Native crustacean species as a bioindicator of freshwater ecosystem pollution: A multivariate and integrative study of multi-biomarker response in active river monitoring.

The aim of this study was to evaluate the ability of Palaemonetes argentinus to evidence the environmental degradation due to pollutants mixture in a freshwater aquatic ecosystem. For this purpose, an active monitoring (96 h exposure) was carried out in seven sites along the Ctalamochita River basin (Córdoba, Argentina), as a case of study. Our results evidenced sewage discharges impact in the water quality index, as well as metal pollution in water (Ag, Al, B, Pb, Hg) and sediments (Hg) with a potential effect on aquatic biota. The accumulation of total metals measured in exposed P. argentinus showed significant correlation with metals in water. Also, metallothioneins in cephalothorax showed significant changes along the basin, correlating with soluble concentrations of Cr, Zn, Cd, Hg, and V measured in shrimp tissues, which would be reflecting their bioavailability in the environment. In addition, the increase in antioxidant and detoxifying enzymes suggests the occurrence of oxidative stress in exposed shrimps. The integrative biomarker response index (IBR) pointed out the effect of metals on P. argentinus but also the occurrence of others pollutants. Finally, a high consensus was observed for water, sediments, and shrimps through the multivariate analysis (90%), indicating that P. argentinus can reflect changes in the abiotic matrixes. Moreover, studied sites were grouped according to their environmental quality. The use of active biomonitoring and the integration of biological responses through an IBR confirm that native biota could be a useful monitoring tool for bioavailable pollutants in aquatic ecosystems constituting a highly valuable approach.

De novo assembly and transcriptome characterization of the freshwater prawn Palaemonetes argentinus: Implications for a detoxification response.

Palaemonetes argentinus, an abundant freshwater prawn species in the northern and central region of Argentina, has been used as a bioindicator of environmental pollutants as it displays a very high sensitivity to pollutants exposure. Despite their extraordinary ecological relevance, a lack of genomic information has hindered a more thorough understanding of the molecular mechanisms potentially involved in detoxification processes of this species. Thus, transcriptomic profiling studies represent a promising approach to overcome the limitations imposed by the lack of extensive genomic resources for P. argentinus, and may improve the understanding of its physiological and molecular response triggered by pollutants. This work represents the first comprehensive transcriptome-based characterization of the non-model species P. argentinus to generate functional genomic annotations and provides valuable resources for future genetic studies. Trinity de novo assembly consisted of 24,738 transcripts with high representation of detoxification (phase I and II), anti-oxidation, osmoregulation pathways and DNA replication and bioenergetics. This crustacean transcriptome provides valuable molecular information about detoxification and biochemical processes that could be applied as biomarkers in further ecotoxicology studies.

Aquaporin in different moult stages of a freshwater decapod crustacean: Expression and participation in muscle hydration control.

Crustaceans, during their moult cycle, at the stages of both pre-moult and post-moult, need water uptake. This movement of water creates a challenge for the regulation of cell volume. The cells of freshwater decapods require a high regulatory capacity to deal with hyposmotic stresses, given the need to face dilution of the haemolymph during their moult cycles. This study investigated the variation in the expression of water channels (aquaporins) along the moult cycle of a freshwater palaemonid shrimp, focusing on their role in cell volume regulation. Moults in Palaemonetes argentinus have been investigated along three stages of its moult cycle: intermoult, late pre-moult and recent post-moult. For the evaluation of tissue volume regulation, the weight of isolatedmuscle, subjected to isosmotic and hyposmotic salines, was followed for 60min. The expression of AQP during the different moult stages was evaluated by immunocytochemistry. Muscle from the three moult stages in isosmotic conditions showed the same pattern of tissue volume regulation. When muscle from animals in pre-moult and intermoult were submitted to hyposmotic stress they swell, followed by volume regulation, while in post-moult the regulation is compromised. The difference in volume regulatory control between pre-moult and post-moult may be related to a possible regulation of water channels, as AQP expression was equal at these stages. This study presents novel findings for crustaceans in general, in the demonstration that AQP expression changes during the moult cycle of a decapod crustacean, together with the regulation of cell volume with the participation of AQPs.

Sensitive biomarker responses of the shrimp Palaemonetes argentinus exposed to chlorpyrifos at environmental concentrations: Roles of alpha-tocopherol and metallothioneins.

