Taxonomy and diversity of the sponge fauna from Walters Shoal, a shallow seamount in the Western Indian Ocean region By Robyn Pauline Payne A thesis submitted in partial fulfilment of the requirements for the degree of Magister Scientiae in the Department of Biodiversity and Conservation Biology, University of the Western Cape. Supervisors: Dr Toufiek Samaai Prof. Mark J. Gibbons Dr Wayne K. Florence The financial assistance of the National Research Foundation (NRF) towards this research is hereby acknowledged. Opinions expressed and conclusions arrived at, are those of the author and are not necessarily to be attributed to the NRF. December 2015 Taxonomy and diversity of the sponge fauna from Walters Shoal, a shallow seamount in the Western Indian Ocean region Robyn Pauline Payne Keywords Indian Ocean Seamount Walters Shoal Sponges Taxonomy Systematics Diversity Biogeography ii Abstract Taxonomy and diversity of the sponge fauna from Walters Shoal, a shallow seamount in the Western Indian Ocean region R. P. Payne MSc Thesis, Department of Biodiversity and Conservation Biology, University of the Western Cape. Seamounts are poorly understood ubiquitous undersea features, with less than 4% sampled for scientific purposes globally. Consequently, the fauna associated with seamounts in the Indian Ocean remains largely unknown, with less than 300 species recorded. One such feature within this region is Walters Shoal, a shallow seamount located on the South Madagascar Ridge, which is situated approximately 400 nautical miles south of Madagascar and 600 nautical miles east of South Africa. Even though it penetrates the euphotic zone (summit is 15 m below the sea surface) and is protected by the Southern Indian Ocean Deep- Sea Fishers Association, there is a paucity of biodiversity and oceanographic data. Thus, a multidisciplinary cruise was initiated in May 2014 on the FRS Algoa as a component of the African Coelacanth Ecosystem Programme. The research presented here focuses exclusively on the diversity, bathymetric distribution patterns and biogeographic affiliations of the sponge fauna of this seamount. Sponges were sampled using SCUBA and a roughed epibenthic sled, from the peak and down two opposing slopes of the seamount, to a depth of 500 m. Two hundred and fifty-five sponge specimens were collected, comprising 78 operational taxonomic units (OTU’s), 23 of which are known to science, 26 which are possibly new, 16 that could only be identified to higher iii taxonomic levels and 13 that could only be designated as morphospecies. Thirteen OTU’s are formally described here, four which are known, and nine possibly new to science. Sponge assemblages demonstrated no significant difference according to location on the shoal, with several species shared by both the western and eastern flanks. In contrast, sponge assemblages differed significantly according to depth, with the mesophotic zone (31 – 150 m) acting as a transition between the shallow (15 – 30 m) and submesophotic (> 150 m) zones. Species richness and the number of putative new species was highest in the submesophotic zone. Biogeographical affiliations were found with both the Western Indo-Pacific and Temperate Southern African realms based on the 23 known species recorded. No affiliations were found with the West Wind Drift Island Province, as has been documented previously for the fish fauna of this seamount, possibly due to the incomplete nature of the online database (World Porifera Database) used to assess affinities. Thirty-nine percent of the known sponge species found at Walters Shoal Seamount are widely distributed in the Indian Ocean, 35% are found exclusively within the Western Indian Ocean region, with this study representing the southernmost distribution record for several of these, and 26% have a restricted distribution around South Africa. December 2015 iv Declaration I declare that Taxonomy and diversity of the sponge fauna from Walters Shoal, a shallow seamount in the Western Indian Ocean region is my own work, that is has not been submitted for any degree or examination in any other university, and that all the sources I have used or quoted have been indicated and acknowledged by complete references. Robyn Pauline Payne December 2015 Signed: v Acknowledgements This thesis, as well as conference attendance to present findings (15th South African Marine Science Symposium (SAMSS): 2014, 14th Deep-Sea Biology Symposium (DSBS): 2015 and the 9th Western Indian Ocean Marine Science Association (WIOMSA) Scientific Symposium: 2015), was made possible via funding provided by the African Coelacanth Ecosystem Programme (ACEP (DST-NRF)), with bursary funding provided by the National Research Foundation (NRF). Resources for the cruise to collect samples included in this study were jointly provided by the South African Institute for Aquatic Biodiversity (SAIAB), the South African Environmental Observation Network (SAEON), the Department of Environmental Affairs (DEA) and the Department of Agriculture, Forestry and Fisheries (DAFF). As such, I am grateful to all