Abstract in English:This work evaluated the efficiency of clove oil as anaesthetic in handling and transportation of Nile tilapia, Oreochromis niloticus (Linnaeus, 1758). In the first experiment, safety concentrations of clove oil were assessed by measuring induction times to anaesthesia. The second experiment evaluated exposure times to anaesthetic. Clove oil efficiency during transportation was evaluated in a 24 h experiment using three concentrations of the anaesthetic (0, 9, and 18 mg.L-1). The most appropriate clove oil concentration to induce surgical anaesthesia was 90 mg.L-1. To biometry or other brief handling, the recommended concentration is 50-60 mg.L-1 as it provides fast recovery. Maximum anaesthesia time should be 10 min. The mortality rate of fish transported using 18 mg.L-1 of anaesthetic was significantly higher than that of the control group at 24 h of transportation and at 96 h after transportation. The fish transported using clove oil as anaesthetic presented more significant Na+ and K+ disorders as compared to the control group. As an anaesthetic, clove oil is efficient in the handling of Nile tilapia in routine fish hatchery procedures, although it should be avoided in the transportation.
Abstract in English:Differences in distribution, prey species, season and social learning opportunities influence the feeding tactics used by marine mammals. Here, we analyze the coordinated feeding behavior of the Guiana dolphin, Sotalia guianensis (Van Bénéden, 1864, Delphinidae) and its relation to seasonality and the presence of calves. In a total of 201 feeding bouts, we observed four types of coordinated feeding tactics, which differed in frequency and in mean number of engaged individuals. Tactics in which dolphins used their bodies to herd and capture prey were the most frequent, presenting a higher frequency and engaging a higher number of individuals, suggesting that these tactics are better for capturing fishes which form larger schools. Furthermore, the seasons influenced the feeding behavior used by dolphins. During spring-summer, a longer duration of bouts and a larger number of individuals engaged in the feeding tactics was observed, which may be related to the seasonal spawning of larger schooling fish, such as Sardinella brasiliensis (Steindachner, 1879). Calves were present in 95% of all coordinated feeding tactic occurrences. This study indicates a complete preference of dolphins for coordinating their actions to capture prey and for the first time reports the presence of calves in the coordinated tactics and jumps. This broadens the current knowledge of the Guiana dolphin feeding tactics.
Abstract in English:Age and growth of Cetengraulis edentulus (Cuvier, 1828) in the Saco dos Limões bight (Southern Brazil) were studied. Sampling was carried out from August 2001 to July 2003. The study of age and growth was based on the interpretation of the periodicity of ring formation in the otoliths sagittae of 491 individuals, temporal variation of otolith edge, relative marginal increments (RMI), age-length key, and von Bertalanffy curve. Cetengraulis edentulus otoliths were adequate for the interpretation of age with 86% of legibility, in which a translucent zone and its adjacent opaque zone were deposited each year. The translucent zone is formed during the cold period and the opaque zone in the warm period. Fish aged 0 (<12 months) - 4.0 year old were found and the population structure reveals the predominance of individuals 1.0 and 2.0 year old. The species has a fast growth, and the growth equation is Lt = 156.70 (1 - e - 1.05 (t - 0.002)). Cetengraulis edentulus attains the sexual maturity with 1.19 year for the females and 1.12 year for the males, which occur in all life stages throughout the year in the study area.
