Abstract
Ammonia is a common environmental stressor encountered during aquaculture, and is a significant concern due to its adverse biological effects on vertebrate and invertebrate including crustaceans. However, little information is available on physiological and molecular responses in crustaceans under long-term ammonia exposure, which often occurs in aquaculture practices. Here, we investigated temporal physiological and molecular responses in the gills, the main ammonia excretion organ, of the swimming crab Portunus trituberculatus following long-term (4 weeks) exposure to three different ammonia nitrogen concentrations (2, 4, and 8 mg l–1), in comparison to seawater (ammonia nitrogen below 0.03 mg l–1). The results revealed that after ammonia stress, the ammonia excretion and detoxification pathways were initially up-regulated. These processes appear compromised as the exposure duration extended, leading to accumulation of hemolymph ammonia, which coincided with the reduction of adenosine 5′-triphosphate (ATP) and adenylate energy charge (AEC). Considering that ammonia excretion and detoxification are highly energy-consuming, the depression of these pathways are, at least partly, associated with disruption of energy homeostasis in gills after prolonged ammonia exposure. Furthermore, our results indicated that long-term ammonia exposure can impair the antioxidant defense and result in increased lipid peroxidation, as well as induce endoplasmic reticulum stress, which in turn lead to apoptosis through p53-bax pathway in gills of the swimming crab. The findings of the present study further our understanding of adverse effects and underlying mechanisms of long-term ammonia in decapods, and provide valuable information for aquaculture management of P. trituberculatus.
Highlights
Ammonia is a common environmental stressor in aquatic ecosystem, and is of significant concern to the aquaculture industry
We investigated the temporal responses associated with ammonia excretion and detoxification, energy metabolism, antioxidant defense, unfolded protein responses (UPR), and apoptosis in the gills, the major excretory organs for ammonia, of P. trituberculatus during long-term ammonia stress
Activity of HK, PK, and succinate dehydrogenase (SDH) in the MA and HA groups were significantly elevated at 1 week, after which their levels decreased as exposure time increased and become lower than the control at 4 week (Figure 1)
Summary
Ammonia is a common environmental stressor in aquatic ecosystem, and is of significant concern to the aquaculture industry. As aquaculture is moving toward more intensive systems with high stocking density and feed supply, there has been rising concerns on ammonia levels in crustacean aquaculture industry. An increasing number of studies have been performed to understand the adverse effects and defensive mechanisms in crustaceans (Zhao et al, 2020). Most of these studies focused on acute ammonia exposure, and there has been limited information available on stress responses in crustaceans under long-term exposure (Liang et al, 2019; Liu F. et al, 2020). It is of great significance to study the stress responses of crustaceans under long-term ammonia stress
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
