Samuel Q. Mazoudier , Michael J. Kingsford , Jessica K. Strickland , Kylie A. Pitt
{"title":"Stable isotopes reveal sargassum rafts provide a trophic subsidy to juvenile pelagic fishes","authors":"Samuel Q. Mazoudier , Michael J. Kingsford , Jessica K. Strickland , Kylie A. Pitt","doi":"10.1016/j.ecss.2023.108548","DOIUrl":null,"url":null,"abstract":"<div><p>Floating macroalgal rafts can form extensive habitat in coastal waters and support abundant and diverse communities of juvenile fishes. Rafts comprised predominantly of <em>Sargassum</em> spp. are common within the Ningaloo Coast World Heritage Area, Western Australia, and may be an important transitional habitat for pre-settlement coastal fishes. We had three aims: 1) to quantify the diversity and abundance of fishes associated with <em>Sargassum</em> rafts; 2) to use stable isotopes to determine whether fishes associating with rafts preyed on nearby plankton or on prey associated with <em>Sargassum</em>; and 3) to determine whether the food web fishes relied upon was ultimately supported by primary production of <em>Sargassum</em> or planktonic phytoplankton (measured as seston). Fishes and macroinvertebrates associating with <em>Sargassum</em> rafts, zooplankton, and seston were collected at six sites in the Ningaloo Marine Park and analysed for δ<sup>15</sup>N and δ<sup>13</sup>C, and the diets of the most common fishes were analysed using MixSIAR. Fishes were more abundant around macroalgal rafts than in open water. Eleven species of juvenile fishes associated with <em>Sargassum</em> rafts, with one species (<em>Histrio histrio</em> (Antennariidae)) represented by juveniles and adults. Four of the five fishes most sampled around <em>Sargassum</em> spp. rafts, (<em>Abudefduf vaigiensis</em> (Pomacentridae)<em>, Helotes sexlineatus</em> (Terapontidae), <em>Colurodontis paxmani</em> (Monacanthidae) and <em>Petroscirtes breviceps</em> (Blenniidae)) had generalist diets whose food webs were ultimately supported by greater contributions of primary production from <em>Sargassum</em> spp. (55–72%) than planktonic seston. <em>H. histrio</em> was predominantly piscivorous but still derived most (64%) of its organic matter indirectly from <em>Sargassum</em> spp. Our results reveal the importance of <em>Sargassum</em> rafts as habitat that provides shelter and food for juvenile fishes and adult <em>H. histrio</em>. Moreover, the prevalence of juvenile fishes associating with <em>Sargassum</em> rafts highlights a bidirectional form of benthic-pelagic coupling whereby macroalgae that detach from the benthos provide habitat and a trophic subsidy for pelagic juvenile fishes before they the transition into benthic coastal habitats.</p></div>","PeriodicalId":50497,"journal":{"name":"Estuarine Coastal and Shelf Science","volume":null,"pages":null},"PeriodicalIF":2.6000,"publicationDate":"2023-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0272771423003384/pdfft?md5=300569dd014ccdfa8b2fde78b1dfbfaa&pid=1-s2.0-S0272771423003384-main.pdf","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Estuarine Coastal and Shelf Science","FirstCategoryId":"89","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0272771423003384","RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"MARINE & FRESHWATER BIOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
Floating macroalgal rafts can form extensive habitat in coastal waters and support abundant and diverse communities of juvenile fishes. Rafts comprised predominantly of Sargassum spp. are common within the Ningaloo Coast World Heritage Area, Western Australia, and may be an important transitional habitat for pre-settlement coastal fishes. We had three aims: 1) to quantify the diversity and abundance of fishes associated with Sargassum rafts; 2) to use stable isotopes to determine whether fishes associating with rafts preyed on nearby plankton or on prey associated with Sargassum; and 3) to determine whether the food web fishes relied upon was ultimately supported by primary production of Sargassum or planktonic phytoplankton (measured as seston). Fishes and macroinvertebrates associating with Sargassum rafts, zooplankton, and seston were collected at six sites in the Ningaloo Marine Park and analysed for δ15N and δ13C, and the diets of the most common fishes were analysed using MixSIAR. Fishes were more abundant around macroalgal rafts than in open water. Eleven species of juvenile fishes associated with Sargassum rafts, with one species (Histrio histrio (Antennariidae)) represented by juveniles and adults. Four of the five fishes most sampled around Sargassum spp. rafts, (Abudefduf vaigiensis (Pomacentridae), Helotes sexlineatus (Terapontidae), Colurodontis paxmani (Monacanthidae) and Petroscirtes breviceps (Blenniidae)) had generalist diets whose food webs were ultimately supported by greater contributions of primary production from Sargassum spp. (55–72%) than planktonic seston. H. histrio was predominantly piscivorous but still derived most (64%) of its organic matter indirectly from Sargassum spp. Our results reveal the importance of Sargassum rafts as habitat that provides shelter and food for juvenile fishes and adult H. histrio. Moreover, the prevalence of juvenile fishes associating with Sargassum rafts highlights a bidirectional form of benthic-pelagic coupling whereby macroalgae that detach from the benthos provide habitat and a trophic subsidy for pelagic juvenile fishes before they the transition into benthic coastal habitats.
期刊介绍:
Estuarine, Coastal and Shelf Science is an international multidisciplinary journal devoted to the analysis of saline water phenomena ranging from the outer edge of the continental shelf to the upper limits of the tidal zone. The journal provides a unique forum, unifying the multidisciplinary approaches to the study of the oceanography of estuaries, coastal zones, and continental shelf seas. It features original research papers, review papers and short communications treating such disciplines as zoology, botany, geology, sedimentology, physical oceanography.