Bibliography and Index of the Sirenia and Desmostylia  

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Castelblanco-Martínez, Delma Nataly; Bermúdez-Romero, Ana Lucia; Gómez-Camelo, Isabel Victoria (detail)
Ecología, distribución y conservación del manatí Trichechus manatus manatus en la Orinoquía colombiana. In: Programa Nacional de Conservación y Manejo de Manatíes en Colombia.
Bogotá, Ministerio de Ambiente, Vivienda y Desarrollo Territorial - Fundación Omacha: 131-142. 4 tabs. 4 figs.
Castelblanco-Martínez, Delma Nataly; Holguín, Victoria E.; Zapata (Morita), José Manuel (detail)
Conservación y manejo del manatí en la Ciénaga de Paredes (Santander). In: Programa Nacional de Conservación y Manejo de Manatíes en Colombia.
Bogotá, Ministerio de Ambiente, Vivienda y Desarrollo Territorial - Fundación Omacha: 105-113. 1 fig.
Castelblanco-Martínez, Delma Nataly; et al. (detail)
Mamíferos aquáticos. Chap. 14 in: Rapp Py-Daniel L. et al. (eds.), Biodiversidade do Médio Madeira: bases científicas para propostas de conservação.
Manaus, Probio/Mma.: 225-238.
Mercadillo-Elguero, Maria Isabel; Castelblanco-Martínez, Delma Nataly; Padilla-Saldívar, Janneth Adriana (detail)
Behavioral patterns of a manatee in semi-captivity: implications for its adaptation to the wild.
Journal of Marine Animals and Their Ecology 7(2): 31-41. 2 tabs. 6 figs.
–ABSTRACT: Rehabilitation of orphaned endangered Antillean manatees (Trichechus manatus manatus) enhances in situ conservation. We investigated the behavior of a five year-old male manatee rescued in Quintana Roo (Mexico) in relation to its failed rehabilitation. This is a unique case of a semi-captive manatee in the Caribbean, and the first endeavor to release a rehabilitated orphan in Mexico. Through 134 hours of direct and ad libitum observations, we described the manatee's behavior and assessed his behavioral time budget. The frequency of states was determined by instantaneous sampling, while the frequency of events was defined by the number of events per time unit. We designed an ethogram of 105 behaviors (56 states and 49 events), distributed in six behavioral categories. Compared with previous catalogs designed for manatees, the subject displayed 43 new behaviors (24 states and 19 events). The manatee showed indications of a daily rhythm; the animal consistently performed displacement behaviors in daytime hours, while engaged in comfort behaviors mainly at night. The use of space depended on the behavioral category and the time of day. The manatee showed dietary preference for the food provided by the caretakers, and virtually no consumption of native aquatic plants. This inadequate feeding behavior, along with a strong attachment with people, made the individual completely dependent on human care. Therefore, despite being free to explore natural areas, the animal remained close to the facilities after release. Future recommendations on the management of rescued manatees are discussed.
Castelblanco-Martínez, Delma Nataly; Bermúdez-Romero, Ana Lucia; Gómez-Camelo, Isabel Victoria; Rosas, Fernando César Weber; Trujillo, Fernando; Zerda-Ordoñez, Enrique (detail)
Seasonality of habitat use, mortality and reproduction of the Vulnerable [sic] Antillean manatee Trichechus manatus manatus in the Orinoco River, Colombia: implications for conservation.
Oryx 43(2): 235-242. 5 tabs. 3 figs.
Castelblanco-Martínez, Delma Nataly; Morales-Vela, Benjamín; Hernández-Arana, H. A.; Padilla-Saldivar, Janneth A. (detail)
Diet of manatees Trichechus manatus manatus in Chetumal Bay, Mexico.
Latin Amer. Jour. Aquatic Mamms. 7(1-2): 39-46.
Castelblanco-Martínez, Delma Nataly; Barba, Everardo; Schmitter-Soto, Juan Jacobo; Hernández-Arana, Héctor Abuid; Morales-Vela, Benjamín (detail)
The trophic role of the endangered Caribbean manatee Trichechus manatus in an estuary with low abundance of seagrass.
