Blastocerus Research Articles

New record in Uruguay of the marsh deer (Blastocerus dichotomus Illiger, 1815) redefines its southern geographic distribution area

New record in Uruguay of the marsh deer (Blastocerus dichotomus Illiger, 1815) redefines its southern geographic distribution area

Isolation of Microascus sp. and Cephalotheca sp. from Bats in Argentina.

Bats worldwide play significant roles in ecosystem functions, encompassing pollination, seed dispersal, and pest control while concurrently serving as diseases reservoirs. As part of a comprehensive wildlife health surveillance effort, bats were systematically sampled within two national protected areas in Argentina. During this study 67 bats were examined and samples were collected from eight Molossus spp. individuals exhibiting conspicuous yellowish or white lesions on their noses. All samples were cultured on Sabouraud dextrose agar and lactrimel agar for fungal growth evaluation. Fungal isolates were identified using morphologic and molecular taxonomic techniques, leading to the detection of Microascus sp. in three Molossus rufus from Ibera National Park and Cephalotheca sp. in five Molossus molossus from Marsh Deer National Park. No fungal growth was identified in samples collected from the healthy hairs of the bats displaying lesions on their noses. The two fungi, which have not previously been isolated from bats, should be considered potentially pathogenic, evidenced by diseased hairs in the affected individuals.

Prevalence and Risk Factors of Bone and Dental Lesions in Neotropical Deer.

Bone and dental lesions have been documented in various deer species globally, affecting the efficiency of ingestion and digestion, consequently influencing their general health and leading to a decline in survival and reproductive performance. The present study aimed to characterize bone and dental lesions in the dry skulls of individual deer, estimate the prevalence of these lesions, and assess potential risk factors associated with the development of bone and dental alterations. This study assessed bone and dental lesions in 180 dry skulls of eleven neotropical deer species, originating from both captivity and wildlife conditions, through direct visual inspection. A high prevalence of bone and dental lesions was observed in all analyzed species. Dental calculus was the most common alteration (96.7%), followed by dental wear (71.1%). Animal age positively correlated with most bone and dental alterations, indicating that older animals showed more lesions. Additionally, the prevalence of these alterations was similar between sexes. Moreover, all lesions were more common in captive-bred animals, likely attributed to their older age and a less diverse diet. Blastocerus dichotomus and Mazama americana were most affected by bone resorption and dental trauma and had the highest dental calculus prevalence, along with Subulo gouazoubira and Passalites nemorivagus. All eleven species evaluated in the present study were susceptible to the occurrence of bone and dental lesions. Therefore, monitoring oral health and diet in captivity are fundamental practices for the conservation of these species.

Fusobacterium necrophorum predomina na microbiota do abscesso dentário mandibular em Blastocerus dichotomus

ABSTRACT: Dental abscess in ruminants is an acute polymicrobial infection, usually resulting from periodontal disease or endodontic infection, with consequences for animal health and welfare. The present study aimed to describe the bacterial microbiota of dental abscesses in Blastocerus dichotomus. Biological material from mandibular dental abscesses, punctured with a sterile syringe and needle during routine veterinary curative procedures or necropsies, was collected from three ex-situ marsh deer. Bacteria were identified using high-throughput sequencing of the 16S ribosomal RNA gene. The three specimens had the presence of facial bulging, and two died because of severe emaciation with a history of progressive weight loss. Bacteroides (38.6%), Fusobacterium (36.65%), and Porphyromonas (7.49%) represented the most abundant genera and Fusobacterium necrophorum (35.69%), Porphyromonas levii (3.12%) and Porphyromonas gulae (1.78%) were among the ten most represented species in the microbiota of mandibular abscess in Blastocerus dichotomus. These molecular findings demonstrate a broader diversity of species in the polymicrobial nature of dental abscesses in B. dichotomus than was previously reported when culture-dependent methods were used in the diagnosis.

