STABLE ISOTOPES ANALYSIS ON BALEEN WHALES (SUBORDER: MYSTICETI): A REVIEW UNTIL 2017

ABSTRACTStable Isotope Analysis (SIA) has provided information on ocean productivity, and ecological aspects related to whales’ habitat use and feeding ecology, stock structure, physiology, and evolution. We reviewed published studies using SIA on whales worldwide from November 1979 to June 2017. Gaps in geographical areas and heterogeneity amongst species studied using this methodology wereassessed. We also investigated which tissue was most frequently analysed, sources of variation in stable isotope values, how this methodology has been combined with other techniques, and how it can be useful for the conservation of the taxon and marine ecosystems. A total of 63 publications were found, and it was possible to detect a general increase in the number of publications along time, as 49% of the studies were from the last 7.5 years of the period analyzed. Almost 55% of studies focused on foraging ecology and habitat use. The baleen plate was the main tissue analyzed. Studies were related to 14 species, the most common being the fi n whale, Balaenoptera physalus (N=19) and the bowhead whale, Balaena mysticetus (N=18). Telemetry and SIA methodologies combined were helpful to understand geographical variations in stable isotope values. The methodology can also be valuable under the current scenario of climate change, for example providing information on feeding plasticity and changes in niche amplitude of diff erent species. Despite uncertainties related with stable isotopes distribution in the ocean, and with its incorporation rates for whales, for example, SIA provides primordial ecological information for effi cient management and conservation of this group. RESUMOA análise de isótopos estáveis (AIE) fornece informações sobre a produtividade do oceano e aspectos ecológicos de baleias relacionados ao uso do habitat e ecologia alimentar, estrutura de estoque, fi siologia e evolução. Foram revisados estudos publicados usando a AIE em baleias em todo o mundo entre novembro de 1979 e junho de 2017. Foram avaliadas lacunas nas áreas geográfi cas eheterogeneidade entre as espécies estudadas usando essa metodologia. Também investigamos quais tecidos foram mais utilizados para análise, as fontes de variação em valores de isótopos estáveis, a combinação desta metodologia com outras técnicas e como pode ser útil para a conservação deste táxon e dos ecossistemas marinhos. Um total de 63 publicações foi encontrado e foi possível detectar aumento no número de publicações, uma vez que 49% dos estudos foram realizados nos últimos 7 anos e meio do período analisado. Quase 55% dos estudos concentraram-se na ecologia de forrageio e no uso do habitat. As cerdas bucais foram o principal tecido analisado. Os estudos investigaram14 espécies, sendo mais comuns aqueles relacionados a baleia-fi n, Balaenoptera physalus (N=19) e a baleia-da-Groenlândia, Balaena mysticetus (N=18). As metodologias de telemetria e AIE combinadas foram úteis para entender as variações geográfi cas em valores de isótopos estáveis. Ametodologia pode também ter valor no cenário de mudanças climáticas fornecendo informações sobre plasticidade alimentar e amplitude de nicho de diferentes espécies, por exemplo. Apesar das incertezas relacionadas à distribuição dos valores de isótopos estáveis no mar e às taxas deincorporação em baleias, por exemplo, a AIE fornece informações ecológicas primordiais para o manejo e conservação desse grupo.Palavras-chave: Balaenopteridae; Balaenidae; Análise de isótopos estáveis; Ecologia da conservação.

Latin American aquatic mammals : an overview of 12 years focusing on molecular techniques applied to conservation

Ecological information useful for conservation purposes have benefitted from recent and rapid advancements in genetic techniques, revealing unknown aspects of behavior, natural history, population structure and demography of several aquatic mammal species, many of them with conservation concerns. Molecular markers have been used to define management units, to settle taxonomic uncertainties, to control illegal wildlife trade, among others, providing valuable information to decision-making to conserve and manage aquatic mammals. We review genetic studies applied to conservation-related issues involving natural populations of more than 40 species of aquatic mammals in Latin America, covering four taxonomic groups. The main goal was to assess which genetic approaches have been used and to identify gaps in genetic research relating to geographic areas and species. We reviewed studies published in peer-reviewed journals between 2011 and 2022, and found that most were focused on population structure, phylogeography, gene flow and dispersal movements. The review revealed that researchers need to increase and improve the knowledge in those species which face major conservation concern. Scarce findings were related to forensics and its application to wildlife trade. In the era of next-generation-sequencing techniques, just a few studies used genomics as a tool for monitoring gene diversity, an important goal to help us predict how species will cope with climate change events. Looking to the future we suggest which species, geographic areas and genetic studies should be prioritized in a scenario of climate change and increased human threats (e.g., fishery bycatch, habitat degradation, etc.) and the urgent need for conservation actions. Finally, we highlight the benefits of the collaborative works and the necessity of generating a conservation genetic network, with an open agenda to discuss the local and regional problematics. All in all, we strongly emphasize the generation of critical information towards the effective conservation and management of aquatic mammals in Latin America.Peer reviewe

Ecologia alimentar do Boto, Tursiops truncatus (Montagu, 1821), no Litoral Norte do Rio Grande do Sul, Sul do Brasil