The aim of this study was to evaluate the toxic effects of chlorpyrifos (CPF) at environmental concentrations on the shrimp Palaemonetes argentinus, a South American native species. Organisms were exposed to environmentally relevant concentrations of CPF (from 3.5 to 94.5ngCPFL(-1)) at laboratory conditions for 96h. A wide battery of biochemical responses including bioaccumulation, damage and defense biomarkers were measured in cephalothorax and abdomen of shrimp. The concentration of CPF was below the detection limit of the method in both body sectors (8ngCPFg(-1)ww), probably indicating fast biotransformation of the parental compound. Our results showed that CPF exposure inhibits acetylcholinesterase activity from 3.5ngCPFL(-1), a concentration below the suggested Argentinean guidelines for the protection of aquatic biota. Moreover, oxidative stress was evidenced by increased H2O2 content and increased levels of TBARs and carbonyl groups in proteins. The induction of antioxidant enzymes like catalase, glutathione S-transferase and glutathione peroxidase seems not be sufficient to prevent oxidative damages. In addition, the mobilization of α-tocopherol from abdomen to cephalothorax was observed and reported for the first time in non-reproductive condition. Likewise, a strong diminution of metallothioneins occurred in cephalothorax from the lowest CPF concentration while induction occurred from the same treatment in abdomen as an oxidative stress response. Finally, significant correlation between Integrated Biomarker Response values and exposure concentrations suggest the usefulness of P. argentinus as bioindicator of CPF exposure at concentrations as low as environmental ones.

Morphometric variability in populations of Palaemonetes spp. (Crustacea, Decapoda, Palaemonidae) from the Peruvian and Brazilian Amazon Basin

Morphometric variability among shrimp populations of the genus Palaemonetes Heller, 1869 from seven lakes (Huanayo and Urcococha, in Peru; Amanã, Mamirauá, Camaleão, Cristalino e Iruçanga, in Brasil) in the Amazon Basin, presumably belonging to Palaemonetes carteri Gordon, 1935 and Palaemonetes ivonicus Holthuis, 1950, were studied. The morphometric studies were carried out from the ratios obtained from the morphometric characters. Multivariated analysis (Principal Components Analysis-PCA, Discriminant Function Analysis and Cluster Analysis) were applied over the ratios. Intra- and interpopulation variations of the rostrum teeth, and the number of spines in the male appendix, were analyzed through descriptive statistics and bivariate analysis (Spearman Rank Correlation test). Results indicated a wide plasticity and overlapping in the studied ratios between populations. The Principal Components Analysis was not able to separate different populations, revealing a large intrapopulation plasticity and strong interpopulation similarity in the studied ratios. Although the Discriminant Functions Analysis was not able to fully discriminate populations, they could be allocated in three subgroups: 1) Cristalino and Iruçanga; 2) Huanayo, Urcococha and Camaleão and 3) Mamirauá and Amanã. The first two groups were morphometrically separated from each other, whereas the third one presented a strong overlap with the former two. The Cluster Analysis confirmed the first two subgroups separation, and indicated that the first and third groups were closely related. Rostrum teeth and number of spines in the appendix masculina showed a large intrapopulation variation and a strong overlapping among the studied populations, regardless of the species.

Foram estudadas as variações morfométricas entre sete populações de camarões do gênero Palaemonetes Heller, 1869 da bacia Amazonica (lago Huanayo e lago Urcococha, no Peru; lago Amanã, lago Mamirauá, lago Camaleão, lago Cristalino e lago Iruçanga, no Brasil), presumivelmente das espécies Palaemonetes carteri Gordon, 1935 e Palaemonetes ivonicus Holthuis, 1950. Os estudos morfométricos foram realizados a partir das razões obtidas dos caracteres morfométricos. Análise multivariada (análise de componentes principais, análise de função discriminante e análise de agrupamento hierárquico) foram aplicadas unicamente sobre as razões. Variações intra- e interpopulacionais do número de dentes de rostro, assim como do número de espinhos no apêndice masculino, foram analisadas mediante estatística descritiva e análise bivariada (teste de Spearman). Os resultados indicaram uma grande plasticidade e sobreposição nos caracteres diagnósticos entre as populações. A análise de componentes principais não conseguiu separar as diferentes populações, revelando uma grande plasticidade intrapopulacional e forte semelhança interpopulacional nas razões estudadas. Embora a análise de funções discriminantes não tenha logrado discriminar completamente as populações, estas ficaram alocadas em três subgrupos: 1) Cristalino e Iruçanga; 2) Huanayo, Urcococha e Camaleão e 3) Mamirauá e Amanã. Os primeiros dois grupos ficaram morfologicamente separados entre si, enquanto que o terceiro apresentou uma forte sobreposição com os dois anteriores. A análise de agrupamento hierárquico confirmou a separação dos primeiros dois subgrupos, e indicou que o primeiro e o terceiro grupos se encontram mais estreitamente relacionados. O número de dentes de rostro e o número de espinhos do apêndice masculino apresentaram uma grande variação intrapopulacional e uma forte sobreposição entre as populações estudadas, independentemente da espécie.