Marsh deer (Blastocerus dichotomus) as a new host for Leptospira borgpetersenii in Argentina

Marsh deer (Blastocerus dichotomus) as a new host for Leptospira borgpetersenii in Argentina

Extreme flooding increases poaching mortality in the southernmost stronghold of the endangered marsh deer

Extreme flooding increases poaching mortality in the southernmost stronghold of the endangered marsh deer

First records of pigmentation anomalies in the marsh deer at its southernmost stronghold: a warning message?

First records of pigmentation anomalies in the marsh deer at its southernmost stronghold: a warning message?

Identification of a new Sarcocystis sp. in marsh deer (Blastocerus dichotomus) from wetlands of Argentina.

The marsh deer (Blastocerus dichotomus) is the largest South American native deer species and is listed as "Vulnerable" by IUCN due to the population reduction. As part of a conservation and disease surveillance program, muscle samples from 14 marsh deer found dead in 2016 and 2017 in northeast Argentina were obtained at necropsy. Samples from each animal were processed as pooled muscles (heart, diaphragm, tongue and hindlimb) by homogenization and direct microscopical observation to detect intracellular Sarcocystis spp. cysts. Sarcocysts were observed in six samples, and several cysts recovered from two samples were processed by transmission electron microscopy. The cysts were thin-walled and showed a cyst-wall ultrastructure with ribbon-like protrusions similar to other species using cervids as intermediate host and canids as definitive hosts. Genomic DNA from individual sarcocysts from three marsh deer were successfully amplified by PCR of 18S rRNA and COI gene fragments and further sequenced. Sequence comparison revealed a 99.3-100% identity among them and only 93.7-96.6% and 88.8-89.7% identity at 18S rRNA and COI markers, respectively, with other Sarcocystis spp. Despite morphological similarities, the high sequence divergence at 18S rRNA and COI fragments allowed the assumption that Sarcocystis sp. from marsh deer is a different species from others using cervids as intermediate hosts. Therefore, we propose the name Sarcocystis blastoceris n. sp. for the species infecting marsh deer.

Activity patterns of the marsh deer: Effects of proxies of human movement, cattle presence, and moon phases on its behavior

AbstractActivity is an important aspect of animal behavior. Intrinsic and extrinsic factors can shape species activity patterns, which can alter and reshape several ecological aspects of the species. Human disturbance is known to modify the activity patterns of various species. The Marsh deer (Blastocerus dichotomus) is the largest Neotropical cervid, and has its southernmost distribution located in the wetlands of the lower Delta of the Paraná river, an area characterized by forestry plantations. We studied how the activity patterns of the marsh deer are affected by proxies of human movement, cattle presence, and moon phases in Argentina. We found that marsh deer presented activity peaks during crepuscular hours and moderate levels of activity during the entire night period. The majority of the independent camera‐trapping events of marsh deer occurred during the first quarter and last quarter phases, and the species was more active on sites far from rivers, which could infer an avoidance of human disturbances. In order to comprehend more deeply the variable effects on the activity patterns of marsh deer in this area, further analyses are needed, particularly using movement data of marked individuals.

Optimally designing drone‐based surveys for wildlife abundance estimation with N‐mixture models

Abstract Hierarchical N‐mixture models have been suggested for abundance estimation from spatiotemporally replicated drone‐based count surveys, since they allow modeling abundance of unmarked individuals while accounting for detection errors. However, it is still necessary to understand how these models perform in the wide variety of contexts and species in which drone surveys are being used. This knowledge is fundamental to plan study designs with optimal allocation of scarce resources in ecology and conservation. We conduct a simulation study to address N‐mixture model (binomial and multinomial) performance and optimal survey effort allocation in different scenarios of local abundance and detectability of individuals, focusing on their application for drone‐based surveys. We also investigate the benefits of using a double‐observer protocol (either human or algorithm) in image review to decompose the detection process in availability and perception. Finally, we illustrate our simulation‐based survey design considerations by applying them to abundance estimation of marsh deer in the Pantanal wetland (Brazil). Accuracy of abundance estimation with N‐mixture models increases with local abundance in sites and especially with the availability of individuals. The optimal design requires more visits at fewer sites when the availability probability is lower, and the optimal design is more flexible as local abundance increases. Two observers checking images can increase the estimator performance even at very high perception probabilities. We quantified how much the use of a double‐observer protocol in image review can reduce fieldwork effort while achieving the same accuracy. N‐mixture models can deliver accurate abundance estimates from spatiotemporally replicated drone surveys in a wide variety of contexts while accounting for imperfect detection. The improvements achieved by a consciously planned design, rearranging survey efforts among sites and visits, as well as using a second observer in image review, can be crucial to detect trends when monitoring a population or to categorize a species as threatened or not.