Abstract in English:Polystictus superciliaris (Wied, 1831) is a small tyrant-flycatcher endemic to mountaintops in the highlands of eastern Brazil. In this paper we present the first description of the breeding biology of P. superciliaris and estimate its reproductive success from a population inhabiting rocky outcrops. This study was conducted during 2005 in the Parque Estadual da Serra do Rola Moça, municipality of Nova Lima (20°03'S, 44°00'W), state of Minas Gerais, southeastern Brazil. Fourteen pairs of P. superciliaris were banded and monitored. The onset of the breeding season in 2005 was assumed to have been sometime before the 26th of July, while it was assumed to have ended on the 23rd of November based on the last observation of a successful brood. Clutch size was invariably two eggs (N = 21), the incubation period averaged 17.7 ± 1.3 days (N = 9), and the nestling period averaged 16.4 ± 1.3 days (N = 8). We estimated the probability of reproductive success for P. superciliaris to be 41.3%, during this particular breeding season. Of the 12 (57.1%) unsuccessful nests, eight (66.7%) had eggs and four (33.3%) had nestlings when they failed. In nine (42.8%) of these cases, the nests were lost to predation, two to parasitism by botflies, and one due to abandonment. This study suggests that the reproductive success of P. superciliaris is intermediate compared to the other species of Tyrannidae that have been studied and closer to the lower limit of the 40%-80% range which is characteristic of tyrant _ flycatcher species that breed in temperate regions.
Abstract in English:The beaches of Espírito Santo encompass the most important nesting sites of the loggerhead sea turtle, Caretta caretta (Linnaeus, 1758), in the South Atlantic Ocean. Previous research has shown that, unlike other nesting sites in Brazil, Espírito Santo harbors a large percentage of male individuals, which play an important role in maintaining the equilibrium of C. caretta populations in the South Atlantic. During the 2006/2007 reproductive season, four beaches presenting considerable geologic differences were monitored. The sedimentary features of the nesting sites (mineral composition, albedo, and grain size), nesting dates, and clutch sizes were correlated with hatching success and incubation duration. Results show that hatching success is mostly affected by clutch size _ and to a lesser extent, by grain size and albedo. Incubation duration is more sensitive to the characteristics of the nesting site, being affected by nesting date, clutch size, mineral composition, and grain size. However, results from one nesting site cannot be generalized or extended to other sites, because sediment properties are functions of the geological framework of the area and the interaction among environmental variables is far too complex. Our results reveal the importance of protecting areas with large geologic diversity, since sedimentary characteristics may affect incubation duration and embryo survival. Our findings are important in the scope of management activities, as nest transfer may alter nest microenvironment, impacting incubation duration and hatching success.
Abstract in English:Macoma biota Arruda & Domaneschi, 2005, is a recently described species known only from the intertidal zone of Praia da Cidade, Caraguatatuba Bay, in the state of São Paulo, southeastern Brazil. The main purpose of the present paper is to describe the biology of M. biota, beginning with a detailed analysis of its anatomy and functional morphology and how these attributes are correlated with its habitat and life history. The morphology of the organs in the pallial cavity and their sorting devices indicate that this species has efficient mechanisms to process large amounts of particles that enter this cavity via the inhalant current. M. biota can rapidly select the material suitable for ingestion and direct the undesired excess to the rejection mantle tracts. These characteristics along with the siphon's behavior and the digestive tract configuration reveal that this species can be classified primarily as a deposit feeder, like other species of the genus; however, it can also behave as a suspension feeder, depending on the environmental conditions.
Abstract in English:The freshwater snail Gundlachia ticaga (Marcus & Marcus, 1962) is widely distributed in Brazil, but its morphology has been poorly studied. We compared the shell morphology of samples from four sites (Vila do Abraão, Vila de Provetá, Parnaioca and Praia do Sul) in Ilha Grande (Angra dos Reis, state of Rio de Janeiro) in order to evaluate differences within and among four populations. We used nine morphometric characters representing shell size and shape. To analyze shell morphology we considered aperture shape, sculpture of teleoconch, apex carving and position. The resulting dataset was correlated by Pearson´s linear correlation and shell differences among populations were tested using ANOVA and Discriminant Function Analysis. The results showed that there is significant variation among populations concerning shell shape and morphology. Shells from preserved localities (Praia do Sul and Parnaioca) and shells from highly modified environments (Vila do Abraão and Vila de Provetá) were the most similar to each other. Results from the visual assessment and from the discriminant analysis were almost identical. The shell indices are the most important variables in the differentiation of samples. The observed variation corroborates the hypothesis that G. ticaga displays phenotypic plasticity, which may lead to wrong identifications. Narrower shells with an elongate aperture could be misidentified as Ferrissia Walker, 1903 and, broader shells with a roundish aperture could be wrongly identified as Burnupia Walker, 1912. We confirmed that the absence of radial lines is not a good diagnostic character for G. ticaga. The analysis of the apical micro-sculpture and soft parts is essential for a correct identification.
