Matthew Bryant Rodrigues Mentor: Dr. David Bybee Brigham Young University - Hawaii - Department of Biological Sciences December 10, 2013 BIOL 494

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1 Reproductive periodicity of the Sea Cucumber Holothuria atra (Echinodermata: Holothuroidea) in the Coastal Waters of Laie, Hawai i Matthew Bryant Rodrigues Mentor: Dr. David Bybee Brigham Young University - Hawaii - Department of Biological Sciences December 10, 2013 BIOL 494

2 Abstract The reproductive season for Holothuria atra varies by location throughout its Indo-Pacific range. Calculation of Gonadal Index for specimens collected from coastal sites of northeast Oahu suggest that peak gonad maturity occurs from August to September and that spawning occurs during October. Understanding the reproductive periodicity of commercially important species is essential for managing breeding stocks and protecting fragile ecosystems. Keywords: Holothuria atra, Breeding, Seasonality, Reproduction Introduction Sea cucumbers (Echinodermata: Holothuroidea) are detritivorous benthic dwellers with a vast distribution that spans the world in every ocean (Fisher 1907, Moriarty 1982). Several species are commercially important due to their rich nutrient profile and unique pharmacological and bioactive activity (Baine 2004, Bordbar 2011, Clarke 2004) with roughly 40 species fished and marketed for human consumption (bêche-de-mer or trepang). This commercialization has been the driving force for research pertaining to the reproductive cycles of many commercially valuable species (Baine and Sze 1999). Sea cucumbers are fecund broadcast spawners (Hoover 2004) with episodic annual reproductive patterns (Conand 1981). Even within a species, breeding patterns are strongly influenced by location. For example, the reproductive season for Holothuria atra has been observed to extend from June to December in the Red Sea coast of Egypt (Abdel-Razek et al. 2005), from June to September in Taiwan (Chao et al. 1994), and from May to June and November to January on the Heron Reef near Australia (Harriott 1985). While H. atra is distributed throughout the tropical Indo-Pacific region little is known about its reproductive patterns in the coastal regions around Hawaii. The purpose of this study 1

3 was to investigate the reproductive patterns of H. atra in in and around Laie Bay Oahu, Hawai i. Material and Methods Approximately 20 adult (15 cm or longer according to Abdel-Razek et al is when H. atra reaches sexual maturity) specimens of Holothuria atra were collected monthly from Laie Bay and Laniloa Bay ( N, W and N, W respectively) at depths up to 2 meters from January to December Specimens were dissected end to end, coelomic fluid was drained, and the complete specimen was weighed to determine wet body weight (WBW). Gonads were then removed by cutting the end of the gonadal duct closest to the oral orifice and weighed to determine wet gonad weight (WGW). The average Gonadal Index (100%*WGW/WBW) was plotted monthly from January to December 2013 and used to determine the reproductive seasonality of H. atra (Keshavarz et al. 2012). Results were analyzed by ANOVA and a two sample t-test. Results While the GI remained relatively level from January through July, the index increased significantly (p < 0.001) in August and September (Figure 1). In October the GI returned to the lower values seen throughout the rest of the year. 2

4 GI (%) * Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month *p < Figure 1. The Average gonadal indices of H. atra during the months of January to December were calculated and then plotted to illustrate gonad weight changes throughout the year. Discussion The reproductive periodicity of H. atra has been reported to vary based on location within its tropical Indio-Pacific distribution range and the results of this study show that gonads were ripest during the two month period of August and September. This is shorter than other reported periods which range from 3-6 months in populations with a single peak. The Laie population does however show some temporal overlap with these other northern hemisphere populations. The only report from a southern hemisphere population shows a double peak, the first of which also has duration of two months. When all available data for H. atra are taken into account it appears that this species has high reproductive plasticity and can adapt well to local environmental cues for synchronous spawning events. 3

