Length-weight relationships of eight reservoir fish species in Puerto Rico

Length-weight relationships (LWR) of eight fish species, Lepomis auritus (Linnaeus, 1758), Amphilophus labiatus (Günther, 1864), Oreochromis mossambicus (Peters, 1852), Cichla ocellaris Bloch & Schneider, 1801, Parachromis managuensis (Günther, 1867), Vieja melanura (Günther, 1862), Pterygoplichthys pardalis (Castelnau, 1855), and Gobiomorus dormitor Lacepède, 1800, collected by electrofishing and gillnetting from ten reservoirs in Puerto Rico were determined using 3,557 individual fish records collected between 1998 and 2014. All LWRs were significant with r² values ranged from 0.900 for A. labiatus (Günther, 1864) to 0.996 for C. ocellaris Bloch & Schneider, 1801. The LWR parameter b ranged from 2.807 for P. pardalis (Castelnau, 1855) to 3.180 for C. ocellaris Bloch & Schneider, 1801. Data presented herein expand the knowledge base for these species as they have limited or no LWR data available. Also, our samples provide a new maximum length data for P. pardalis (Castelnau, 1855).     

Amazon fish bacterial communities show structural convergence along widespread hydrochemical gradients

The world's richest freshwater fish community thrives in gradients of contrasting environments in Amazonia, ranging from ion‐poor acidic black waters, to ion‐rich circumneutral white waters. These hydrochemical gradients structure Amazonian fish assemblages via ecological speciation events. Fish bacterial communities contain an important genetic heritage essential for their hosts' survival and are also involved in adaptive divergence via niche adaptation processes, but the extent to which they evolve in response to hydrochemical gradients in Amazonia is unknown. Here we investigated bacterial communities (gut and skin mucus) of two ecologically and phylogenetically divergent host species (Mesonauta festivus and Serrasalmus rhombeus) distributed throughout these hydrochemical gradients. The goal was to characterize intra‐ and interspecific Amazonian fish microbiome variations across multiple scales. Using a 16S metabarcoding approach, we investigated the microbiota of 43 wild M. festivus, 32 S. rhombeus and seven water samples, collected at seven sampling sites encompassing both water colours. Taxonomical structures of bacterial communities from both host species were significantly correlated to the environmental continua of magnesium, sodium, dissolved organic carbon, calcium, dissolved O₂, pH, potassium, hardness and chloride. Analysis of discriminating features in community structures across multiple scales demonstrated intra‐ and interspecific structural parallelisms in the response to the hydrochemical gradients. Together, these parallelisms suggest the action of selection on bacterial community structures along Amazonian hydrochemical gradients. Functional approaches along with reciprocal transplant experiments will provide further insights on the potential contribution of Amazonian fish microbiomes in host adaptation and ecological speciation events.     

Metabolic adjustment of Pyrrhulina aff. brevis exposed to different climate change scenarios

The increases in CO₂ concentrations and, consequently, temperature due to climate change are predicted to intensify. Understanding the physiological responses of Pyrrhulina aff. brevis to the climatic scenarios proposed by the IPCC (2014) for the next 100 years is of fundamental importance to determine its susceptibility. Thus, the present study aimed to evaluate the effects of the predicted climatic scenarios for the year 2100 on the metabolic adjustments of P. aff. brevis . Specifically, the rate of oxygen uptake, electron transport system capacity, glycogen and lactate content and the role of Na⁺K⁺-ATPases and H⁺-ATPase were evaluated. P. aff. brevis individuals were exposed for 15 days to the simulated climatic scenarios in climate scenario rooms, where temperature and CO₂ in the air were controlled. Two rooms were used to simulate the climatic scenarios predicted by the IPCC (2014): moderate (RCP 6; 2.5 °C and 400 μatm CO₂ above current levels) and extreme (RCP 8.5; 4.5 °C and 900 μatm CO₂ above current levels), in addition to the "control room" that represents the current scenario. There was an increase in the metabolic rate (MO₂) in the animals acclimated to the climate change scenarios (RCP 6 and RCP 8.5) compared to the current scenario. These responses showed a typical effect of temperature on energy demand in relation to the increase in temperature and CO₂. Our data showed an increase in O₂ consumption (MO₂), lactate levels and H⁺-ATPase activity of the animals acclimated to the moderate and extreme climate change scenarios. Such adjustments presented a clear metabolic imbalance, an alteration that may imply challenges for survival, growth, distribution and reproduction in the face of the expected environmental changes for the year 2100.     

