Silvina Botta

Universidade Federal do Rio Grande (FURG) | FURG · Institute of Oceanography - IO

We analyzed δ13C and δ15N values in different tooth portions (Growth Layer Groups, GLGs) of franciscanas, Pontoporia blainvillei, to investigate their effect on whole tooth (WT) isotopic values and the implications for dietary estimates. Tooth portions included the dentin deposited during the prenatal development (PND), the first year of life (GLG1...

Organic contaminants with toxic effects, like the conventional brominated flame retardants (BFRs) and BFRs of emergent concern, and their synergistic effects with other micropollutants, can be an additional threat to delphinids. Rough-toothed dolphins (Steno bredanensis) populations strongly associated with coastal environments already face a poten...

Populations usually considered foraging generalists may include specialized individuals that feed on a restricted subset of the prey spectrum consumed by the population. By analyzing the time series of δ¹³C and δ¹⁵N values in sequential growth layer groups within tooth dentin, we measured population- and individual-level variation in resource use o...

We report the first known occurrence of South American sea lion (Otaria flavescens) twins on the South American coast. In January 2021 a female pregnant with dizygotic male and female fetuses was found dead in southern Brazil. The timing of the stranding event suggests that the pregnancy was near-term. However, the total body length and weight of f...

River dolphins from the genus Inia are widely distributed in the Amazon, Orinoco and Tocantins River basins. Current knowledge on the dietary habits of these species is poor and based on stomach contents from stranded animals. We used carbon and nitrogen stable isotopes to evaluate the diet preferences and trophic niche of the boto (Inia geoffrensi...

The Atlantic sector of the Southern Ocean has been rapidly changing over the last century. Many of those changes are driven by climate anomalies such as the El Niño Southern Oscillation and the Southern Annular Mode, which affect biological processes that scale up the food web. In this paper, we use δ13C and δ15N time-series of dentine growth layer...

Trace elements bioaccumulation patterns can be an important tool to assess differences among cetaceans' populations. In this work, their use as potential chemical markers to differentiate franciscanas (Pontoporia blainvillei) populations was evaluated. Franciscanas were collected from three states in southeastern Brazil, which comprise three differ...

On November 5th, 2015, the Fundão dam collapsed in Minas Gerais, southeastern Brazil, releasing millions of cubic meters of mud containing mining residue into the Doce River. Two weeks later, the mud arrived to the marine environment, triggering changes in franciscana dolphin habitat, Pontoporia blainvillei, from Franciscana Management Area Ia. Thi...

Threats to aquatic mammals may occur in isolation or in combination, leading to cumulative effects on populations and their ecosystems. Thus, conservation actions must consider the complexity of factors involved in patterns of habitat use, including feeding ecology, such as ontogenetic, spatial and temporal dietary shifts. The Amazonian manatee (Tr...

1. The niche variation hypothesis (NVH) proposes that populations composed by trophic specialized individuals will show a wider population niche than populations composed by more “homogeneous” individuals. To the present, the NVH has little empirical support probably because most studies analyzing individual specialization were based on morphologic...

Skipjack tuna Katsuwonus pelamis sustains the largest catches among tuna species. Despite its relevance for global food security and the tuna canning industry, information about its foraging ecology in the southwestern Atlantic Ocean (SWAO) is limited. We combined amino acid (AA) and bulk tissue nitrogen isotope (δ15N) with stomach content analysis...

Trophic niche width and individual specialization among marine predators are often subjected to seasonal constraints. Differences are expected to arise for sexually dimorphic species exposed to distinct ecological opportunities, as well as intrinsic differences in physiological abilities or energetic requirements. We assess seasonal and sexual diff...

Trophic ecology information about cetaceans is essential to understand their role in ecosystem dynamics. Stable isotope analysis is a valuable complementary approach to conventional methods usually applied to the study of the foraging behavior of cetaceans because it provides dietary information over different time scales and can potentially use ti...

We conducted a meta-analysis of the franciscana (Pontoporia blainvillei ) diet based on published data on stomach contents and stable isotopes, from 1867 to 2021. We provide an assessment of the spatial and temporal variation in the occurrence of franciscana prey throughout its distributional range. Pelagic prey was more frequent in the diet of fra...