Medium and large-sized mammals of a private protected wetland in the Cerrado-Amazon biological corridor, Brazil.

Brazil is the world's richest country in biodiversity, including mammal species. In the Brazilian Cerrado biome, mammalian diversity is vast, with about 251 species, 32 of them are endemic and 22 listed as threatened species. In this work, we investigated species diversity of medium- and large-sized mammals in the private protected area RPPN Pontal do Jaburu (RPPN-PJ) and its surroundings, which is a flooded area located in an important biological corridor in the Cerrado-Amazon ecotone zone, a priority area for biodiversity conservation in Brazil. We used camera-trapping, active search (night and day), and track survey during dry season (Apr - Aug 2016). We recorded 29 mammal species, being the Carnivora order the most representative with 11 species. Regarding threat status, 35.7% of the recorded species were listed as threatened in Brazil and 32.1% worldwide. We highlight the high relative frequency of threatened species records such as Tapirus terrestris, Panthera onca, Blastocerus dichotomus, Pteronura brasiliensis, Priodontes maximus, and other, as well as the presence of the newly described aquatic mammal species Inia araguaiaensis. We stress the importance of RPPN-PJ and its surroundings for mammal conservation, which include complex habitats (wetlands) located in an important ecotone zone.

Phylogenetic position of Theileria cervi detected in Blastocerus dichotomus (Artiodactyla: Cervidae) with clinical symptoms from Argentina

The results of this study document the molecular detection of Theileria cervi in a symptomatic adult marsh deer Blastocerus dichotomus (Artiodactyla: Cervidae) from Argentina and characterize the phylogenetic position of the Argentinian strain. The animal was founded with signs of obnubilation, anaemia, and ataxia on Isla Talavera in the Paraná Delta, Argentina. Biochemical, haematological and post mortem histopathological studies resulted in the detection of symptoms associated with Theileria infections. Piroplasmid DNA was detected in a blood sample and the complete 18S rDNA gene sequence could be archived. Phylogenetic analyses of the obtained sequence verify the genetic relationship of the Argentinian strain with strains of T. cervi found in other deer species in North America. This result, together with reports of T. cervi detected in various deer species that inhabit countries from Canada in the North to Argentina in the Western Hemisphere, indicates that this Piroplasmorida possess a low host specificity. Although the majority of T. cervi infections results asymptomatic or in mild course of the disease, it must be considered that T. cervi is circulating in Argentinian B. dichotomus populations and can cause serve course of the disease. Therefore, further studies are needed to investigate its prevalence, distribution and veterinary impact.

Unmanned aerial vehicle surveys reveal unexpectedly high density of a threatened deer in a plantation forestry landscape

AbstractThe Vulnerable marsh deer Blastocerus dichotomus, the largest native cervid in South America, is declining throughout its range as a result of the conversion of wetlands and overhunting. Estimated densities in open wetlands of several types are 0.1–6.8 individuals per km2. We undertook the first unmanned aerial vehicle (UAV) survey of the marsh deer to estimate the density of this species in a 113.6 km2 area under forestry management in the lower delta of the Paraná River, Argentina. During 6–8 August 2019, at a time of year when canopy cover is minimal, we surveyed marsh deer using Phantom 4 Pro UAVs along 94 transects totalling 127.8 km and 8.6 km2 (8.1% of the study area). The 5,506 photographs obtained were manually checked by us and by a group of 39 trained volunteers, following a standardized protocol. We detected a total of 58 marsh deer, giving an estimated density of 6.90 individuals per km2 (95% CI 5.26–8.54), which extrapolates to 559–908 individuals in our 113.6 km2 study area. As it has generally been assumed that marsh deer prefer open habitats, this relatively high estimate of density within a forestry plantation matrix is unexpected. We discuss the advantages of using UAVs to survey marsh deer and other related ungulates.