Estuaries and Coasts 35(1): 60-77. 4 tabs. 4 figs. DOI 10.1007/s12237-011-9420-8. Jan. 2012 (publ. online June 11, 2011).
Castelblanco-Martínez, Delma Nataly; Morales-Vela, Benjamín; Padilla-Saldivar, Janneth A. (detail)
Using craniometrical predictors to infer body size of Antillean manatees.
Mammalia 78(1): 109-115. DOI:10.1515/mammalia-2012-0136
–ABSTRACT: Body size determines many physiological and ecological variables; however, there are few studies on this parameter for the Antillean manatee (Trichechus manatus manatus). We studied an osteological collection and databases of Antillean manatees in Mexico to infer body measurements and to determine the body mass (BM)/body length (BL) relationship. The studied sample included 165 specimens: skulls (n=60), necropsies (n=51), and individuals captured for health assessment purposes (n=54). Specific regression equations for estimating BM were derived using the following craniometrical parameters: condylobasal length (BSL), occipital condyle width (OCW), and foramen magnum width (FMW). OCW and FMW were not significantly correlated with BL. The equation of the fitted model was BL=-121.644+10.8861×BSL (p<0.05, r2=0.93, SE=14.72). The allometric equation of weight/length relationship was defined as BM=exp (2.7477+0.0110957×BL) (p<0.05, r2=0.99, SE=0.07). The model showed a significant relationship between BL and BSL (>95%). Regression equations proved to be useful in estimating BL when only highly decomposed carcasses or skull dry bones are available, and in estimating weight when it is impossible to do it directly. Studies on biology history and age determination in T. m. manatus are required in order to establish an adequate age classification.
Castelblanco-Martínez, Delma Nataly; Nourisson, Coralie; Quintana-Rizzo, Ester; Padilla-Saldivar, Janneth A.; Schmitter-Soto, Juan Jacobo (detail)
Potential effects of human pressure and habitat fragmentation on population viability of the Antillean manatee Trichechus manatus manatus: a predictive model.
Endang. Species Res. 18: 129-145.
–ABSTRACT: We present a population viability analysis for the metapopulation of the Antillean manatee Trichechus manatus manatus with the aim of predicting its tendencies under various hypothetical scenarios of conservation. Multiple individual Monte Carlo simulations of deterministic and stochastic factors were run on VORTEX 9.73 software. Populations were defined using genetic structure, geographic barriers, and typical ranging behavior. Demographic characteristics and life history parameters were inferred from the most recent compilation of information on the subspecies or were extrapolated from the Florida manatee T. m. latirostris. The baseline model describes a metapopulation with a positive growth. This model was sensitive to changes in mortality, but did not show any significant response to variations in assumed carrying capacity, age at first reproduction, maximum reproductive age, or initial population size. We simulated different scenarios by modifying human pressure, habitat fragmentation, and catastrophic events (i.e. hurricanes). Additional combined models were developed to simulate the best- and worst-case scenarios for human pressure level and fragmentation. The model suggested that the metapopulation would not be able to withstand an annual anthropogenically induced mortality rate >5%. A decrease in the survival of transient individuals could also lead to a decline of the population. Variations of the hurricane parameters did not yield important changes in the population curves, but other effects of climatic change are discussed. The extensive geographical area used by manatees requires international collaboration to ensure the protection of the metapopulation through effective conservation strategies across countries.
Castelblanco-Martínez, Delma Nataly; Padilla-Sáldivar, Janneth A.; Hernández-Arana, Héctor Abuid; Slone, D. H.; Reid, James P.; Morales-Vela, Benjamín (detail)
Movement patterns of Antillean manatees in Chetumal Bay (Mexico) and coastal Belize: A challenge for regional conservation.
Mar. Mamm. Sci. 29(2): E166-E182. 3 tabs. 5 figs. DOI: 10.1111/j.1748-7692.2012.00602.x Apr. 2013 (publ. online Sept. 17, 2012).
