Hematological Values of Two Species of Amazonian Caimans, Caiman crocodilus AND Melanosuchus niger

doi:10.21203/rs.3.rs-3962563/v1

Download PDF

Short Report

Hematological Values of Two Species of Amazonian Caimans, Caiman crocodilus AND Melanosuchus niger

https://doi.org/10.21203/rs.3.rs-3962563/v1

This work is licensed under a CC BY 4.0 License

Version 1

posted

You are reading this latest preprint version

The Amazon is one of the most biodiverse regions for crocodilians globally. Four of the five Amazonian caimans species exist in the Brazilian Amazon region. Determining hematological values is essential to provide baseline health and condition data. We evaluated the hematological parameters of free-living specimens of Caiman crocodilus and Melanosuchus niger from the middle Negro River region of Brazil. We captured 18 C. crocodilus and 16 M. niger, which averaged 60.5 ± 13.0 cm and 46.1 ± 18.5 cm in total length, respectively. Blood was drawn using syringes containing 10% EDTA, and blood parameters were determined according to the previously described methodology. The analyzed erythrocyte parameters were similar between the species, demonstrating that, despite presenting different sizes, they have similar strategies for absorption and transport of oxygen in the blood. In the morphological analysis of blood cells, erythrocytes, erythroblasts, thrombocytes, lymphocytes, neutrophils, azurophils, heterophils, and basophils were found and, in the quantification of leukocytes and thrombocytes, it was noted that lymphocytes are the central cells in the blood of Caiman of Amazonian. In the results found for plasma metabolites, no significant differences were observed between glucose and total protein levels. The information generated herein is intended to aid in establishing management plans, conservation, and farming of these species of Caiman Amazonian.

Blood

morphology

erythrogram

biochemistry

comparative

Caiman are considered opportunistic generalist predators (Wolfe et al. 1987) whose food habits differ due to prey availability, sex, size, and individual specialization (Wolfe et al. 1987; Gabrey 2010). Caiman are predators at the top of the food chain and are essential in maintaining the ecological balance of their places of occurrence (Marione et al. 2021). Brazil has six caiman species, all belonging to the Alligatoridae family (Cuvier 1807). The Amazon region is one of the most biodiverse regions for caimans globally, and four of the five Amazonian caiman species exist in the Brazilian Amazon (Da Silveira 2002).

Caiman crocodilus and Melanosuchus niger are two species whose populations are at risk from poaching, despite being considered low risk, of biological extinction, according to Appendix II of CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora). They live in tropical and subtropical areas in various aquatic habitats (forest streams, rivers, marshes, swamps, lakes, and others) and are considered giant freshwater dwellers (Martin 2008).

The species are economically important due to the use of their skin as a raw material for making bags, shoes, and other items, which are also used in interaction tourism (Mendonça et al. 2023). In addition, there is a market for their meat, which is often salt-cured (Sotero-Martins et al. 2015). As for other animals, the determination of hematological values helps understand the state of animal health, such as turtles (Anselmo et al. 2020), caimans (Mendonça et al. 2023; 2023a), fish (Castro et al. 2020, 2020a), and elasmobranchs (Oliveira et al. 2011, 2016, 2017, 2017a, 2021). In practice, animals with an insufficient diet or inadequate handling become stressed, have depressed immunity, become dehydrated, lose weight, become anemic, sick, become vulnerable to pathogens and infectious agents, and tend to die (Oliveira et al. 2015).

Mendonça et al. (2023) simulated interactions between tourists and Amazonian crocodilians and evaluated the effects of handling and use of photographic flashes on black caiman M. niger and spectacled caiman C. crocodilus on circulating corticosterone and lactate. Thus, increased corticosterone concentrations in black caiman were characterized by an increase caused by handling and were more intense after flashes than in controls, but the combination of handling and flash had no effect. During handling in simulated tourist interactions, anaerobic respiration increased lactate in black caiman but not in spectacled caiman (Mendonça et al. 2023).

Thus, Conservation physiology was defined by Wikelski and Cooke (2006) as the study of organisms' physiological responses to changes in the natural environment that can cause or contribute to the population decline of various taxonomic groups. According to Stevenson et al. (2005), this area is important because it aims to understand in detail the mechanisms that cause conservation problems based on animals' hematological, metabolic, endocrine, and immunological parameters.

Monitoring the hematological profile is an essential method of monitoring health and welfare. Studies should consider both wild populations to understand how seasonality, feeding frequency, diet quality, and variety interact with the biochemistry or hematology of the species (Barajas-Valero et al. 2021). In this sense, monitoring the hematological profile is an essential factor that must be considered for the proper assessment of animal welfare since this provides information regarding the presence of infections and parasites as well as the nutritional conditions of the animals. As a result, it is possible to elucidate which diseases affect captive animals, free-living, or both (Campbell 2004).