Sub-Antarctic fur seals, Arctocephalus tropicalis, are widely distributed in the southern hemisphere, breeding on islands north of the Antarctic Convergence in the South Atlantic, South Indian, and Southwestern Pacific Oceans. At their breeding grounds, sub-Antarctic fur seals feed on a variety of fish, cephalopods, crustaceans, and occasionally, o...

One of the largest environmental disasters worldwide occurred on November 5th, 2015, when the Fundão dam collapsed in Mariana (Minas Gerais State, Southeast Brazil). The tailing mud flooded the Doce River basin and reached the sea in the coast of Espírito Santo State (ES), Southeast Brazil. This coastal region is the habitat of the most isolated po...

We investigated the trophic structure and habitat use of ten cetacean species occurring in the oceanic waters of the western South Atlantic using naturally-occurring stable isotopes. We analysed δ15N in individual amino acids (AA) to estimate cetacean trophic position (TP) and to evaluate the spatial differences in baseline δ15N (source AAs). We ad...

The main aim of this work was to evaluate historical changes in the foraging ecology of Lahille's bottlenose dolphin (Tursiops truncatus gephyreus) along its distributional range. Stable isotopes of carbon (δ¹³C) and nitrogen (δ¹⁵N) were analyzed in bone samples from specimens deposited in scientific institutions from Brazil (BR), Uruguay (UY) and...

In order to assess trophic ecology and feeding areas of free-ranging odontocetes sampled in the oceanic waters of the Southwestern Atlantic Ocean we measured the bulk carbon (δ13C), bulk nitrogen (δ15N) and compound specific amino acid (AA) nitrogen isotopic composition of their skin. AA-δ15N data were applied to estimate cetacean trophic position...

We analyzed skin of free-ranging odontocetes sampled in the oceanic waters of the Southwestern Atlantic Ocean. Stable isotopes of carbon (δ13C) and nitrogen (δ15N) were measured in bulk-skin and δ15N was analyzed in individual amino acids (AA). AA-δ15N data were applied to estimate cetacean trophic position (TP) and to evaluate the spatial differen...

Skipjack tuna (Katsuwonus pelamis) sustain a large-scale fishery in the southwest Atlantic Ocean (SWA), but information about its foraging ecology in this region is still limited. Here we use carbon (δ¹³C) and nitrogen (δ¹⁵N) stable isotope analysis of muscle collected from individuals in 2017–2018 (n = 383) to quantify diet composition and charact...

RESUMO A 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 a...

Two subspecies of bottlenose dolphins are observed, not simultaneously, in a narrow coastal area of the western South Atlantic Ocean. However, their trophic interaction is unknown. Such information can be explored using stable isotope composition in teeth, warranting time series data. We analyzed carbon and nitrogen isotopic values (δ13C and δ15N)...

Large diversity and abundance of cetacean species occur along the Brazilian outer continental shelf and slope waters. In the present study, we analyzed carbon (δ13C) and nitrogen (δ15N) stable isotopes in skin biopsies of ten odontocete species (Delphinidae and Physeteridae) to assess the intra- and inter-specific patterns in the use of resources a...

Age estimation of marine mammals provides important information about ecological and life history parameters. Counting growth layer groups (GLGs) in the dentine and cementum of teeth is the most common technique for age estimation in pinnipeds. In this study, we used acid-etched canines (n = 38) and decalcified stained postcanine sections (n = 40)...

The Neotropical otter, Lontra longicaudis, is a semiaquatic mustelid that preys upon fish, amphibians, and crustaceans, in variable proportions according to habitat and/or season. Due to the difficulty of observing this species in the wild, information on its ecology is typically obtained through vestiges, such as feces, which usually do not provid...

We analysed stable isotopic composition in dentine Growth Layers Groups (GLGs) – in canines from mummified (~100 yr) seals from Marambio Island. GAMMs (General Aditive Mixed Models) were run to understand the ontogenetic variation in δ¹⁵N and δ¹³C values. Additionally, we analysed whisker segments of mummified and actual crabeater seals to estimate...

Sympatric species are expected to differ in ecological requirements to minimize niche overlap and avoid competition. Here we assess the trophic interactions among three coexisting dolphin species from southern Brazil: the franciscana dolphin (Pontoporia blainvillei), the Guiana dolphin (Sotalia guianensis), and the Lahille's bottlenose dolphin (Tur...

