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Examining Sources of Primary Production and Bottom-Up Limitations

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Examining Sources of Primary Production and Bottom-Up Limitations Examining sources of primary production and bottom- up limitations in nearshore ecosystems of the northeast Pacific Ocean using fish based indicators Item Type Thesis Authors Biela, Vanessa Rebeca von Download date 04/10/2021 08:22:13 Link to Item http://hdl.handle.net/11122/5766 EXAMINING SOURCES OF PRIMARY PRODUCTION AND BOTTOM-UP LIMITATIONS IN NEARSHORE ECOSYSTEMS OF THE NORTHEAST PACIFIC OCEAN USING FISH BASED INDICATORS By Vanessa Rebeca von Biela RECOMMENDED: Dr. Brjan A. Black Dr. Franz J. Mueter Dr. Stephen'R. Okkonen Dr. Christianristian E.(fcimrimmerman Dr. Gordon H. Kruse, Advisory Committee Chair Dr. Shannon Atkinson, Chair, Graduate Program in Fisheries APPROVED: Braddoek Ocean Sciences Graduate School EXAMINING SOURCES OF PRIMARY PRODUCTION AND BOTTOM-UP LIMITATIONS IN NEARSHORE ECOSYSTEMS OF THE NORTHEAST PACIFIC OCEAN USING FISH BASED INDICATORS A THESIS Presented to the Faculty of the University of Alaska Fairbanks in Partial Fulfillment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY By Vanessa Rebeca von Biela, B.S., M.S. Fairbanks, Alaska May 2015 Abstract Our ability to forecast the fate of ecosystems and species hinges on an understanding of how biological systems respond to their environment. In this dissertation, natural indicators of diet (stable isotopes) and production (otolith growth increment width) in two common fishes were used to investigate energy pathways and biophysical relationships in nearshore kelp forests spanning two large marine ecosystems with contrasting oceanography, the upwelling system of the California Current and the downwelling system of the Alaska Coastal Current. Stable isotope analysis indicated high proportions of kelp-derived carbon in two common predatory fish, pelagic-feeding Black Rockfish and benthic-feeding Kelp Greenling. Routinely using both kelp and phytoplankton energy channels reflects strong benthic-pelagic coupling in nearshore marine food webs and may confer food web resilience to perturbations in either energy channel. A network of annual otolith growth chronologies were used to test bottom-up limits of production for nearshore systems and later explore other possible correlates of production. Results of hypothesis tests were consistent with bottom-up forcing of nearshore marine ecosystems, with light and nutrients constraining primary production in pelagic food webs and temperature constraining benthic food webs. A separate exploratory analysis indicated that biophysical relationships were common with (1-2 years) and without time lags and suggested that differences in the abundance and quality of prey influenced the growth of fish through bottom-up processes. The findings from the separate exploratory analysis were generally consistent with findings from hypothesis testing. Lagged relationships were consistent with increasing higher nearshore prey abundance during warm conditions in the Alaska Coastal Current and during cool conditions in the California Current in both pelagic and benthic food webs. Relationships without time lags indicated that benthic prey quality increased during warm v conditions in both current systems, while the quality of pelagic nearshore prey increased during cool conditions in the California Current and warm conditions in the Alaska Current. Overall, results of this dissertation demonstrate that kelp provides a source of energy to higher trophic level predators and that continued warming will likely have a negative influence at lower latitudes first (e.g., California Current), while production in higher latitudes (e.g., Gulf of Alaska) may initially increase. vi Table of Contents Page Signature Page ............................................................................................................................................ i Title Page................................................................................................................................................... iii Abstract ........................................................................................................................................................ v Table of Contents.....................................................................................................................................vii List of Figures............................................................................................................................................xi List of Tables.......................................................................................................................................... xiii List of Appendices................................................................................................................................... xv Acknowledgments.................................................................................................................................xvii Introduction................................................................................................................................................. 1 Chapter 1: Widespread kelp-derived carbon in pelagic and benthic nearshore fishes..................... 7 1.1 Introduction........................................................................................................................ 7 1.2 Methods............................................................................................................................. 11 1.2.1 Sample collection and stable isotope analysis...................................................... 11 1.2.2 Statistics and stable isotope mixing models..........................................................12 1.3 Results............................................................................................................................... 16 1.4 Discussion..........................................................................................................................17 1.4.1 Change in 5 13C with fish length............................................................................. 18 1.4.2 Differences in 513C between black rockfish and kelp greenling.........................19 1.4.3 Differences in kelp versus phytoplankton-derived carbon use among sites 19 1.5 Acknowledgements......................................................................................................... 24 1.6 Literature cited..................................................................................................................25 1.7 Appendices....................................................................................................................... 42 vii Page Chapter 2: Evidence of bottom-up limitations in nearshore marine systems based on otolith proxies of fish growth..............................................................................................................................45 2.1 Introduction...................................................................................................................... 46 2.2 Methods.............................................................................................................................51 2.3 R esults...............................................................................................................................57 2.4 Discussion..........................................................................................................................58 2.4.1 Sea surface temperature........................................................................................... 59 2.4.2 Upwelling and chlorophyll......................................................................................62 2.4.3 Research and management implications................................................................66 2.4.4 Conclusions................................................................................................................67 2.5 Acknowledgements......................................................................................................... 67 2.6 References........................................................................................................................ 68 2.7 Appendices....................................................................................................................... 89 Chapter 3: Influence of basin and local-scale conditions on nearshore production in the northeast Pacific Ocean............................................................................................................................................91 3.1 Introduction...................................................................................................................... 92 3.2 M ethods.............................................................................................................................95 3.3 R esults............................................................................................................................. 101 3.4 Discussion........................................................................................................................104 viii Page 3.4.1 Black Rockfish, California Current..................................................................... 105 3.4.2 Black Rockfish, Alaska Coastal Current .............................................................107 3.4.3 Kelp Greenling, California Current..................................................................... 108 3.4.4 Kelp Greenling, Alaska Coastal Current.............................................................110
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