Mountain passes are higher at low latitudes for madicolous insect communities of the Neotropical region

Aim

To test whether spatial turnover patterns of mountain madicolous insect communities in the Southern Hemisphere support the ‘mountain passes are higher in the Tropic’ hypothesis (MPHT). To do this, we compared madicolous communities in the Amazon Mountains (equator) and the Atlantic Forest Mountains (23°S).

Location

Brazil.

Methods

We characterized madicolous insect communities in two elevational gradients between 90 to 3000 m a.s.l. separated by 23° of latitude, totalling 108 sampling sites. Since the MPHT predicts a more intense turnover along elevational gradients at lower latitudes than at higher latitudes, we evaluated beta diversity in the Amazon mountains, at the equator, and in the Atlantic Forest mountains, in the subtropical region. We quantified multiple-site abundance-based dissimilarity to assess whether beta diversity was different between both regions. We also performed constrained ordination (db-RDA) analyses to assess whether community dissimilarity (balanced variation in abundances) was uniquely or jointly explained by environmental, spatial and/or elevational predictors. Additionally, we independently assessed the relationship between community dissimilarity and altitudinal difference in each region and tested for differences in model parameters between regions.

Results

Although we found high species turnover in both regions, the community variation explained by environmental factors and altitude was higher in the Amazon than in the Atlantic Forest, as evidenced by db-RDA and altitudinal difference models. In general, communities were remarkably constrained by spatial predictors, which result from low dispersion capacity of most madicolous insects and low connectivity of madicolous systems. Consequently, the composition of madicolous insects notably diverged between regions, highlighting the complementarity and high conservation value of both systems.

Main Conclusions

Our results indicate that the MPHT explains, at the community level, the differences between low- and high-latitude mountain systems in community turnover along elevational gradients, even within a relatively short latitudinal distance in the Southern Hemisphere.     

New records of Mansonella ozzardi: a parasite that is spreading from the state of Amazonas to previously uninfected areas of the state of Acre in the Purus River region

Mansonella ozzardi infections are common in the riverside communities along the Solimões, Negro and Purus Rivers in the state of Amazonas (AM). However, little is known about the presence of this parasite in communities located in regions bordering AM and the state of Acre. The prevalence rate of M. ozzardi infections was determined in blood samples from volunteers according to the Knott method. A total of 355 volunteers from six riverine communities were enrolled in the study and 65 (18.3%) were found to be infected with M. ozzardi. As expected, most of the infections (25%) occurred in individuals involved in agriculture, cattle rearing and fishing and an age/sex group analysis revealed that the prevalence increased beginning in the 40-50-years-of-age group and reached 33% in both sexes in individuals over 50 years of age. Based on the described symptomatology, articular pain and headache were found to be significantly higher among infected individuals (56 and 65% prevalence, respectively, p < 0.05). Sera from volunteers were subjected to ELISA using a cocktail of recombinant proteins from Onchocerca volvulus to evaluate the specificity of the test in an endemic M. ozzardi region. No cross-reactions between M. ozzardi-infected individuals and recombinant O. volvulus proteins were detected, thus providing information on the secure use of this particular cocktail in areas where these parasites are sympatric.     

Dealing with allometry in linear and geometric morphometrics: a taxonomic case study in the Leporinus cylindriformis group (Characiformes: Anostomidae) with description of a new species from Suriname