–ABSTRACT: Information from 15 satellite-tracked Antillean manatees (Trichechus manatus manatus) was analyzed in order to assess individual movements, home ranges, and high-use areas for conservation decisions. Manatees were captured in Chetumal Bay, Mexico, and tagged with Argos-monitored satellite transmitters. Location of the manatees and physical characteristics were assessed to describe habitat properties. Most manatees traveled to freshwater sources. The Maximum Area Size (MAS) for each manatee was determined using the observation-area method. Additional kernel densities of 95% home range and 50% Center of Activity (COA) were also calculated, with manatees having 1–3 COAs. Manatees exhibited two different movement patterns: remaining in Chetumal Bay, and long-distance (up to 240 km in 89 d). The residence time in Chetumal Bay was higher for females (89.6% of time) than for males (72.0%), but the daily travel rate (0.4–0.5 km/d) was similar for both sexes. Most of the COAs fell within Natural Protected Areas (NPA). However, manatees also travel for long distances into unprotected areas, where they face uncontrolled boat traffic, fishing activities, and habitat loss. Conservation of movement corridors may promote long-distance movements and facilitate genetic exchange.
Aragones, Lemnuel V.; LaCommare, Katherine S.; Kendall, Sarita; Castelblanco-Martinez, Delma Nataly; Gonzalez-Socoloske, Daniel (detail)
Boat- and land-based surveys for sirenians. Chap. 20 in: E. M. Hines et al. (eds.), Sirenian conservation: issues and strategies in developing countries (q.v.).
Gainesville, University Press of Florida (xiv + 326): 179-185. 3 tabs. 2 figs.
Flores-Cascante, Lavinia; Morales-Vela, Benjamín; Castelblanco-Martínez, Delma Nataly; Padilla-Saldívar, Janneth; Auil, Nicole (detail)
Diet items of manatee Trichechus manatus manatus in three priority sites for the species in Mexico and Belize.
Revista Ciencias Marinas y Costeras 5: 25-36. 3 tabs. 2 figs. Dec. 2013.
–ABSTRACT: Manatees (Trichechus manatus manatus) are herbivorous mammals with opportunistic habits that feed on approximately 60 species of plants. The focus of this paper was to identify diet elements of the manatee by fecal analysis in two sites in Mexico (Jonuta, Tabasco and Bahía de la Ascensión, Quintana Roo) and one site in Belize (Southern Lagoon). Samples were obtained from wild manatees and captive manatees temporarily captured for health assessment and sampling during 2004-2006. A total of 24 samples were analyzed. Diet components were assessed by microhistological analysis of feces. Items were separated and compared with bibliography and histological collections. Samples were also analyzed to detect invertebrates. Vegetal species found included Thalassia testudinum, Rhizophora mangle, Halodule wrightii, Ruppia sp. and Panicum sp., the latter confirmed for the first time for Mexico. No evidence of invertebrates was found in the samples. Relative importance of vegetal species consumed by manatees coincides with the findings reported for other areas in the Americas. Further systematic sampling efforts are needed in areaswhere manatee diet items are unknown.
Franzini, André M.; Castelblanco-Martínez, Delma Nataly; Rosas, Fernando César Weber; Silva, Vera Maria Ferreira da (detail)
What do local people know about Amazonian manatees? Traditional ecological knowledge of Trichechus inunguis in the Oil Province of Urucu, AM, Brazil.
Natureza & Conservação (Brazilian Journal of Nature Conservation) 11(1): 75-80. 1 tab. 3 figs. Supplementary material at July 2013.
–ABSTRACT: During 2005-2007, a series of interviews were carried out with the riverside populations of the Oil Province of Urucu (AM, Brasil). The main goal of this work was to characterize the knowledge of the inhabitants of this area regarding the Amazonian manatee (Trichechus inunguis) (listed as Vulnerable on the IUCN Red List). Interviews were conducted with 74 local inhabitants from 33 communities. Between 2004 and 2007, 20 poached or entangled Amazonian manatees were reported in the area. Poaching with harpoon is the principal cause of mortality, but manatees are also incidentally caught in fishing nets. Interviewers described details of manatee hunting techniques in the area. The trade of manatee meat, although currently forbidden by Brazilian laws, still occurs in the area. Data obtained from the interviews suggest a dietary preference of the manatee for at least 29 species of aquatic and semi-aquatic plants. The interviewed fishermen showed a sound knowledge of Amazonian manatee biology and behavior. This information may be important to assist future conservation plans in the Amazon.
