ResearchOnline@JCU This file is part of the following reference: Courtney, Robert (2016) Life cycle, prey capture ecology, and physiological tolerances of Medusae and polyps of the 'Irukandji' jellyfish: Carukia barnesi. PhD thesis, James Cook University. Access to this file is available from: http://researchonline.jcu.edu.au/49935/ The author has certified to JCU that they have made a reasonable effort to gain permission and acknowledge the owner of any third party copyright material included in this document. If you believe that this is not the case, please contact [email protected] and quote http://researchonline.jcu.edu.au/49935/ Life Cycle, Prey Capture Ecology, and Physiological Tolerances of Medusae and Polyps of the ‘Irukandji’ Jellyfish: Carukia barnesi Thesis Submitted by: Robert Courtney BSc (Hons 1A) November 11, 2016 For the Degree of: Doctor of Philosophy College of Public Health, Medical and Veterinary Sciences James Cook University Supervisors: Principle Supervisor: Associate Professor Jamie Seymour, Australian Institute of Tropical Health and Medicine, College of Public Health, Medical and Veterinary Sciences, James Cook University, Cairns [email protected] Co-Supervisor: Emeritus Professor Rhondda Jones, Australian Institute of Tropical Health and Medicine, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville [email protected] Co-Supervisor: Dr Nik Sachlikidis, NGSAquatic, [email protected] Thesis Dedication: I would like to dedicate this thesis to The Lions Foundation of Australia, for their continual financial support dedicated to stinger research, and to Dr. Jack Barnes, for his pioneering work in the field of Irukandji research. i Statement of the Contribution of Others: Robert Courtney is the primary author of this Thesis and was extensively involved in all aspects of this work under the supervision of: Associate Professor Jamie Seymour; Emeritus Professor Rhondda Jones; and Dr Nik Sachlikidis. Dr Tobin Northfield provided statistical support and assisted with the ecological modeling. Sally Browning assisted with animal husbandry, polyp culture maintenance, and photography. The Lions Foundation of Australia assisted with financial support of this project, providing collection equipment and the research vessel. The Australian Postgraduate Award (APA) scholarship provided financial support for Robert Courtney during this candidature. ii Acknowledgments: First and foremost, I would like to thank my primary supervisor, Jamie Seymour. Jamie, I am lost for words, the support that you have given me since we met during my first undergraduate class, to the time we spend together now, are the best times of my life. You have been not only a mentor, advisor, supervisor, employer, but also a cherished friend, father figure, and solid mate to me on every day of every year, through thick and thin, no matter what. I hope this will never change, thank you Jamie. None of this could have been achieved without your help, wisdom, and unrelenting support. I would also like to thank Rhondda Jones and Nik Sachlikidis for their supervision and support of this project. It is with great pride that I have you both on my team, the dream team, and the confidence you both bestow upon me is immeasurable. Richard Fitzpatrick: thank you for all of your help over the years, you have contributed substantially to this project and I seriously appreciate your involvement, your help, and friendship. Tobin Northfield: thank you for spending countless hours with me, and introducing me to the powers of ecological modeling. Jeff Warner: best research student monitor ever, thanks mate. I would also like to thank the many volunteers and employees that have directly assisted this project: Anna, Athena, Bridey, Billy, Bjoern, Damien, Sandy, Silvia, our research group, and the Aquarium Volunteers. Professionally, I would like to thank The Lions Foundation of Australia. Without the financial support from Lions Club members this project would not be possible. Thank you. I would also like to thank the Surf Life Savers Queensland, for all of the support they have provided over the years. Mum, Lyn Courtney, none of this would have been possible without your help, wisdom, tenacity, and capacity to drive me to a place where I could realize my dreams. You have always not only assisted, but lead by example, always challenging me, always encouraging, never allowing me to fall. Thank you, Mum. I would like to thank my children, Robby and Amba, not only for understanding the times I spend away, but also for helping with the collection of probably a million jellyfish over the last four years. Chrissy: thank you for your love and support over the years. I could not have done this without you. Last, but far from least, I would like to thank Jessica Sleeman and Sally Browning. You two have never, ever, let me down. I want you both to know that you are the future dream team, and without you, I would not be able to achieve this. Thank you both for your help, kindness, friendship, support, expertise, and everything else. Seriously, this is