For several species of reptiles for which blood parameters are either unknown or inaccurate (Hidalgo-Vila et al. 2007). This is mainly the case for crocodilians, and most studies involving these organisms have been carried out with captive animals (Stacy and Whitaker 2000; Mussart et al. 2006). However, studies have recently been conducted with animals in a natural environment (Mendonça et al. 2023; 2023a). Barão-Nóbrega et al. (2017), when studying the body condition and blood parameters of C. crocodilus and M. niger in the central Amazon during the nesting period, concluded that body condition index values and blood parameter estimates for these species provide reference values for future studies monitoring health conditions, establishing the limits between well-being and morbidity. This work aimed to describe and compare the hematological profile, as well as morphologically describe the blood cells of free-living specimens of C. crocodilus and M. niger from the middle Negro River, Amazonas state, Brazil.

Study area and capture

The specimens of C. crocodilus and M. niger were collected with the aid of a steel loop during the period from November 2015 to January 2018 in creeks of the middle Negro River basin, Barcelos, Amazonas, Brazil (Fig. 1). The experimental procedures adopted during these animals' capture and blood analysis were registered and approved by the Brazilian Institute of the Environment and Renewable Natural Resources-IBAMA under Process No. 15116-1. The research was developed and approved by the Ethics Commission on the Use of Animals (ECUA) of the Federal University of Amazonas under Process No. 2015/010.02.0905. The sampling was conducted according to local and ARRIVE guidelines (Persie Du Sert et al. 2020). The animals were captured with ropes that were directed to the neck of the animals. No injury to the animal was caused, and all animals appeared healthy. After capture, the animals were restrained and blindfolded to reduce stress. In the present study, 18 specimens of C. crocodilus and 16 samples of M. niger, the length (snout to tail) of each caiman was recorded with a measuring tape with a resolution of 0.5 centimeters.

The animals presented 60.5 ± 13.0 cm and 46.1 ± 18.5 cm (total length), respectively, were captured, and they are young (C. crocodilus) animals and puppies (M. niger).

Hematological parameters

Immediately after the immobilization of the animals, blood samples were collected via puncture of the postoccipital sinus of the spinal vein (Duncan et al. 2021) using syringes containing EDTA (10%). Total handling and processing time was < 1 minute to reduce the animals' suffering, stress, and pain. The captured caimans were recorded full-length and then released near their capture sites.

The blood was collected and stored in liquid nitrogen until the moment of the analysis that took place in the Biology Laboratory of the Federal Institute of Education, Science and Technology of Amazonas. In the whole blood count, the erythrocyte count (RBC) was calculated in a Neubauer chamber (Oliveira et al. 2017). In contrast, the hemoglobin concentration (Hb) and hematocrit (Ht) were computed using the cyanmethemoglobin method and the microhematocrit method, respectively (Oliveira et al. 2017). Based on these findings, the mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and mean corpuscular hemoglobin concentration (MCHC) hematimetric indices were derived (Oliveira et al. 2016).

Oliveira et al. (2015) followed instructions in preparing and staining blood extensions, which were then utilized to ascertain the morphology and count the various blood cell types. After centrifuging plasma at 750 G, it was immediately frozen in liquid nitrogen (-86°C) for biochemical testing. Enzymatic-colorimetric methods were used to quantify the plasma biochemical variables, such as glucose, triglycerides, total cholesterol, total proteins, and urea, using commercial kits (Labtest^®, Brazil) that were specific for each parameter.

Statistical analyses

The Shapiro-Wilk normality test was used to evaluate the data distribution. Therefore, the non-parametric Kruskal Wallis test was employed following Dunn's posterior test to compare the hematological parameters of C. crocodilus and M. niger of the present study and the data available in the literature for other caimans presentation Table 1 (erythrograms values). The Mann-Whitney test was used to compare means between C. crocodilus and M. ninger, leukocyte count and thrombocyte values (Table 2) and plasma biochemistry (Table 3). Were performed at 5% significance, and the software used was R^® (version 4.3.1)

The results of the erythrogram of this study and the data found in the literature for the species Caiman crocodilus and Melanosuchus niger are shown in Table 1. All erythrocyte parameters analyzed were similar between C. crocodilus and M. niger (p > 0.05), demonstrating that despite presenting having different sizes, these species have similar strategies for absorption and transport of oxygen in the blood. However, when comparing the studied species with data from species described in the literature, significant differences (p < 0.05) were observed for the hemoglobin and hematocrit parameters, thus showing particularities in the physiological state between the species and also according to the location and living conditions (free-living or captivity).