Abstract in English:Previous studies have demonstrated that river-based surveys can provide an inexpensive source of information for neotropical zoologists, yet little information is available to inform the application of this technique for the long term monitoring of neotropical turtle species. We aimed to fill this gap by presenting an assessment of data collected during 333 river surveys over 50 months along rivers in a newly protected area in the Peruvian Amazon. A total of 14,138 basking Podocnemis unifilis Troschel, 1848 were recorded during 13,510 km of river-based surveys. We used generalized additive models (GAMs) to explore the influence of a series of abiotic and seasonal variables on the recorded abundances at two temporal scales: monthly and per trip. Our analysis revealed that there was a significant increase in turtle abundances during the study period and we also found a significant seasonal periodicity in monthly abundances. Abiotic factors strongly influenced trip level abundances, with more individuals per kilometer recorded during sunny days in the dry season, with temperatures between 25 and 30°C. The results demonstrate that turtle populations are increasing following the establishment of the protected area and that river-based surveys are likely to be more effective when carried out within a limited set of key abiotic conditions.
Abstract in English:This study describes the composition and structure of the benthic community associated with bryophytes in a first-order stream, located in a biological reserve of the Atlantic Forest, during two seasons. During three months of the dry season of 2007 and three months of the rainy season of 2008, samples of bryophytes attached to stones were collected randomly, along a 100 m stream reach. The structure of the community was analyzed through the mean density of individuals, Shannon's diversity index, Pielou's evenness, family richness, dominance index, and the percentage of Ephemeroptera, Plecoptera and Trichoptera (% EPT). Chironomidae larvae were dominant in the two periods of study, followed by Ceratopogonidae in the rainy season, and Naididae in the dry season. The orders EPT contributed 14 families. The results showed that bryophytes constitute suitable habitat which is able to shelter an abundant and diversified benthic fauna in a small extension of the stream. This habitat provides refuge during spates, and thus minimizes downstream transport of the macroinvertebrate fauna.
Abstract in English:Zooplankton may be regarded as a sensitive tool for monitoring environmental variations in coastal lagoons due to their ability to immediately react to changes in the water column trophic features and salinity levels. As a coastal lagoon with a broad history of anthropic influence, Rodrigo de Freitas Lagoon (Rio de Janeiro, Brazil) is widely used for water sports and artisanal fishing. The present study aimed to expand the knowledge base about zooplankton in the Rodrigo de Freitas Lagoon by assessing the composition and time-spatial distribution of the major zooplankton groups. Samples were collected fortnightly from at four distinct sampling points August 2001 to July 2002. At each point, salinity, temperature, dissolved oxygen and water transparency were measured. During the study period, the lagoon behaved as an spatially homogeneous environment in what regards the abiotic variables. However, all these variables showed significant differences along the time, mainly related to seasonality (air temperature and rainy and dry periods). The zooplankton community showed low taxonomic richness, with the predominance of species commonly found in coastal lagoons, especially with mesohaline conditions, as well as those found in estuaries. An interesting fact was the rise in zooplankton abundance at all sampling points right after a fish kill event. Such increase was caused mainly by the Brachionus plicatilis O.F. Müller 1786 species. Thus, the zooplankton community was affected by physical and chemical factors, mainly by the dissolved oxygen decline event and variations in the influx of seawater into the lagoon. In addition, phytoplankton availability and fish predation pressure were suggested as important regulating factors of the zooplankton community.
