Abstract
Drift experiments are essential to understand stranding patterns and estimate the mortality of beached animals. Most studies do not use telemetry technology due to the high costs of this ...methodology. The objective of this paper is to describe the possibilities of tracking marine tetrapod carcasses with a low‐cost and replicable methodology. The study was carried out on the Southern Subtropical Shelf (~28°–34°S), a highly productive and key ecological region of the southwestern Atlantic Ocean (SWA).
We designed and tested a low‐cost mixed methodology that includes Global Positioning System trackers, passive drifters (reused glass bottles) and Citizen Science (through an instant message platform and email) to track carcasses of marine tetrapods. We conducted four drift experiments during the four seasons of 2019. We released 787 drifters (600 nonbiological and 187 carcasses of seabirds, sea turtles, and cetaceans) at sea, at five equally separated distances (5–25 km) from the coast. Beach surveys and citizen science were implemented to recover the beached drifters.
We recovered 71.83% of non‐biological drifters and 27.27% of carcasses released. We tracked the movements of 38 carcasses (25 sea turtles and 13 cetaceans) with 17 GPS devices. The drifting time, until reaching the beach, ranged from 12 h to 17 days for carcasses and 12 h to 406 days for bottles. Citizen Science was the most important source of recovery of nonbiological drifters, representing 66.67% of the total recovered bottles. For carcasses, active search was the most important recovery source, representing 64.7% of the total carcasses recovered.
Our study contributes with new findings on marine tetrapod drift patterns in the SWA and describes an accessible low‐cost mixed methodology for small and medium‐budget projects that can be replicated in other coastal regions of the world for tracking a wide range of marine tetrapod species.
Resumo
Experimentos de deriva são essenciais para se entender os padrões de encalhe e estimar a mortalidade de animais encalhados. A maioria dos estudos não utilizam telemetria devido aos altos custos desta tecnologia. O objetivo deste trabalho é descrever as possibilidades de rastreamento de carcaças de tetrápodes marinhos com uma metodologia de baixo custo e replicável. O estudo foi conduzido na região subtropical da Plataforma Sul Brasileira (~ 28° ‐ 34° S), considerada uma região ecológica chave e altamente produtiva do Oceano Atlântico Sul Ocidental (ASO).
Nós projetamos e testamos uma metodologia mista de baixo custo, incluindo rastreadores com Sistema de Posicionamento Global (GPS), derivadores passivos (garrafas de vidro reutilizadas), e ciência cidadã (através de plataformas de mensagem instantânea e correio eletrônico) para rastrear carcaças de tetrápodes marinhos. Nós realizamos quatro experimentos de deriva, durante as quatro estações do ano em 2019. Nós soltamos 787 derivadores (600 não‐biológicos e 187 carcaças de aves marinhas, tartarugas marinhas e cetáceos) no mar, em cinco pontos equidistantes 5km um do outro (5 – 25km) a partir da linha de costa. Monitoramentos de praia e ciência cidadã foram utilizados como metodologias para recuperação dos derivadores que encalharam.
Nós recuperamos 71.83% dos derivadores não‐biológicos e 27.27% das carcaças soltas. Nós rastreamos o movimento de 38 carcaças (25 tartarugas marinhas e 13 toninhas, Pontoporia blainvillei) com 17 aparelhos de GPS. O tempo de deriva, até o encalhe, variou de 12h até 17 dias para carcaças e de 12h até 406 dias para as garrafas. A ciência cidadã foi a fonte mais importante de recuperação de derivadores não biológicos, representando 66.67% do total de garrafas recuperadas. Para carcaças, a busca ativa foi a fonte mais importante de recaptura, representando 64.7% do total de carcaças recuperadas.
Nosso estudo contribui com novos achados sobre os padrões de deriva de tetrápodes marinhos no ASO e descreve uma metodologia mista acessível e de baixo custo para projetos com orçamentos pequenos e médios e que pode ser replicada em outras regiões costeiras do mundo para rastreamento de uma ampla gama de espécies de tetrápodes marinhos.
