Short-term warming does not affect intrinsic thermotolerance but induces strong sustaining photoprotection in tropical evergreen citrus genotypes.

Consequences of warming and postwarming events on photosynthetic thermotolerance (PT ) and photoprotective responses in tropical evergreen species remain elusive. We chose Citrus to answer some of the emerging questions related to tropical evergreen species' PT behaviour including (i) how wide is the genotypic variation in PT ? (ii) how does PT respond to short-term warming and (iii) how do photosynthesis and photoprotective functions respond over short-term warming and postwarming events? A study on 21 genotypes revealed significant genotypic differences in PT , though these were not large. We selected five genotypes with divergent PT and simulated warming events: Tmax 26/20°C (day-time highest maximum/night-time lowest maximum) (Week 1) < Tmax 33/30°C (Week 2) < Tmax 36/32°C (Week 3) followed by Tmax 26/16°C (Week 4, recovery). The PT of all genotypes remained unaltered despite strong leaf megathermy (leaf temperature > air temperature) during warming events. Though moderate warming showed genotype-specific stimulation in photosynthesis, higher warming unequivocally led to severe loss in net photosynthesis and induced higher nonphotochemical quenching. Even after a week of postwarming, photoprotective mechanisms strongly persisted. Our study points towards a conservative PT in evergreen citrus genotypes and their need for sustaining higher photoprotection during warming as well as postwarming recovery conditions.

First detection of Herpesvirus anguillae (AngHV-1) associated with mortalities in farmed giant mottled eel (Anguilla marmorata) in Vietnam.

Giant mottled eel (Anguilla marmorata) farming in Vietnam is a multistage process starting from wild harvest of glass eels through the so-called "hatcheries" and distribution centres from which individuals are transferred to rearing farms and subsequently sold by one eel farm to another every 3-5 months. The information on viral agents spread and persistence in the Vietnamese eel aquaculture is scarce. Therefore, the mortality of A. marmorata at the Van Xuan Farm was the prerequisite to identify the possible aetiologic agent and additionally to formulate first recommendations for viral disease screening in the Vietnamese eel aquaculture. Juvenile giant mottled eels with haemorrhagic lesions in the skin and liver, and hyperaemia of the gut were tested with qPCR and end-point PCR for AngHV-1 presence. Here, we report the first detection of AngHV-1 associated with mortality in giant mottled eel in winter and spring seasons. On the basis of the obtained results, we recommend to test eel seeds in "hatcheries," since tropical eel farms operate in interconnected scheme and monitoring of AngHV-1 prevalence requires well-implemented measures. Disease screening in the rearing centres and on-growing facilities should be based on everyday health checks, including by-catch fish used as a base of the feeding programmes at eel farms in Vietnam.

Genetic validation of the unexpected presence of a tropical tuna, bigeye tuna (Thunnus obesus), in the Mediterranean.

Bigeye tuna (Thunnus obesus, Lowe, 1839) is one of the eight recognized species of the genus Thunnus. It is considered a tropical species distributed in the Atlantic, Pacific and Indian Oceans. To date, no validated presence of this species has been reported inside the Mediterranean Sea. This study, however, confirms, for the first time, the presence of three young individuals of this species within the Mediterranean Sea.

Freshwater neotropical oligochaetes as native test species for the toxicity evaluation of cadmium, mercury and their mixtures.

The toxicity of metals, whether isolated or in mixtures, involves changes in biochemical processes as well as in cell membranes, which may lead to deleterious short- and long-term effects on the affected organisms. Among metals, cadmium and mercury stand out due to their abundance in nature, frequent use for industrial activities and biological accumulation, with high levels of residence in trophic chains. Benthic communities are particularly prone to metal pollution since metals usually accumulate in sediments. The aim of this study was to evaluate the acute toxicity of mercury and cadmium, single and in mixture, to two native species of epibenthic oligochaetes: Allonais inaequalis and Dero furcatus. In order to assess the potential of these species as bioindicators, we compared their sensitivity with those of other internationally used species by applying the species sensitivity distribution approach. The 96h-LC50 of cadmium chloride was 627 and 364 µg L-1 for A. inaequalis and D. furcatus, respectively, evidencing that the latter species is almost twice as sensitive to this metal than A. inaequalis. For mercury chloride, the 96h-LC50 was 129 µg L-1 for A. inaequalis and 92 µg L-1 for D. furcatus. The sensitivities of these oligochaetes were superior or similar to that of other frequently used oligochaete test species such as Tubifex tubifex and Lumbriculus variegatus. The metal mixtures had synergism in general (D. furcatus) or at high doses only (A. inaequalis), implying a potentiation of their toxic effects when both metals co-occur in the environment. By comparing the derived toxicity values with concentrations of cadmium and mercury measured in the field, it can be concluded that aquatic organisms are likely to be at risk when exposed to the environmental relevant concentrations of cadmium and mercury here tested, especially when they are both present.