Morphometric variability in populations of Palaemonetes spp. (Crustacea, Decapoda, Palaemonidae) from the Peruvian and Brazilian Amazon Basin

Morphometric variability among shrimp populations of the genus Palaemonetes Heller, 1869 from seven lakes (Huanayo and Urcococha, in Peru; Amanã, Mamirauá, Camaleão, Cristalino e Iruçanga, in Brasil) in the Amazon Basin, presumably belonging to Palaemonetes carteri Gordon, 1935 and Palaemonetes ivonicus Holthuis, 1950, were studied. The morphometric studies were carried out from the ratios obtained from the morphometric characters. Multivariated analysis (Principal Components Analysis-PCA, Discriminant Function Analysis and Cluster Analysis) were applied over the ratios. Intra- and interpopulation variations of the rostrum teeth, and the number of spines in the male appendix, were analyzed through descriptive statistics and bivariate analysis (Spearman Rank Correlation test). Results indicated a wide plasticity and overlapping in the studied ratios between populations. The Principal Components Analysis was not able to separate different populations, revealing a large intrapopulation plasticity and strong interpopulation similarity in the studied ratios. Although the Discriminant Functions Analysis was not able to fully discriminate populations, they could be allocated in three subgroups: 1) Cristalino and Iruçanga; 2) Huanayo, Urcococha and Camaleão and 3) Mamirauá and Amanã. The first two groups were morphometrically separated from each other, whereas the third one presented a strong overlap with the former two. The Cluster Analysis confirmed the first two subgroups separation, and indicated that the first and third groups were closely related. Rostrum teeth and number of spines in the appendix masculina showed a large intrapopulation variation and a strong overlapping among the studied populations, regardless of the species.

Foram estudadas as variações morfométricas entre sete populações de camarões do gênero Palaemonetes Heller, 1869 da bacia Amazonica (lago Huanayo e lago Urcococha, no Peru; lago Amanã, lago Mamirauá, lago Camaleão, lago Cristalino e lago Iruçanga, no Brasil), presumivelmente das espécies Palaemonetes carteri Gordon, 1935 e Palaemonetes ivonicus Holthuis, 1950. Os estudos morfométricos foram realizados a partir das razões obtidas dos caracteres morfométricos. Análise multivariada (análise de componentes principais, análise de função discriminante e análise de agrupamento hierárquico) foram aplicadas unicamente sobre as razões. Variações intra- e interpopulacionais do número de dentes de rostro, assim como do número de espinhos no apêndice masculino, foram analisadas mediante estatística descritiva e análise bivariada (teste de Spearman). Os resultados indicaram uma grande plasticidade e sobreposição nos caracteres diagnósticos entre as populações. A análise de componentes principais não conseguiu separar as diferentes populações, revelando uma grande plasticidade intrapopulacional e forte semelhança interpopulacional nas razões estudadas. Embora a análise de funções discriminantes não tenha logrado discriminar completamente as populações, estas ficaram alocadas em três subgrupos: 1) Cristalino e Iruçanga; 2) Huanayo, Urcococha e Camaleão e 3) Mamirauá e Amanã. Os primeiros dois grupos ficaram morfologicamente separados entre si, enquanto que o terceiro apresentou uma forte sobreposição com os dois anteriores. A análise de agrupamento hierárquico confirmou a separação dos primeiros dois subgrupos, e indicou que o primeiro e o terceiro grupos se encontram mais estreitamente relacionados. O número de dentes de rostro e o número de espinhos do apêndice masculino apresentaram uma grande variação intrapopulacional e uma forte sobreposição entre as populações estudadas, independentemente da espécie.

Molt cycle of the natural population of Palaemonetes argentinus (Crustacea, Palaemonidae) from Los Padres Lagoon (Buenos Aires, Argentina)

The molt cycle of the natural population of Palaemonetes argentinus Nobili, 1901 from Los Padres Lagoon, Buenos Aires, Argentina, was studied in relation to age, sex, and environmental factors. A total of 1645 individuals (740 females, 539 males, and 366 juveniles) were collected and analyzed between December 1995 and December 1996. The results indicate that the sex ratio (males:females) remains around 1:1.4 throughout most of the year. The reproductive period extends from September until February (spring and summer), with maximum sexual activity in October and November. Two cohorts originated in the spring and in the summer were differentiated. Ovigerous females arrest their molt cycle during the intermolt period to restart it after oviposition. The duration of the intermolt period does not differ between adults and juveniles. Since the percentage of premolt individuals represents 60% of the total cycle, it was classified as a diecdysic cycle. Within the studied range of water temperatures, the observed variations in the span of the different stages, indicate that this factor does not alter the molt frequency. Like in the rest of decapods, the intermolt duration of P. argentinus is modified by ovarian maturation.