Arévvalo-Gonzalez, G. Katerin; Castelblanco-Martínez, Delma Nataly; Sánchez-Palomino, P.; López-Arévalo, H. F.; Marmontel, Miriam (detail)
Complementary methods to estimate population size of Antillean manatees (Sirenia: Trichechidae) at Ciénaga de Paredes, Santander, Colombia.
Journal of Threatened Taxa 6(6): 5830-5837. 2 tabs. 3 figs. DOI:10.11609/JoTT.o3156.5830-7. June 26, 2014.
–ABSTRACT: Information on manatee population size in Colombia is limited. This study was aimed at determining manatee population size in the Cienaga de Paredes (Colombia) by three different methods: boat-based surveys, side-scan Sonar (SSS) surveys and local interviews. Manatees were counted during breathing events by direct observation during the dry season, with the number of sightings per hour (NSH) and maximum number of simultaneous sightings (MNSS) used as occurrence indices. In 2002, we obtained an average NSH of 27.62 (SD=12.34) and the MNSS was 18; in 2010 the values were 55.71 (SD=29.79) and four respectively. Using linear-transect SSS data we estimated a population size of 12 individuals (%CV=27.3). The local community claimed that no hunting or entanglements had taken place in the area for over 20 years. These methods have pros and cons in terms of investment, effort, efficiency and community involvement, and their efficiency may vary in different seasons. Applying them in a complementary way and at greater spatial and temporal scales could enhance the accuracy of results.
Navarro-Martínez, Zenaida M.; Álvarez-Alemán, Anmari; Castelblanco-Martínez, Delma Nataly (detail)
Componentes de la dieta en tres individuos de manatí en Cuba [Diet components in three manatees in Cuba].
Revista de Investigaciones Marinas 34(2): 1-11. 2 tabs. 4 figs. Jan.-June 2014.
–ABSTRACT: Manatees Trichechus manatus depend on aquatic vegetation. The objective of this study was to compare the presence of diet items among different regions of the digestive tract with different levels of degradation, in three individuals. In addition, we developed a reference collection of images of seagrass fragments and other common diet items, which can be useful in studies of digestive material. We conducted microhistological analyses of manatee digestive samples(stomach, intestine, and feces) from manatees of southern Varadero (Matanzas)and northern coast of Villa Clara. The studied individuals used marine vegetation as food source. The abundance of rhizomes in feces suggests a rooting behavior. Despite the fact that the quantification of the diet components can be affected in several regions of the digestive tract, due to the differential degradation of the diet items along the tract, the identification of the main diet components was possible in all of these regions.
 RESUMEN: El manatí Trichechus manatus depende de vegetación acuatica como fuente de alimento. El presente trabajo tiene como objetivos comparar la aparición de los componentes mas importantes de la dieta de tres individuos entre diferentes porciones de su tracto digestivo. Ademas, elaborar una colección de fotografías de referencia de los fragmentos de las fanerógamas marinas y otros elementos que pueden ser comúnmente observados en la dieta de individuos de esta especie, para su identificación en estudios de material digestivo. Para ello se realizó un analisis microhistológico del contenido digestivo (estómago, intestino y heces) de animales procedentes del sur de Varadero (Matanzas) y costa norte de Villa Clara. Todos los componentes encontrados fueron característicos de ecosistemas marinos, lo que indica el uso de este tipo de habitat como sitio de alimentación por estos individuos. Se encontró alta abundancia de rizomas en las muestras fecales de manatí, lo que sugiere la remoción de la planta completa durante su alimentación. A pesar de la variación observada en la composición de la dieta en diferentes regiones del tracto digestivo, esta parece estar influenciada por el nivel de degradación al que se somete el alimento en cada región, los componentes que pueden ser importantes para la alimentación de esta especie se mantienen hasta su expulsión en forma de heces.