A ecologia alimentar do boto, Tursiops truncatus, foi avaliada através da análise do conteúdo estomacal de 25 espécimes encontrados encalhados, entre novembro de 1991 e outubro de 2009, no litoral norte do Rio Grande do Sul, sul do Brasil. As presas foram identificadas a partir de estruturas mais resistentes à digestão, como otólitos de teleósteos e bicos de cefalópodes. A frequência de ocorrência (%FO), a frequência numérica (%FN) e o índice de importância relativa (IIR) foram utilizados para determinar a importância de cada presa na dieta de T. truncatus. Dos 25 estômagos analisados, dois estavam vazios e dois continham apenas ossos de teleósteos que não puderam ser identificados. Nos 21 estômagos restantes foram encontrados 1.477 itens, correspondendo a um mínimo de 794 presas. Um total de 17 espécies de presas foi identificado, incluindo 15 teleósteos e dois cefalópodes. Os peixes foram responsáveis por 99,01% do total de presas ingeridas, sendo que os cefalópodes representaram 0,99%. As três principais presas identificadas foram Trichiurus lepturus, Paralonchurus brasiliensis e Mugil sp., dentre os teleósteos. Dorytheutis plei, foi a espécie mais importante dentre os cefalópodes. No entanto, os cefalópodes não foram considerados representativos na dieta da espécie. Os dados coletados indicam que T. truncatus, no sul do Brasil, é um predador oportunista, de amplo espectro alimentar, que se alimenta de uma grande variedade de tipos de presa na zona costeira, apresentando preferência por estas três espécies de teleósteos no litoral norte do Rio Grande do Sul.The feeding ecology of the bottlenose dolphin, Tursiops truncatus, was analyzed through the analysis of stomach contents from 25 stranded specimens, between November 1991 and October 2009, in the northern coast of Rio Grande do Sul state, southern Brazil. The preys were identified throughout most digest resistant structures, like fish otoliths and cephalopod beaks. The frequency of occurrence (%FO), numeric frequency (%FN) and the Index of Relative Importance (IRI) were taken into consideration to determine of importance for each prey found in the diet of T. truncatus. From the 25 stomachs analyzed, two were empty and other two had only a few fish bones that couldn’t be identified and were not taken into account. The other 21 stomachs had 1.447 items, corresponding to 794 preys. In this study, 17 prey species were identified, including 15 bone fishes and two cephalopods. Fishes were responsible for 99,01% of the total prey ingested, whereas the cephalopods represented only 0,99% of the total. Three main prey species were identified, including Trichiurus lepturus, Paralonchurus brasiliensis, and Mugil sp.. Dorytheutis plei was the most important cephalopod species. This last group was not considered as a major prey for T. truncatus in the area. The present data shows that T. truncatus, in southern Brazil, has a wide feeding spectrum although an opportunistic predator, feeding on a big variety of prey in coastal areas, showing preference for this three teleost species in the northern coast of Rio Grande do Sul, southern Brazil

Overview of Balaenoptera whales strandings in Southern Brazil from 1993 to 2018

The ecology and distribution of most baleen whales are poorly known in Brazilian waters, despite the history of whaling and the recent increase in the research effort. Although stranding data presents some caveats, it is useful to understand patterns of distribution and occurrence and to detect population trends. In this scenario, data from 25 years of a monitoring marine mammal stranding program were used to evaluate the composition and spatial-temporal patterns of Balaenoptera whales in southern Brazil. A stretch of 270 km on the coast of Rio Grande do Sul State (from 29°20’S to 31°21’S) was surveyed year-round between 1993 and 2018. Whales were identified, measured and sex determined whenever possible. Molecular identification through mtDNA analysis was obtained for 22 individuals and confirmed field identification in 17 cases. Forty-eight whales of four species were recorded: common minke whale B. acutorostrata n = 27, Antarctic minke whale B. bonaerensis n = 1, Bryde’s whale B. brydei n = 13, fin whale B. physalus n = 1. In addition, six whales were not identified at species level due to advanced decomposition. The larger number of strandings of common minke and Bryde’s whales may be related to their greater abundance and/or more coastal distribution. Both species were recorded year-round, but strandings of common minke and Bryde’s whales occurred mostly during winter/spring (77.77%) and spring/summer (66.66%), respectively. Although Bryde’s whales appear to remain in southern Brazilian waters during the entire year, the results suggest the existence of seasonal inshore-offshore movements. Moreover, the greater number of strandings of juveniles of common minke whales compared to adults (ratio 1.86:1) and their occurrence in different seasons suggest that some immature individuals may not leave this region, as previously pointed out by other studies. This long-term survey brings new evidence of the importance of this region in the Southwestern Atlantic Ocean for some Balaenoptera species

Trophic overlap between marine mammals and fisheries in subtropical waters in the western South Atlantic

