Seabird Habitat Use And Zooplankton Abundance And Biomass In Relation To Water Mass Properties In The Northern Gulf Of Alaska Item Type Thesis Authors De Sousa, Leandra Download date 26/09/2021 02:51:03 Link to Item http://hdl.handle.net/11122/9077 SEABIRD HABITAT USE AND ZOOPLANKTON ABUNDANCE AND BIOMASS IN RELATION TO WATER MASS PROPERTIES IN THE NORTHERN GULF OF ALASKA By Leandra de Sousa RECOMMENDED: Dr. Ronald Barry Dr. Alan Springer C / k—' Dr. George HunOr. 1 ^ rr— __________ Dr. Thomas“Wjei^gamier, Advisory Committee Co-Chair Dr. Kgnneth Coyle, A ^s^p C o m m ittee Chair f5r. Katrin Iken Head, Program in Marine Science and Limnology APPROVED: Dr. Michael Castellini Dean, School ofErsheries and Ocean Sciences /K _________ Dr. Laurence Duffy, Dean of the Gradj/ate School SEABIRD HABITAT USE AND ZOOPLANKTON ABUNDANCE AND BIOMASS IN RELATION TO WATER MASS PROPERTIES IN THE NORTHERN GULF OF ALASKA 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 Leandra de Sousa, B.S. and Licensed Teacher Fairbanks, Alaska August 2011 UMI Number: 3484667 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. UMI' Dissertation Publishing UMI 3484667 Copyright 2011 by ProQuest LLC. All rights reserved. This edition of the work is protected against unauthorized copying under Title 17, United States Code. uestA ® ProQuest LLC 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106-1346 ABSTRACT Understanding of biological and physical mechanisms that control the Gulf of Alaska (GOA) ecosystem is of major importance to predicting the responses of bird and zooplankton communities to environmental changes in this region. I investigated seasonal (March-October) changes in seabird abundance in relation to changes in zooplankton biomass and water mass properties from 1998 to 2003. Oceanodroma furcata and Fratercula cirrhata were most abundant during the peak of the zooplankton production season (May-August). Overall abundance of seabirds did not follow seasonal changes in zooplankton biomass. Seabird abundance was low in the study area when compared to other regions in the GOA. Furthermore, low bird densities suggest that productivity in this study area is not high enough to sustain a significant seasonal increase in local seabird abundance. I further investigated the distribution and abundance of seabird foraging guilds across the neritic and oceanic domains in relation to water mass properties and zooplankton biomass during March and April. Overall zooplankton biomass increased from the inner shelf to the oceanic domain. Highest density of subsurface-foraging seabirds occurred in the middle shelf and surface-feeding seabirds were most abundant in the middle shelf and oceanic domain. Murre ( Uria spp.) abundance was positively correlated with the biomass of Thysanoessa inermis, and Northern Fulmars (Fulmarus glacialis) were associated with cephalopod paralarvae andEucalanus bungii. Elevated biomass of Thysanoessa inermis in March and April may be an important factor influencing habitat choice of wintering murres in this region. Lastly, I investigated the inter-annual variation in the abundance of sixteen zooplankton taxa in relation to water mass properties during May from 1998 to 2009. Significant variations in temperature, salinity and zooplankton abundance were identified. Thysanoessa inermis and Calanus marshallae had increased abundances in years when there was a strong phytoplankton spring bloom preceded by anomalously cold winters. However, abundances of Pseudocalanus spp.,Neocalanus plumchrus/Neocalanus flemingeri, Euphausiapacifica and Oithona spp. were not strongly affected by relatively higher mean water temperatures. The abundance of zooplankton in the northern GOA was highly influenced by advective processes. V TABLE OF CONTENTS Page Signature Page........................................................................................................................... i Title Page...................................................................................................................................ii Abstract.....................................................................................................................................iii Table of Contents..................................................................................................................... v List of Figures.......................................................................................................................... ix List of Tables......................................................................................................................... xvi List of Appendices.................................................................................................................xix Acknowledgements................................................................................................................xx Introduction...............................................................................................................................1 Seabirds ...........................................................................................................................1 Physical environment.................................................................................................... 3 Zooplankton and hydrography..................................................................................... 5 Seabirds, zooplankton and hydrography..................................................................... 8 Chapter 1. Seasonal characterization of seabird distribution and habitat use in the northern Gulf of Alaska........................................................................................................11 Abstract ..................................................................................................................................... 11 Introduction ...............................................................................................................................12 Methods 15 Seabirds 15 Seasonality................................................................................................................... 18 Hydrography................................................................................................................ 19 Zooplankton................................................................................................................. 19 Data analyses...............................................................................................................20 Results ....................................................................................................................................... 23 Seabirds ........................................................................................................................ 23 Zooplankton.................................................................................................................26 Seabirds and zooplankton .......................................................................................... 26 Water column structure and seabirds ........................................................................ 28 Discussion .................................................................................................................................28 Acknowledgements ..................................................................................................................35 References.................................................................................................................................37 Chapter 2. Habitat partitioning of seabird foraging guilds in the northern Gulf of Alaska in relation to water masses and zooplankton biomass...................................... 72 Abstract .....................................................................................................................................72 Introduction ...............................................................................................................................73 Methods.....................................................................................................................................75 Study area..................................................................................................................... 75 Seabirds ........................................................................................................................ 76 Zooplankton.................................................................................................................77 Hydrography................................................................................................................78 Data analyses...............................................................................................................79 Results ....................................................................................................................................... 83 Discussion .................................................................................................................................88 Physical environment.................................................................................................