ABSTRACT A notable diversity of marine mammals inhabits the Atlantic and Pacific waters of South America. For decades, South American countries have been producing scientific research focused on these species. However, still, there is no systematic assessment of the magnitude and main subjects on which this research has been focused. This study analyzes the trends and patterns in scientific research on marine mammals in South America, evaluating a pool of bibliometric indicators and mapping collaborative relationships among countries, authors, and research areas. Academic documents were retrieved from two bibliographic databases: SCOPUS and SciELO, from 1990 to 2020. Results showed a gradual increase in publications along the three study decades. Brazil played a central role in the number of publications in both databases, followed by Argentina and Chile. The South American publications on marine mammals were centralized in a small number of journals, and few authors were responsible for a large proportion of contributions. The authors showed a moderate level of collaboration, mainly reflecting stronger links among neighbor countries, including co-authorships with North American and European countries. The most frequent keywords reflected three clusters centered in taxonomic groups (Cetacea, Odontoceti, and Pinnipedia) and two centered in research subjects (pollution and phylogenetics). The scope of the contributions differed among collections. Nevertheless, both databases were complementary and contributed to show marine mammals' research in South America.

ResumoA formação de novas colônias de pinípedes é uma consequência da dinâmica complexa na qual algumas delas podem ser transformadas de colônias de descanso em áreas de reprodução. O objetivo deste estudo foi estimar a abundância deOtaria flavescens e Arctocephalus australis em duas áreas pouco conhecidas no Uruguai "Isla Verde-Islote Coronilla" (IV-IC), a mais oriental, e "Las Pipas" (LP), a mais ocidental. As contagens foram feitas de barco em LP e levantamentos aéreos em IVIC de junho de 2008 a junho de 2009. Em LP, foram registradas ambas as espécies de pinípedes, com a maior abundância em julho, num total de 202 animais. O. flavescens esteve presente durante todo o ano, e foram registrados principalmente machos adultos, enquanto que A. australis apenas foi observada a partir de junho até outubro. LP foi definido, então, como sendo uma colônia de descanso, especialmente para O. flavescens. No IV-IC, foram contados entre 225 e 521 indivíduos de O. flavescens. O número de animais aumentou na primavera e verão. A categoria mais abundante foi a das fêmeas e ocorreu em março. De acordo com essa estrutura de idade e a presença de prole, propõe-se que a área teria uma atividade de reprodução incipiente. Sugerimos que essa colônia deveria ser monitorada como parte de sua inclusão numa área marinha protegida.

AbstractThe establishment of new pinniped colonies is a consequence of complex dynamics in which some colonies may transform from haul-outs into breeding sites. The aim of this article was to estimate the abundance of Otaria flavescens and Arctocephalus australis at two poorly known sites of Uruguay, the easternmost “Isla Verde-Islote Coronilla” (IV-IC) and the westernmost “Las Pipas” (LP). From June 2008 to June 2009 count from boats were conducted at LP, and aerial censuses at Isla Verde. At LP both pinniped species were recorded, and the abundance was maximum in July with a total of 202 animals.O. flavescens was present throughout the year, mainly adult males, while A. australis was only observed from June to October. LP is defined as a haul-out structure used as resting area, especially for O. flavescens. At IV-IC between 225 and 521 O. flavescens were recorded. The number of animals increased in Spring and Summer. Females were the most abundant category and pups were recorded in March. According to the age structure and the presence of pups, we propose it would have and incipient reproductive activity. This colony should be monitored in relation with its category as a marine protected area.

As a top predator, California sea lions (Zalophus californianus) can be used as sentinels to record ecosystem conditions because of the trace metals that bioaccumulate in their tissues and are biomagnified in the trophic webs. The concentration of 11 trace elements (Al, As, Cd, Co, Cu, Fe, Hg, Ni, Pb, Se, and Zn) was measured in California sea lion skulls from four regions of the Gulf of California (Mexico): Northern Gulf, Ángel de la Guarda, Central Gulf, and Southern Gulf. The aims of this study were (1) to determine and compare the mean concentration of trace elements among the four regions, and (2) to estimate the pollution situation of each region using the more toxic trace elements. The elements found in higher concentration in sea lion bone were Al (overall mean of 73.70 μg g-1) and Zn (60.78 μg g-1). Only the concentration of As and Hg showed significant differences among regions: As was higher in the Central Gulf than in Ángel de la Guarda and the Northern Gulf, while Hg was higher in the Northern Gulf and Ángel de la Guarda than in the Central and Southern Gulf. The comparative analysis of the pollution situation indicated that the Central Gulf was the most affected by As and Cd, and the Northern Gulf and Ángel de la Guarda by Hg. Regions with different trace element concentrations may reflect different feeding habits and oceanographic conditions, and are congruent with other regional patterns suggested for the Gulf of California.

Como depredador tope, el lobo marino de California (Zalophus californianus) puede ser utilizado como especie centinela para registrar condiciones ecosistémicas por los elementos traza que bioacumula y que son biomagnificados en las redes tróficas. Se midió la concentración de 11 elementos traza (Al, As, Cd, Co, Cu, Fe, Hg, Ni, Pb, Se y Zn) en los cráneos de lobo marino de California de cuatro regiones del golfo de California: Golfo Norte, Ángel de la Guarda, Golfo Central y Golfo Sur. Los objetivos del estudio fueron (1) determinar y comparar la concentración de elementos traza entre las cuatro regiones, y (2) estimar el estado de polución de cada región usando los elementos traza más tóxicos. Los elementos encontrados en mayor concentración en hueso de lobo marino fueron Al (media global: 73.70 µg g-1) y Zn (60.78 µg g-1). Sólo las concentraciones de As y Hg mostraron diferencias significativas entre regiones. El As fue más alto en la región Golfo Central que en Ángel de la Guarda y en Golfo Norte, mientras que el Hg fue más alto en la región Golfo Norte y Ángel de la Guarda que en Golfo Central y Golfo Sur. El análisis comparativo del estado de polución en cada región indicó que la región Golfo Central fue la más afectada por As y Cd, y las regiones Golfo Norte y Ángel de la Guarda por Hg. Las regiones con diferentes concentraciones de elementos traza podrían reflejar diferencias en los hábitos alimentarios y condiciones oceanográficas, y son congruentes con otros patrones regionales sugeridos para el golfo de California.