Ecophysiological Responses of Macroalgae to Submarine Groundwater Discharge in Hawaiʻi
Total Page:16
File Type:pdf, Size:1020Kb
ECOPHYSIOLOGICAL RESPONSES OF MACROALGAE TO SUBMARINE GROUNDWATER DISCHARGE IN HAWAIʻI A DISSERTATION SUBMITTED TO THE GRADUATE DIVISION OF THE UNIVERSITY OF HAWAI‘I AT MĀNOA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY IN BOTANY May 2015 By Daniel William Amato Dissertation Committee: Celia Smith, Chairperson Cynthia Hunter Thomas Kaeo Duarte Samir Khanal Craig Glenn Keywords: Algae, Nutrients, Submarine Groundwater Discharge, Wastewater, Coral Reef UMI Number: 3717142 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent on 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 3717142 Published by Proquest LLC (2015). Copyright in the Dissertation held by the Author. Microform Edition © ProQuest LLC. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code. ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, MI 48106 - 1346 i ACKNOWLEDGEMENTS I, truly and wholeheartedly, thank each and every person, agency, organization, university, and government that has assisted me on this incredible academic journey. I cannot express in words the gratitude I have for my academic committee. Since the inception of this work, Dr. Celia Smith, Dr. Craig Glenn, Dr. Kaeo Duarte, Dr. Cynthia Hunter, and Dr. Samir Khanal have been nothing less than outstanding advisors and collaborators in this work. The research within this dissertation would not have been possible without financial support from the United States Environmental Protection Agency (USEPA) Science To Achieve Results (STAR) Fellowship program (agreement no. FP-91727301-2), University of Hawaiʻi Sea Grant, L. Stephen Lau Water Research Endowed Scholarship, and the University of Hawaiʻi (UHM) Graduate Student Organization Grants and Awards Program. I would also like to acknowledge financial support provided by research and teaching assistantships through the Botany, Biology and Geology and Geophysics departments at UHM. I would like to acknowledge the support of Dr. Henrieta Dulaiova, whose expertise in the field, lab, and classroom made this work possible. I would like to thank Robert Whittier (State of Hawaiʻi, Department of Health) for assistance with groundwater modeling and access to pertinent GIS data. I appreciate the assistance of Rachel Wade, Dr. Charles O’Kelly, and the UHM Algal Biodiversity Lab in the molecular identification of algal samples. I would like to thank the City and County of Honolulu (Board of Water Supply) for assistance with sampling groundwater wells and tunnels. In addition, I appreciate the help of the Hawaiʻi Undersea Research Laboratory for access to the Makai Pier. I am grateful for the cooperation of the County of Maui (Division of Aquatic Resources), Kuʻulei Rodgers, Paul Jokiel, Ivor Williams, and Eric Brown for access to CRAMP data. I appreciate the support and guidance that Wendy Wiltse and Hudson Slay (USEPA, region 9) have provided. I am extremely thankful for the field and lab support provided by Joseph Fackrell, Chris Schuler, Christine Waters, Scott Chulakote, Samuel Wall, Jill Rotaru, Celine Stevens, Migiwa Kawachi, Mike Amato, Gabrielle Stewart, Morgan DePartee, Sean Croucher, Eli Clemens, Sandrine Meltewomu, and Jerimiah Simpson. It has been a great pleasure to work with James Bishop during our Maui adventures. I appreciate the support of my fellow grad students, the ii UHM Department of Botany faculty and staff, and the members of the Limu lab (Dave Spafford, Erin Cox, Heather Spalding, Cheryl Squair, Scott Chulakote, Ken Hamel, Sarah Vasconcellos, Donna Brown, Matthew Lurie, and others). I would especially like to thank my partner Elizabeth Rademacher for her unwavering love and support in the field and lab during this research. Lastly, I acknowledge the love and support of my sisters, brothers, mothers, fathers, and extended family, without whom this work may have never been possible. Mahalo nui loa iii ABSTRACT Submarine groundwater discharge (SGD) is a ubiquitous process that delivers significant amounts of nutrients and other solutes to coastal ecosystems worldwide. Although the quality and quantity of SGD has been characterized at many sites, the biological implications of this process remain poorly understood. The objective of this work was to compare the physiological response of macroalgae and benthic community structure across gradients of SGD and nutrient loading in Hawai‘i. Common marine algae were collected and/or deployed at several sites on O‘ahu, and Maui. Selection of sites was informed by adjacent land use, known locations of wastewater injection wells, and previous estimates of environmental risk due to onsite sewage disposal systems (OSDS). For deployed samples, initial values of algal tissue nitrogen (N) parameters were determined after pretreatment in low nutrient conditions. At all locations, algal tissue nitrogen (N) parameters (δ15N, N %, and C:N) were compared with the N parameters (δ15N and N concentration) of coastal groundwater , marine surface water, or groundwater simulations. Algal tissue N was highest (> 2 %) in samples located nearshore at sites adjacent to coastal aquifers enriched with anthropogenic sources of N. The lowest tissue N values (< 1 %) were found offshore or at relatively unimpacted sites. In general, the δ15N values of algal tissues and water samples were highest (9 - 18 ‰) at sites adjacent to high-volume wastewater injection wells and high densities of OSDS; lowest values (< 4 ‰) were observed in samples adjacent to sugarcane fields. Benthic diversity was greatest in locations with low anthropogenic impact. In contrast, highly impacted locations were dominated by opportunistic species. This work advances the use and interpretation of algal bioassays by highlighting the importance of onshore-offshore trends, and deviations from initial N parameter values, for the detection of N source and relative N availability. Wastewater was detectable and a major source of N at many locations. These results support recent studies that indicate SGD is a significant transport pathway for anthropogenic pollutants with important biogeochemical implications. Minimizing contaminant loads to coastal aquifers will reduce pollutant delivery to nearshore reefs in areas with SGD flux. iv TABLE OF CONTENTS ABSTRACT………………………………………………………………………………………………………………………………... iv LIST OF TABLES…………………………………………………………………………………………………….…………………… ix LIST OF FIGURES………………………………………………………………………………………………………………….….… x CHAPTER 1. BACKGROUND INFORMATION .................................................................................... 1 Introduction ............................................................................................................................. 1 Nitrogen and productivity in marine ecosystems ................................................................... 3 Macroalgae as bioindicators of water column N loading ....................................................... 5 Stable isotopes of N in the coastal environment .................................................................... 6 Nitrogen source determination using plant tissue δ15N values .............................................. 8 Submarine groundwater discharge in coastal environments ............................................... 10 Physiological stress associated with SGD: Salinity ................................................................ 12 Physiological stress associated with SGD: Temperature ....................................................... 13 SGD measurement techniques .............................................................................................. 14 Summary and objectives ....................................................................................................... 16 CHAPTER 2. SUBMARINE GROUNDWATER DISCHARGE MODIFIES PHOTOSYNTHESIS, GROWTH, AND MORPHOLOGY FOR TWO SPECIES OF GRACILARIA (RHODOPHYTA) ................................... 18 Abstract ................................................................................................................................. 18 Introduction ........................................................................................................................... 19 Methods ................................................................................................................................ 22 Field experiment: Wailupe Beach Park ............................................................................. 22 Simulated SGD study ......................................................................................................... 26 Results ................................................................................................................................... 29 Field experiment: Wailupe Beach Park ............................................................................. 29 Physical conditions at Wailupe ..................................................................................... 29 Physiological response of deployed algae .................................................................... 33 Benthic community diversity at Wailupe...................................................................... 38 v Simulated SGD study ........................................................................................................