An Examination of the Distribution, Abundance, and Habitat Preferences of Soft Corals (Octocorallia: Alcyonacea) in Offshore Nova Scotian Waters
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An examination of the distribution, abundance, and habitat preferences of soft corals (Octocorallia: Alcyonacea) in offshore Nova Scotian waters ENVS 4902 Environmental Science Undergraduate Honours Thesis Lauren Ballantyne BSc. Honours Co-op Environmental Science minor in Biology Dalhousie University, Halifax, NS Supervisor: Dr. Susan Gass Senior Instructor and Academic Advisor Environmental Science Dalhousie University, Halifax, NS Supervisor: Dr. Francisco Javier Murillo Perez Research Scientist Ocean and Ecosystem Science Division of DFO Bedford Institute of Oceanography, Dartmouth, NS Course Instructor: Dr. Tarah Wright Professor Environmental Science Dalhousie University, Halifax, NS April 20, 2018 TABLE OF CONTENTS LIST OF FIGURES..................................................................................................................... IV LIST OF TABLES......................................................................................................................... V GLOSSARY ................................................................................................................................. VI ABSTRACT .............................................................................................................................. VIII 1.0 INTRODUCTION .................................................................................................................... 1 2.0 LITERATURE REVIEW ........................................................................................................ 8 2.1 CORAL TAXONOMY ........................................................................................................................................ 9 2.2 IMPORTANCE OF COLD-WATER CORALS AS HABITAT....................................................................... 10 2.3 SOFT CORALS IN CANADIAN AND ADJACENT WATERS .................................................................... 11 2.4 CORAL CONSERVATION ............................................................................................................................. 14 2.4.1 Cold-water coral conservation............................................................................................................. 14 2.4.2 Soft coral conservation ............................................................................................................................ 16 2.5 KNOWLEDGE GAPS ...................................................................................................................................... 18 3.0 METHODS.............................................................................................................................. 20 3.1 OVERVIEW ..................................................................................................................................................... 20 3.2 STUDY AREA ................................................................................................................................................. 21 3.3 SAMPLING DESIGN AND RATIONAL ....................................................................................................... 22 3.4 IDENTIFICATION FEATURES BY SPECIES ............................................................................................... 25 3.4.1 Anthomastus grandiflorus ...................................................................................................................... 25 3.4.2 Drifa glomerata .......................................................................................................................................... 26 3.4.3 Drifa sp.2 ....................................................................................................................................................... 27 3.4.4 Duva florida ................................................................................................................................................. 28 3.4.5 Gersemia fruticosa .................................................................................................................................... 29 3.4.6 Gersemia rubiformis ................................................................................................................................. 30 3.4.7 Heteropolypus sol ...................................................................................................................................... 31 3.4.8 Pseudoanthomastus agaricus................................................................................................................ 32 3.5 ANALYSIS ....................................................................................................................................................... 33 3.6 LIMITATIONS AND DELIMITATIONS ....................................................................................................... 34 4.0 RESULTS ................................................................................................................................ 36 4.1 SPECIES ALLOCATION ................................................................................................................................. 36 4.2 SPATIAL DISTRIBUTION OF SOFT CORALS ............................................................................................ 39 4.2.1 Distribution by family .............................................................................................................................. 39 4.2.2 Distribution by species ............................................................................................................................ 40 4.3 ABUNDANCE OF SOFT CORALS ................................................................................................................ 44 4.4 ENVIRONMENTAL CONDITIONS ............................................................................................................... 45 4.4.1 Temperature and salinity ........................................................................................................................ 45 4.4.1 Depth ............................................................................................................................................................... 46 5.0 DISCUSSION.......................................................................................................................... 52 5.1 CORAL IDENTIFICATION ............................................................................................................................ 53 5.2 CORAL DISTRIBUTION ................................................................................................................................ 54 5.2.1 Environmental conditions ....................................................................................................................... 54 5.2.2 Depth ............................................................................................................................................................... 56 5.4 ABUNDANCE BASED SOFT CORAL HOTSPOT ........................................................................................ 57 5.5 CONSIDERATIONS FOR SOFT CORAL CONSERVATION ....................................................................... 58 ii 5.6 IMPLICATION OF RESEARCH AND FUTURE WORK .............................................................................. 59 6.0 CONCLUSION ....................................................................................................................... 61 ACKNOWLEDGEMENTS ......................................................................................................... 62 REFERENCES ............................................................................................................................. 63 APPENDIX A. SCLERITE PREPARATION AND MOUNTING .......................................... 68 APPENDIX B. SPECIES-SPECIFIC ABUNDANCE MAPS ..................................................70 APPENDIX C. TEMPERATURE, SALINITY, AND DEPTH RANGE BY SPECIES ........78 iii List of Figures Figure 1 Project study area 22 Figure 2 Sclerite sample locations 24 Figure 3 Description of Anthomastus grandiflorus 26 Figure 4 Description of Drifa glomerata 27 Figure 5 Description of Drifa sp.2 28 Figure 6 Description of Duva florida 29 Figure 7 Description of Gersemia fruticosa 30 Figure 8 Description of Gersemia rubiformis 31 Figure 9 Description of Heteropolypus sol 32 Figure 10 Description of Pseudoanthomastus agaricus 33 Figure 11 Number of colonies belonging to Nephtheidae 37 Figure 12 Number of analyzed colonies belonging to Nephtheidae 38 Figure 13 Number of colonies belonging to Alcyoniidae 38 Figure 14 Family based distribution map 40 Figure 15 Multi-species based distribution map 41 Figure 16.1 Individual species maps of G. rubiformis, G. fruticosa, D. glomerata, and Drifa sp.2 42 Figure 16.2 Individual species maps D. florida, A grandiflorus, H. sol, and P. agaricus 43 Figure 17 Proportional abundance map 45 Figure 18 Map of Average Maximum Bottom Temperature 47 Figure 19 Species-specific Average Maximum Bottom Temperature boxplots 47 Figure 20 Map of Average Minimum Bottom Temperature 48 Figure 21 Species-specific Average Minimum Bottom Temperature boxplots 48 iv Figure 22 Map of Average Maximum Bottom Salinity 49 Figure 23 Species-specific Average Maximum Bottom Salinity boxplots 49 Figure 24 Map of Average Minimum Bottom Salinity 50 Figure 25 Species-specific Average Minimum Bottom Salinity boxplots 50 Figure 26 Species-specific