Anthropogenic disturbance has been pointed to as one of the major causes of the world´s biodiversity crisis. Among them, noise pollution is a potential underestimated threat, projected to increase in ...the next decades accompanying urban expansion. Rising levels of noise pollution may result in negative impacts on species highly dependent on acoustic communication. Amphibians have long served as model organisms for investigating animal acoustic communication because their reproduction depends on transmitting and receiving acoustic signals. A few studies have investigated the effects of anthropogenic noise on anurans, but there is still limited knowledge on how it affects them. In this study, we test the effect of two intensities of traffic noise on calling males of two Neotropical treefrogs species. We expect to record more changes in call parameters, to avoid masking effect, at higher intensity noise treatments, and in the species with higher call/noise frequency overlap. We performed a set of field playback experiments exposing male frogs to road noise at two different intensities (65dB and 75dB). Focal species are Boana bischoffi (high call/noise frequency overlap) and B. leptolineata (low call/noise frequency overlap). Both species changed acoustic parameters during or after the exposure to traffic noise. Advertisement call rate of B. bischoffi decreased during road noise, and dominant frequency decreased over time. Call length of B. leptolineata increased or decreased, depending on the order of noise intensity. We also observed spatial displacement in both species, which moved away from the noise source. Our results provide evidence that traffic noise affects anuran calling behavior, and noise intensity is an important factor affecting how species respond.
We used species distribution modeling to investigate the potential effects of climate change on 24 species of Neotropical anurans of the genus Melanophryniscus. These toads are small, have limited ...mobility, and a high percentage are endangered or present restricted geographical distributions. We looked at the changes in the size of suitable climatic regions and in the numbers of known occurrence sites within the distribution limits of all species. We used the MaxEnt algorithm to project current and future suitable climatic areas (a consensus of IPCC scenarios A2a and B2a for 2020 and 2080) for each species. 40% of the species may lose over 50% of their potential distribution area by 2080, whereas 28% of species may lose less than 10%. Four species had over 40% of the currently known occurrence sites outside the predicted 2080 areas. The effect of climate change (decrease in climatic suitable areas) did not differ according to the present distribution area, major habitat type or phylogenetic group of the studied species. We used the estimated decrease in specific suitable climatic range to set a conservation priority rank for Melanophryniscus species. Four species were set to high conservation priority: M. montevidensis, (100% of its original suitable range and all known occurrence points potentially lost by 2080), M. sp.2, M. cambaraensis, and M. tumifrons. Three species (M. spectabilis, M. stelzneri, and M. sp.3) were set between high to intermediate priority (more than 60% decrease in area predicted by 2080); nine species were ranked as intermediate priority, while eight species were ranked as low conservation priority. We suggest that monitoring and conservation actions should be focused primarily on those species and populations that are likely to lose the largest area of suitable climate and the largest number of known populations in the short-term.
Crypsis and aposematism are important forms of antipredatory strategies. Through cryptic coloration, animals reduce their detectability by matching the coloration of backgrounds, while through ...aposematic coloration, prey species signal to potential predators their unprofitability by conspicuous coloration. The efficacy of aposematism depends on a predator’s ability to identify and avoid unprofitable prey. Among amphibians, both strategies are well known for many species. Most species of red‐bellied toads, Melanophryniscus spp., present conspicuous coloration with a likely aposematic function, both dorsally and ventrally, and display the behavior known as the unken reflex. However, there are a few species, like M. cambaraensis, that only present ventral conspicuous coloration. The dorsal coloration of this species is dull green, which is usually associated with camouflage. Although this species is diurnal and toxic, the exposition of red ventral coloration does not seem to serve as an aposematic signal. Here, we evaluated experimentally if the green dorsal color of M. cambaraensis functions as warning coloration for visually oriented natural predators. We conducted field predation experiments using clay models, representing M. cambaraensis (green models) and a generalized cryptic frog (brown models), to compare attack rates between treatments. The avian attacks were concentrated mainly on the anterior end, suggesting models were perceived as prey. However, attack rates were similar on green and brown frog models. Our results suggest that the green dorsal color of the species does not act as an aposematic signal, but functions as a cryptic color. Although crypsis in poisonous species remains a complex topic, under certain circumstances, the selection pressures imposed by predators may favor a cryptic coloration instead of a conspicuous coloration, even for diurnal species.
Through aposematic coloration, prey species signal their unprofitability to potential predators by conspicuous coloration. Here, we evaluated experimentally if the green dorsal color of Melanophryniscus cambaraensis functions as warning coloration. The green dorsal color of the species did not act as an aposematic signal, suggesting that aposematism is not always the best strategy for unpalatable prey species.