Castelblanco-Martínez, Delma Nataly; Kendall, Sarita; Orozco, D. L.; González, K. A. (detail)
La conservación de los manatíes (Trichechus inunguis y Trichechus manatus) en áreas no protegida de Colombia. In: E. Payán, C. A. Lasso, & C. Castaño-Uribe (eds.), Conservación de grandes vertebrados en áreas no protegidas de Colombia.
Inst. de Investigación de Recursos Biológicos Alexander von Humboldt, 81-98.
Castelblanco-Martínez, Delma Nataly; Morales-Vela, Benjamín; Slone, D. H.; Padilla-Saldivar, Janneth A.; Reid, James P.; Hernández-Arana, H. A. (detail)
Inferring spatial and temporal behavioral patterns of free-ranging manatees using saltwater sensors of telemetry tags.
Mammalian Biology - Zs. f. Säugetierk. 80: 21-30.
Niño-Torres, Carlos Alberto; Garcia-Rivas, Maria del Carmen; Castelblanco-Martínez, Delma Nataly; Padilla-Saldivar, Janneth Adriana; Blanco-Parra, Maria del Pilar; de la Parra-Venegas, Rafael (detail)
Aquatic mammals from the Mexican Caribbean; a review.
Hidrobiologica 25(1):127-138. April 2015.
–ABSTRACT: We present a review of the aquatic mammal species occurring in the Mexican Caribbean. Several published sources were reviewed to find information about aquatic mammals reported for the Mexican Caribbean. Additionally, we consulted 29 national and international collections and museums. Based on documents, collections, direct records and local news, we analyzed 18 confirmed species of aquatic mammals for the study area [Tursiops truncatus, Stenella clymene, S. frontalis, S. longirostris, Steno bredanensis, Grampus griseus, Globicephala macrorhynchus, Peponocephala electra; Pseudorca crassidens, Orcinus orca, Physeter macrocephalus, Kogia breviceps, K. sima, Ziphius cavirostris, Mesoplodon europaeus, Trichechus manatus manatus, Lontra longicaudis annectens and Monachus tropicalis (extinct)]. In order to gather solid baseline information that enhances efficient long-term management, regular and systematic population censuses of the aquatic mammal community are recommended. We recommend the use of the "Mexican Caribbean" area as a separate unit of management and conservation, differently as has been included in the macro region "Gulf of Mexico/Mexican Caribbean".
Arévalo-Sandi, Alexander Roldán; Castelblanco-Martínez, Delma Nataly (detail)
Interactions between calves of Amazonian manatees in Peru: a study case.
Acta Biol. Colombiana 21(2): 355-364. 2 tabs. 5 figs. doi: May-Aug. 2016.
–ABSTRACT: Trichechus inunguis is an endemic species of the Amazon, which inhabits mainly in lakes and calm rivers. The objective of this study case was to describe the social behaviour of two female-orphaned calves, of T. inunguis in captivity. They were kept in the same pool at the facilities of the Amazon Rescue Center (ARC, Iquitos, Peruvian Amazon). Between February and October 2011, the individuals were observed during day and night times, completing 352 hours of observation. Through ad libitum observation of the individuals, we developed a catalogue of social behaviors that includes descriptions of 93 behaviours, classifed in eight behavioural categories. The frequency of behaviours was assessed by instantaneous sampling (for states) and continuous recording (for events). Manatees displayed mainly social behaviours, and the most frequent interaction was the simultaneous starting of the same behaviour by both individuals. Most of social behaviours occurred during the day, but 'group resting' was recorded mostly at night. 'Synchronized breathing' and 'group feeding' did not have temporary variation between days or between daytimes. Regarding the use of the space, the majority of interactions occurred in shaded places. This study revealed strong interactions between con?ned calves, suggesting that social activity may play an important role in their learning process.