Abstract in English:Saquarema-Jaconé lagoonal system (SJLS) comprises a sequence of five interconnected shallow brackish lagoons with access to the sea by a single permanent tidal channel. It is a eutrophic system, receiving constant input of organic load from its urbanized catchments. The relationship between several environmental variables and the spatial-temporal distribution of the benthic macrofauna was assessed during four seasonal samplings (dry and wet periods of 2007-2009). Sediment replicates were sampled at seven sites for biological identification and analyzes of organic matter, carbonates, phytopigments, grain size and heavy metals. Salinity, dissolved oxygen and redox potential were measured in situ. SJLS was characterized by sandy bottoms with very reducing conditions. Redox potential significantly discriminated between the dry and wet periods and anoxic conditions were observed in the latter. No significant seasonal differences were observed in the macrofauna. A total of 37 taxa were identified, of which Capitella sp, oligochaetes and Laeonereis culveri (Webster, 1880) were the dominant, representing the early stage of community recovery following dystrophic crises. The faunistic pattern seems to be determined by complex combinations of silt+clay with salinity, organic matter and redox potential. On the other hand, the low concentrations of heavy metals found did not seem to influence the structure and distribution of the biota. SJLS is undergoing persistent environmental stress, dominated by first-order opportunistic species linked to organically enriched sediments.
Abstract in English:Large-scale agricultural production in Brazil preferentially occupies plateaus reclaimed from areas originally covered by Cerrado (savanna). Depending on the region, a percentage of the pristine vegetation coverage must be preserved by law, resulting in the creation of fragmented legal Cerrado reserves. The geometry of these relatively small legal reserves creates new habitat edges and ecotones, whose effects on the invertebrate fauna are poorly understood. This study aimed to assess the effects of abrupt edges resulting from soy production on ground-dwelling ant assemblages in the Brazilian Cerrado. The study sites are located within the Amazon region, in the state of Maranhão, northern Brazil, but were covered by Cerrado on a relatively low plateau, irregularly inter-spaced with gallery forests along streams. We compared species richness and species composition of ground-dwelling ants along eight transects set 0, 50, 100, 150, 200, and 250 m into the sensu stricto Cerrado and 50 and 100 m into the soy field. The collecting periods covered the wet and dry seasons. Effects on ant species richness were non-significant, although composition of the assemblages was significantly affected by edge effects, which were, in part, found to be species specific. We hypothesize that edge effects are probably greater than estimated because of the shape and complexity of reserves. Consideration of edge effects in the Cerrado Biome should enable the design of appropriate reserve sizes and shapes to meet conservation goals.
Abstract in English:Despite the great diversity of Brazilian Atlantic forest small mammals, natural history of most species is unknown due to their cryptic and nocturnal habits, but also due to the inadequacy of methods to capture some species, especially those of arboreal habits. A new technique, based on the use of artificial nests (AN) to record arboreal marsupials, is presented. Artificial nests were combined with traditional live traps to study the population ecology of four didelphid marsupial species. After 62 months of monitoring, 119 individuals were recorded 243 times (total success = 5.2%). Only 26 individuals (22%) were recorded by both AN and live trap methods, and two of the four species were never captured by live traps, only by AN. Live traps alone would have provided biased data of the structure of small mammal assemblages, creating artificial tendencies in population dynamics of many species. Detectability estimates based on mark-recapture data could correct bias resulting from the use only live traps, but these estimates require that at least some individuals of each age class or stage are captured. Only the combination of AN and live traps can produce more accurate data on population dynamics and assemblage structure. This study demonstrates that artificial nests represent a new method that should be combined with live traps in studies of small mammal assemblages and populations.
