California State University, Monterey Bay Digital Commons @ CSUMB Capstone Projects and Master's Theses Capstone Projects and Master's Theses Summer 2020 Hydrothermal Vent Periphery Invertebrate Community Habitat Preferences of the Lau Basin Kenji Jordi Soto California State University, Monterey Bay Follow this and additional works at: https://digitalcommons.csumb.edu/caps_thes_all Recommended Citation Soto, Kenji Jordi, "Hydrothermal Vent Periphery Invertebrate Community Habitat Preferences of the Lau Basin" (2020). Capstone Projects and Master's Theses. 892. https://digitalcommons.csumb.edu/caps_thes_all/892 This Master's Thesis (Open Access) is brought to you for free and open access by the Capstone Projects and Master's Theses at Digital Commons @ CSUMB. It has been accepted for inclusion in Capstone Projects and Master's Theses by an authorized administrator of Digital Commons @ CSUMB. For more information, please contact [email protected]. HYDROTEHRMAL VENT PERIPHERY INVERTEBRATE COMMUNITY HABITAT PREFERENCES OF THE LAU BASIN _______________ A Thesis Presented to the Faculty of Moss Landing Marine Laboratories California State University Monterey Bay _______________ In Partial Fulfillment of the Requirements for the Degree Master of Science in Marine Science _______________ by Kenji Jordi Soto Spring 2020 CALIFORNIA STATE UNIVERSITY MONTEREY BAY The Undersigned Faculty Committee Approves the Thesis of Kenji Jordi Soto: HYDROTHERMAL VENT PERIPHERY INVERTEBRATE COMMUNITY HABITAT PREFERENCES OF THE LAU BASIN _____________________________________________ Ivano Aiello, Chair Moss Landing Marine Laboratories _____________________________________________ Stacy Kim Moss Landing Marine Laboratories _____________________________________________ Kenneth Coale Moss Landing Marine Laboratories _____________________________________________ Kris Roney, Dean Associate VP for Academic Programs and Dean of Undergraduate and Graduate Studies ______________________________20 July 2020 Approval Date iii Type text here Copyright © 2020 by Kenji Jordi Soto All Rights Reserved iv The Trochophores are larval tops the Polychaetes set spinning With just a ciliated ring – at least in the beginning – They feed, and feel an urgent need to grow more like their mothers, So sprout some segments on behind, first one, and then the others. –Walter Garstang, “The Trochophores” from Larval Forms 5 ABSTRACT Hydrothermal Vent Periphery Invertebrate Community Habitat Preferences of the Lau Basin by Kenji Jordi Soto Master of Science in Marine Science California State University Monterey Bay, 2020 The Eastern Lau Spreading Center (ELSC), located between 19°20’S and 22°45’S, is a back-arc basin containing active hydrothermal vents, and is characterized by gradients of several geological and chemical variables that follow along a north – south axis. The northern section of the ELSC spreads faster than the southern section resulting in farther distance from the Tofua Arc and vent geology and chemistry more akin to mid- oceanic ridges. In the Southern section, where distance from the arc is less, substrates are more heavily influenced by water resulting in andesitic substrates as opposed to basaltic substrates in the north. There are also north to south biological patterns, where in the northern vent peripheral zone communities are dominated by anemones, and by sponges in the south. This project used a replacement type experiment to test whether the anemone and sponge community distributions are due to substrate preferences (either basalt or andesite) or location effects. In September 2006, 17 basalt and 18 andesite rock blocks were set out in the peripheral vent zone at three locations in the Lau Basin; 42 months later, in May 2009, the rocks were recovered. After collection and identification (to lowest taxonomic level) of all invertebrates, rock block surface area and roughness was determined. This report found that while the basalt rock blocks used were smaller and had smoother surface roughness than andesite rocks, both rock types were evenly distributed throughout each location. Through this conclusion, rock type was determined not to affect the invertebrate community and that there was some other location specific effect responsible for the invertebrate community, possibly sulfide distribution. Southern locations had more brecciated substrates, allowing for more sulfide to distribute farther laterally, resulting in more primary productivity, and thus an increase in taxa belonging to groups Copepoda, Polychaeta, and Gastropoda. Specifically, southern sites showed higher densities of the copepod Amphiascus sp. and from the family Dirivultidae, the molluscs Lepetodrilus sp. and from the family Sutilizonidae, and polychaetes from the families Serpulidae, Ampharetidae, and Hesionidae. 6 TABLE OF CONTENTS PAGE ABSTRACT .........................................................................................................................5 LIST OF TABLES ...............................................................................................................8 LIST OF FIGURES .............................................................................................................9 ACKNOWLEDGEMENTS ...............................................................................................10 INTRODUCTION .............................................................................................................12 History of Hydrothermal Vent Discovery, Study, and Governance ................12 Introduction to Hydrothermal Vents ................................................................14 Back-arc Basins ...............................................................................................15 Hydrothermal Vent Chemistry .........................................................................17 General Hydrothermal Vent Ecology ..............................................................19 Lau Faunal Assemblage Patterns .....................................................................21 Macroscopic Near Vent Fauna .............................................................21 Macroscopic Peripheral Zone Fauna/Pattern .......................................23 Microscopic Peripheral Zone Fauna ....................................................26 Copepods..................................................................................26 Polychaetes ..............................................................................27 Molluscs: Gastropods and Bivalves .........................................29 Barnacles ..................................................................................30 Miscellaneous arthropods: Amphipoda, Tanaidacea, Ostracoda, and Isopoda ............................................................32 HYPOTHESIS ...................................................................................................................32 MATERIALS AND METHODS .......................................................................................34 Outplant Experiment ........................................................................................34 Sample Processing ...........................................................................................35 Statistical Analysis ...........................................................................................38 RESULTS ..........................................................................................................................39 Rock Characteristics ........................................................................................39 Multivariate Community Analysis ...................................................................40 7 Multivariate Figure Visualizations ..................................................................40 Simper on Density Data ...................................................................................41 DISCUSSION ....................................................................................................................41 Rock Type and Source Effects .........................................................................41 Location Effects ...............................................................................................44 CONCLUSION ..................................................................................................................49 Mining and Broader Impacts ...........................................................................51 REFERENCES ..................................................................................................................55 APPENDIX: IMAGES OF SELECTED FAUNA ..........................................................111 8 LIST OF TABLES PAGE Table 1. Pysical characteristics summmary of sites along the Eastern Lau Spreading Center ................................................................................................................... 74 Table 2. Location of outplanted rock substrates and sulfide and temperature measurements taken in 2006 and 2009 ................................................................ 75 Table 3. ROV surveys from Kim 2012 showing maximum/mean/minimum distances of sponges and anemones from effluent sources ...................................................... 76 Table 4. Location of dredges taken to obtain rock substrates and general location of placement and naming convention....................................................................... 77 Table 5. Rock