 RESUMEN: Trichechus inunguis es una especie endémica del Amazonas que vive principalmente en lagos y ríos de aguas tranquilas. El objetivo de este estudio de caso fue describir el comportamiento social de dos crías hembras huérfanas de T. inunguis en cautiverio, mantenidas en el mismo estanque en el Centro de Rescate Amazónico (CREA, Iquitos, Amazonía peruana). Entre febrero y octubre de 2011, las crías fueron observadas durante el día y la noche, para un total de 352 horas de observación. Mediante observación ad libitum de los individuos, desarrollamos un catálogo de comportamientos social que incluye descripciones de 93 comportamientos clasi?cados en ocho categorias comportamentales. La frecuencia de comportamientos fue evaluada por muestreo instantáneo (para estados) y registro continúo (para eventos). Los manatíes exhibieron principalmente comportamientos sociales, y la interacción más frecuente fue el inicio simultáneo del mismo comportamiento por ambos individuos. La mayoría de los comportamientos sociales ocurrieron durante el día, pero 'descanso grupal' fue registrado mayormente en la noche. 'Respiración sincronizada' y 'alimentación grupal' no tuvieron variación diaria entre días o entre horas del día. En lo que respecta al uso de espacio, la mayoría de interacciones ocurrió en lugares sombreados. Este estudio reveló fuertes interacciones entre crías en cautiverio, sugiriendo que la actividad social cumple un rol importante en los procesos de aprendizaje de los manatíes.
Landeo-Yauri, Sarah Sofía; Castelblanco-Martínez, Delma Nataly; Williams, Martha (detail)
Behavior and habitat use of released rehabilitated Amazonian manatees in Peru.
Latin Amer. Jour. Aquat. Mamms. 12(1-2): 17-27. 3 tabs. 5 figs. Dec. 30, 2017.
–ABSTRACT: The Amazonian manatee (Trichechus inunguis) is endangered due to illegal hunting. In Peru, the Centro de Rescate Amazónico (CREA) rehabilitates and releases rescued manatees. Three females and two males were released in El Dorado Lake in July 2011 and radio tracked until November 2011. Movements, habitat use and behavior recorded during the post-release period were used to evaluate the manatees' adaptation to free-living conditions. A total of 140 locations was registered during 91 days of tracking. Females showed greater residence time than males, which migrated out of the lake. Females selectively used the micro habitats of the study area, preferring floating vegetation, followed by open water and lastly shore macrophytes. Most idling behaviors were registered in areas with floating macrophytes, and open water was mainly used for traveling. No correlation between sighting hour and sighting location (micro habitat type) was detected. The use of suitable zones, in addition to natural behavior, suggests that these rescued manatees responded well to free-living conditions after release. Some considerations are provided with the purpose of strengthening manatee rehabilitation programs and improving future releases, emphasizing the importance of choosing appropriate individuals, as well as suitable areas and times to help improve release outcome.
 RESUMEN: El manatí amazónico (Trichechus inunguis) es una especie amenazada, principalmente debido a la caza ilegal. En Perú, el Centro de Rescate Amazónico (CREA) desarrolla esfuerzos para rehabilitar manatíes rescatados y liberarlos posteriormente a la vida silvestre. Tres hembras y dos machos fueron liberados en la cocha El Dorado en julio del 2011, siendo rastreados mediante telemetría VHF hasta noviembre del mismo año. El monitoreo post liberación incluyó el registro de los desplazamientos, uso de hábitat y comportamiento de los animales, con el fin de evaluar su adaptación a las condiciones de vida libre. A lo largo de 91 días de rastreo, se obtuvo un total de 140 localizaciones. Las hembras mostraron un mayor tiempo de residencia que los machos, quienes migraron fuera de la zona de liberación. También se determinó que las hembras usaron selectivamente los micro habitats en el área de estudio, prefiriendo zonas de vegetación flotante seguidas por aguas abiertas y finalmente orillas asociadas a vegetación. La mayoría de desplazamientos fueron observados en aguas abiertas, mientras que comportamientos de permanencia ocurrieron generalmente en vegetación flotante. No se encontró ninguna correlación entre el tipo de micro habitat ocupado y la hora del día. El uso selectivo de zonas adecuadas por parte de los individuos, sumado a reportes previos sobre el comportamiento de la especie en vida silvestre, sugiere que los manatíes liberados tuvieron una respuesta positiva a las condiciones del medio natural. Se incluyen algunas recomendaciones con el fin de fortalecer programas de rehabilitación y mejorar futuras liberaciones, enfatizando la importancia de seleccionar adecuadamente los individuos a ser liberados, así como las áreas y tiempos de liberación.