Aposematic signals as well as body behaviours may be important anti-predator defences. Species of the genus Melanophryniscus are characterised by having toxic lipophilic alkaloids in the skin and for ...presenting a red ventral colouration, which can be observed when they perform the behaviour called the unken reflex. Both the reflex behaviour and the colouration pattern are described as defence mechanisms. However, there are currently no studies testing their effectiveness against predators. This study aimed to test experimentally if both ventral conspicuous colouration and the unken reflex in Melanophryniscus cambaraensis function as aposematic signals against visually oriented predators (birds). We simulated the species studied using three different clay toad models as follows: (a) in a normal position with green coloured bodies, (b) in the unken reflex position with green coloured body and extremities and (c) in the unken reflex position with a green body and red extremities. Models were distributed on a known M. cambaraensis breeding site and in the adjacent forest. More than half of the attacks on the models were from birds; however, there was no preference for any model type. Thus, just the presence of the red colour associated with the motionless unken reflex position does not seem to prevent attacks from potential predators. It is possible that the effective aposematic signal in Melanophryniscus is achieved through the unken reflex movement together with the subsequent exhibition of the warning colouration and the secretion of toxins.
•Roundup (R2) increases time to reach metamorphic climax (GS 42).•R2 decreases timing between GS 42 and GS 46 in Melanophryniscus admirabilis.•Mixtures (M2: R2+B1, M3: R1+B2, M4: R2+B2) decrease the ...time to reach GS 42.•Only M2 and M4 shortened the time for tadpoles to complete metamorphosis (GS 46).•Mortality ranged from 29 % (M2) to 71 % (R2) with advancing metamorphosis.
The bufonid species Melanophryniscus admirabilis is restricted to a single location in the southern Atlantic Forest, Brazil. Although the site of occurrence of M. admirabilis is covered with native forest and it is not directly exposed to pesticides application, the area is surrounded by agricultural activity. Our objectives were to evaluate possible alterations in morphological parameters (body mass, snout-vent length, and body index), metamorphosis (time to reach Gosner stages 42, 46 and to complete metamorphosis), and survival of M. admirabilis exposed to isolated Roundup® Original DI (R1: 234 and R2: 2340 µg.L−1 of glyphosate) and Boral® 500 SC, (B1: 130 and B2: 980 µg.L−1 of sulfentrazone) or mixed (R1+B1, R2+B1, R1+B2, R2+B2). Spawns of M. admirabilis were collected in natural lakes in the municipality of Arvorezinha and taken to laboratory cultivation. After the tadpoles acquired free swimming, the animals were acclimated for five days and fed ad libitum. The aquariums were contaminated with herbicides on the sixth day of cultivation, and the animals stayed in these aquariums for four days. Afterwards, the tadpoles were transferred to aquariums with clean water and monitored until metamorphosis (Gosner stage 46), when they were weighed, measured (snout-cloacal length) and cryoeuthanized. We observed no alterations in morphological parameters; however, survival was reduced in exposed groups (mortality index: 71 % in R2 and 29–64 % in mixed groups), suggesting energy allocation for metamorphosis at the expense of survival. Boral did not alter metamorphosis time. Roundup isolated and mixed with Boral altered the timing of Gosner stages 42 and 46 and reduced metamorphosis time, suggesting endocrine disruption. Thus, monitoring the presence and limiting the use of these pesticides in the area where M. admirabilis occurs can be crucial for conservation strategies.
Quantifying how much carrion is produced temporally and spatially in ecosystems is considered one of the most important aspects of carrion ecology. Marine-derived inputs transferred from the ocean to ...terrestrial ecosystems are the principal source of energy and biomass for many coastal ecosystems. Here, we provide a comprehensive quantification of the carrion biomass of marine tetrapods across space and time at the ocean-land interface on the Brazilian coastline. Based on 3 large datasets, we estimated carrion biomass of 57274 marine tetrapods beached along 1980 km of coastline over a 3 yr period (2016-2019). A total of 1744986 kg of carrion biomass was estimated from 76 species, ranging from a total of 30 g to 14082 kg for each species. The 10 most abundant species accounted for 91.78% of total records but only 21.28% of total estimated biomass. We highlight the importance of both migratory and resident marine tetrapods as a predictable resource for the Brazilian coastline, especially in the winter and spring. Although baleen whales contributed higher values of carrion biomass, their true availability as a food source is affected by management procedures adopted after stranding events. A significant amount of carrion biomass is removed every year from the Brazilian coastal system. It is therefore imperative to assess the impacts of management procedures on the ecology of scavengers and the entire coastal system.