involved in the cruise, including the captain of the RV Algoa (Geordie MacKenzie), officers and crew, as well as the staff members from the institutions mentioned above whose contributions made this project a reality. More specifically, I would like to express my sincere gratitude to my supervisors: Dr Toufiek Samaai (DEA), Prof Mark J. Gibbons (University of the Western Cape) and Dr Wayne K. Florence (Iziko Museum) for their ongoing assistance, guidance and advice. Special thanks are extended to Dr Toufiek Samaai for introducing me to the fascinating world of sponge taxonomy. A word of thanks is also extended to Liesl Janson (DEA) and Seshnee Maduaray (DEA), for their continued help with sponge processing techniques, thesis advice and friendship; Dr Tanya Haupt-Schuter (DEA), for advice and reading an earlier version of this manuscript; Miranda Waldron (Electron Microscope Unit, UCT) for help with the scanning electron microscope and Marcel van den Berg (DEA) for assistance with Surfer 9 and compiling the bathymetric figures of Walters Shoal Seamount. vi My sincerest thanks go to the editors of the World Porifera Database (especially Rob van Soest) for their quick response, access to data and key taxonomic papers, interest in future collaborations, overall friendliness and willingness to assist. I would be remiss if I didn’t extend thanks to all the people that have brightened my days at the Department of Environmental Affairs, including: Asma Damon, Darrell Anders, Imtiyaaz Malick, Jabulile Nhleko, Keshnee Pillay, Leon Jacobs, Marco Worship, Dr Maya Pfaff, Dr Stephen Kirkman and Taryn Joshua. Special thanks are extended to my closest friend, Zoleka Filander (DEA), for her belief in me and mentorship. Finally, I wish to thank my family: my parents, grandmother and two sisters for never-ending support and encouragement. vii Contents Title Page i Keywords ii Abstract iii Declaration v Acknowledgements vi Contents Page viii List of Figures ix List of Tables xi Chapter 1 – Introduction 1 – 21 1.1 A deep-sea habitat: the seamount 2 1.2 Seamounts of the Indian Ocean 10 1.3 Why sponges? 15 1.4 Hypotheses 20 Chapter 2 – Methodology 22 – 26 2.1 Collection 22 2.2 Taxonomic procedure 22 2.3 Sample storage 25 2.4 Location and depth analyses 25 2.5 Biogeography analyses 26 Chapter 3 – Results 27 – 66 3.1 Systematics 27 3.2 Descriptions 28 3.3 Location and depth affiliations 62 3.4 Biogeographical affiliations 64 Chapter 4 – Discussion 67 – 77 4.1 Diversity 67 4.2 Location and depth affiliations 69 4.3 Biogeographical affiliations 72 4.4 Study limitations and future work 75 4.5 Conclusion 77 Figures 78 – 100 Tables 101 – 131 References 132 – 160 Appendix 161 – 175 viii List of Figures Fig. 1: Map showing the location of Walters Shoal Seamount within the 78 bathymetric context of the Western Indian Ocean region. Fig. 2: Bathymetric map of Walters Shoal Seamount. 79 Fig. 3: Sponge specimen sampling strategies: SCUBA dives and the use of a 80 roughed epibenthic sled. Fig. 4: Bathymetric map of Walters Shoal Seamount with sampling locations. 81 Fig. 5: Sheet completed per sponge specimen to denote macroscopical features. 82 Fig. 6: Map showing the ecoregions, as defined by Spalding et al. (2007), 83 surrounding Walters Shoal Seamount that were included in the biogeographical analyses. Fig. 7: Plate of Agelas ceylonica Dendy, 1905. 84 Fig. 8: Plate of Ptilocaulis sp. • 85 Fig. 9: Plate of Callyspongia (Callyspongia) sp. • 86 Fig. 10: Plate of Lissodendoryx (Lissodendoryx) pygmaea (Burton, 1931). 87 Fig. 11: Plate of Fibulia ectofibrosa (Lévi, 1963). 88 Fig. 12: Plate of Latrunculia (Biannulata) sp. • 89 Fig. 13: Plate of Clathria (Clathria) sp. • 90 ix Fig. 14: Plate of Halichondria (Halichondria) sp. • 91 Fig. 15: Plate of Aaptos sp. • 92 Fig. 16: Plate of Tethya sp. • 93 Fig. 17: Plate of Ancorina sp. • 94 Fig. 18: Plate of Chelotropella sp. • 95 Fig. 19: Plate of Penares intermedia (Dendy, 1905). 96 Fig. 20: Non-metric MDS ordination of sampling locations according to location. 97 Fig. 21: Non-metric MDS ordination of sampling locations according to depth. 98 Fig. 22: Biogeographical affinities of the 23 known sponge species recorded 99 from Walters Shoal Seamount. Fig. 23: The low spatial complexity and growth profile of Walters Shoal 100 Seamount. x List of Tables Table 1: Invertebrate (including sponge) collection sampling strategy. 101 Table 2: Microwave 5mm/2 layer method for sponge specimen histology 102 processing. Table 3: Ecoregions included in the biogeographical analyses. 103 Table 4: Sponge species documented from Walters Shoal Seamount per sampling 104 location. Table 5: Sponge species documented from Walters Shoal Seamount. 106 Table 6: Spicule dimensions of Agelas ceylonica Dendy, 1905. 112 Table 7: Spicule dimensions of Ptilocaulis sp. • 112 Table 8: Spicule dimensions of Callyspongia (Callyspongia) sp. • 112 Table 9: Spicule dimensions of Lissodendoryx (Lissodendoryx) pygmaea 113 (Burton, 1931). Table 10: Spicule dimensions of Fibulia ectofibrosa (Lévi, 1963). 113 Table 11: Spicule dimensions of Clathria (Clathria) sp.