Life span variation in 13 Drosophila species: a comparative study on life span, environmental variables and stress resistance.

Recently, heterogeneity of the environment has been suggested as an important player in the evolution of life span variation. Established ageing theories propose that life span variation is the result of coevolution with other traits, such as stress resistance. This study aimed to compare these alternative hypotheses by examining the relationship between four environmental variables and different types of stress resistance traits with life span in 13 Drosophila species originating from tropical, subtropical and temperate environments (ecotypes). Average life span was found to differ significantly both between species and sexes, but only male life span correlated with the environment and cold resistance. While controlling for phylogeny, the environmental variable precipitation seasonality and resistance against cold-induced stress explained most variation in male life span. Furthermore, male life span varied between species in a manner represented by environmental variables linked to the different ecotypes, such that tropical species lived longer and were less cold resistant. The current results suggest that general mechanisms underlying stress resistance and life span are unlikely. In addition, our results point to the environment independently shaping variation in life span and cold resistance rather than genetic interactions.

Lippia alba (Verbenaceae): A new tropical autopolyploid complex?

• Premise of the study: Tropical regions have high species diversity, and polyploidization is a major mechanism of speciation in plants. However, few cases of natural polyploidy have been reported in tropical regions. Lippia alba, is a tropical, aromatic shrub with a wide distribution, extensive morphological plasticity, and several chemotypes. The species has long been recognized as a diploid with 2n = 30 chromosomes. Recently, two variations in chromosome number (2n = 60; 2n = 12-60) have been reported, suggesting the occurrence of polyploidy within the species.• Methods: Flow cytometry was used to investigate the genome size in 106 accessions from 14 Brazilian States. Conventional and molecular cytogenetic techniques and pollen viability analysis were employed to characterize each chromosome number observed.• Key results: The DNA 1C-value varied from 1.17 to 3.45 pg, showing a large variation in genome size. Five distinct chromosome numbers were observed (2n = 30, 38, 45, 60, 90); three are cytogenetically described here for the first time. The 5S rDNA signals varied proportionally according to each chromosome number, but 45S rDNA sites did not. High rates of meiotic irregularity were observed, mainly in cytotypes with higher chromosome numbers.• Conclusions: The data provide new support for the occurrence of a polyploid series in Lippia alba. We provide a hypothesis for how this complex may have arisen. Other cryptic polyploid complexes may remain undiscovered in tropical regions.

Acute and chronic toxicity of chromium and cadmium to the tropical cladoceran pseudosida ramosa and the implications for ecotoxicological studies.

In this study, the acute and chronic toxicity of the metals chromium and cadmium were tested against the tropical freshwater cladoceran Pseudosida ramosa. Acute tests showed that the 48-h LC50 of chromium was 29 µg L(-1) , while that of cadmium was 12 µg L(-1) . P. ramosa had a similar sensitivity to those of other cladoceran species cultured in the same conditions as in this study, or a higher sensitivity when water hardness was raised. Long-term chronic exposure of P. ramosa to chromium decreased maternal survival, fecundity, and fertility at a concentration of 10 µg L(-1) . For cadmium, reductions in the same endpoints were observed at a concentration of 3 µg L(-1) . Moreover, the degree of toxicity of the chromium and cadmium to P. ramosa after release of the first brood was similar to the result obtained after 21 days, using reproduction as the endpoint. Brazilian water bodies located near industrial areas already show concentrations of chromium and cadmium higher than levels causing acute and chronic toxicity to P. ramosa in our study. Many water quality criteria in tropical regions are based on ecotoxicological tests with non-native species and, consequently, this may lead to errors of interpretation when the permitted maximum levels of for each toxic substance are established. Therefore, we reinforce the idea of using native species to establish the maximum concentrations of toxic substances in water quality criteria, especially for metals, since their effects are related to water hardness, pH, and temperature specific to each region.

Physical, mechanical and hydration kinetics of particleboards manufactured with woody biomass (Cupressus lusitanica, Gmelina arborea, Tectona grandis), agricultural resources, and Tetra Pak packages.