Low STR variability in the threatened marsh deer, Blastocerus dichotomus, detected through amplicon sequencing in non-invasive samples.

Blastocerus dichotomus is the largest deer in South America. We have used 25 microsatellite markers detected and genotyped by Next Generation Sequencing to estimate the genetic variability of B. dichotomus in Argentina, where most of its populations are threatened. Primer design was based on the sequence of a shallow partial genome (15,967,456 reads; 16.66% genome coverage, mean depth 1.64) of a single individual. From the thousands of microsatellite loci found, even under high stringency selection, we chose and tested a set of 80 markers on 30 DNA samples extracted from tissue and feces from three Argentinean populations. Heterozygosity levels were low across all loci in all populations (H=0.31 to 0.40). Amplicon sequencing is a fast, easy, and affordable technique that can be very useful for the characterization of microsatellite marker sets for the conservation genetics of non-model organisms. This work is also one of the first ones to use amplicon sequencing in non-invasive samples and represents an important development for the study of threatened species.

Afecções bucais em uma população ex situ de cervos-do-pantanal (Blastoceru dichotomus): um estudo retrospectivo (1990-2020)

ABSTRACT: Oral diseases are limiting to health, welfare, and conservation practices, especially in the case of endangered animals. In this retrospective study, a survey on oral health-related conditions noted in the clinical records for 261 deer comprised in an ex situ population of the Marsh Deer Conservation Center (CCCP) over 30 years (1990-2020) was carried out. Of these, 49 (18.77%) marsh deer (31 females - 63.27% and 18 males - 36.73%) had clinical oral affections; the affected deer’s mean age was 8.9 years. Logistic regression analysis was performed, and the variable age was significantly associated with the presence of dental affections. Thus, with a change in the age category, a deer had eight times the chance of manifesting oral affections; therefore, age can be considered a risk factor for the manifestation of oral affections in the species. Increased facial volume (65.3%), accumulation of food in the mouth (36.7%), tooth loss (22.4%), fistulas (22.4%), mucosal or palatal lesions (22.4%), tooth wear (20.4%), and tooth root exposure (18.3%) were the most frequently recorded lesions. The relatively high occurrence of oral affections in Blastocerus dichotomus reiterates the importance of oral health care when deer are kept in human care.

Behavioral response of captive marsh deer to an economic and easy-to-install repellent: a potential mitigation solution for conflict?

Deer species can cause serious damages to trees through browsing and antler rubbing, and these impacts can generate significant economic losses. As a tool to minimize damages to trees by deer, repellents based on odor, visual and/or taste stimulus have been developed and tested. Repellents vary greatly in terms of costs, forms of use, duration, and/or the local context. Thus, selection of the most-effective repellent to each situation should consider the local environmental and socioeconomic contexts. Pyrazine analogs have been recognized to induce avoidance and fear-related behaviors in deer. These compounds are also found in ordinary and daily-use products, such as coffee, which can be easily obtained. The marsh deer (Blastocerus dichotomus) is the largest native deer of South America. The southernmost population of this species is found in the lower Delta of the Paraná River in Argentina, a large wetland highly modified due to commercial afforestation of Salicaceae. Local forestry producers usually report damage to plantations attributed to marsh deer, with a minor fraction of these producers perceiving high levels of damage and economic losses. We tested an easy-to-install repellent system based on coffee grounds by conducting trials focused on four captive marsh deer. The trials consisted in offering pellets of grain and fiber to deer, dividing the overall ration into two identical factions separated by 15 meters within the enclosure. In the “repellent site”, a subset of the regular food was placed on the ground and treated with the repellent, whereas the other subset, also located in the ground but not treated, was used as the “control site”. Whereas deer individuals presented alert behavior (50-100% of the times) after approaching the repellent site, this behavior was never observed at the control site. Significant differences were found among individuals probably due to a dominance interaction inside the group. The weight of food remains in the repellent site was significantly higher than in the control site at the end of the study. A repellency system based on coffee grounds could be an economic solution to be used by forestry producers of the Paraná River delta or by anyone interested in diminish damages to particular resources. In addition, it is a biodegradable option with insignificant environmental impact and could be especially useful to be applied at small spatial scales, since it requires domestic materials and a relatively limited installation cost in terms of time spent to set up the system. Supplemental data for this article is available online at https://doi.org/10.1080/09670874.2021.2024619.