In the morphological characterization of blood cells, in the blood of C. crocodilus and M. niger, erythrocytes, erythroblasts, thrombocytes, lymphocytes, neutrophils, azurophils, heterophils, and basophils are observed. The erythrocytes (Fig. 2-I) present an elliptical shape, with the nucleus determining the cell's condition and abundant cytoplasm occupying about 70% of the cell. Neutrophils (Fig. 2-I) have a rounded shape and cytoplasm with neutrophilic granulations, and a bilobate nucleus is observed in some cells. The lymphocytes (Fig. 2-I) present varied forms, from rounded to amorphous, and have basophilic cytoplasm and no visible granulations. Granulocytes (Fig. 2-II) are predominantly oval cells, have basophilic granulations, and their nucleus is eccentric and usually bilobate.

Erythroblasts (Fig. 2-III) are generally rounded cells with hyaline cytoplasm, but they have a higher nucleus-cytoplasm ratio when compared to erythrocytes. Thrombocytes (Fig. 2-IV) present a fusiform shape, with hyaline cytoplasm concentrating only at the end of the cell and a nucleus that occupies almost the entire cell. Heterophils (Figs. 2-IV and 2-VI) are predominantly rounded cells with cytoplasm filled by heterophilic granulations. The nucleus is usually tiny and eccentric and rarely segmented; occasionally, these granulocytes are degranulated. Azurophils (Fig. 2-V) are cells of varying sizes and shapes. They may or may not present vacuoles and have basophilic cytoplasm with azurophilic granulations. The quantification of leukocytes and thrombocytes demonstrated that lymphocytes are the primary cells in the blood of these Amazonian caimans (Table 2).

The results of the plasma metabolites are presented in Table 3, in which no significant differences were observed between the analyzed species' glucose and total protein levels. However, C. crocodilus showed an upward trend in protein levels, which probably resulted in this species' high urea levels (p < 0.05). Regarding lipid levels, it was observed that triglycerides did not differ between C. crocodilus and M. niger (p < 0.05).

The analysis of hematological parameters has already been used to evaluate the health status of several taxonomic groups (Stacy and Whitaker 2000; Tavares-Dias and Moraes 2004; Jenkins-Perez 2012). These parameters may indicate hemoconcentration or hemodilution, and hemoconcentration may be a strategy used to increase blood transport capacity under high energy demand in stress situations. However, stressors and polluters that may compromise iron absorption and stimulate erythrocyte malformation or hemolysis, inhibition of hemoglobin synthesis, and competition for the oxygen binding site may cause hemodilution or anemia in animals, thereby reducing oxygen transport capacity (Mendonça et al. 2023a).

In the present study, hematocrit values were 21.3 ± 4.0 and 25.3 ± 0.6 for the C. crocodilus and M. niger, respectively. These values are similar to those described for Crocodilus palustris (Brian and Whitaker 2000; Rajesh et al. 2013)d latirostris and C. yacare (Barboza et al. 2007), demonstrating that there is no significant difference for these values between individuals in captivity and from natural areas. Higher hematocrit values have been reported for C. crocodilus during the dry seasons, probably related to hemoconcentration caused by dehydration (Ramirez et al. 1978; Rossini et al. 2011). The hematocrit and hemoglobin values of the wild C. crocodilus agreed with those reported for animals of the same species between 2 and 5 years of age (Ramirez et al. 1978).

The number of erythrocytes in reptiles is lower than that of birds and mammals (Amin and Shrivastav 2014). Among reptiles, lizards have more erythrocytes than turtles and crocodiles. The erythrocyte values obtained for C. crocodilus in this study were similar to those reported previously for Alligator mississippiensis (Raskin 2000) but lower than those described for Crocodilus palustris (Brian and Whitaker 2000; Rajesh et al. 2013) and Gavialis gangeticus (Amin and Shrivastav 2014). Our values do not suggest hemolysis. In addition, erythrocytes are relatively resistant to osmotic and mechanical damage (Brian and Whitaker 2000). The MCV values for C. crocodilus and M. niger are more significant than that for C. palustris and C. porosus. This difference can be related to age, sexual dimorphism, reproductive status, diet, and dynamics of the sample populations, as well as environmental conditions such as temperature and water levels.

From the comparison between the data of the present study with those available in the literature, it was verified that P. trigonatus, another Amazonian species, has a different strategy from the other species and invests in a lower number of circulating erythrocytes, which resulted in a low level of hematocrit. However, these cells have a large volume and high corpuscular hemoglobin concentration (Table 1) to compensate for this low amount of erythrocytes. This difference in blood parameters may be related to the small size of P. trigonatus (< 1.40 m total length) and its differentiated habitat (inland streams and small bodies of water) (Magnusson and Lima 1991); therefore, it does not require an ample supply of oxygen to perform prolonged dives given the low depth of the streams.

