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Florida Red Tides, Manatee Brevetoxicosis, and Lung Models
Abstract:
In 1996, 149 Florida manatees, Trichechus manatus latirostris, died along the southwest coast of Florida. Necropsy pathology results of these animals indicated that brevetoxin from the Florida red tide, Karenia brevis, caused their death. A red tide bloom had been previously documented in the area where these animals stranded. The necropsy data suggested the mortality occurred from chronic inhalation and/or ingestion. Inhalation theories include high doses of brevetoxin deposited/stored in the manatee lung or significant manatee sensitivity to the brevetoxin. Laboratory models of the manatee lungs can be constructed from casts of necropsied animals for further studies; however, it is necessary to define the breathing pattern in the manatee, specifically the volumes and flow rates per breath to estimate toxin deposition in the lung. To obtain this information, two captive-born Florida manatees, previously trained for husbandry and research behaviors, were trained to breathe into a plastic mask placed over their nares. The mask was connected to a spirometer that measured volumes and flows in situ. Results reveal high volumes, short inspiratory and expiratory times and high flow rates, all consistent with observed breathing patterns.
Insights
Florida manatees experienced high mortality due to Florida red tide (Karenia brevis) toxin. Researchers studied manatee breathing patterns to understand toxin inhalation, revealing high volumes and rapid breaths.
Area of Science:
- Marine Mammal Health
- Ecotoxicology
- Respiratory Physiology
Background:
- Mass mortality events of Florida manatees (Trichechus manatus latirostris) in 1996 were linked to brevetoxin from Florida red tide (Karenia brevis) blooms.
- Necropsy findings suggested chronic inhalation or ingestion of brevetoxin as the cause of death.
- Understanding manatee respiratory patterns is crucial for estimating toxin deposition in the lungs and assessing inhalation risk.
Purpose of the Study:
- To define the breathing pattern of Florida manatees, including respiratory volumes and flow rates.
- To provide data necessary for constructing laboratory models of manatee lungs for further toxicological studies.
Main Methods:
- Two trained, captive-born Florida manatees were fitted with a mask over their nares.
- The mask was connected to a spirometer to measure breathing volumes and flow rates in situ.
- Data were collected while manatees breathed normally through the mask.
Main Results:
- Manatees exhibited high tidal volumes.
- Inspiratory and expiratory phases were characterized by short durations.
- High respiratory flow rates were recorded, consistent with observed natural breathing behaviors.
Conclusions:
- The study successfully characterized Florida manatee breathing patterns, demonstrating high volumes and rapid, high-flow breaths.
- These findings are essential for future research on brevetoxin inhalation and risk assessment in manatees.
- This data will aid in developing more accurate models of toxin deposition in the manatee respiratory system.
