Ocean acidification, hypoxia and warming impair digestive parameters of marine mussels Fahim Ullah Khan a, b, c, 1 , Menghong Hu a, b, 1 , Hui Kong a, b , Yueyong Shang a, b , Ting Wang a, b , Xinghuo Wang a, b , Ran Xu a, b , Weiqun Lu a, b, ** , Youji Wang a, b, * a International Research Center for Marine Biosciences at Shanghai Ocean University, Ministry of Science and Technology, Shanghai, 201306, China b Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Shanghai Ocean University), Ministry of Education, Shanghai, 201306, China c Fisheries and Aquaculture Programme, Department of Zoology, Quaid-i-Azam University, Islamabad, Pakistan highlights graphical abstract  Low pH, low DO and high tempera- ture showed drastic effects on digestive enzyme activities.  Low pH, low DO and high tempera- ture synergistically reduced digestive enzyme activities.  Lysozyme showed increased and then decreased activities with time.  Combinations of low pH, low DO and high temperature showed more se- vere effects on digestive enzymes than single factors.  Hypoxia and high temperature showed similar effects on digestive enzyme activities. article info Article history: Received 22 April 2020 Received in revised form 13 May 2020 Accepted 15 May 2020 Available online 16 May 2020 Handling Editor: Jim Lazorchak Keywords: Ocean acidification Hypoxia Temperature Digestive enzyme Interactive effect Mussel abstract Global change and anthropogenic activities have driven marine environment changes dramatically during the past century, and hypoxia, acidification and warming have received much attention recently. Yet, the interactive effects among these stressors on marine organisms are extremely complex and not accurately clarified. Here, we evaluated the combined effects of low dissolved oxygen (DO), low pH and warming on the digestive enzyme activities of the mussel Mytilus coruscus. In this experiment, mussels were exposed toeight treatments, including two degrees of pH (8.1, 7.7), DO (6, 2 mg/l) and temperature (30  C and 20  C) for 30 days. Amylase (AMS), lipase (LPS), trypsin (TRY), trehalase (TREH) and lysozyme (LZM) activities were measured in the digestive glands of mussels. All the tested stress conditions showed significant effects on the enzymatic activities. AMS, LPS, TRY, TREH showed throughout decreased trend in their activities due to low pH, low DO, increased temperature and different combi- nations of these three stressors with time but LZM showed increased and then decreased trend in their activities. Hypoxia and warming showed almost similar effects on the enzymatic activities. PCA showed a positive correlation among all measured biochemical parameters. Therefore, the fitness of mussel is * Corresponding author. International Research Center for Marine Biosciences at Shanghai Ocean University, Ministry of Science and Technology, Shanghai, 201306, China. ** Corresponding author. International Research Center for Marine Biosciences at Shanghai Ocean University, Ministryof Science and Technology, Shanghai, 201306, China. E-mail addresses: wqlv@shou.edu.cn (W. Lu), youjiwang2@gmail.com (Y. Wang). 1 These authors contributed equally to this work. Contents lists available at ScienceDirect Chemosphere journal homepage: www.elsevier.com/locate/chemosphere https://doi.org/10.1016/j.chemosphere.2020.127096 0045-6535/© 2020 Elsevier Ltd. All rights reserved. Chemosphere 256 (2020) 127096