The comparison between the subspecies C. crocodilus and C. yacare revealed a difference in hemoglobin concentration and MCHC (Table 1), which may have been influenced by habitat since these animals inhabit different hydrographic basins. The blood parameters analyzed indicate that the sampled animals were healthy since no evidence of anemia or other hematological disorders was found. It was also observed that the erythrogram of C. crocodilus and M. niger are similar (Table 1).

Thus, in Table 1, it is observed that the species C. crocodilus and M. niger have less hemoglobin inside the erythrocytes (CHCM), which reflects in the total amount of this variable (Hb) also being low when compared to the other species described in Table 1. However, these shared values did not indicate compensation for the increase in Ht and RBC values, which presented intermediate values for the species described in Table 1. Thus, it is essential to carry out more studies of free-living Caiman species to confirm whether these changes are caused by lifestyle or whether it is a characteristic of the species.

For the morphology of the cell types found in the present study (Fig. 2), six cell types were shown, similar to those found in other Amazonian aquatic reptiles belonging to the turtle group (Oliveira et al. 2011). However, in the present study, the presence of neutrophils was observed, while in that study, the presence of eosinophils was observed. It is worth highlighting the difficulty in morphological determination in identifying blood cell types. In the present study, the morphology was similar to that portrayed for the turtles Podocnemis unifilis, Podocnemis expansa and Podocnemis sextuberculata (Oliveira et al. 2011).

Significant individual variation was found for the leukogram and thrombogram (Table 3), similar to the findings for Amazon turtles (Tavares-Dias et al. 2011). The present study's total leukocyte and thrombocyte values were lower than turtles P. expansa, P. unifilis and P. sextuberculata (Tavares-Dias et al. 2011). The concentration pattern of cell types in Amazonian caimans revealed that lymphocytes are the predominant cells, followed by neutrophils, heterophils and azurophils, with practically equal values. For Amazon turtles, heterophils were the principal cells (around 65%) (Tavares-Dias et al. 2011), indicating that the leukocyte responses of Amazon caimans are distributed in a larger cell group, while in turtles, there is a concentration in a single cell type.

There were statistical differences in the plasma metabolites of C. crocodilus and M. niger (Table 3), which probably reflect differences according to the type of food that each species ingests. Elevated plasma urea levels are associated with the species and the type of diet of the top-of-the-food-chain species, which are classified as carnivores (Marione et al. 2013). Reptiles, in general, are uricotelic animals, preferentially excreting uric acid as a nitrogen compound; however, aquatic animals or those that spend a predominant part of life in the aquatic environment are considered partially ureotelic and can use both uric acid and urea for nitrogen excretion (Singer 2003).

Differences in plasma lipid levels are likely related to their different dietary habits. According to Santos (1997), crocodilians change their diet throughout growth, and the young consume mainly insects, then proceed to consume crustaceans and mollusks as they grow, and finally end up eating vertebrates. Due to the small size of the specimens of M. niger captured in this study (46.1 ± 21.1 cm), it is possible that the diet of these animals was predominantly comprised of crustaceans, which would explain the high levels of total cholesterol since the level of cholesterol is more elevated in crustaceans when compared to fish (Vaz-Pires 2006).

The results of this study serve as the basis for future investigations aimed at monitoring the health status of these species of Amazonian caimans in the long term and in the face of environmental changes and assist in the understanding of physiology and the creation of conservation, management, and captive production plans of these species. Based on information from this work, critical physiological parameters were established to monitor the health condition of C. crocodilus and M. niger. Thus, it is possible to take this information to the production of these animals in captivity and thus reduce the commercial exploitation of free-ranging animals.

Acknowledgments

To fishermen from the city of Barcelos, Amazonas, Brazil. The Fundação de Amparo a Pesquisa do Estado do Amazonas (FAPEAM) through the Propesca Project - Rio Negro (Call 010/14). Adriano Teixeira de Oliveira is a research fellowship recipient from CNPq/Brazil.

Author Contributions

ATO conceived and designed the experiments performed the experiments, analyzed the data, prepared figures and tables, authored or reviewed article drafts, and approved the final draft. MQCS conceived and designed the experiments performed the experiments, analyzed the data, authored or reviewed drafts of the article, and approved the final draft. JRGL conceived and designed the experiments, performed the experiments, analyzed the data, authored or reviewed drafts of the article, and approved the final draft. ANAS performed the experiments, authored or reviewed article drafts, and approved the final draft. CCG performed the experiments, authored or reviewed article drafts, and approved the final draft. MWSR performed the experiments, authored or reviewed article drafts, and approved the final draft. PHRA conceived and designed the experiments, performed the experiments, analyzed the data, authored or reviewed drafts of the article, and approved the final draft.