Marine mammals and humans are apex predators and both may compete for fish in ecosystems under continuous fishing pressure. We assessed the degree of trophic overlap between prey species found in the diet of 5 marine mammals (39 specimens of sea lion Otaria flavescens, 61 fur seals Arctocephalus australis, 76 franciscana dolphins Pontoporia blainvillei, 25 bottlenose dolphins Tursiops truncatus and 28 Lahille's bottlenose dolphins T. gephyreus) and the catches of the 6 main commercial fishing gears used in southern Brazil (coastal gillnets, oceanic gillnets, purse seine, demersal pair trawling, bottom [single] trawl and double-rig trawling) between 1993 and 2016. An adjusted general overlap index indicated an overall moderate to high overlap. Specific overlap analysis showed that O. flavescens and T. truncatus presented high trophic relationships with fisheries, followed by T. gephyreus. Smaller interactions were observed for A. australis and P. blainvillei, even though they also exploit commercial fishing resources. Coastal gillnet and pair bottom trawling are the fisheries that most target the fish species favoured by O. flavescens, T. gephyreus and T. truncatus. The information presented in this study on trophic interactions may assist decision making for both fishery management and conservation measures for these apex predators. Commercial fishing activities are a major threat to marine mammals both regionally and globally. Current levels of fishing or its intensification may lead to dramatic changes in the coastal marine food web, including additional threats to coastal marine mammal populations in southern Brazil.Fil: Machado, Rodrigo. Universidade Federal do Rio Grande do Sul; Brasil. Grupo de Estudos de Mamíferos Aquáticos do Rio Grande do Sul; Brasil. Universidade do Extremo Sul Catarinense; BrasilFil: Rosa de Oliveira, Larissa. Grupo de Estudos de Mamíferos Aquáticos do Rio Grande do Sul; Brasil. Universidad de Vale do Rio dos Sinos; BrasilFil: Ott, Paulo Henrique. Grupo de Estudos de Mamíferos Aquáticos do Rio Grande do Sul; Brasil. Universidade Estadual do Rio Grande do Sul; BrasilFil: Haimovici, Manuel. Universidade Federal Do Rio Grande; BrasilFil: Cardoso, Luis Gustavo. Universidade Federal Do Rio Grande; BrasilFil: Milmann, Lucas. Universidade Estadual de Santa Cruz; Brasil. Grupo de Estudos de Mamíferos Aquáticos do Rio Grande do Sul; BrasilFil: Romero, Maria Alejandra. Universidad Nacional del Comahue. Centro de Investigación Aplicada y Transferencia Tecnológica en Recursos Marinos "Almirante Storni". - Provincia de Río Negro. Ministerio de Agricultura, Ganadería y Pesca. Centro de Investigación Aplicada y Transferencia Tecnológica en Recursos Marinos "Almirante Storni". Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Centro Nacional Patagónico. Centro de Investigación Aplicada y Transferencia Tecnológica en Recursos Marinos "Almirante Storni"; ArgentinaFil: Dos Santos, Roberta Aguiar. Instituto Chico Mendes de Conservação da Biodiversidade; Brasil. Centro Nacional de Pesquisa e Conservação da Biodiversidade Marinha do Sudeste e Sul; BrasilFil: Borges-Martins, Márcio. Universidade Federal do Rio Grande do Sul; Brasil. Grupo de Estudos de Mamíferos Aquáticos do Rio Grande do Sul; Brasi

Marine debris ingestion by odontocete species from the Southwest Atlantic Ocean: Absence also matter

In this paper, we examined the ingestion of large marine debris (1 mm–1010 mm) in 21 odontocete species that were found dead or by-caught in low frequency in southern Brazil (Rio Grande do Sul State) and northern Argentina (Buenos Aires) between 1988 and 2020. Eight percent of the total individuals studied (13 out of 156), representing nine species, had ingested marine debris. Most of items were made of plastics (68 %), and within them, single-use plastic (e.g. plastic bags) were the dominant man-made items. Seven of the nine species that had ingested marine debris have been previously registered ingestion of this pollutant in other areas of their distribution. We also incorporated endemic odontocetes of the Southwest Atlantic Ocean to the list of affected marine organisms: the Burmeister's porpoise Phocoena spinipinnis, and the Lahille's bottlenose dolphin, Tursiops gephyreus.Fil: Padula, Antonella Daira. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Machado, Rodrigo. Grupo de Estudos de Mamíferos Aquáticos do Rio Grande do Sul; Brasil. Universidade do Extremo Sul Catarinense; BrasilFil: Milmann, Lucas. Grupo de Estudos de Mamíferos Aquáticos do Rio Grande do Sul; Brasil. Universidade Federal do Rio Grande; BrasilFil: de León, Marta Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Gana, Joaquín Carlos Mario. Grupo de Estudos de Mamíferos Aquáticos do Rio Grande do Sul; Brasil. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Wickert, Jonaína C. Grupo de Estudos de Mamíferos Aquáticos do Rio Grande do Sul; Brasil. Centro de Estudos Costeiros Limnológicos e Marinhos; BrasilFil: Argañaraz, María Eugenia. Fundación Mundo Marino (fmm);Fil: Bastida, Ricardo Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Rodriguez, Diego Horacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Denuncio, Pablo Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentin