Trophic structure of the eastern Chukchi Sea PDF
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NOAA Technical Memorandum NMFS-AFSC-318 doi:10.7289/V5/TM-AFSC-318 Trophic Structure of the Eastern Chukchi Sea: An Updated Mass Balance Food Web Model G. A. Whitehouse and K. Y. Aydin U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Marine Fisheries Service Alaska Fisheries Science Center April 2016 NOAA Technical Memorandum NMFS The National Marine Fisheries Service's Alaska Fisheries Science Center uses the NOAA Technical Memorandum series to issue informal scientific and technical publications when complete formal review and editorial processing are not appropriate or feasible. Documents within this series reflect sound professional work and may be referenced in the formal scientific and technical literature. The NMFS-AFSC Technical Memorandum series of the Alaska Fisheries Science Center continues the NMFS-F/NWC series established in 1970 by the Northwest Fisheries Center. The NMFS-NWFSC series is currently used by the Northwest Fisheries Science Center. This document should be cited as follows: Whitehouse, G. A., and K. Y. Aydin. 2016. Trophic structure of the eastern Chukchi Sea: An updated mass balance food web model. U.S. Dep. Commer., NOAA Tech. Memo. NMFS-AFSC-318, 175 p. doi:10.7289/V5/TM-AFSC-318. Document available: http://www.afsc.noaa.gov/Publications/AFSC-TM/NOAA-TM-AFSC-318.pdf Reference in this document to trade names does not imply endorsement by the National Marine Fisheries Service, NOAA. NOAA Technical Memorandum NMFS-AFSC-318 doi:10.7289/V5/TM-AFSC-318 Trophic Structure of the Eastern Chukchi Sea: An Updated Mass Balance Food Web Model by G. A. Whitehouse1,2, and K. Y. Aydin1 1Resource Ecology and Fisheries Management Division Alaska Fisheries Science Center National Marine Fisheries Service National Oceanic and Atmospheric Administration 7600 Sand Point Way NE Seattle, WA 98115 2Joint Institute for the Study of the Atmosphere and Ocean University of Washington Box 354925 Seattle, WA 98195 U.S. DEPARTMENT OF COMMERCE Penny. S. Pritzker, Secretary National Oceanic and Atmospheric Administration Kathryn D. Sullivan, Under Secretary and Administrator National Marine Fisheries Service Eileen Sobeck, Assistant Administrator for Fisheries April 2016 This document is available to the public through: National Technical Information Service U.S. Department of Commerce 5285 Port Royal Road Springfield, VA 22161 www.ntis.gov ABSTRACT This is a 2010s update of the previous 1990s Ecopath trophic mass balance model of the eastern Chukchi Sea. In the time since the original 1990s model was developed, a number of datasets have been produced and several reports and journal articles published documenting the findings of recent field studies in the eastern Chukchi Sea, including the completion of the BOEM-funded Arctic Ecosystem Integrated Survey (Arctic Eis). In this report we use published and unpublished datasets from many of these recent studies to update several input parameters from the preliminary 1990s Ecopath model of eastern Chukchi Sea, so it is more representative of the current (2010s) state of the eastern Chukchi Sea food web. Overall, 93 input parameters were updated and the data quality was improved for 34 parameters. A total of 9 new functional groups were added, 6 for seabirds and 3 for fish. Here we document all model parameters that we were able to update with improved information, including estimates of biomass, production, consumption, and diet composition. Changes in the included species, the species composition of functional groups, and their related parameters resulted in higher biomass for marine mammals, seabirds, fish and zooplankton, and decreased biomass for benthic invertebrates, jellies, microbes, and phytoplankton. Additionally, we calculate several ecosystem-level metrics for both models and compare the results between the original model and our updated model. In both models, benthic invertebrates represent the dominant portion of total ecosystem biomass, and energy flow is dominated by benthic resources. Total energy flow, total production, total biomass, and net primary production decreased from the preliminary model to the updated model. A key result common to both the preliminary model and the updated model is that trawl-survey-derived estimates of demersal fish biomass were insufficient to balance the model. Fish biomass needed to be several times greater to meet the modeled trophic demand from predators. Changes in the ecosystem metrics are the reflection of the updated and improved (higher quality) model inputs, and do not necessarily reflect any change in ecosystem state between the two model time periods. Given the number of updated parameters and improved data quality in the updated model (2010s), we recommend using the updated model over the preliminary model (1990s) for future modeling studies and as a baseline of this system’s food web. iii CONTENTS Abstract ........................................................................................................................................................ iii Figures .......................................................................................................................................................... ix Tables ........................................................................................................................................................... xi Introduction .................................................................................................................................................. 1 Methods ........................................................................................................................................................ 3 Study System .................................................................................................................................... 3 General Methodology for the Model Update .................................................................................. 6 Modeling Framework ....................................................................................................................... 6 Data Sources and Data Quality ........................................................................................................ 8 Cetaceans ....................................................................................................................................... 12 Caniforms ....................................................................................................................................... 13 Seabirds .......................................................................................................................................... 15 New seabird functional groups ......................................................................................... 15 Fish ................................................................................................................................................. 20 New and changed fish functional groups ......................................................................... 25 Benthic Invertebrates .................................................................................................................... 28 Model Comparisons ....................................................................................................................... 30 Results ......................................................................................................................................................... 31 Outline ........................................................................................................................................... 31 Cetaceans ....................................................................................................................................... 32 Beluga ............................................................................................................................... 32 Gray whale ........................................................................................................................ 32 Bowhead whale ................................................................................................................ 33 Caniforms ....................................................................................................................................... 34 Polar bear (Chukchi stock) ................................................................................................ 34 Polar bear (Southern Beaufort stock) ............................................................................... 35 Pacific walrus .................................................................................................................... 36 Bearded seal ..................................................................................................................... 37 v Ringed seal ........................................................................................................................ 