Can Diving-induced Tissue Nitrogen Supersaturation Increase the Chance of Acoustically Driven Bubble Growth in Marine Mammals?
✍ Scribed by D.S. HOUSER; R. HOWARD; S. RIDGWAY
- Book ID
- 102613506
- Publisher
- Elsevier Science
- Year
- 2001
- Tongue
- English
- Weight
- 300 KB
- Volume
- 213
- Category
- Article
- ISSN
- 0022-5193
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✦ Synopsis
The potential for acoustically mediated causes of stranding in cetaceans (whales and dolphins) is of increasing concern given recent stranding events associated with anthropogenic acoustic activity. We examine a potentially debilitating non-auditory mechanism called recti"ed di!usion. Recti"ed di!usion causes gas bubble growth, which in an insoni"ed animal may produce emboli, tissue separation and high, localized pressure in nervous tissue. Using the results of a dolphin dive study and a model of recti"ed di!usion for low-frequency exposure, we demonstrate that the diving behavior of cetaceans prior to an intense acoustic exposure may increase the chance of recti"ed di!usion. Speci"cally, deep diving and slow ascent/descent speed contributes to increased gas-tissue saturation, a condition that ampli"es the likelihood of recti"ed di!usion. The depth of lung collapse limits nitrogen uptake per dive and the surface interval duration in#uences the amount of nitrogen washout from tissues between dives. Model results suggest that low-frequency recti"ed di!usion models need to be advanced, that the diving behavior of marine mammals of concern needs to be investigated to identify at-risk animals, and that more intensive studies of gas dynamics within diving marine mammals should be undertaken.