Coral Coast IMMA

Criterion A – Species or Population Vulnerability

West Indian manatees (Trichechus manatus) are sensitive to changes in coastal environments, and are threatened by entanglement in fishing nets, boat strikes, and above all, the loss of habitat (Borges et al., 2007; Meirelles, 2008). Globally the species is classified as Vulnerable on the IUCN Red List of Threatened species (Deutsch et al. 2008). In Brazil, the frequent occurrence of stranded manatees, in particular neonates, reflects anthropogenic threats including the degradation of the estuaries in which the species breeds, gives birth and nurses young (Lima et al., 1992 ; Aquasis, 2016; Medeiros et al., 2021). Given the considerable pressures on the surviving wild populations, the West Indian manatee is one of Brazil’s most threatened aquatic mammals (MMA, 2022), with the total population in the Brazilian Northeast estimated to be just over 1,000 individuals (Alves et al., 2015). The coast of Alagoas, including the Coral Coast, comprises the southernmost area of the distribution of the remaining population.

Criterion B: Distribution and Abundance

Sub-criterion B1: Small and Resident Populations

The IMMA contains prime habitat for manatees and hosts both a resident native population and approximately 50 rehabilitated and re-introduced individuals, with several documented observations of interaction between wild and released animals. Aerial surveys conducted along Brazil’s coast in 2010 yielded relatively high sightings rates in the IMMA in comparison with areas to the north and south, demonstrating the area’s importance for the species (Alves et al., 2015).

The Coral Coast was chosen as the main release site for rehabilitated manatees based on the availability of a suitable food supply, sources of fresh water, and shallow and protected water. Since 1994 approximately 50 animals have been released into the waters of the IMMA (Normande et al., 2016). Satellite tracking of these released individuals demonstrates that the IMMA encompasses the home ranges and centres of activity of the tagged individuals, and that they move between the estuarine and coastal portions of the IMMA.  The home range size, based on kernels that encompassed 95% of tracking points, varied from 4.24 to 30.96 km2 (mean = 11.56 ± 8.60). (Normande et al., 2016).  The maximum distance of satellite location points from the coast varied from 0.97 to 3.31 km (mean 1.93–0.71), and core areas were in locations by the presence of coral and sand reefs or within estuaries or rivers, and the majority of these areas contained fresh water sources and/or seagrass beds (Normande et al., 2016).  Although satellite tracking data is not available for the naturally occurring native population, it could be reasonably assumed that they have similar home ranges and habitat use patterns within the IMMA, although longer range movements may also be possible.

Criterion C: Key Life Cycle Activities

Sub-criterion C1: Reproductive Areas

Several estuaries on the Coral Coast provide connectivity between coastal and marine environments. The presence of these environments (estuaries) and the extensive coverage of coral reefs provides an environment with shallow, warm and protected waters, favourable for manatee calving and nursing young.

The naturally occurring population is observed annually with newborn offspring, while several reintroduced animals have already reproduced in the wild on the Coral Coast (Attademo et al., 2022). The births of 13 calves from six reintroduced females have been documented in this area. Six (37.5%) of the 16 females released in Alagoas have been confirmed to have calves post-release. Two of these six parturient females delivered their calves in the marine portion of the IMMA, and four in the estuarine portions of the IMMA (Attademo et al., 2022).

Sub-criterion C2: Feeding Areas

Borges et al. (2008) analysed stomach content samples from manatees accidentally caught in the states of Rio Grande do Norte, Paraíba and Alagoas. A wide range of items was recorded, such as seagrass, algae and mangroves.  Tropical seagrass meadows, situated between coral reefs, sand flats and estuaries, provide the main source of food for manatees in the region (Attademo et al., 2022). Macroalgae comprise another important component of the marine flora that occurs in the region (including the Caulerpaceae, Cladophoraceae, and Udoteaceae families) and many of these are constituents of the diet of West Indian manatees, and some of these species are abundant in the IMMA (Borges et al., 2008; Attademo et al., 2022).