Aquatic mammals play an important role in community structure. The present study applied stable isotope analysis (SIA) to evidence trophic relationships and resource partitioning among aquatic mammals inhabiting different environments in the Amazon estuarine complex and adjacent coastal zone (AE) and Northeastern coast (NC) of Brazil. In addition,...

Reproductive parameters of 168 franciscana dolphins, Pontoporia blainvillei (73 females and 95 males) incidentally caught (n = 163) or stranded (n = 5) between 2005 and 2016 in southeastern Brazil are presented. Ovarian macroscopic analysis revealed 55 immature (75.3%) and 18 mature (24.7%) females. Annual pregnancy rate was estimated to be 0.36, w...

This study describes the age structure and sex‐specific growth patterns of Lahille's bottlenose dolphins (Tursiops truncatus gephyreus), a subspecies endemic to the Southwest Atlantic Ocean (SWAO). The ages of 120 animals collected in southern Brazil between 1976 and 2017 were determined. We found high frequencies of young animals, mostly males, wi...

Characterizing the patterns of stable carbon (δ13C) and nitrogen (δ15N) isotopes at the base of the food webs (baseline) is essential in ecological studies for assessing the feeding habits and migration patterns of marine predators. We analysed δ13C and δ15N in zooplankton samples collected in spring and autumn (2012-2015), along the south (SCM) an...

Varying levels of population structure may arise from interactions between intrinsic behavioral and demographic factors and extrinsic environmental factors. Social organization, habitat use, resource partitioning, or even individual preferences are putative drivers of population genetic differentiation over fine spatial scales. Here, genome-wide da...

We assessed the feeding habits of the Amazonian manatee inhabiting blackwater (Negro River) and clearwater (Tapajós River) igapós (floodplains) using δ¹³C and δ¹⁵N of dentin and bone collagen from different ontogenetic classes (nursing calves, juveniles, and adults). Within an individual, the dentine δ¹³C and δ¹⁵N values did not vary with tooth pos...

The Neotropical otter, Lontra longicaudis, is an opportunistic species usually found in freshwater habitats; however, it has also been recorded in environments with marine influence (e.g., islands and estuaries). Thus, we hypothesized that the isotopic niche of the Neotropical otter is wider in a coastal island (Santa Catarina Island—SC) and in a r...

The southwestern Atlantic Ocean (SWA) represents an important foraging ground for loggerhead sea turtles (Caretta caretta). Most studies at the region have focused on adult females and juveniles, and little is known about males. Here, we present the first insights about origin and foraging ecology of male loggerheads from the SWA, by integrating ge...

Individual variation in habitat and resource use has been reported for many top predators. This variation becomes important when comparing individuals taking into account sex, size, or age classes, since it can influence population dynamics and stability. We evaluated the individual variation and sexual/geographical isotopic niche overlap of the So...

We evaluated the feeding habits of the Amazonian manatee (Trichechus inunguis) inhabiting blackwater (Negro River; n=19) and clearwater (Tapajós River; n=17) igapós ((oodplains) using δ 13 C and δ 15 N values in dentin and bone collagen from diierent ontogenetic classes (lactating calves, juveniles and adults). There were no signiicant correlations...

The ecology of marine mammals has been largely benefited from the use of biogeochemical markers. In this chapter we compiled information about studies using these tracers, with the aim of highlighting their relevance to understand some aspects of the trophic and spatial ecology of cetaceans, pinnipeds and sirenians from southwestern Atlantic Ocean...

The Antarctic Peninsula (AP) region is one of the areas under faster warming rates worldwide, and where food web changes have been observed in the last decades. Among these changes are the development of cryptophytes under warmer conditions in detriment of diatoms, and the reduced krill availability in the environment. An isotopic approach was used...

In the present study we used stable carbon (δ¹³C) and nitrogen (δ¹⁵N) analysis of whiskers to investigate the isotopic niche overlap and partition among three pack ice seals sampled along the Danco Coast, Western Antarctic Peninsula (WAP). Isotopic values in serially sampled whiskers of 34 leopard (Hydrurga leptonyx, HL), 13 crabeater (Lobodon carc...

We used an isotopic approach to investigate the intra- and interspecific differences in spatial and trophic ecology of three species of the fur seal genus Arctocephalus that inhabit distinct climatic zones: subtropical (A. australis n = 22), subantarctic (A. tropicalis n = 8), and polar (A. gazella n = 10). We obtained sequential δ13C and δ15N valu...

