Abalone under moderate heat stress have elevated metabolic rates and changes to digestive enzyme activities

• Published in: Comparative biochemistry and physiology. Part A, Molecular & integrative physiology Molecular & integrative physiology, 2022-08, Vol.270, p.111230-111230, Article 111230
• Main Authors: Frederick, Alyssa R., Lee, Ariana M., Wehrle, Beck A., Catabay, Caitlyn C., Rankins, Daniel R., Clements, Kendall D., German, Donovan P.
• Format: Article
• Language: English
• Subjects: abalone; alkaline phosphatase; alpha-glucosidase; amylases; Climate change; Digestibility; digestible carbohydrates; digestible organic matter; digestible protein; Digestive enzymes; food intake; Gastropods; Haliotis rufescens; Heat stress; heat treatment; Marine heatwaves; Metabolic rate; Nutrition; Physiology; Pāua; Red abalone; temperature; trypsin
• ISSN: 1095-6433; 1531-4332
• DOI: 10.1016/j.cbpa.2022.111230

Abalone around the world are subject to increasing frequency of marine heatwaves, yet we have a limited understanding of how acute high temperature events impact the physiology of these commercially and ecologically important species. This study examines the impact of a 5 °C temperature increase over ambient conditions for six weeks on the metabolic rates, digestive enzyme activities in the digestive gland, and digestive efficiency of Red Abalone (Haliotis rufescens) and Pāua (H. iris) on their natural diets. We test the hypothesis that abalone digestive function can keep pace with this increased metabolic demand in two separate experiments, one for each species. H. iris had higher food intake in the heat treatment. Both species had higher metabolic rates in the heat treatment with Q10 = 1.73 and Q10 = 2.46 for H. rufescens and H. iris, respectively. Apparent organic matter digestibility, protein digestibility, and carbohydrate digestibility did not differ between the heat treatment and the ambient (control) treatment in either experiment. H. rufescens exhibited higher maltase, alanine-aminopeptidase, and leucine-aminopeptidase activities in the heat treatment. Amylase, β-glucosidase, trypsin, and alkaline phosphatase activities in the digestive gland tissue did not differ between temperature treatments. H. iris exhibited lower amylase and β-glucosidase activities in the heat treatment, while maltase, trypsin, leucine-aminopeptidase, and alkaline phosphatase activities did not differ between treatments. We conclude that over six weeks of moderate heat stress both abalone species were able to maintain digestive function, but achieved this maintenance in species-specific ways. [Display omitted] •Nutrient and organic matter digestibility are maintained at higher temperature•Heat leads to higher maltase and aminopeptidase activities in red abalone•Heat leads to lower amylase and β-glucosidase activities in pāua•Both abalone species can maintain digestion during short-term heat stress