ALBERT

Description: Cleaning symbioses play an important role in the health of certain coastal marine communities. These interspecific associations often occur at specific sites (cleaning stations) where a cleaner organism (commonly a fish or shrimp) removes ectoparasites/damaged tissue from a “client” (a larger cooperating fish). At present, the potential impact of climate change on the fitness of cleaner organisms remains unknown. The present study investigated the physiological and biochemical responses of tropical ( Lysmata amboinensis ) and temperate ( L. seticaudata ) cleaner shrimp to global warming. Specifically, thermal limits (CTMax), metabolic rates, thermal sensitivity, heat shock response (HSR), lipid peroxidation [malondialdehyde (MDA) concentration], lactate levels, antioxidant (GST, SOD and catalase) and digestive enzyme activities (trypsin and alkaline phosphatase) at current and warming (+ 3 °C) temperature conditions. In contrast to temperate species, CTMax values decreased significantly from current (24 – 27 °C) to warming temperature conditions (30 °C) for the tropical shrimp, where metabolic thermal sensitivity was affected and the HSR was significantly reduced. MDA levels in tropical shrimp increased dramatically, indicating extreme cellular lipid peroxidation, which was not observed in the temperate shrimp. Lactate levels, GST and SOD activities were significantly enhanced within the muscle tissue of the tropical species. Digestive enzyme activities in the hepatopancreas of both species were significantly decreased by warmer temperatures. These data suggested tropical cleaner shrimp were less able to acclimatize and would be more vulnerable to global warming than temperate species like Lysmata seticaudata which evolved in a relatively unstable environment with seasonal thermal variations that may have conferred greater adaptive plasticity. This indicated tropical cleaning symbioses may be challenged by warming-related anthropogenic forcing, with potential cascading effects on the health and structuring of tropical coastal communities (e.g., coral reefs). This article is protected by copyright. All rights reserved.