Castelblanco-Martínez, Delma Nataly; Blanco-Parra, M. P.; Charruau, P.; Prezas, B.; Zamora-Vilchis, I.; Niño-Torres, Carlos Alberto (detail)
Detecting, counting and following the giants of the sea: a review of monitoring methods for aquatic megavertebrates in the Caribbean.
Wildlife Research 46(7): 545-556. Oct. 9, 2019.
–ABSTRACT: The Caribbean is a mega-diverse and bio-geographically important region that consists of the Caribbean Sea, its islands, and surrounding coastlines. Among the billions of aquatic species inhabiting this region, the mega-vertebrates stand out for their social, economic and ecologic relevance. However, the Caribbean has been threatened by climate change, poverty, pollution, environmental degradation and intense growth of the tourism industry, affecting megafauna species directly and indirectly. Population monitoring plays a critical role in an informed conservation process and helps guide management decisions at several scales. The aim of the present review was to critically examine the methods employed for monitoring marine megafauna in the Caribbean, so as to create a framework for future monitoring efforts. In total, 235 documents describing protocols for the monitoring of sirenians, cetaceans, elasmobranchs, sea turtles and crocodilians in the Caribbean region, were reviewed. The methods included community-based monitoring (interviews, citizen science and fisheries monitoring), aerial surveys (by manned and unmanned aerial vehicles), boat-based surveys (including manta tow, and side-scan sonars), land-based surveys, acoustic monitoring, underwater surveys, baited remote underwater video, mark–recapture, photo-identification and telemetry. Monitoring efforts invested on aquatic megafauna in the Caribbean have been highly different, with some species and/or groups being prioritised over others. The present critical review provides a country-based overview of the current and emerging methods for monitoring marine megafauna and a critical evaluation of their known advantages, disadvantages and biases.
Garcés-Cuartas, Natalia; Niño-Torres, Carlos Alberto; Castelblanco-Martínez, Delma Nataly (detail)
Vibrissae growth rate of captive Antillean manatees (Trichechus manatus manatus Linnaeus, 1758).
Mar. Mamm. Sci. 35(4): 2 tabs. 4 figs. Jan. 2020; publ. online Aug. 5, 2019.
Corona-Figueroa, M. F.; Ríos, N.; Castelblanco-Martínez, D. N.; Vichez-Mendoza, S.; Delgado-Rodriguez, D.; Niño-Torres, C. A. (detail)
Searching for manatees in the dark waters of a transboundary river between Mexico and Belize: a predictive distribution model.
Aquat. Ecol. Nov. 5, 2020.
–ABSTRACT: Antillean manatees in the Hondo River have been recorded from aerial and aquatic surveys, and interviews. However, these studies have been conducted only in the lower riverbed, leaving a gap of information about their presence and habitat characteristics in the rest of the river. We characterize and determine the ecohydrological variables influencing the presence and habitat use of manatees in the Hondo River. During 2017 and 2018, 30 boat-based field trips were conducted in five consecutive transects of 15 km each. A mixed methodology was used for manatee detection: side-scan sonar, direct sightings, and feces collection. Ecohydrological variables were measured in all transects and fixed points. The survey effort was 136.5 h. We recorded 123 manatees: 47% were observations during the boat-based surveys, 29% were at fixed points, and 24% were opportunistic. Additionally, 10 manatee feces were found. The first transect of the river showed the highest relative abundance for the two sampled seasons (windy?=?0.27 manatees/km, dry?=?0.55 manatees/km). According to the Poisson model, the estimated population was equal to 51 manatees. A random forest model suggested high probability of observing manatees in the first transects and decreasing at the upstream. The ecohydrological variables influencing the detection of manatees were conductivity, transparency, depth, and proximity to the Four Mile lagoon. The first two transects have ecohydrological characteristics that make a benign environment for refuge, rest and feeding of manatees. We recommend carrying out conservation efforts in the first transects, such as protection and the regulation of boat transit.