a product of your support, and I could not have done this without you; and you two are next. Thank you, Sally and Jess. iii Abstract This study focuses on the Irukandji jellyfish Carukia barnesi Southcott, 1967. Little is known about the general ecology of C. barnesi; however, the medusa stage is considered oceanic, planktonic, has been found around coral reefs or islands, and under certain conditions, on beaches. Carukia barnesi is a relatively small box jellyfish species (bell size up to 35 mm), that are typically present during the summer monsoonal summer months between November and May in Queensland, Australia, which is commonly referred to as the ‘stinger’ season. Although not well defined, the distribution of this species is considered along the Great Barrier Reef and adjacent coastline, between Lizard Island and Fraser Island. There is evidence that the length of the Irukandji season in the Queensland region has progressively increased over the last 50 years, based on annual sting records, from 15 days long historically to over 150 days long currently, which has been speculated to be attributed to increased seawater temperatures. Similarly, there have been anecdotal reports that the southern distribution of C. barnesi has also increased over the last 50 years. A sting from C. barnesi commonly results in Irukandji syndrome, which is often severely painful, potentially fatal, and frequently requires hospitalization for treatment. The direct cost associated with treating envenomed victims, and the negative impact this species has on the Australian tourism industry through reduced revenue, are substantial (i.e., an estimated 65 million dollars in lost tourism revenue in 2002 alone). Further exacerbating the impact of this species is the simple fact that there are currently no methods in place for mitigating stings when this species is present other than through beach closures. Stinger exclusion nets are commonly used iv along the north-eastern coast of Queensland; however, these nets are designed to exclude large cubozoan species, primarily Chironex fleckeri, and do not exclude small species such as C. barnesi. Also, this species occurs with substantial spatial and temporal variability during the monsoonal summer months. Therefore, understanding the factors that contribute to this variability may facilitate the ability to model, and therefore predict, when and under what circumstances this species may be more prevalent. Currently, the ecological data required to produce a predictive model does not exist. Prior to the commencement of this research project, the early life history of C. barnesi had never been observed, or described, and nothing was known about the thermal and osmotic tolerance, or preference, of any of its life stages. This study first describes the early life history C. barnesi, from egg fertilization through to medusa production, and elucidates that this species develops an encapsulated planula stage that remains viable for six days to over six months. The polyps of C. barnesi asexually reproduce ciliated swimming polyps and produce medusae through monodisc strobilation. This study resulted in the first verified culture of C. barnesi polyps. With the polyp stage of the life cycle in culture, the opportunity to conduct manipulative temperature and salinity experiments were pursued, which provides new insights into potential polyp habitat suitability. Primary findings revealed 100% survivorship in osmotic treatments between 19‰ and 46‰, with the highest proliferation at 26‰. As salinity levels of 26‰ do not occur within the waters of the Great Barrier Reef or Coral Sea, it is concluded that the polyp stage v of C. barnesi are probably found in estuarine environments, where these lower salinity conditions commonly occur. With the relationship of temperature and salinity on the polyp stage known, focus was shifted to exploration of these factors on the medusa stage. The thermal and osmotic tolerance of C. barnesi medusae were investigated to determine if environmental parameters drive the marked seasonality of this species. By exploring oxygen consumption over a range of temperatures, the minimum thermal requirement for C. barnesi was estimated at 21.5ºC, which does not explain the seasonal occurrence of this species. The optimum temperature for swimming pulse rate was determined to occur between 27.5ºC and 30.9ºC and the optimum temperature was estimated at 29.2ºC, which encompasses the typical summer thermal regime in situ. This research concludes that reduced fitness associated with environmental temperatures that departure from optimum may better explain the seasonal pattern of this species. Conversely, departure from optimum temperature did not explain the southern distribution limits of this species, suggesting that C. barnesi could theoretically persist further south than their loosely defined southern distribution limits. The optimum salinity of C. barnesi medusae was estimated at 35.8‰ and fitness was reduced as salinity levels reduced below 29‰, adding further support that C.