Data Availability

The information was supplied in supplementary material.

Compliance with ethical standards

Ethics approval and consent to participate

The experimental procedures adopted during these animals' capture and blood analysis were registered and approved by the Brazilian Institute of the Environment and Renewable Natural Resources-IBAMA under Protocol No. 15116-1.

Consent for publication

Not applicable.

Conflict of interest

The authors declare no conflict of interest.

Amin S, Shirivastav AB (2014) Hematology and serum biochemistry of captive gharial (Gavialis gangeticus) in India. Veterinary World 7(10): 794-798.
Anselmo NP, Silva CKP, Franca MFL, Santos MQC, Aride PHR, Pantoja-Lima J, Oliveira AT (2021) Hematological parameters of captive big-headed Amazon river turtles, Peltocephalus dumerilianus (Testudines: Podocnemididae). Acta Biologica Colombiana 26: 207-213. https://doi.org/10.15446/abc.v26n2.80616
Aride PHR, Oliveira AT, Oliveira AM, Ferreira MS, Baptista RB, Santos SM, Pantoja-Lima J (2016) Growth and hematological responses of tambaqui fed different amounts of cassava (Manihot esculenta). Arquivo Brasileiro de Medicina Veterinária e Zootecnia 68: 1697-1704. https://doi.org/10.1590/1678-4162-8704
Aride PHR, Oliveira AM, Batista RB, Ferreira MS, Pantoja-Lima J, Ladislau DS, Castro PDS, Oliveira AT (2018) Changes in physiological parameters of Tambaqui (Colossoma macropomum) fed diets supplemented with fruit camu camu (Myrciaria dubia). Brazilian Journal of Biology 78: 360-367. https://doi.org/10.1590/1519-6984.169442
Aride PHR, Oliveira AM, Ferreira MS, Liebl ARS, Comassetto L, Ladislau D, Bassul LA, Silva BR, Mattos DC, Lavander HD, Souza AB, Polese MF, Ribeiro M, Castro PDS, Oliveira AT (2021) Growth and hematological responses of tambaqui, Colossoma macropomum fed different levels of rice, Oryza spp. Brazilian Journal of Biology 81(4): 962-968. http://dx.doi.org10.1590/1519-6984.232560
Barajas-Valero S, Rodríguez-Almonacid C, Rojas-Sereno Z, Moreno-Torres C, Matta NE (2021) Original Research. DOI: 10.3389/fvets.2021.694354
Barboza NM, Mussart NB, Coppo JA, Fioranelli SA, Koza GA (2007) Oscilaciones del eritrograma en Caimanes criados por sistema ranching. Rev. Vet. 18(2): 84-91.
Barboza NN, Mussart NB, Prado W, Koza GA, Coppo JA (2006) Cambios del eritrograma durante el cautiverio de Caiman latirostris y Caiman yacare. Comunicaciones Científicas y Tecnológicas 4 p.
Barão-Nóbrega JAL, Marioni B, Botero-Arias R, Nogueira AJA, Lima ES, Magnusson WE, Silveira R, Marcon JL (2018) J Comp Physiol B 188: 127–140. 10.1007/s00360-017-1103-8
Brian SA, Whitaker N (2000) Hematology and blood biochemistry of captive mugger crocodiles. Journal of Zoo and Wildlife Medicine 31(3): 339-347. DOI: 10.1638/1042-7260
Campbell TW (2004) Clinical chemistry of reptiles. In: Thrall MA, Baker DC, Campbell TW, DeNicola D, Fettman MJ, Lassen ED, Rebar A, Weiser G. Veterinary Hematology and Clinical Chemistry. Lippincott, Williams, and Wilkins, Philadelphia, PA: 493-498.
Castro PDS, Ladislau D, Ribeiro MWS, Lopes ACC, Lavander HD, Bassul LA, Mattos DC, Liebl ARS, Aride PHR, Oliveira AT (2020) Hematological parameters of three species of tucunarés (Cichla spp.) from Lake Balbina, Presidente Figueiredo, Amazonas. Brazilian Journal of Biology 80, p. 1-7. https://doi.org/10.1590/1519-6984.219409
Castro PDS, Ladislau DS, Ribeiro MWS, Paiva AJV, Liebl ARS, Pantoja-Lima J, Aride PHR, Oliveira AT (2020a) Ecophysiological interactions in species of peacock bass Cichla spp. from the Amazon. Revista Ibero-americana de Ciências Ambientais 11, 594-599. https://doi.org/10.6008/CBPC2179-6858.2020.005.0053
Da Silveira R. 2002. Avaliação preliminar da distribuição, abundância e da caça de jacarés no Baixo Rio Purus. In: Deus, C. P., (Ed.) Piagaçu-Purus: Bases científicas para criação de uma RDS. Manaus: IDSM. 61-64.