Abstract in English:The appropriate feeding regime for larvae and post-larvae of crustacean decapods is essential for successful larval culture. Reports on the development and morphology of the mouthparts and foregut of these crustaceans have aided in the selection of appropriate larval foodstuffs and consequently increased larval survival and growth rate during development. In the present study, the functional morphology of foregut and mouthparts was investigated in larvae and post-larvae of the freshwater prawn M. amazonicum (Heller, 1862). From observations gathered on both the outer and inner feeding apparati the first stage larvae have obligatory lecithotrophy and feeding behaviour is initiated after molting to the second stage. The foregut of the larvae undergoes diverse morphological changes during larval development and the larval foregut of this species is primarily a mixing organ due to the absence of gastric mills and similar structures. After metamorphosis into post-larvae, drastic morphological changes occur in the foregut and mouthparts to adapt the animals to feed on the greater diversity of foods that are available in their new benthic habitat.
Abstract in English:Seira Lubbock, 1869 is the most speciose genus of Collembola in Brazil. Herein, we describe and illustrate a new species of Seira, Seira ritae sp. nov., collected in João Pessoa, state of Paraíba, Brazil, in an urban seaside area. The new species shows many similarities with S. mendoncea Bellini & Zeppelini, 2009 especially in what concerns the dorsal distribution of the macrochaetae of the head, the metathorax, and the first three abdominal segments. However, the two species can be distinguished by the chaetotaxy of the mesothorax and abdominal segment IV. The type locality of the species probably indicates some level of natural resistance to the impacts associated with human activities.
Abstract in English:The isotopic composition ( δ13C and δ 15N) of muscle, carapace and claw was determined from six wild individuals of Phrynops geoffroanus (Schweigger, 1812) in order to verify the variation between those tissues. The mean values of δ13C e δ 15N were, respectively, -19.48 ± 0.81‰ (-20.8 - -18.64‰) and 7.23 ± 0.67‰ (6.49 - 8.3‰) for muscle, -16.52 ± 0.98‰ (-17.88 - -15.43‰) and 7.29 ± 0.54‰ (6.74 - 7.97‰) for carapace and -18.57 ± 0.97‰ (-19.97 - -17.26‰) and 4.36 ± 0.33‰ (3.93 - 4.79‰) for claw. We found a significant difference for the tissues evaluated for both δ13C and δ15N. Muscle and claw were statistically similar and more depleted in 13C than the carapace. Nonetheless, claw was more depleted in 15N than muscle and carapace tissues. These results are likely related to differences in metabolic processes involved on each tissue formation. The description of the isotopic signatures variation in P. geoffroanus tissues provides a baseline for future investigations on the diet reconstruction of this species when more than one tissue is involved.
Abstract in English:Psammolestes tertius Lent & Jurberg, 1965 is a sylvatic triatomine bug species that occurs in thornbird nests in Brazil. We studied infestation of 527 nests of Phacellodomus rufifrons Wied, 1821 and Phacellodomus ruber Vieillot, 1817 by P. tertius in eight Brazilian states across the Cerrado and Caatinga ecoregions. Psammolestes tertius occurred in 44% of the nests, mainly in those of P. ruber. Overall, 3,261 specimens (52% nymphs) were captured, with an average of 14 bugs per infested nest (range 1-75). While P. tertius occurrence and age structure (percentage of nymphs) were similar in Cerrado and Caatinga nests, infestation intensity (bugs/infested nest) was higher in the Cerrado. Last-stage nymphs and adults were predominant in P. tertius populations from both P. ruber and P. rufifrons nests. The results indicate that Phacellodomus nests are favourable habitats for P. tertius in the open/dry ecoregions of Brazil. The percentage of adult P. tertius specimens (48%) was higher than that observed in other triatomine species (usually less than 5% under either experimental or natural conditions), suggesting that adult bugs tend to remain in thornbird nests. The stable blood supply provided by resident/breeding birds would favor steady P. tertius infestation of thornbird nests across Brazilian Cerrado and Caatinga ecoregions.