Diet of the Antillean Manatee (Trichechus manatus manatus) in Belize, Central America

• Main Author: Allen, Aarin Conrad
• Format: Others
• Published: NSUWorks 2014
• Subjects: Antillean Manatee; Sirenia; Microhistological Analysis; Feeding Ecology; Dietary Habits; Belize; Herbivory; Marine Biology
• Online Access: http://nsuworks.nova.edu/occ_stuetd/9; http://nsuworks.nova.edu/cgi/viewcontent.cgi?article=1002&context=occ_stuetd

Belize has been identified as an important location for Antillean manatees (Trichechus manatus manatus), harboring the highest known population density of this subspecies. Information about their dietary habit is important in determining habitat requirements and aiding in conservation efforts. The main objective of this study was to identify the key plant species consumed by manatees in Belize and to establish differences in diet based on location, sex, size classification, and season. Samples were collected from two different locations within Belize where manatees are known to aggregate: Southern Lagoon and the Drowned Cayes off of Belize City. The contents of thirteen mouth, six digestive tract (stomach, duodenum and colon), and 124 fecal samples were analyzed. Five species of seagrasses (Halodule wrightii, Thalassia testudinum, Ruppia maritima, Syringodium filiforme, and Halophila sp.) made up the highest percentage of plants consumed; undigested rhizome was most prevalent. A vascular plant, the red mangrove (Rhizophora mangle), was identified as an important food item of manatees in Belize. Algae (Chara sp., Lyngbia sp., and Ulvasp.) and invertebrates (diatoms and sponges) were represented as well. These items are comparable to other reports of manatee diets in areas near Belize and areas with similar habitat. Variation in the percentage of seagrass, mangrove, and algae consumption was analyzed as a 4-factor factorial Analysis of Variance (ANOVA) with main effects and interactions for locality (Southern Lagoon and the Drowned Cayes), sex, size classification (>245 cm & ˂245 cm), and season (December – May and June – November). Sex and season did not influence diet composition; differences for locality and size classification were observed. Seagrass was more often consumed in Southern Lagoon (P = 0.03), whereas mangroves and algae were more prevalent in the Drowned Cayes (P = 0.03). No differences among size classifications in consumption of seagrasses or mangroves were observed. A significantly higher number of samples from adults (>245 cm) than juveniles (˂245 cm) contained algae (P = 0.04). This is most likely attributed to inexperience in foraging. Findings from these results suggest that diet composition analysis can be used to interpret Antillean manatee habitat and resource utilization and can aid in the conservation of this endangered species.