{"id":1888,"date":"2022-10-05T12:46:16","date_gmt":"2022-10-05T04:46:16","guid":{"rendered":"https:\/\/www.oceanecol.com\/?p=1888"},"modified":"2022-10-05T12:48:39","modified_gmt":"2022-10-05T04:48:39","slug":"new-paper-on-feeding-strategies-of-planktivorous-fishes-skinner-et-al-front-ecol-evol","status":"publish","type":"post","link":"https:\/\/www.oceanecol.com\/?p=1888","title":{"rendered":"New paper on feeding strategies of planktivorous fishes (Skinner et. al., Front. Ecol. Evol.)"},"content":{"rendered":"

Stable isotopes elucidate body-size and seasonal fluctuations in the feeding strategies of planktivorous fishes across a semi-enclosed tropical embayment<\/a><\/h1>\n

Christina Skinner<\/span>1<\/sup>, Yu-De Pei<\/span>1<\/sup>, Naoko Morimoto2<\/sup>, Toshihiro Miyajima2<\/sup>, Alex S.J. Wyatt<\/strong>1,3<\/sup><\/p>\n

1<\/sup>Department of Ocean Science, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong. <\/em>2<\/sup>Atmosphere and Ocean Research Institute, The University of Tokyo, Japan.<\/em> 3<\/sup>Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, China.\u00a0<\/em><\/p>\n

Reef fish may switch feeding strategies due to fluctuations in resource availability or through ontogeny. A number of studies have explored these trophodynamics using carbon (\u03b413<\/sup>C) and nitrogen (\u03b415<\/sup>N) stable isotopes, but additional tracers such as sulfur isotopes (\u03b434<\/sup>S) show strong potential in systems where \u03b413<\/sup>C and \u03b415N results are ambiguous. We tested the utility of adding \u03b434<\/sup>S to conventional \u03b413C and \u03b415<\/sup>N analysis to detect seasonal and body size changes in resource use of two planktivorous damselfish, Dascyllus reticulatus<\/em> and D. trimaculatus<\/em> across the Puerto Galera embayment in the Philippines. We analysed stable isotope ratios (\u03b413<\/sup>C, \u03b415<\/sup>N, and \u03b434<\/sup>S) in multiple fish tissues (liver, eye, muscle) to represent different dietary timeframes. We then compared fish tissue isotopes against particulate organic matter (POM: \u03b413<\/sup>C and \u03b415<\/sup>N) and POM suspension feeder (the tunicate Polycarpa aurata<\/em>: \u03b413<\/sup>C, \u03b415<\/sup>N, and \u03b434<\/sup>S) across the same sites. There were size-based and seasonal differences in damselfish resource use, the latter of which were most pronounced in fast-turnover liver. Small fish (< 70 mm) demonstrated significant seasonality, appearing to switch their resource use between the rainy season and the dry season, while there was no seasonal variation in larger fish (>70 mm). This suggests that smaller fish across the embayment employ an opportunistic feeding strategy to take advantage of fluctuating resource availability, while larger fish exhibit more consistent resource use. Isotope ratios of tunicates and POM further confirmed strong seasonality in this system, and a lack of a spatial isotopic gradient. \u03b415<\/sup>N did not seem to contribute to consumer resource use patterns, while by contrast, \u03b434<\/sup>S fluctuated significantly between sampling periods and was crucial for demonstrating seasonality in resource use. We recommend including \u03b434<\/sup>S when attempting to disentangle seasonal differences in resource use in aquatic food webs using stable isotopes..<\/p><\/blockquote>\n

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