Melanophryniscus admirabilis
is a microendemic and critically endangered toad, known from a single population. This microendemic species inhabits a small fragment of the Atlantic Forest in South ...Brazil, an area significantly impacted by hydroelectric power plant projects, livestock farming, agricultural activities, biopiracy, and tourism. Given the exclusive and limited population of
M. admirabilis
, preserving and conserving this species is of utmost importance in Brazil. Research on this species primarily concentrates on its biology, ecology, and ecotoxicology. Currently, there is no knowledge about antimicrobial resistance (AMR) bacteria present in wild
M. admirabilis
, despite the potential for studying them to provide valuable insights into environmental pollution. To this end, Enterobacteriaceae species (
n
= 82) obtained from 15 wild
M. admirabilis
toads were subjected to the standard Kirby–Bauer disk diffusion method to test their AMR. The results showed that Enterobacteriaceae species had the highest antibiotic resistance to IPM (45.1%), CIP (39%), NIT (32.5%), AMP (31.3%), TET (18.3%), and FOX (17%). Of the tested species, 18 (21.9%) species tested were susceptible, 40 (48.8%) were resistant to 1 or 2 different antibiotic classes, and 24 (29.3%) were classified as multidrug-resistant. Overall, our findings suggest that the incidence of AMR in Enterobacteriaceae isolated from wild
M. admirabilis
is high, indicating environmental stress caused by anthropic pollution in their habit.
Melanophryniscus admirabilis
is a small toad, critically endangered with a microendemic distribution in the Atlantic Forest in southern Brazil. The amphibian skin microbiome is considered one of the ...first lines of defense against pathogenic infections, such as
Batrachochytrium dendrobatidis
(
Bd
). The knowledge of skin amphibian microbiomes is important to numerous fields, including species conservation, detection, and quantification of environmental changes and stressors. In the present study, we investigated, for the first time, cultivable bacteria in the skin of wild
M. admirabilis
, and detected
Bd
fungus by nested polymerase chain reaction (PCR) technique. Skin swab samples were collected from 15 wild
M. admirabilis
, and the isolation of bacteria was performed by means of different culture strategies. A total of 62 bacterial isolates being
Bacillus
(
n
= 22; 34.48
%
),
Citrobacter
(
n
= 10; 16.13
%
)
,
and
Serratia
(
n
= 12; 19.35
%
) were more frequently isolated genera. Interestingly, all skin samples tested were
Bd
negative. Some bacterial genera identified in our study might be acting in a synergic relationship and protecting them against the
Bd
fungus. In addition, these bacteria may play an essential role in maintaining this species in an environment modulated by anthropic actions. This first report of skin cultivable bacteria from
M. admirabilis
natural population improves our knowledge of skin amphibian microbiomes, contributing to a better understanding of their ecology and how this species has survived in an environment modulated by anthropic action.
Fossorial vertebrates such as amphisbaenians suffer from morphological constraints as a result of their burrowing strategies. The morphology is conserved in many groups and taxonomic arrangements may ...be confusing within closely related species. Amphisbaena munoai and A. prunicolor slender bodied worm lizards associated with the Amphisbaena darwinii species group and distributed in southern South America (southern Brazil and Uruguay) were traditionally considered allopatric and distinguished from each other mainly by their coloration pattern and cephalic shields. However, the reassessment of morphological variation including specimens from new localities indicated the need for a taxonomic reappraisal. We used morphological, molecular and distributional data in an integrative approach to reassess taxonomic diversity and propose a phylogenetic hypothesis for the evolution of the group. Our results indicated a hidden diversity, allowing the description of three new species from Coastal and Grasslands formations in southern Brazil. Amphisbaena tiaraju sp. nov. occurs in the northwestern region of Rio Grande do Sul State; Amphisbaena arenicola sp. nov. is restricted to Restinga formations in the coastal plain of Santa Catarina State and Amphisbaena nana sp. nov. is restricted to the northern portion of the Sul-rio-grandense Shield in Rio Grande do Sul State.
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