Abstract

Iron is an important mineral that serves many functions in the body, including oxygen transport and oxidative metabolism.¹ Hemosiderosis is a pathologic condition that can affect a variety of different vertebrates, including dolphins.^2,5,7,9 There are a number of different risk factors that have been associated with the development of this disease in captive zoological species, including diet, genetics, stress, infectious diseases, and toxins.^2,3,5,10 Hemosiderosis occurs as a result of excessive iron absorption.² There are a number of different endogenous and exogenous factors that can affect iron absorption.^1,2,4,8 Gastric acid secretion is an endogenous factor that can exert significant influence on iron absorption.^4,8 A recent study measuring the dietary iron being provided to a captive population of dolphins found levels to be higher than that expected for humans.⁶ The purpose of this study was to determine if gastric pH has an affect on serum iron and total iron binding capacity levels in a captive population of Atlantic bottlenose dolphins with a history of hemosiderosis. Six captive, adult female dolphins were sampled for this study. Blood and gastric samples were collected from each animal monthly for 12 months. There was no significant difference in gastric pH (F= 0.4, p=0.5), serum iron (F=2.7, p=0.2) or serum TIBC (F=0.16, p=0.86) over time (within subjects). There was a strong negative correlation between gastric pH and serum iron (r= -0.85) and TIBC (r= - 0.74) levels, suggesting that dolphins with lower gastric pH levels have higher serum iron and TIBC levels. There was also a strong positive correlation between serum iron and TIBC levels (r=0.94). The results of this study suggest that low gastric pH may play a role in the absorption of iron from the stomach of dolphins.

Acknowledgements

The authors would like to acknowledge Institute for Marine Mammal Studies for funding the project, Marine Animal Productions, Marine Life Oceanarium for providing the animals and facility and Tim Hoffland, Marci Romagnoli and other trainers for training the animals and acquiring the samples.

References

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