Ticks (Acari: Ixodidae) on marsh deer (Blastocerus dichotomus) at a conservation center: infestation and Rickettsia parkeri infection dynamics along nine years

The objective of this work was to evaluate the relationship between the populations of the ticks Amblyomma triste Koch, 1844, Rhipicephalus microplus (Canestrini, 1888), Amblyomma sculptum Berlese, 1888, the pathogenic bacteria Rickettsia parkeri and a marsh deer (Blastocerus dichotomus) population after its removal from a pristine environment. For this purpose, ticks were collected from the cervical region of deer at the Marsh Deer Conservation Center in Promissão, São Paulo State, Brazil for nine consecutive years (2000 - 2008). Deer in captivity at the Center were kept in 2,000 m² paddocks surrounded by two-meter-high fences in the Tiete-river marsh. In total, 1,012 ticks of 26 deer were collected. Prevalence of the species A. triste among tick-infested hosts was the highest in the first triennium but decreased to the second and further to the third triennium. In contrast, the R. microplus prevalence amidst infested host population, increased from the first to the third triennium and was the species that attained the highest infestation intensity. Amblyomma sculptum was the tick with the lowest infestation prevalence and intensity throughout the period. The change in the proportion between the two most prevalent species was attributed to the new environment, specifically its restricted size and within it a dry area more suitable for R. microplus. DNA of 424 ticks processed in 276 pools was tested for Rickettsia genetic material by polymerase chain reactions (PCR). Twenty samples of the study were positive for the rickettsial gltA gene. Of these, 18 were from A. triste ticks and revealed the presence of the ompA spotted fever group gene as well. Eleven samples were sequenced and showed 100% identity with R. parkeri sensu stricto. Two samples from R. microplus did not amplify ompA gene neither yielded product in a PCR specific for Rickettsia bellii. Sequencing of the gltA gene in the DNA of these two ticks was also 100% identical with R. parkeri s.s. In conclusion, the changes in the deer environment modified the tick populations but maintained, at least temporary, R. parkeri bacteria in A. triste ticks. Rhipicephalus microplus was refractory to the R. parkeri infection and bacterial DNA in this tick species indicated DNA spill over from other tick species. It was demonstrated that captive marsh deer may sustain cattle tick populations on its own. This would hardly occur under pristine conditions because of the inadequacy the marsh deer´s naturally humid habitat for the cattle tick. However, deer transportations of R. microplus ticks from one farm to another may occur whenever habitat loss pushes this wild animal towards farms.

FIRST REPORT OF GENUS Cryptosporidium IN CERVIDS SPECIES: Mazama americana, Mazama nana AND Blastocerus dichotomus.

We analyzed Cryptosporidium spp. in fecal samples of wild cervids (Ozotoceros bezoarticus, Blastocerus dichotomus, Mazama nana, Mazama americana, and Mazama bororo) from many Brazilian regions, a fact unprecedented in the literature. Sniffer dogs were used to collect 936 fecal samples of cervids from 14 Brazilian localities. Cervids species were identified using polymerase chain reaction (PCR) performed from genomic DNA extracted from 563 fecal samples of Ozotoceros bezoarticus, Blastocerus dichotomus, Mazama nana, Mazama americana, and Mazama bororo. Cryptosporidium spp. oocyst screening was performed using malachite green negative staining. Nested PCR (nPCR) protocols targeting the 18S rRNA and GP60 genes followed by genetic sequencing were performed for Cryptosporidium spp. detection and Cryptosporidium parvum subtyping, respectively. Nested PCR targeting actin gene and genetic sequencing were performed in samples with non-identified Cryptosporidium species by 18S rRNA amplicon sequencing. The association between the occurrence of Cryptosporidium and the presence of bovines in the same locality was evaluated using Fisher's exact test. The positivity rates of diagnostic methods were compared by McNemar test and the Kappa correlation coefficient. The prevalence rates of Cryptosporidium spp. in cervids were 1.42% (8/563) and 0.36% (2/563) by nPCR and malachite green negative staining, respectively. C. parvum IIaA16G3R1 isolate was identified in three fecal samples from M. americana, two from M. nana and one from B. dichotomus. Cryptosporidium ryanae were found in one sample from B. dichotomus. We identified a new Cryptosporidium genotype, named Cryptosporidium deer genotype BR, from one M. americana fecal sample.