Lignocellulosic wastes resulting from agricultural activities as well as Tetra Pak residues from urban centres can cause significant levels of pollution. A possible action to minimize this problem is to use them in the production of particleboards. The purpose of this study was to evaluate the physical, mechanical, and hydration properties of particleboards manufactured with the mixture of woody biomass (Cupressus lusitanica, Gmelina arborea, and Tectona grandis) and either agricultural wastes [pineapple leaves (Ananas comosus) and palm residues (Elaeis guineensis)] or Tetra Pak residues (TP). The results show that the particleboards prepared with TP and woody biomass can reduce the swelling and water absorption in up to 40% and 50% compared with particleboards without TP. Also, these particleboards had increased flexure resistance and shear stress (up to 100%) compared with those without TP. On the contrary, particleboards prepared with pineapple leaves in combination with woody biomass showed the lowest mechanical properties, particularly for tensile strength, hardness, glue-line shear, and nail and screw evaluation.

Sugarcane vinasse provokes acute and chronic responses and bioaccumulation of metals in benthic macroinvertebrates.

Brazil is a major producer of sugarcane bioethanol, which has raised concerns about its environmental impact. The industrial process for obtaining ethanol generates a by-product with a high pollution potential called vinasse. If vinasse reaches watercourses, it may affect the biological communities, such as the aquatic macroinvertebrates, which include species sensitive to environmental contamination. Thus, this study evaluated the ecotoxicological effects of sugarcane vinasse on tropical benthic macroinvertebrates (Allonais inaequalis, Chironomus sancticaroli, Strandesia trispinosa, and Hyalella meinerti). The study was divided into three phases. First, acute toxicity tests were carried out with the four species. The species A. inaequalis (average LC50 = 0.460% confidence interval, CI 0.380-0.540%) was more sensitive to vinasse than C. sancticaroli (LC50 0.721%, CI 0.565-0.878%), H. meinerti (EC50 0.781%, CI 0.637-0.925%), and S. trispinosa (EC50 1.283%, CI 1.045-1.522%). In the second phase, the consequences of chronic exposure to vinasse were assessed in the two more sensitive species. Impairments in reproduction and population growth rates for A. inaequalis and on the development, metamorphosis, and body growth of C. sancticaroli larvae occurred. Finally, the bioaccumulation of metals after chronic exposure was determined in the third phase. Vinasse provoked decreases in the body residue of the essential metals Zn and Mn and the accumulation of Cd, Pb, and Cr with the potential for biomagnification throughout the food webs. Low concentrations of vinasse (below 1%) provoked lethal and sublethal effects on benthic organisms, with several cascade effects on aquatic environments, given the ecological importance of this group in freshwater and terrestrial ecosystems.

Are standard aquatic test species and methods adequate surrogates for use in environmental risk assessment of pesticides in tropical environments?

In regulatory risk assessment, surrogate species of fish, aquatic invertebrates, and primary producers are tested to assess toxicity and subsequently the risk of pesticides to freshwater biota. This study evaluates whether the standard, surrogate test species (mostly temperate in latitudinal distribution) used in many parts of the world are suitable surrogates for first-tier risk assessments involving tropical freshwater biota. Data for the toxicity of pesticides to tropical fish, invertebrates, and primary producer species were extracted from the USEPA ECOTOX database and peer-reviewed literature. For each pesticide, the most sensitive regulatory endpoint extracted from the US Environmental Protection Agency (USEPA) and European Food Safety Authority (EFSA) dossiers for freshwater fish, invertebrates, and primary producers was selected. The ratios of the endpoint for tropical species and for the most sensitive regulatory endpoint for the appropriate taxonomic group were determined. A value >1 indicates that the tropical species is less sensitive than the respective standard regulatory species. Tropical fish species were less sensitive than standard fish species in 84% of the comparisons, and in 93.5% of the comparisons, tropical fish were less or similarly sensitive (within a factor of 5). For aquatic invertebrates, 78.1% of the evaluated tropical species were less sensitive than standard species and 93.3% of tropical invertebrates species were less or similarly sensitive. For primary producers, 96% of tropical species were less sensitive than standard test species. Overall, standard species used globally were more sensitive or similarly sensitive compared to tropical species in more than 93% of the cases. In conclusion, the data show that freshwater toxicity data for pesticides from tests using standard test species, tested according to international accepted guidelines, are appropriate for use in first-tier risk assessments for tropical environments. Integr Environ Assess Manag 2023;19:202-212. © 2022 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

An Overview of the Isoprenoid Emissions From Tropical Plant Species.

