Ảnh hưởng của nhiệt độ và hàm lượng oxy thấp lên cấu trúc cơ quan hô hấp của cá tra (pangasianodon hypophthalmus)

MINISTRY OF EDUCATION AND TRAINING CAN THO UNIVERSITY LE MY PHUONG THE EFFECTS OF ELEVATED TEMPERATURE AND HYPOXIA ON THE RESPIRATORY ORGANS OF Pangasianodon hypophthalmus PHD DISSERTATION MAJOR: AQUACULTURE MAJOR CODE: 62 62 03 01 2017 MINISTRY OF EDUCATION AND TRAINING CAN THO UNIVERSITY LE MY PHUONG THE EFFECTS OF ELEVATED TEMPERATURE AND HYPOXIA ON THE RESPIRATORY ORGANS OF Pangasianodon hypophthalmus PHD DISSERTATION MAJOR: AQUACULTURE MAJOR CODE: 62 62 03 01 SUPERVISORS Supervisor: Assoc Prof Dr DO THI THANH HUONG Co-supervisor: Assoc Prof Dr MARK BAYLEY 2017 Data sheet Title: The effects of elevated temperature and hypoxia on the respiratory organs of Pangasianodon hypophthalmus Subtitle: PhD Dissertation Author: Le My Phuong Affiliation: College of Aquaculture & Fisheries, Can Tho University, Vietnam; Zoophysiology, Department of Bioscience, Aarhus University, Denmark Publication year: 2017 Cite as: Phuong L.M (2017) The effects of elevated temperature and hypoxia on the respiratory organs of Pangasianodon hypophthalmus PhD Dissertation College of Aquaculture & Fisheries, Can Tho University, Vietnam and Zoophysiology, Department of Bioscience, Aarhus University, Denmark Keywords: climate change, hypoxia, temperature, morphometric, swim bladder, gill remodelling, air-breathing fish, Pangasianodon hypophthalmus Supervisor: Associate Professor Do Thi Thanh Huong, Deparment of Aquatic Nutrition and Products Processing, College of Aquaculture and Fisheries, Can Tho University, Vietnam Co-supervisor: Associate Professor Mark Bayley, Zoophysiology, Deparment of Bioscience, Aarhus University, Denmark Co-supervisor: Professor Jens Randel Nyengaard, Core Center for Molecular Morphology, Section for Stereology and Microscopy, Centre for Stochastic Geometry and Advanced Bioimaging, Aarhus University, Denmark Table of Contents Data sheet Table of Contents ACKNOWLEDGEMENTS SUMMARY Chapter 1: INTRODUCTION 1.1 Oxygen requirement and adaptive mechanisms of fish to hypoxia 1.2 Striped catfish (Pangasianodon hypophthalmus) 1.3 General gill structure in teleosts 1.4 Osmo-respiratory compromise in fish gills 11 1.5 Gill plasticity and environmental factors causing gill plasticity 12 1.6 Methods applied in morphometric studies 14 1.7 Objectives of dissertation…… ………… …………………………………….17 REFERENCES 17 Chapter (PAPER 1) 26 Recovery of blood gases and haematological parameters upon anaesthesia with Benzocaine, MS-222 or Aqui-S in the air-breathing catfish (Pangasianodon hypophthalmus) 26 Chapter (PAPER 2) 48 Gill remodelling and growth rate of striped catfish Pangasianodon hypophthalmus under impacts of hypoxia and temperatures 48 Chapter (PAPER 3) 76 Ontogeny and morphometric of the gill and swim bladder of air-breathing striped catfish Pangasianodon hypophthalmus 76 Chapter (PAPER 4) 104 Gill remodelling does not affect the rate of acid-base regulation in the striped catfish Pangasianodon hypophthalmus 104 Chapter 6: Conclusions and Perspectives… 121 APPENDICE…………………………………………………………… ………… 125 ACKNOWLEDGEMENTS Foremost, I would also like to give my thanks to Assoc Prof Do Thi Thanh Huong and Prof Nguyen Thanh Phuong in Can Tho University for always supporting, encouraging, and watching my steps during my study I would also like to express my gratitude to Assoc Prof Mark Bayley who has found and built my passions and directions for science as who I am and what I have today His guidance and enthusiasm have inspired and supported me moving forward and working by my best during my research and writing this thesis I am also grateful to Prof Jens Randel Nyengaard for teaching me stereological methods and supporting me during my working in his laboratory My sincere thanks also go to Prof Tobias Wang, Prof Atsushi Ishimatsu, and Prof Hans Malte for giving me special advices and precious and initiative suggestions which contribute importantly in my thesis Also, I acknowledge Christian Damsgaard who greatly contributed