Satellite DNA in Neotropical Deer Species

The taxonomy and phylogenetics of Neotropical deer have been mostly based on morphological criteria and needs a critical revision on the basis of new molecular and cytogenetic markers. In this study, we used the variation in the sequence, copy number, and chromosome localization of satellite I-IV DNA to evaluate evolutionary relationships among eight Neotropical deer species. Using FISH with satI-IV probes derived from Mazama gouazoubira, we proved the presence of satellite DNA blocks in peri/centromeric regions of all analyzed deer. Satellite DNA was also detected in the interstitial chromosome regions of species of the genus Mazama with highly reduced chromosome numbers. In contrast to Blastocerus dichotomus, Ozotoceros bezoarticus, and Odocoileus virginianus, Mazama species showed high abundance of satIV DNA by FISH. The phylogenetic analysis of the satellite DNA showed close relationships between O. bezoarticus and B. dichotomus. Furthermore, the Neotropical and Nearctic populations of O. virginianus formed a single clade. However, the satellite DNA phylogeny did not allow resolving the relationships within the genus Mazama. The high abundance of the satellite DNA in centromeres probably contributes to the formation of chromosomal rearrangements, thus leading to a fast and ongoing speciation in this genus, which has not yet been reflected in the satellite DNA sequence diversification.

Effects of cattle on habitat use and diel activity of large native herbivores in a South American rangeland

Cattle grazing usually has negative effects on wildlife. We studied the effects of cattle on the patterns of habitat use and diel activity of three neotropical herbivores, capybara (Hydrochoerus hydrochaeris), gray brocket (Mazama gouazoubira) and marsh deer (Blastocerus dichotomus) across the savannas of northeastern Argentina. We conducted a camera-trap survey with 234 stations in three habitat types (grasslands, forests, pine plantations) with and without cattle. We used occupancy models to evaluate the effect of cattle (presence or recording rate), season (winter vs spring-summer, and its interaction with cattle), distance to water bodies, and density of vegetation, on the probability of detection (p) of the native herbivores. We also evaluated the effect of cattle, habitat type, structural complexity of the vegetation, proportion of marshlands and forests in the landscape, season, and relative accessibility by humans, on the probability of occupancy (ψ) of these species. Using kernel density functions, we estimated the overlap in diel activity pattern of native herbivores with that of cattle, comparing this overlap between stations with and without cattle. Several variables, but not cattle, affected ψ. For marsh deer p was lower when cattle were present. For brocket, p was much lower in winter when cattle were present. For the marsh deer and the capybara, ψ increased (but in brocket decreased) with increasing cost of human access, a proxy of hunting. For capybara and brocket, ψ increased with increasing structural complexity of vegetation. Cattle were more diurnal in grasslands than in forests and plantations. Native herbivores became more nocturnal, with lesser overlap with the diel pattern of cattle, in grasslands, when cattle were present. Cattle seem to exert interference competition on the native herbivores which used less frequently areas where cattle were present and avoided being simultaneously active with grazing cattle. Livestock production should strive to mitigate the negative competitive effects of cattle on wildlife by maintaining cattle free protected areas. It should also reduce some indirect effects of this activity on the native herbivores (e.g., hunting of wildlife and frequent burning of grasslands).