Duncan WP, Júnior JNA, Mendonça WCS, Santa Cruz IF, Samonek JF, Morais EJF, Marcon JL, Da Silveira R (2022) Physiological stress response in free-living Amazonian caimans following experimental capture. J. Experim. Zoology Part A: Ecological and Integr. Physiol. 337, 282–292. https://doi.org/10.1002/jez.2565
Gabrey SW (2010) Demographic and geographic variation in food habits of American alligators (Alligator mississippiensis) in Louisiana. Herpetological Conservation and Biology 5: 241–250.
Hidalgo-Vila J, Diaz-Paniagua C, Perez-Santigosa N, Plaza A, Camacho I, Recio F (2007) Hematologic and Biochemical Reference Intervals of Free-living Mediterranean Pond Turtles (Mauremys leprosa). Journal of Wildlife Diseases 43(4): 798-801. 10.7589/0090-3558-43.4.798
Jenkins-Perez J (2012) Hematologic Evaluation of Reptiles: A diagnostic Mainstay. Veterinary Technician 1-8.
Liebl ARS, Cáo MA, Nascimento MS, Castro PD, Duncan WLP, Pantoja-Lima J, Aride PHR, Bussons MRFM, Furuya WM, Faggio C, Oliveira AT (2022) Dietary lysine requirements of Colossoma macropomum (Cuvier, 1818) based on growth performance, hepatic and intestinal morphohistology and hematology. Vet Res Commun. 46(1): 9-25. doi:10.1007/s11259-021-09872-6
Liebl ARS, Nascimento MS, Aride PHR, Duncan WLP, Aride PHR, Pantoja-Lima J, Bussons MRFM, Furuya WM, Oliveira AT (2021) Lysine effect on the characterization of fillet, by-products, residues, and morphometry of tambaqui Colossoma macropomum (Cuvier, 1818). Latin Amer. J. Aquatic Res. 49(4): 620-631. doi:10.3856/vol49-issue4-fulltext-2701
Magnusson WE, Lima AP (1991) The ecology of a cryptic predator, Paleosuchus trigonatus, in a tropical rainforest. Journal of Herpetology 25: 41-48. 10.2307/1564793
Marioni B, Barao-Nobrega JAL, Botero-Arias R, Muniz FL, Campos Z, Da Silveira R, Magnusson WE, Vilamarin-Jurado F (2021) Science and conservation of amazonian crocodilians: a historical review. Aquatic Conservation-Marine and Freshwater Ecosystems p. aqc.3541-12. https://doi.org/10.1002/aqc.3541
Marioni B, Farias I, Verdade LM, Bassetti L, Coutinho ME, Mendonça SHST, Vieira TQ, Magnusson WE, Campos Z (2013) Avaliação do risco de extinção do jacaré-açu Melanosuchus niger (Spix, 1825) no Brasil. Biodiversidade Brasileira 3(1), 31-39.
Martin CB (2008) A mente na natureza. Oxford University Press.
Mendonça WCS, Duncan WP, Vidal MD, Magnusson WE, Da Silveira R (2023) Conservation implications of tourism and stress for Amazonian caimans. Journal of Wildlife Management 87: e22482.
Mendonça WCS, Duncan WP, Vidal MD, Magnusson WE, Da Silveira R (2023a) Blood Biochemical Reference Intervals of Amazonian Black Caiman and Spectacled Caiman. Journal of Wildlife Diseases (in press).
Mussart NB, Barboza NN, Fioranelli SA, Koza GA, Prado WS, Coppo JA (2006) Age, sex, year, season, and handling system modify the leukocyte parameters from captives Caiman latirostris and Caiman yacaré (Crocodylia: Alligatoridae). Rev Vet (17): 3-10.
Oliveira AT, Cruz WR, Pantoja-Lima J, Araujo SB, Araujo MLG, Marcon JL, Tavares-Dias M (2011) Morphological and cytochemical characterization of thrombocytes and leukocytes in hatchlings of three species of Amazonian freshwater turtle. Veterinarski Arhiv 81, 657-670.
Oliveira AT, Pantoja-Lima J, Aride PHR, Tavares-Dias M, Marcon JL (2015) Fisiologia de arraias de água doce: subsídios para aplicabilidade na aquicultura. In: Tavares-Dias M, Mariano WS. Aquicultura no Brasil: novas perspectivas. 1ed. São Carlos: Pedro & João, v. 1, p. 45-74.
Oliveira AT, Santos MQC, Araújo MLG, Lemos JRG, Sales RSA, Pantoja-Lima J, Tavares-Dias M, Marcon JL (2016) Hematological parameters of three freshwater stingray species (Chondrichthyes: Potamotrygonidae) in the middle Rio Negro, Amazonas state. Biochemical Systematics and Ecology 69: 33-40. https://doi.org/10.1016/j.bse.2016.07.002
Oliveira AT, Araújo MLG, Lemos JRG, Santos MQC, Pantoja-Lima J, Aride PHR, Tavares-Dias M, Marcon JL (2017) Ecophysiological interactions and water-related physicochemical parameters among freshwater stingrays. Brazilian Journal of Biology 77: 616-621. https://doi.org/10.1590/1519-6984.01816