38 Spotted seal ...................................................................................................................... 39 Seabirds .......................................................................................................................................... 40 All seabirds ........................................................................................................................ 40 Procellarids ....................................................................................................................... 45 Cormorants ....................................................................................................................... 47 Scolopacids ....................................................................................................................... 48 Larids ................................................................................................................................. 49 Alcids piscivorous .............................................................................................................. 52 Alcids planktivorous .......................................................................................................... 56 Fish ................................................................................................................................................. 59 All fish functional groups .................................................................................................. 59 Large-mouth flatfish ......................................................................................................... 59 Small-mouth flatfish.......................................................................................................... 61 Large-mouth sculpin ......................................................................................................... 62 Other sculpins ................................................................................................................... 63 Eelpouts ............................................................................................................................ 64 Pelagic forage fish ............................................................................................................. 65 Miscellaneous shallow fish ............................................................................................... 66 Other snailfish ................................................................................................................... 67 Variegated snailfish ........................................................................................................... 68 Alaska skate ...................................................................................................................... 69 Walleye pollock ................................................................................................................. 71 Pacific cod ......................................................................................................................... 72 Saffron cod ........................................................................................................................ 73 Arctic cod .......................................................................................................................... 74 Salmon outgoing ............................................................................................................... 75 Salmon returning .............................................................................................................. 76 Benthic Invertebrates .................................................................................................................... 77 Cephalopods ..................................................................................................................... 77 Bivalves ............................................................................................................................. 78 Snails ................................................................................................................................. 79 Snow crab ......................................................................................................................... 80 Other crabs ....................................................................................................................... 82 Shrimps ............................................................................................................................. 82 vi Sea stars ............................................................................................................................ 83 Brittle stars ........................................................................................................................ 84 Basket stars ....................................................................................................................... 85 Urchins, dollars, cucumbers .............................................................................................. 86 Sponge .............................................................................................................................. 87 Benthic urochordate ......................................................................................................... 88 Anemones ......................................................................................................................... 89 Corals ................................................................................................................................ 89 Benthic Amphipods ........................................................................................................... 90 Polychaetes ....................................................................................................................... 90 Worms, etc. ....................................................................................................................... 92 Miscellaneous crustaceans ............................................................................................... 93 Pelagic Invertebrates and Microbes .............................................................................................. 94 Jellyfish .............................................................................................................................. 94 Copepods .......................................................................................................................... 95 Other zooplankton ............................................................................................................ 96 Pelagic microbes ............................................................................................................... 96 Benthic microbes .............................................................................................................. 97 Phytoplankton ................................................................................................................................ 98 Detritus ........................................................................................................................................ 100 Model Balancing .......................................................................................................................... 102 Model Comparisons ..................................................................................................................... 104 Updated model versus preliminary model ..................................................................... 104 DISCUSSION ............................................................................................................................................... 111 Fish ............................................................................................................................................... 112 Conclusions ............................................................................................................................................... 118 Acknowledgments ..................................................................................................................................... 120 Citations .................................................................................................................................................... 121 Appendix A ................................................................................................................................................ 165 Diet Matrix ................................................................................................................................... 165 Appendix B ................................................................................................................................................ 173 Data Pedigree ............................................................................................................................... 173 vii
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