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Fao/Government Cooperative Programme Scientific Basis for Ecosystem-Based Management in the Lesser Antilles Including Interactio

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Fao/Government Cooperative Programme Scientific Basis for Ecosystem-Based Management in the Lesser Antilles Including Interactio FI:GCP/RLA/140/JPN TECHNICAL DOCUMENT No. 8 FAO/GOVERNMENT COOPERATIVE PROGRAMME SCIENTIFIC BASIS FOR ECOSYSTEM-BASED MANAGEMENT IN THE LESSER ANTILLES INCLUDING INTERACTIONS WITH MARINE MAMMALS AND OTHER TOP PREDATORS THE APPLICATION OF STABLE ISOTOPE ANALYSIS IN MARINE ECOSYSTEMS FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS Barbados, 2008 FI:GCP/RLA/140/JPN TECHNICAL DOCUMENT No. 8 FAO/GOVERNMENT COOPERATIVE PROGRAMME SCIENTIFIC BASIS FOR ECOSYSTEM-BASED MANAGEMENT IN THE LESSER ANTILLES INCLUDING INTERACTIONS WITH MARINE MAMMALS AND OTHER TOP PREDATORS THE APPLICATION OF STABLE ISOTOPE ANALYSIS IN MARINE ECOSYSTEMS Report prepared for the Lesser Antilles Pelagic Ecosystem Project (GCP/RLA/140/JPN) by M. Aaron MacNeil School of Marine Sciences and Technology, University of Newcastle, Newcastle upon Tyne, NE1 7RU, UK FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS Barbados, 2008 The designations employed and the presentation of material in this information product do not imply the expression of any opinion whatsoever on the part of the Food and Agriculture Organization of the United Nations (FAO) concerning the legal or development status of any country, territory, city or area or of its authorities,or concerning the delimitation of its frontiers or boundaries. The mention of specific companies or products of manufacturers, whether or not these have been patented, does not imply that these have been endorsed or recommended by FAO in preference to others of a similar nature that are not mentioned. The views expressed in this information product are those of the author(s) and do not necessarily reflect the views of FAO. All rights reserved. Reproduction and dissemination of material in this information product for educational or other non-commercial purposes are authorized without any prior written permission from the copyright holders provided the source is fully acknowledged. Reproduction of material in this information product for resale or other commercial purposes is prohibited without written permission of the copyright holders. Applications for such permission should be addressed to: Chief Electronic Publishing Policy and Support Branch Communication Division FAO Viale delle Terme di Caracalla, 00153 Rome, Italy or by e-mail to: [email protected] © FAO 2008 ABSTRACT Scientific Basis for Ecosystem-Based Management in the Lesser Antilles Including Interactions with Marine Mammals and Other Top Predators: The application of stable isotope analysis in marine ecosystems, by M. Aaron MacNeil. FAO, Barbados, 2008. xii + 97 pp. , 10 Tables and 31 Figures. FI:GCP/RLA/140/JPN. Technical Document No. 8 Stable isotope analysis has become common in ecology, particularly in the aquatic sciences, to describe energy flow and food-web structure. Biochemical properties of stable isotopes affect their distribution in biological materials and, through processes of synthesis and metabolism, record an animal’s dietary history in its tissues. Carbon and nitrogen have been the primary isotopes used in food web studies, recording source and trophic information respectively. But the application of stable isotopes in ecological studies is new, and many of their biochemical properties have yet to be analysed. Problems such as missed sources, uncertainties in fractionation, and differences among species and tissues must be recognized. This paper reviews the basics of stable isotope chemistry and the roles of nitrogen and carbon isotopes in ecosystem studies. It also provides examples from a decade of stable isotope research while presenting the most current stable isotope models, and provides a bibliography of stable isotope literature. Sampling protocols for marine systems are included in an appendix. While stable isotopes can be powerful tracers in aquatic systems, substantial care is needed in their application and interpretation. Keywords: Ecosystem Approach to Fisheries; Diet Analysis; Stable Isotope; Lesser Antilles; Pelagic Ecosystem iii iv TABLE OF CONTENTS LIST OF FIGURES.......................................................................................................VII LIST OF TABLES.......................................................................................................... XI LIST OF TABLES.......................................................................................................... XI GLOSSARY ..................................................................................................................XII GLOSSARY ..................................................................................................................XII 1 BACKGROUND ................................................................................................... 1 PART 1 – REVIEW OF STABLE ISOTOPES IN MARINE ECOLOGY .................. 3 1 STABLE ISOTOPE ANALYSIS IN ECOLOGY ................................................ 3 2 STABLE ISOTOPE CHEMISTRY ....................................................................... 5 2.1 Nitrogen ............................................................................................................ 7 2.1.1 Nitrogen as a Biomarker ....................................................................... 7 2.1.2 Physiological Properties........................................................................ 8 2.1.3 Spatial Considerations......................................................................... 10 2.2 Carbon ............................................................................................................. 11 2.2.1 Carbon as a Biomarker ........................................................................ 11 2.2.2 Physiological Properties...................................................................... 12 2.2.3 Spatial Considerations......................................................................... 15 3 ECOLOGICAL APPLICATIONS ..................................................................... 17 3.1 Tracing Dietary Sources................................................................................ 17 3.1.1 Salmon Nutrients in Alaskan Streams .............................................. 17 3.1.2 Tracer Addition to Detect a Benthic-Pelagic Couple ...................... 20 3.1.3 Feeding Habitats for Juvenile Reef Fish in Spanish Water Bay..... 21 3.2 Elucidating Food-Web Structure................................................................. 24 3.2.1 Food Webs of the Rocky Mediterranean........................................... 24 3.2.2 Trophic Relationships in the Arctic ................................................... 26 3.2.3 Tracking Long-Term Changes in Trophic Level.............................. 29 3.3 Applied Ecological Questions...................................................................... 31 3.3.1 Size Based Trophic Structure.............................................................. 31 3.3.2 Tracking Invasion Effects on Food Web Structure.......................... 34 3.3.3 Ecosystem Implications of Increases in Jellyfish ............................. 37 3.4 Species-Specific Questions ........................................................................... 39 3.4.1 Tuna and Dolphin Associations in the Northeast Atlantic ............ 39 3.5 Source Models ................................................................................................ 42 v 3.5.1 Two-Source Models..............................................................................42 3.5.2 Multi-Source Models............................................................................43 3.6 Potential Ecosystem Prediction Models......................................................51 4 SAMPLING CONSIDERATIONS FOR STABLE ISOTOPES IN MARINE ECOSYSTEMS .............................................................................................52 4.1 Sample Quality ...............................................................................................52 4.1.1 Guidelines..............................................................................................54 4.2 Sample Quantity.............................................................................................54 4.2.1 Guidelines..............................................................................................54 4.3 Laboratory Preparation .................................................................................54 4.3.1 Guidelines..............................................................................................56 PART 2 - ANALYSIS OF STABLE ISOTOPES SAMPLES FROM THE LESSER ANTILLES PELAGIC ECOSYSTEM PROJECT .......................................................57 1 OVERVIEW..........................................................................................................57 2 SPATIAL STRUCTURE......................................................................................57 3 SIZE-BASED TROPHIC STRUCTURE ............................................................59 4 COMMUNITY METRICS ..................................................................................61 5 ONTOGENETIC SHIFTS...................................................................................64 6 FUNCTIONAL GROUP RESULTS ..................................................................64 7 REFERENCES......................................................................................................86 APPENDIX 1 FIELD SAMPLING PROTOCOL ...................................................94 A 1.2 Sampling Plankton.........................................................................................94
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