Oliveira AT, Lemos JRG, Santos MQC, Sales RSA, Pantoja-Lima J, Aride PHR, Araujo MLG, Tavares-Dias M (2021) Morphological, cytochemical, and ultrastructural aspects of blood cells in freshwater stingray species in the middle Rio Negro basin of Amazonian Brazil. Scientific Reports 11: 1-11. https://doi.org/10.1038/s41598-021-95183-4
Percie du Sert N, Hurst V, Ahluwalia A, Alam S, Avey MT, Baker M, Browne WJ, Clark A, Cuthill IC, Dirnagl U, Emerson M, Garner P, Holgate ST, Howells DW, Karp NA, Lazic SE, Lidster K, MacCallum CJ, Macleod M, Pearl EJ, Petersen OH, Rawle F, Reynolds P, Rooney K, Sena ES, Silberberg SD, Steckler T, Würbel H (2020) The ARRIVE guidelines 2.0: Updated guidelines for reporting animal research. PLoS Biol 18, e3000410. https://doi.org/10.1371/journal.pbio.3000410
Rajesh NV, Jayathangaraj MG, Sridhar R, Raman M, Muthuramlingam T (2013) Comparative hematology of Captive Mugger Crocodilles (Crocodylus palustres). Research Journal of Animal, Veterinary and Fishery Sciences 1(2): 9-11.
Ramirez F, Arocha CL, Montiel SG (1978) Elementos figurados, hemoglobina y proteínas de la sangre em el Caiman crocodilos (Linnneaus) Cells, hemoglobina and protein in the blood of the Caiman crocodilos (Linnneuas). Acta Cient Venez 29: 268-273.
Raskin RS (2000) Reptilian complete blood count. In: Fudge AM. Laboratory Medicine: Avian and Exotic pets. 3^rd Philadelphia, PA: WB. Saunders Company, 193-200.
Rossini M, Garcia G, Rojas J, Zerpa H (2011) Hematological and sérum biochemical reference values for the wild Spectacled Caiman, Caiman crocodilos crocodilos, from the Venezuelan plains. Veterinary Clinical Pathology 40(3): 374-379.
Santos SA (1997) Dieta e Nutrição de crocodilianos. Centro de Pesquisa Agropecuária do Pantanal 17-18.
Singer M (2003) Do mammals, birds, reptiles, and fish have similar nitrogen-conserving systems? Comparative Biochemistry and Physiology 134: 543-558. 10.1016/S1096-4959(03)00027-7
Sotero-Martins A, Kluczkovski-Junior A, Markendorf F, Marioni B, Ferreira-Coimbra R, Martinez-Freira G, Da Silveira R (2015) Riscos na qualidade sanitária da carne de jacaré da Amazônia Central. Vigilância Sanitária em Debate: Sociedade, Ciência & Tecnologia 3(4), 99-105.
Stacy B, Whitaker N (2000) Hematologia e bioquímica do sangue de crocodilos assaltantes cativos (Crocodylus palustris). Journal of Zoo and Wildlife Medicine 31(3): 339-347.
Stevenson RD, Tuberty SR, Defur PL, Wingfield JC (2005) Ecophysiology and Conservation: The Contribution of Endocrinology and Immunology. Integrative and Comparative Biology 45: 1-3. 10.1093/ICB/45.1.1
Tavares-Dias M, Silva MG, Oliveira AT, Oliveira-Junior AA, Marcon JL (2011) Propriedades do sangue de três espécies de quelônios do gênero Podocnemis de vida livre na Reserva Biológica do Abufari, baixo Rio Purus, Amazonas, Brasil.In:Silva-Souza AT, Lizama MAP, Takemoto RM.Patologia e sanidade de organismos aquáticos. 1ed.Maringá, Paraná: Massoni, v. 1, p. 195-220.
Tavares-Dias M, Moraes FR (2004) Hematology of teleosts fish. 1. ed.: Villimpress, Ribeirão Preto. 144 p.⁠
Vaz-Pires P (2006) Tecnologia do pescado. Instituto do Porto: Instituto de Ciências Biomédicas, Abel Salazar, 211 p.
Vieira TQ, Silva FB, Heubel MTCD (2002) Biometria, hematologia e genética de Caiman latirostris (Daudin, 1801) na região de Bauru (SP). Salusvita 21: 3, 67-75.
Wikelski M, Cooke SJ (2006) Conservation physiology. Trends in Ecology and Evolution 21(2): 38-46. 10.1016/j.tree.2005.10.018
Wolfe KH, Li WH, Sharp PM (1987) Rates of nucleotide substitution vary greatly among plant mitochondrial, chloroplast, and nuclear DNAs. Proc Natl Acad Sci U S A 84(24): 9054-9058. doi:10.1073/pnas.84.24.9054
Zayas MA, Rodriguez HA, Galoppo GH, Stoker C, Durando M, Luque EH, Muñoz-de-Toro M (2011) Hematology and blood biochemistry of young healthy broad-snouted caimans (Caiman latirostris). Journal of Herpetology 45(4): 516-524. 10.1670/10-158.1