in interpreting and discussing data of the last manuscript in this thesis I would like to thank the staffs at the College of Aquaculture and Fisheries, Can Tho University (Vietnam), at the Zoophysiology Section, Department of Biological Sciences, and at Core Center for Molecular Morphology, Section for Stereology and Microscopy, Centre for Stochastic Geometry and Advanced Bioimaging, Aarhus University, Denmark where my projects were carried out Especially, I would like to thank Maj-Britt Lundorf for teaching me with helpful skills in histology and Per Guldhammer Henriksen for helping me during my experiments in Aarhus University I would also like to thank my fellow friends in iAQUA project: Nguyen Thi Kim Ha, Le Thi Hong Gam, Dang Diem Tuong, and Phan Vinh Thinh for their friendship and all the funs we have during the time we worked together in the project Finally, I would like to thank my family and my friends for their love and spiritually supporting me throughout my research, my writing, and my whole life My project was funded by The Danish International Development Agency (DANIDA), Ministry Affairs of Foreign Denmark, iAQUA project SUMMARY The striped catfish Pangasianodon hypophthalmus is one of the most important species in terms of both economy and physiology The overall objective of this study is to provide input to the assessment of the effects of elevated temperature and/or hypoxia on the respiratory organs of air-breathing catfish Pangasionodon hypophthalmus by implementing stereological methods to reveal plasticity This research will play a key role in a better understanding the capacity for adaptation of air-breathing fish to temperature increases Four main projects were investigated in this study In the first project, the disturbances in blood gasses and haematological parameters, caused by the three different anaesthetics, commonly used in aquaculture during transport as well as for surgical procedures, were investigated during recovery in Pangasianodon hypophthalmus We found that these parameters were normalized within 24h and this was the first indication that P hypophthalmus is unusual among air-breathing fish with its strong capacity for acid-base regulation In addition, this study demonstrated that this species lacks the β-adrenergic swelling responses in red blood cells In the second project, by applying vertical sections in stereology, gill morphometrics of P hypophthalmus exposed to the average Mekong river present temperature (27°C) as well as to a constant 6°C elevation were investigated These temperature treatments were combined with normoxic and hypoxic oxygen levels We found strong plasticity in gills lamellar surface areas (SA), with highest SA under elevated temperature and hypoxia whereas almost eliminated This plasticity was due to proliferation of cell mass between the secondary lamellae (ILCM), which was thus most developed in the normoxic low temperature group Further, the diffusion distance from water to blood (HM) was thinnest (approximately 1.0µm) in the fish exposed to hypoxia and high temperature At their largest, the gills of this species are on a weight specific basis similar to active water-breathers, such as trout, but with significantly shorter HM This is the first documentation of ILCM in catfish and is similar to that found in cyprinids and seems to present support for the osmo-respiratory compromise phenomenon In this study it was also demonstrated for the first time that this species grows much faster at higher than present temperatures, with an 8-fold higher growth rate at 33°C than 27°C The third project, we examined the development of the gill and air-breathing organ (ABO) SA and HM with body size By calculating the anatomical diffusion factor, it was possible to evaluate the importance of gills and ABO for oxygen uptake and to make interspecies comparisons Here I found that the ADF of the gills is high (comparable to an active water-breather such as rainbow trout), even with fully developed ILCM Further, when required, the gills can change rapidly (