Landeo-Yauri, Sarah Sofía; Ramos, Eric Angel; Castelblanco-Martínez, Delma Nataly; Niño-Torres, Carlos Alberto; Searle, Linda (detail)
Using small drones to photo-identify Antillean manatees: a novel method for monitoring an endangered marine mammal in the Caribbean Sea.
Endangered Species Research 41: 79-90. 2 tabs. 5 figs. Jan. 30, 2020.
–ABSTRACT: Population assessments and species monitoring for many endangered marine megafauna are limited by the challenges of identifying and tracking individuals that live underwater in remote and sometimes inaccessible areas. Manatees can acquire scars from watercraft injury and other incidences that can be used to identify individuals. Here we describe a novel method for photo-identification of Antillean manatees Trichechus manatus manatus using aerial imagery captured during flights with a small multirotor drone. Between 2016 and 2017, we conducted 103 flights to detect and observe manatees in Belize, primarily at St. George's Caye (SGC) near the Belize Barrier Reef. Review of aerial videos from these flights resulted in 279 sightings of manatees (245 adults, 34 calves). High-resolution images of individual manatees were extracted and classified according to image quality and distinctiveness of individual manatees for photo-identification. High-quality images of manatees classified as sufficiently distinctive were used to create a catalog of 17 identifiable individuals. At SGC, 21% of all sighted adult manatees (N = 214) were considered photo-identifiable over time. We suggest that the method can be used for investigating individual site fidelity, habitat use, and behavior of manatee populations. Our photo-identification protocol has the potential to improve long-term monitoring of Antillean manatees in Belize and can be applied throughout clear, shallow waters in the Caribbean and elsewhere.
Ortega-Argueta, A.; Castelblanco-Martínez, Delma Nataly (detail)
Is captive breeding a priority for manatee conservation in Mexico?
Castelblanco-Martínez, Delma Nataly; Alvarez-Alemán, A., Torres, R.; Teague, A. L.; Barton, S. L.; Rood, K. A.; Ramos, E. A.; Mignucci-Giannoni, A. A. (detail)
First documentation of long-distance travel by a Florida manatee to the Mexican Caribbean.
Ethology, Ecology & Evolution DOI: 10.1080/03949370.2021.1967457
Castelblanco-Martínez, Delma Nataly; Slone, D. H.; Landeo-Yauri, S. S.; Ramos, E.; Alvarez-Aleman, A.; et al. (detail)
Analysis of body condition indices reveals different ecotypes of the Antillean manatee.
Sci. Repts. 11(19451): 6 tabs. 6 figs. Sept. 30, 2021.
–ABSTRACT: Assessing the body condition of wild animals is necessary to monitor the health of the population and is critical to defining a framework for conservation actions. Body condition indices (BCIs) are a non-invasive and relatively simple means to assess the health of individual animals, useful for addressing a wide variety of ecological, behavioral, and management questions. The Antillean manatee (Trichechus manatus manatus) is an endangered subspecies of the West Indian manatee, facing a wide variety of threats from mostly human-related origins. Our objective was to define specific BCIs for the subspecies that, coupled with additional health, genetic and demographic information, can be valuable to guide management decisions. Biometric measurements of 380 wild Antillean manatees captured in seven different locations within their range of distribution were obtained. From this information, we developed three BCIs (BCI1?=?UG/SL, BCI2?=?W/SL3, BCI3?=?W/(SL*UG2)). Linear models and two-way ANCOVA tests showed significant differences of the BCIs among sexes and locations. Although our three BCIs are suitable for Antillean manatees, BCI1 is more practical as it does not require information about weight, which can be a metric logistically difficult to collect under particular circumstances. BCI1 was significantly different among environments, revealing that the phenotypic plasticity of the subspecies have originated at least two ecotypes -- coastal marine and riverine -- of Antillean manatees.

Daryl P. Domning, Research Associate, Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, D.C. 20560, and Laboratory of Evolutionary Biology, Department of Anatomy, College of Medicine, Howard University, Washington, D.C. 20059.
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