Table 1

Comparative table (mean and standard deviation) of the erythrograms of Amazonian caimans species.
Species	Parameters
Species	Hb (g/dL)	Ht (%)	RBC (millions/µL)	MCV (fL)	MCHC (g/dL)	MCH (pg)	Locality/ Countries	Reference
Caiman crocodilus	4.7 ± 1.3^a	21.3 ± 4.0^ab	0.48 ± 0.07^a	452 ± 99^ab	23.0 ± 7.0^a	102 ± 36^a	Free-living/ Brazil	Present study
Melanosuchus niger	5.2 ± 0.7^a	25.3 ± 1.6^b	0.52 ± 0.01^a	488 ± 35^b	20.8 ± 2.7^a	101 ± 13^a	Free-living/ Brazil	Present study
Caiman yacare	6.1 ± 1.0^b	21.6 ± 3.4^a	0.51 ± 0.09^a	421 ± 34^a	28.7 ± 3.6^b	119 ± 18^a	Captive/ Argentina	Barboza et al. (2006)
Caiman latitrostris	9.9 ± 2.5^c	17.7 ± 3.6^c	0.40 ± 0.10^c	460 ± 111^ab	23.9 ± 6.6ª	52.6 ± 8.7^c	Captive/ Brazil	Vieira et al. (2002)
Caiman latitrostris	8.5 ± 0.4^d	28.6 ± 1.2^d	0.73 ± 0.05^d	391 ± 240^c	29.7 ± 3.3^b	116.4 ± 80^a	Captive/ Argentina	Zayas et al. (2011)
Different letters between the columns indicate significant differences (p = < 0.001) between the species of caimans. Degree of freedom equal to 14

Table 2

The mean value of leukocyte count and thrombocytes of two caimans species in the middle Negro River, Amazonas state, Brazil.
Species		Melanosuchus niger
Leukocytes (µL)	5,222 ± 1,997	3,832 ± 1,074
Thrombocytes (µL)	1,090 ± 492	989 ± 637
Lymphocytes (%)	36.1 ± 12.8	42.8 ± 9.7
Lymphocytes (µL)	1,960 ± 1,369	1,631 ± 531
Neutrophils (%)	20.7 ± 10.6	26.9 ± 11.3
Neutrophils (µL)	1,128 ± 726	1,102 ± 868
Heterophils (%)	20.2 ± 6.8	25.1 ± 8.9
Heterophils (µL)	1,020 ± 406	917 ± 520
Azurophils (%)	19.5 ± 5.3	15.0 ± 1.5
Azurophils (µL)	1,007 ± 404	573 ± 163
Basophils (%)	3.5 ± 1.4	3.7 ± 1.0
Basophils (µL)	184 ± 101	141 ± 53

Table 3

Mean values of plasma biochemistry of two caimans species from the middle Negro River, Amazonas state, Brazil
Species	Parameters
Species	Glucose (mM/L)	Triglycerides (mM/L)	Total cholesterol (mM/L)	Urea (mM/L)	Total proteins (g/L)
Caiman crocodilus	4.9 ± 0.4	2.0 ± 0.6	3.6 ± 0.4^a	1.7 ± 0.5^a	45.3 ± 10.9
Melanosuchus niger	5.1 ± 0.8	2.3 ± 0.6	12.2 ± 6.7^b	1.2 ± 0.4^b	41.4 ± 11.2
Different letters the columns indicate significant differences (p < 0.05)

No competing interests reported.

Download PDF

Version 1

posted

You are reading this latest preprint version

Hematological Values of Two Species of Amazonian Caimans, Caiman crocodilus AND Melanosuchus niger

Status:

Version 1

Abstract

Figures

Introduction

Materials and Methods

Study area and capture

Hematological parameters

Statistical analyses

Results

Discussion

Declarations

References

Tables

Additional Declarations

Status:

Version 1