Terrestrial vegetation is the largest contributor of isoprenoids (a group of biogenic volatile organic compounds (BVOCs)) to the atmosphere. BVOC emission data comes mostly from temperate regions, and less is known about BVOC emissions from tropical vegetation, even though it is estimated to be responsible for >70% of BVOC emissions. This review summarizes the available data and our current understanding of isoprenoid emissions from tropical plant species and the spatial and temporal variation in emissions, which are strongly species-specific and regionally variable. Emission models lacking foliar level data for tropical species need to revise their parameters to account for seasonal and diurnal variation due to differences in dependencies on temperature and light of emissions from plants in other ecosystems. More experimental information and determining how emission capacity varies during foliar development are warranted to account for seasonal variations more explicitly.

In Vitro Conservation through Slow Growth Storage Technique of Fruit Species: An Overview of the Last 10 Years.

Plant genetic resources conservation may be a potential option for the improvement of agricultural crops through modern biotechnologies, and in vitro conservation is a tool available to safeguard plant biodiversity. Ex situ conservation of plant genetic resources using the in vitro procedures is in progress in many countries. The slow growth storage (SGS) technique is a valid in vitro approach to preserve several vegetatively propagated species by controlling the growth and development of plantlets, economizing storage space and labor and reducing costs. Moreover, SGS prolongs the timing between subcultures, lowers the risk of losing germplasm through handling errors, such as contamination problems, and decreases the risk of genetic instability due to the reduction in the number of subcultures. SGS is applied by considering different factors: temperature, light or darkness conditions, medium composition, including mineral or sucrose concentrations, and the presence/absence of plant growth regulators, osmotic agents and growth inhibitors. SGS protocols for some fruit species have been well defined, others require additional research. The present review focuses on the effect of several factors that influence the SGS of in vitro shoots derived from temperate and tropical fruit species during the last ten years.

Climate vulnerability of South American freshwater fish: Thermal tolerance and acclimation.

Freshwater fish are restricted by their physiology to rivers and lakes, and are generally limited in their capacity to disperse across basins. As a result, there is often a close match between the evolutionary history of river basins and their natural history. Thus, the regional landscape and ecological features, such as temperature, have shaped the evolution and adaptation of local fish assemblages. Climate change is expected to affect fish diversity and increase extinction, especially in low latitudes, and it has been suggested that species that inhabit low latitude species are more susceptible since they live close to their maximum thermal limits and have low capacity for acclimation. To understand the mechanisms of variation in thermal tolerance across a broad-scale of South American fishes is fundamental to be able to assess the vulnerability of species and habitat to global warming. Herein, we present the first attempt to analyze the vulnerability of South American freshwater fish species, based on the review of upper thermal limits of 106 species from a broad range of latitudinal habitats. Our findings show that upper thermal limits decrease with latitude, while the thermal safety margin (TSM) increase. Furthermore, the latitude has little effects on the acclimation response ratio, and the TSM decreased with rising temperatures. These data suggest that thermal phenotypic acclimation has low potential for mitigating global warming. These results indicate that South American fish species living in tropical areas are more susceptible to global warming since they are already living close to their maximum habitat temperature.

Metabolic and physiological alterations indicate that the tropical broadleaf tree Eugenia uniflora L. is sensitive to ozone.

Eugenia uniflora L. is an important fruit tree native to tropical South America that adapts to different habitats, thanks to its metabolic diversity and ability to adjust the leaf antioxidant metabolism. We hypothesized that this metabolic diversity would also enable E. uniflora to avoid oxidative damage and tolerate the enhanced ozone (O3) concentrations that have been registered in the (sub)tropics. We investigated whether carbohydrates, polyphenols and antioxidants are altered and markers of oxidative damage (ROS accumulation, alterations in leaf gas exchange, growth and biomass production) are detected in plants exposed to two levels of O3 (ambient air and twice elevated ozone level in a O3-FACE system for 75 days). Phytotoxic O3 dose above a threshold of 0 nmol m-2 s-1 (POD0) and accumulated exposure above 40 ppb (AOT40) were 3.6 mmol m-2 and 14.898 ppb h at ambient, and 4.7 mmol m-2 and 43.881 ppb h at elevated O3. Twenty-seven primary metabolites and 16 phenolic compounds were detected in the leaves. Contrary to the proposed hypothesis that tropical broadleaf trees are relatively O3 tolerant, we concluded that E. uniflora plants are sensitive to elevated O3 concentrations. Experimental POD0 values were lower than the critical levels for visible foliar O3, because of low stomatal conductance. In spite of this low stomatal O3 uptake, we found classic O3 injury, e.g. reduction in carbohydrates and fatty acids concentrations; non-significant changes in the polyphenol profile; inefficient antioxidant responses; increased contents of ROS and indicators of lipid peroxidation; reductions in stomatal conductance, net photosynthesis, root/shoot ratio and height growth. However, we also found some compensation mechanisms, e.g. increased leaf concentration of polyols for protecting the membranes, and increased leaf number for compensating the decline of photosynthetic rate. These results help filling the knowledge gap about tropical tree responses to O3.