Evaluación de palaemonetes argentinus (Decapoda, Natantia) en el control biológico de larvas de Culex pipiens (Diptera, Culicidae) en condiciones de laboratorio

The predator-prey relationship of Palaemonetes argentinus Nobili, 1901 and Culex pipiens s.l. larvae was studied under laboratory conditions. The prawns were separated in two groups, isolated and grouped ones. Mosquitoe larvae were offered to prawns in two forms, limited and unlimited offer to both groups. In the first analysis, values of predation did not differ significantly between males and females of P. argentinus. Predation in 24 h was 14,9 ± 4,2 larvae/prawn. A reduction of predation was observed with unlimited offer for the same hour, during all the experiment. Predation with unlimited offer was higher on the first day than on the second, but returned to high values on the third day, for both groups. In the grouped experiment, predation with limited offer was total on the first days, decreasing to the last day. As a result, P. argentinus was considered an efficient predator of C. pipiens s.l. larvae under laboratory conditions.

Molt cycle of the natural population of Palaemonetes argentinus (Crustacea, Palaemonidae) from Los Padres Lagoon (Buenos Aires, Argentina)

The molt cycle of the natural population of Palaemonetes argentinus Nobili, 1901 from Los Padres Lagoon, Buenos Aires, Argentina, was studied in relation to age, sex, and environmental factors. A total of 1645 individuals (740 females, 539 males, and 366 juveniles) were collected and analyzed between December 1995 and December 1996. The results indicate that the sex ratio (males:females) remains around 1:1.4 throughout most of the year. The reproductive period extends from September until February (spring and summer), with maximum sexual activity in October and November. Two cohorts originated in the spring and in the summer were differentiated. Ovigerous females arrest their molt cycle during the intermolt period to restart it after oviposition. The duration of the intermolt period does not differ between adults and juveniles. Since the percentage of premolt individuals represents 60% of the total cycle, it was classified as a diecdysic cycle. Within the studied range of water temperatures, the observed variations in the span of the different stages, indicate that this factor does not alter the molt frequency. Like in the rest of decapods, the intermolt duration of P. argentinus is modified by ovarian maturation.

Evaluación de palaemonetes argentinus (Decapoda, Natantia) en el control biológico de larvas de Culex pipiens (Diptera, Culicidae) en condiciones de laboratorio

The predator-prey relationship of Palaemonetes argentinus Nobili, 1901 and Culex pipiens s.l. larvae was studied under laboratory conditions. The prawns were separated in two groups, isolated and grouped ones. Mosquitoe larvae were offered to prawns in two forms, limited and unlimited offer to both groups. In the first analysis, values of predation did not differ significantly between males and females of P. argentinus. Predation in 24 h was 14,9 ± 4,2 larvae/prawn. A reduction of predation was observed with unlimited offer for the same hour, during all the experiment. Predation with unlimited offer was higher on the first day than on the second, but returned to high values on the third day, for both groups. In the grouped experiment, predation with limited offer was total on the first days, decreasing to the last day. As a result, P. argentinus was considered an efficient predator of C. pipiens s.l. larvae under laboratory conditions.

Evaluación de palaemonetes argentinus (Decapoda, Natantia) en el control biológico de larvas de Culex pipiens (Diptera, Culicidae) en condiciones de laboratorio

The predator-prey relationship of Palaemonetes argentinus Nobili, 1901 and Culex pipiens s.l. larvae was studied under laboratory conditions. The prawns were separated in two groups, isolated and grouped ones. Mosquitoe larvae were offered to prawns in two forms, limited and unlimited offer to both groups. In the first analysis, values of predation did not differ significantly between males and females of P. argentinus. Predation in 24 h was 14,9 ± 4,2 larvae/prawn. A reduction of predation was observed with unlimited offer for the same hour, during all the experiment. Predation with unlimited offer was higher on the first day than on the second, but returned to high values on the third day, for both groups. In the grouped experiment, predation with limited offer was total on the first days, decreasing to the last day. As a result, P. argentinus was considered an efficient predator of C. pipiens s.l. larvae under laboratory conditions.

