanography. Occasionally volumes are devoted to collections of papers and conference proceedings of exceptional interest. Essential reading for all oceanographers.