Neurotoxic and respiratory effects of human use drugs on a Neotropical fish species, Phalloceros harpagos.

Pharmaceutical drugs are usually and continuously carried to the aquatic environment in different ways. Thus, they are pseudo-persistent in the environment, and they may exert deleterious effects on aquatic organisms. The objective of the present study was to investigate the acute and chronic effects of two widely used pharmaceutical drugs, paracetamol (analgesic and antipyretic) and propranolol (ß-blocker) on the activity of specific biomarkers (namely cholinesterase enzymes and lactate dehydrogenase) of the neotropical fish Phalloceros harpagos. The obtained results indicate an inhibition of the activity of the enzyme lactate dehydrogenase (LDH) after acute exposure to paracetamol, and an increase in cholinesterase activity in acutely propranolol-exposed fish. Chronic exposure to both drugs did not modify the enzymatic activities. Such short-term changes in enzymatic activities may be harmful to organisms, altering the preferential pathway of energy metabolism, and may induce behavioral changes that may compromise prey capture and predator escape, and in the longer term may induce population declines.

Crustacean Proteases and Their Application in Debridement.

Digestive proteases from marine organisms have been poorly applied to biomedicine. Exceptions are trypsin and other digestive proteases from a few cold-adapted or temperate fish and crustacean species. These enzymes are more efficient than enzymes from microorganism and higher vertebrates that have been used traditionally. However, the biomedical potential of digestive proteases from warm environment species has received less research attention. This review aims to provide an overview of this unrealised biomedical potential, using the debridement application as a paradigm. Debridement is intended to remove nonviable, necrotic and contaminated tissue, as well as fibrin clots, and is a key step in wound treatment. We discuss the physiological role of enzymes in wound healing, the use of exogenous enzymes in debridement, and the limitations of cold-adapted enzymes such as their poor thermal stability. We show that digestive proteases from tropical crustaceans may have advantages over their cold-adapted counterparts for this and similar uses. Differences in thermal stability, auto-proteolytic stability, and susceptibility to proteinase inhibitors are discussed. Furthermore, it is proposed that the feeding behaviour of the source organism may direct the evaluation of enzymes for particular applications, as digestive proteases have evolved to fill a wide variety of feeding habitats, natural substrates, and environmental conditions. We encourage more research on the biomedical application of digestive enzymes from tropical marine crustaceans.

Novel salivary gland allergens from tropical mosquito species and IgE reactivity in allergic patients.

BACKGROUND: Mosquito allergy is common in tropical countries but remains under-diagnosed. This may be due to the lack of knowledge and diagnostic tools for tropical mosquito allergens. OBJECTIVE: We aimed to characterize allergens from tropical mosquito species and investigate IgE reactivity in mosquito-allergic patients to the salivary gland proteins from these mosquitoes. METHODS: Salivary gland extract (SGE) from 4 mosquito species, highly distributed in the tropics, including Aedes aegypti, Aedes albopictus, Culex quinquefasciatus, and Anopheles dirus b, were studied. SGE-specific IgE and IgG ELISA were developed, and serum from 64 mosquito-allergic and 22 non-allergic healthy control subjects was assayed. Further investigations using IgE-immunoblots followed by mass spectrometry analysis were performed to identify and characterize allergens from each species. RESULTS: Mosquito-allergic subjects have detectable serum IgE to SGE derived from local mosquito species, while the IgE levels to Aedes communis using commercially available ELISA were mostly minimal. IgE-immunoblot analysis and mass spectrometry identified 5 novel mosquito allergens from A. albopictus (Aed al 2, Aed al 3), C. quinquefasciatus (Cul q 2.01, Cul q 3), and A. dirus b (Ano d 2). Interestingly, 4 of the 5 new allergens belong to the D7 protein family. CONCLUSIONS & CLINICAL RELEVANCE: Five novel allergens from 3 tropical mosquito species were characterized. The majority of mosquito-allergic subjects who live in the tropics have IgE reactivity to these allergens. Our study paves the way for the development of diagnostic tests, component-resolved diagnostics, and future immunotherapy for mosquito allergy in tropical countries.

