Nutritional composition of manatee’s diet in the Western Caribbean: from the river to the reef

Abstract

The endangered Greater Caribbean manatee (Trichechus manatus manatus), one of the largest aquatic herbivores in the Caribbean, plays a crucial role in nutrient recycling within the ecosystem, and the study of its feeding ecology is important for its conservation. Despite several studies determining the items consumed by manatees, there remains limited understanding of their nutritional significance for the species in the Western Caribbean. This study, aimed to analyze the bromatological composition of the food components in the manatee’s diet in the Mexican Caribbean across three distinct environments. We manually collected aquatic and semi-aquatic primary producers potentially part of the manatee diet in marine, brackish and riverine areas of the southern region of Quintana Roo, Mexico. Then, we analyzed them for moisture, crude protein, crude fiber, ash, ether extract, digestible nutrients, and digestible energy. We present the initial data on nutrient values in the manatee diet in the Caribbean, establishing a foundation for exploring the factors that influence spatial, temporal, and species-specific variations in nutrient content at a regional level. Our bromatological analysis demonstrated that the most nutritionally important plants for manatees, based mainly on protein content and freshwater contribution, include the seagrasses Halodule wrightii, Syringodium filiforme, Thalassia testudinum, the water lily Pontederia crassipes, and Vallisneria sp. Effective habitat management for manatees is crucial for their survival, ensuring that feeding resources are maintained in both enough quantity and high quality. Given its nutritional significance for manatees, we recommend that seagrasses in the region should be prioritized as conservation targets.