To achieve maximum efficacy, taxonomic studies that seek to distinguish amongst species must first account for allometric shape variation within species. Two recently developed software packages (SMATR and MorphoJ) offer regression‐based allometric approaches that are notable for their statistical power and ease of use and that may prove highly useful to taxonomists working with linear or geometric morphometric data. We investigate species delimitation of the slender‐bodied fishes in the Leporinus cylindriformis group using these programs and demonstrate the utility of the allometric corrections that they provide. Without allometric correction, many pairs of species are difficult to distinguish on the basis of morphometrics, but once regressions are used to account for marked allometric variation within species, most of the recognized species in this group can be readily distinguished with linear or geometric morphometrics, particularly using variation in the depth of the body. Both approaches returned congruent patterns of separation amongst putative species, but the geometric approach in MorphoJ distinguished amongst four more pairs of species than did the linear approach in SMATR and appears to provide slightly more statistical power. Based on distinctive morphometrics, meristics, and coloration, a highly elongate species of Leporinus from the Suriname, Corantijn, and Coppename rivers of Suriname is described herein as a new species, Leporinus apollo sp. nov. The unique L. cylindriformis holotype from Porto de Moz, Brazil differs in morphology, meristics, and pigmentation from specimens commonly referred to that species from the main basin of the Amazon; the latter specimens may represent an additional undescribed species. The L. cylindriformis holotype itself may represent a rare species or a specimen collected at the edge of its native range. Measurements of the holotype and paratype of Leporinus niceforoi, which were collected in the Amazonian slope of Colombia, differ substantially from similarly pigmented and putatively conspecific specimens from Amazonian portions of Ecuador and Peru. Recently collected specimens from Colombia are needed to determine whether the observed morphometric variation encompassed by the current concept of L. niceforoi indicates a morphocline within a single species, suggests the presence of multiple cryptic species, or results from shrinkage of the types. In all these cases, linear or geometric morphometric data can reliably differentiate amongst species, but only after one accounts for allometric shape variation. The new SMATR and MorphoJ software packages both offer easy and effective approaches to such allometrically informed taxonomy, and may prove useful to any systematist working on taxa that change shape as they grow. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 162 , 103–130.     

Comparative morphology,phylogenetic relationships,and historical biogeography of plesiolebiasine seasonal killifishes (Teleostei: Cyprinodontiformes: Rivulidae)

Phylogenetic and biogeographical analyses were performed for the Plesiolebiasini, a group of 20 small and rare species of South American annual killifishes, some threatened with extinction, occurring in river basins of Brazil, Bolivia, Paraguay, and Argentina. The results of a maximum parsimony analysis of 142 morphological characters highly corroborate monophyly of the Plesiolebiasini. Monophyly of each plesiolebiasine genus is supported and Plesiolebias is hypothesized to be the sister group to a clade comprising the remaining plesiolebiasine genera (Papiliolebias, Pituna, Maratecoara, and Stenolebias), corroborating studies based on mitochondrial genes. The phylogenetic analysis supports sister group relationships between Papiliolebias and the clade containing Pituna, Maratecoara, and Stenolebias, and between Maratecoara and Stenolebias. The biogeographical analysis indicates a complex historical biogeographical scenario for plesiolebiasines. A vicariance event between the western Paraguay area and northern river basins may be related to the isolation of the Chaco region from the Amazon between the Late Oligocene and Early Miocene. A vicariance event involving the Paraguay River basin and northern rivers, and the multiple occurrence of area hybridism along the Araguaia depression are tentatively identified as a consequence of tectonic subsidence events occurring during the Pleistocene. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 162 , 131–148.     

Copepod communities in karstic mediterranean lakes along the eastern Adriatic coast

The copepod communities of karstic lakes along the eastern Adriatic coast were studied. Lakes were divided in several groups according to their morphology (deep, shallow, barrage and reservoirs), production (oligotrophic, mesotophic and eutrophic), and salinity of water: freshwater and brackish. Copidodiaptomus steueri, Eucyclops serrulatusand Macrocyclops albidus belong to the group that inhabited most of the lakes under the study, regardless of lake type. The shallow karstic lakes are usually inhabited by Thermocyclops dybowskii, T. oithonoides, Cyclops vicinus and Eudiaptomus padanus etruscus in freshwater biotopes, and Calanipedia aquaedulcis and Copidodiaptomus steueri in brackish biotopes. The last two species can also be found in deep karstic lakes with brackish water (Bacina lakes in the Neretva River delta). Species like Cyclops abyssorumcan be found in most deep freshwater lakes. Some Calanoida were recorded in only one lake, like Eudiaptomus transsylvanicusin the deep Lake Vrana on the island of Cres, or Eudiaptomus hadzici in the barrage Lake Visovac. Production of the lakes, expressed as copepod biomass, depends on lake trophy, and in some lakes also on hydrology and salinity. Most of the meso-eutrophic lakes in the study area had Calanoida dominating, while Cyclopoida dominated in some oligotrophic and eutrophic lakes as well.     

Intestinal helminths in wild Peruvian red uakari monkeys (Cacajao calvus ucayalii) in the northeastern Peruvian Amazon

Parasites are important in the management of the health of primate populations. We examined 36 fecal samples from Peruvian red uakari monkeys (Cacajao calvus ucayalii) collected from wild animals in the northeastern Peruvian Amazon. Samples were positive for helminth infection. Nematodes egg: Strongyloididae, Trypanoxyuris sp., Spirurid, and a cestode egg were identified.