In the last decades, knowledge about the biology of the Amazon river dolphin Inia geoffrensis has increased considerably. Accordingly, we present a review of the published literature on this river dolphin, with a focus on topics with the most advancements and those that are important to the species conservation. We also present new information, including emerging knowledge on the other species of Inia. We summarize the current knowledge of the biology of Inia, covering aspects of taxonomy, distribution, life history and reproduction, genetics, anatomy and physiology, health, behavior, ecology, demographic parameters, and population trends. We also highlight the main anthropogenic threats affecting the species and the resulting conservation efforts.

We assessed the health status and hematologic and blood chemistry values of 48 juvenile green turtles (Chelonia mydas) on the southeastern coast of Brazil (25°S 48°W). We investigated the impact of size and weight, nutritional condition, and presence of epibionts and fibropapilloma tumors. Nutritional status was good for 39 animals; these animals had higher serum albumin, cholesterol, and phosphorus concentrations than 9 animals with a fair nutritional score. Reference values for hematology and biochemistry were calculated for 39 individuals without fibropapillomas (FPs). Turtles with epibionts (n = 33) had lower hemoglobin (Hb) than turtles without epibionts (n = 15; t = −2.09, p = 0.04), and the area occupied by epibionts was positively correlated with the white blood cell count (r = 0.37, p = 0.03). FP turtles had significantly lower hematocrit (Hct), Hb, and red blood cell (RBC) counts than non-FP turtles; serum albumin and cholesterol were higher in non-FP than FP turtles. A negative correlation between curved carapace length (CCL) and Hct (r = −0.51, p = 0.0002) and RBC (r = −0.47, p = 0.0007), and between serum cholesterol, sodium, and uric acid and CCL (r = −0.53, p = 0.0001; r = −0.38, p = 0.007; r = −0.35, p = 0.014, respectively) were identified. The health of turtles appears to deteriorate as they get larger, which manifests in more FPs, decreased body condition, and systemic physiologic changes consistent with chronic disease including lower Hct, RBC counts, serum cholesterol, sodium, and uric acid.

Hematological values are of primary importance when investigating the health and physiological status of populations as they reflect the biological equilibrium of aquatic ecosystems. The objectives of this study are to produce baseline values for hematological parameters of the Amazon River dolphin (Inia geoffrensis), as well as to investigate significant variations according to sex, age, reproductive status and stress level. One-hundred-and-ten dolphins from Mamirauá Sustainable Development Reserve (3°3’S, 64°51’W), Central Amazon, Brazil, were live captured and sampled in November 2004 and 2005. Further, the means, standard deviations, minimum and maximum values and reference values (90% CI) were calculated. Correlations were performed to assess the relationships among blood values and cardiac rate (CR), respiratory frequency (RF), handling time and level of stress. No significant differences were found between sexes. Also, no differences occurred among pregnant and non-pregnant females, pregnant females and adult males or non-pregnant females and adult males. Calves had a higher white blood cell (WBC) count, and the neutrophil and lymphocyte absolute counts were significantly higher in calves than adults. The level of stress determined by empirical observation positively correlated with the WBC, neutrophil, lymphocyte and monocyte absolute counts and CR and RF. It was found that less stressed animals tend to present lower platelet counts and lower CR. The handling time of the dolphins was positively correlated with hematocrit (Hct), red blood cells (RBC) and Hb level. The hematological and physiological parameters varied according to time of handling and proved to be a good bioindicator of acute stress in Amazon River dolphins. The data provided here can complement long-term monitoring and identify the early warning indicators of health problems at the population level.