Eustra yinggelingensis sp. nov., a new flanged bombardier beetle from Yinggeling Nature Reserve, Hainan, China with contribution to the knowledge of Chinese Eustra species (Coleoptera, Carabidae, Paussinae).

A new species of flanged bombardier beetle form Hainan Island, China, Eustra yinggelingensis sp. nov. (Coleoptera, Carabidae, Paussinae, Ozaenini) is described. The new species was collected in rotten wood from Yinggeling Nature Reserve. Habitus and diagnostic features of the new species are illustrated. List, key and distribution map of all known Chinese Eustra species are given.

Impacts of dredging on biomarkers responses of caged bivalves in a semi-arid region (Ceará State, NE Brazil).

In this study, the performance of two native bivalves in responding to sediment resuspension was investigated during dredging operations of a semi-arid bay (Mucuripe, NE Brazil). The clam Anomalocardia flexuosa and the oyster Crassostrea rhizophorae were selected and caged in two sites influenced by the dredging plume. We assessed the bioaccumulation of metals and hydrocarbons in both species as biomarkers of exposure and then, biomarkers' responses were assessed in gills and digestive glands over a 28 days period, at 7 days intervals: the activities of phase I and II, and antioxidant enzymes, levels of lipid peroxidation and DNA strand breaks. Both transplanted bivalves accumulated Cu, polycyclic aromatic hydrocarbons (PAHs), and linear alkylbenzenes (LABs) in their whole-body tissues, whereas Ni, Pb and Zn accumulation was species-dependent. The exposure time set at day 28 was considered appropriate. Biomarkers exhibited time-related responses in both species, but gills exhibited a more sensitive response, indicating a function of barrier against the uptake of chemicals and also a relevant tissue to be targeted. In clams, Phase I and II enzymes (ethoxyresorufin O-deethylase and glutathione S-transferase) were induced during the period of intense dredging, while in oysters they were activated at the end of operations. Induction of antioxidant enzymes (glutathione peroxidase and glutathione reductase) and elevated levels DNA damage were observed in both exposure surveys. Clams and oysters were sensitive and responded to the exposure of resuspended sediments and the biomarkers of effects were associated with bioaccumulation of contaminants in the integrated analysis. These results indicate that The clam A. flexuosa and the oyster C. rhizophorae are suitable models to be used in monitoring programs or field exposure experiments in tropical regions.

Assessment of biochemical alterations in the neotropical fish species Phalloceros harpagos after acute and chronic exposure to the drugs paracetamol and propranolol.

Over time, many pollutants of anthropogenic origin have caused the contamination of aquatic ecosystems. Among several characteristics, these compounds can reach the trophic chain, causing deleterious interactions with the biota. Pharmaceutical substances can be included in this scenario as emerging contaminants that reach the aquatic environment because of direct human and veterinary usage, and release by industrial effluents, as well as through domestic dumping of surplus drugs. The effects of these compounds on exposed organisms have been studied since the 1990s, but ecotoxicological data for such chemicals are still scarce especially concerning aquatic organisms from tropical regions. Paracetamol and propranolol were selected for this study since they are frequently found in surface waters. Paracetamol is a drug used as analgesic and antipyretic, while propranolol, a ß-blocker, is used in the treatment of hypertension. The objective of this study was to assess the toxic effects of these substances on the neotropical freshwater fish Phalloceros harpagos after acute (96 h) and chronic (28 days) exposures. In order to understand the effects of these drugs on P. harpagos, biochemical markers were selected, including the enzymes involved in oxidative stress, xenobiotic metabolism, and neurotransmission (catalase, glutathione-S-transferase, and cholinesterase activities, respectively). After acute exposure, no significant alterations were observed for catalase activity, suggesting the absence of oxidative stress. On the contrary, significant alterations in glutathione-S-transferases activity were described for the higher concentrations of both pharmaceuticals after acute exposure. In addition, acute exposure to paracetamol caused a significant increase of cholinesterase activity. None of the tested pharmaceuticals caused significant changes in catalase or cholinesterase activities after chronic exposure. Glutathione S-transferases activity was significantly increased for propranolol following chronic exposure, indicating the potential involvement of phase II detoxification pathway.