We combined stomach content analysis and stable isotopes to investigate long-term changes in the feeding ecology of common bottlenose dolphins (Tursiops truncatus) from the Patos Lagoon estuary and adjacent marine coast, southern Brazil, during the past 35 years. Stomach contents of bottlenose dolphins collected between 2002 and 2012 (Period II) we...

Studies involving various aspects of the biology and ecology of sea turtles have successfully applied stable isotope analysis (SIA). In many of these studies the chemical extraction of ¹³C-depleted lipids of sea turtle tissues has been used as a standard protocol, often without testing whether the time-consuming lipid removal is required. Furthermo...

We assessed the feeding habits of franciscanas (Pontoporia blainvillei) from southern Brazil through carbon and nitrogen stable isotopes measured in the tooth dentin of dolphins from different age classes. Generalized additive models were fitted to assess whether sex, age, and total body length explained changes in franciscanas isotope ratios. Baye...

Rationale: The analysis of stable isotopes in tissues such as teeth and bones has been used to study long-term trophic ecology and habitat use in marine mammals. However, carbon isotope ratios (δ(13) C values) can be altered by the presence of (12) C-rich lipids and carbonates. Lipid extraction and acidification are common treatments used to remov...

This report compiles the current information on morphology, genetics, stable isotopes, acoustics and parasites of bottlenose dolphins along the Southwest Atlantic Ocean (SWAO), which includes waters of Brazil, Uruguay and Argentina. The authors also briefly review the proposed taxonomy for the genus along the Atlantic coast of South America.

The estuarine dolphin, Sotalia guianensis, is one of the most abundant cetacean species in Brazil. Determination of age and of aspects associated with the development of this species is significant new studies. Counts of growth layer groups in dentin are used to estimate age of these animals, though other ways to evaluate development are also adopt...

Despite bottlenose dolphins being well studied in several regions around the world, there is very limited information about the reproduction of these animals in the Southwestern Atlantic Ocean (SWA). In this study, data from a long-term mark-recapture and stranding monitoring program were used to estimate life history traits of female bottlenose do...

Teeth and otoliths are metabolically inert structures that preserve a chronology of chemical variations that may be related to the environmental histories experienced by each organism. Because of the natural decrease of barium and increase of strontium bioavailability in water with increasing salinity, these elements may be especially useful to tra...

A dual stable isotope approach (δ13C and δ15N) was used to investigate inter- and intra-specific variations in feeding ecology and habitat use of 7 delphinids from coastal/estuarine, continental shelf and offshore marine environments from southern Brazil: Tursiops sp., Orcinus orca, Stenella frontalis, Steno bredanensis, Delphinus delphis, Pseudorc...

Age and length data of 291 franciscana dolphins (Pontoporia blainvillei) incidentally captured on the coast of Rio Grande do Sul State (RS), southern Brazil, were used to fit growth curves using Gompertz and Von Bertalanffy growth models. A small sample of franciscanas (N ¼ 35) from Buenos Aires Province (BA), Argentina, were used to see if there a...

Neste trabalho foram verificadas as variações temporais na comunidade gastrointestinal helmíntica da toninha, Pontoporia blainvillei, no sul do Rio Grande do Sul, Brasil, e estabelecida a relação da helmintofauna gastrointestinal de P. blainvillei com a rede trófica na qual a espécie está inserida. A comunidade de helmintos gastrointestinais e a co...

Neste trabalho foram verificadas as variações temporais na comunidade gastrointestinal helmíntica da toninha, Pontoporia blainvillei, no sul do Rio Grande do Sul, Brasil, e estabelecida a relação da helmintofauna gastrointestinal de P. blainvillei com a rede trófica na qual a espécie está inserida. A comunidade de helmintos gastrointestinais e a co...

Due to the limited availability of cetaceans, body mass as a measurement of body size is often hard to estimate resulting in reduced sample sizes. Therefore, models for estimating body mass from an analysis of morphometric relationships are useful and practical tools to overcome such difficulties. In the present work, we propose specific models to...

We conducted a double blind experiment in an artisanal gillnet fishery in Argentina to determine the effectiveness of acoustic deterrents (pingers) at reducing bycatch of the Franciscana dolphin (Pontoporia blainvillei). The fishery was conducted by small inflatable and fiberglass vessels operating between 0.5 and 7 km from the coast. Each vessel c...