Molt cycle of the natural population of Palaemonetes argentinus (Crustacea, Palaemonidae) from Los Padres Lagoon (Buenos Aires, Argentina)

The molt cycle of the natural population of Palaemonetes argentinus Nobili, 1901 from Los Padres Lagoon, Buenos Aires, Argentina, was studied in relation to age, sex, and environmental factors. A total of 1645 individuals (740 females, 539 males, and 366 juveniles) were collected and analyzed between December 1995 and December 1996. The results indicate that the sex ratio (males:females) remains around 1:1.4 throughout most of the year. The reproductive period extends from September until February (spring and summer), with maximum sexual activity in October and November. Two cohorts originated in the spring and in the summer were differentiated. Ovigerous females arrest their molt cycle during the intermolt period to restart it after oviposition. The duration of the intermolt period does not differ between adults and juveniles. Since the percentage of premolt individuals represents 60% of the total cycle, it was classified as a diecdysic cycle. Within the studied range of water temperatures, the observed variations in the span of the different stages, indicate that this factor does not alter the molt frequency. Like in the rest of decapods, the intermolt duration of P. argentinus is modified by ovarian maturation.

ESTRATÉGIA REPRODUTIVA E ALGUNS ASPECTOS DEMOGRÁFICOS DO CAMARÃO Palaemonetes carteri GORDON, 1935 NA AMAZONIA CENTRAL, RIO NEGRO

The ecology of the prawn Palaemonetes carteri Gordon, 1935(Decapoda: Palaemonidae) was studied through field collections realized in Central Amazon, in lhe vicinities of Manaus. P. carteri inhabits the submerged litter of small forest streams submitted to annual flooding. From January 1989 to May 1990, 4,441 individuals were found. Reproductive strategy, some demographic traits and sex ratio fluctuations were investigated. P. carteri showed sexual dimorphism in size, females being bigger than males. The reproductive period was restricted to rising and high waters. Females carried 5 to 39 large eggs. There was no significant correlation between clutch size and females carapace length. The sex ratio of adults was ca 0.60 without significant seazonal variations.

A ecologia do camarão Palaemonetes carteri Gordon, 1935 (Decapoda: Palaemonidae) foi estudada através de coletas mensais, realizadas de janeiro 1989 até maio 1990, na região de Manaus. P. carteri vive na liteira submersa dos igarapés de terra firme em áreas baixas inundadas periodicamente pelas enchentes dos rios. A estratégia de reprodução e a dinâmica da razão sexual foram estudados na base dos 4,441 indivíduos coletados. P. carteri mostrou um dimorfismo sexual do comprimento, as fêmeas sendo maiores que os machos. O período de reprodução foi restrito a enchente e a cheia das águas. O número de ovos por fêmea variou entre 5 e 39, sem nenhuma correlação com o tamanho das fêmeas. A razão sexual mostrou uma predominância de fêmeas sem nenhuma variação sazonal significativa.

ESTRATÉGIA REPRODUTIVA E ALGUNS ASPECTOS DEMOGRÁFICOS DO CAMARÃO Palaemonetes carteri GORDON, 1935 NA AMAZONIA CENTRAL, RIO NEGRO

The ecology of the prawn Palaemonetes carteri Gordon, 1935(Decapoda: Palaemonidae) was studied through field collections realized in Central Amazon, in lhe vicinities of Manaus. P. carteri inhabits the submerged litter of small forest streams submitted to annual flooding. From January 1989 to May 1990, 4,441 individuals were found. Reproductive strategy, some demographic traits and sex ratio fluctuations were investigated. P. carteri showed sexual dimorphism in size, females being bigger than males. The reproductive period was restricted to rising and high waters. Females carried 5 to 39 large eggs. There was no significant correlation between clutch size and females carapace length. The sex ratio of adults was ca 0.60 without significant seazonal variations.

A ecologia do camarão Palaemonetes carteri Gordon, 1935 (Decapoda: Palaemonidae) foi estudada através de coletas mensais, realizadas de janeiro 1989 até maio 1990, na região de Manaus. P. carteri vive na liteira submersa dos igarapés de terra firme em áreas baixas inundadas periodicamente pelas enchentes dos rios. A estratégia de reprodução e a dinâmica da razão sexual foram estudados na base dos 4,441 indivíduos coletados. P. carteri mostrou um dimorfismo sexual do comprimento, as fêmeas sendo maiores que os machos. O período de reprodução foi restrito a enchente e a cheia das águas. O número de ovos por fêmea variou entre 5 e 39, sem nenhuma correlação com o tamanho das fêmeas. A razão sexual mostrou uma predominância de fêmeas sem nenhuma variação sazonal significativa.