# Assessing Bottlenose Dolphins’ (Tursiops truncatus) Health Status Through Functional Muscle Analysis, and Oxidative and Metabolic Stress Evaluation: A Preliminary Study

## TL;DR

This study explores oxidative stress and muscle health in captive bottlenose dolphins, finding no strong link between biochemical markers and oxidative stress, but a possible connection between tissue turnover and antioxidant defenses.

## Contribution

The study introduces a preliminary investigation into oxidative and metabolic stress in bottlenose dolphins, highlighting sex and age-related differences in antioxidant responses.

## Key findings

- Male dolphins showed significantly higher pro-oxidant levels than females, suggesting a protective role of female hormones.
- Older dolphins produced more ROS but had higher antioxidant capacity, likely to compensate for oxidative damage.
- A moderately positive correlation was found between LDH and antioxidant capacity, indicating a possible link between tissue turnover and antioxidant defenses.

## Abstract

This study aims to assess the systemic pro-oxidant and antioxidant state of 11 common bottlenose dolphins (Tursiops truncatus) under human care, and to investigate the correlation between oxidative stress and biochemical parameters that indicate tissue damage or metabolic alterations. Blood aspartate aminotransferase, creatine kinase, lactate dehydrogenase, and glucose were evaluated as biochemical parameters. This study may elucidate the impact of oxidative stress on the metabolism and tissue function of the captive dolphin population. The management of marine mammals requires regular monitoring and blood assessment evaluation, in order to provide effective care and to promote their health and well-being.

Oxidative stress (OS) occurs when there is an imbalance between the production of reactive oxygen species (ROS) and the body’s antioxidant defenses, causing damage to lipids, proteins, and DNA. In marine mammals, physiological adaptation to aquatic life conditions, such as prolonged and repeated dives resulting in cycles of hypoxia followed by reperfusion, is associated with increased production of ROS. This study examines the relationship between oxidative stress, muscular stress, and metabolic damage in the blood serum of eleven captive bottlenose dolphins (Tursiops truncatus), six males and five females. This relationship is investigated using oxidative stress markers (d-ROMs, OXY, and Oxidative Stress index, OSi) and biochemical parameter measurements, including glucose (GLU), aspartate aminotransferase (AST), creatine kinase (CK), and lactate dehydrogenase (LDH). Pearson’s sex correlation was performed, and males exhibited significantly higher pro-oxidant levels than females, suggesting a potential protective role of female hormones. Also, a positive correlation between pro-oxidants and antioxidants has been observed in relation to age, as older dolphins produced more ROS but also exhibited higher antioxidant capacity, likely to compensate for oxidative damage. Results show no significant correlation between biochemical parameters and oxidative stress markers. However, a moderately positive correlation between LDH and antioxidant (OXY) capacity was observed (r = 0.458), suggesting a possible association between tissue turnover and antioxidant defenses. The results indicate that the biochemical markers analyzed are not strong predictors of oxidative stress in bottlenose dolphins. However, the correlation between LDH and antioxidant capacity suggests that tissue turnover may affect antioxidant defenses. This is a preliminary study, and further research is needed to clarify these relationships in order to better understand physiological adaptations in dolphins and their implications for management, health, and welfare.