5 Although spawning was not observed in nature during this study the statistically significant drop in gonad size during the month of October suggests that spawning may occur in October. This is correlated with a seasonal decrease in water temperature identified as a cue for spawning in other windward invertebrate populations on Oahu (Bybee et al 2007). Determining the reproductive periodicity of broadcast spawners is important for establishing sustainable fisheries of these organisms. When populations become too sparse reproduction is ineffective and the risk of depletion increases. Because of their important ecological role as detritivores and waste managers, adverse effects may be seen if exploitation continues to occur. The market for sea cucumbers in Asia has recently been expanding because of increased demand (Baine 2004, Clarke 2004). The broadening market in Asia for products such as bêchede-mer, and the new discoveries of the medicinal properties of many species of sea cucumbers, will likely increase demand for these organisms and put additional pressures on fragile ecosystems. Moreover, the depletion of high value sea cucumber species has caused a shift in the market to less valuable species (Purcell et al. 2009), such as H. atra. Understanding reproduction in local populations of H. atra will facilitate the management of this fishery, the conservation of local coral reef ecosystems and potentially the culture of this species. Cited Resources Abdel-Razek, F. A., Abdel-Rahman, S. H., El-Shimy, N. A., Omar, H. A Reproductive Biology of the Tropical Sea Cucumber Holothuria atra (Echinodermata: Holothuroidea) in the Red Sea coast of Egypt. Egyptian Journal of Aquatic Research (31) 2: Baine, M From the sea to the market place: an examination of the issues, problems and opportunities in unravelling the complexities of sea cucumber fisheries and trade. Advances in Sea Cucumber Aquaculture and Management. FAO Fisheries Technical Paper (463):

6 Baine, M. and Sze, C.P Sea cucumber fisheries in Malaysia, towards a conservation strategy. SPC Beche-de-mer Information Bulletin (12): Bordbar, S., Anwar, F., Saari, N High-Value Components and Bioactives from Sea Cucumbers for Functional Foods A Review. Marine Drugs. (9): Bybee, D. R., J. H. Bailey-Brock and C. S. Tamaru Gametogenesis and Spawning Periodicity in the Fan worm Sabellastarte spectabilis (Grube 1878) (Polychaeta: Sabellidae). Marine Biology 151: Chao, S. M., Chen, C. P., Alexander P.S Reproduction and Growth of Holothuria atra (Echinodermata: Holothuroidea) at two contrasting sites in southern Taiwan. Marine Biology (119): Chen J Overview of sea cucumber farming and sea ranching practices in China. SPC Beche-de-mer Information Bulletin (18): Clarke, S Understanding pressures on fishery resources through trade statistics: a pilot study of four products in the Chinese dried seafood market. Fish and Fisheries (5): Conand, C Sexual Cycle of Three Commercially Important Holothurian Species (Echinodermata) from the Lagoon of New Caledonia. Bulletin of Marine Science. 31(3): Fisher, W. K Holothurians of the Hawaiian Islands. U.S. National Museum. Proceedings (32): Harriott, V. J Sexual and Asexual reproduction of Holothuria atra, Jaeger at Heron Island Reef, Great Barrier Reef. Australian Journal of Marine & Freshwater Research (16): Hoover, J. P Sea Creatures of Hawaii: A Guide to Hawai i s Marine Invertebrates. Mutual Publishing. Honolulu Keshavarz, M., Mohammadikia, D., Dabbagh, A. R., Kamrani, E Reproductive Biology of the Sea Cucumbers for Successful Breeding: a Review. Journal of Animal Production Advances 2(5): Moriarty, DJW Feeding of Holothuria atra and Stichopus chloronotus on bacteria, organic carbon and organic nitrogen in sediments of the Great Barrier Reef. Australian Journal of Marine and Freshwater Research (33): Purcell, S. W., Gossuin, H. and Aguado, N. N Status and management of the sea cucumber fishery of la Grande Terre, New Caledonia. World Fish Center Studies and Reviews (1901):

7 Acknowledgements I would like to thank Dr. David Bybee for being my mentor. A special thanks to the biology department staff and professors for their assistance in every stage of this project. I also want to express my gratitude to Roger Goodwill for teaching me about how to properly identify Holothuria atra and teaching the anatomy. I am also grateful for Paul Hurst of the Brigham Young University if Hawaii Department of Mathematics for his assistance in the statistical analysis. I would also like to extend to my fellow classmates for their willingness to help with data collections. I offer a special thanks to Aaron William Sanders for help in the lab. 6

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