Respostas ecofisiológicas de Cybistax antisyphilitica Mart. (Ipê verde) em função das alterações na intensidade de luz

Light varies widely in both time and space in forest formation of “Bioma Cerrado”. Cybistax antisyphilitica occurs in areas typical of this biome, such as cerrado sensu stricto, “cerradões”, and altered areas. The aim of this study was to understand the morphological and physiological responses of C. antisyphilitica to alterations in light intensity. Juvenile plants (5 month of age) were taken to a fragment of semideciduous forest in Uberlândia-MG, and were divided into three treatments: 50 were maintained under the canopy (UC) 20 were kept in small gap (SG) and 20 were maintained under in full sun (FS). The daily courses of chlorophyll a fluorescence were made at the beginning, middle and end of dry season in 2015. At the end of the experiment measurements of chlorophyll content, gas exchange and growth were made. The plants showed dynamic photoinhibition as exhibited by reductions on Fv/Fm close to midday at the end of the dry season. Regarding the effective quantum yield (ΔF/Fm'), plants under FS showed reduced values that coincided with the higher values of electron transport rates (ETR). Plants under FS showed higher values of net CO2 assimilation rates, stomatal conductance, transpiration rates, water use efficiency and chlorophyll content compared to plants under UC. The stem diameter, dry mass of leaves and stem, total dry mass and relative growth rate were higher in plants under FS than plants under UC. On the other hand, plants under UC showed superior values of height, specific leaf area and leaf area ratio. Our results indicate that C. antisyphilitica has plasticity to survive in the contrasting light environments of the semideciduous forests, but this species was able to growth better under full sun conditions.

Utilização de peptídeos sintéticos derivados de moléculas imunodominantes de Toxoplasma gondii para diagnóstico sorológico da toxoplasmose em ovinos e galinhas caipiras

Chapter I - The obligate intracellular parasite Toxoplasma gondii is the causative agent of toxoplasmosis, a disease that affects humans and generates economic losses in farm animals. When prevention fails disease refers to the diagnosis and subsequent treatment if the individual is diagnosed as positive. Therefore, the development of new accurate diagnostic tools for detecting T. gondii infection is a need in particular to determine the environmental source of infection which can result in more appropriate public health policies against different routes of infection and prevent potential damage that toxoplasmosis can cause when animals are infected. Chapter II - The domestic chicken (Gallus gallus domesticus) are considered epidemiological sentinels, still representing a major source of recombinant strains when predated by cats, it is common to find them with multiple infections. We evaluate the diagnostic potential of six synthetic peptides (SAG2Y, MIC1, M2AP, GRA10, ROP2 and ROP7) predicted in silico from tachyzoites immunodominant markers of T. gondii in samples from naturally infected chickens, comparing synthetic peptides with antigen total soluble (STAg). In general, our results demonstrated that reactivity rates and positivity for these peptides are similar to the STAg, and the ROP7 peptide and the combination of peptides MIC1+ROP2 have significant sensitivity, confirming them as potential diagnostic tools for the diagnosis of toxoplasmosis in chickens. Chapter III - Sheep (Ovis aries) are commonly infected with Toxoplasma gondii due to his eating habits. Infection in pregnant sheep can have serious consequences such as embryonic death, fetal resorption, mummification, and neonatal death. One concern regarding the infection in these animals is that the meat can be a source of contamination to humans and other carnivores. Therefore perform accurate diagnosis in these animals is of fundamental importance. In the present study we evaluated the potential of new synthetic peptides as a diagnostic tool. Synthetic peptides (SAG2Y, SRS52A, MIC14, GRA4, GRA10 and GRA15) were predicted in silico from immunodominant proteins of T. gondii. We determine the levels of IgG antibodies using sera obtained from two farms in the city of Uberlândia. Analyzing the results together, the peptide combination GRA10+GRA15 (Accuracy = 0,82) showed better characteristics compared with the other mixtures. This preparation could be better analyzed with an antigenic mixture potential use in the diagnosis of toxoplasmosis in sheep and other species.

Enrofloxacina e toltrazuril reduzem a infecção por Toxoplasma gondii em células trofoblásticas humanas e em explantes de vilos placentários humanos de terceiro trimestre

The classical treatment for congenital toxoplasmosis is based on combination of sulfadiazine and pyrimethamine plus folinic acid. Due to teratogenic effects and bone marrow suppression caused by pyrimethamine, the establishment of new therapeutic targets is indispensable to minimize the undesirable effects and improve the control of the infection. Previous studies demonstrated that enrofloxacin and toltrazuril were able to control the infection triggered by Neospora caninum and Toxoplasma gondii. Therefore, the aim of this present study was evaluate the efficacy of enrofloxacin and toltrazuril in the control of T. gondii proliferation in human trophoblast cells (BeWo lineage) and in human villous explants from third trimester. BeWo cells and villous were treated with several concentrations of enrofloxacin, toltrazuril, sulfadiazine, pyrimethamine or association (sulfadiazine + pyrimethamine) in other to verify their viability by MTT or LDH assay, respectively. Next, BeWo cells were infected with T. gondii RH (2F1 clone) or ME49 strain, whereas villous were infected only with RH strain (2F1 clone), after, both cells and villous were treated or not with the same antibiotics and analyzed to T. gondii intracellular proliferation by beta-galactosidase assay (for RH strain) or blue toluidine staining (for ME49 strain). ELISA was performed in the supernatant to evaluate the cytokine profile. Enrofloxacin and toltrazuril did not change strongly the viability in cells and villous. Furthermore, the drugs decreased the parasite intracellular proliferation regardless T. gondii strain in BeWo cells and villous explants when compared to untreated and infected conditions. In BeWo cells infected by RH, enrofloxacin induced high levels of IL-6 low levels of MIF, while both cytokines were upregulated by enrofloxacin and toltrazuril in BeWo cells infected by ME49 strain. Additionally, in villous explantes, enrofloxacin induced high MIF production. Thus, enrofloxacin and toltrazuril were able to control the parasitism in BeWo cells and villous explants, and probably it occurs by modulation of immune response in these cells or tissues and direct action on parasite, but future experiments are necessary to verify this hypothesis.

Manipulação gênica do protozoário Neospora caninum como ferramenta para o estudo das interações parasito-hospedeiro

Neospora caninum is an obligate intracellular parasite classified in the phylum Apicomplexa, characterized by the presence of the apical complex composed by micronemes proteins, rhoptries and dense granules, used by parasite during the adhesion and invasion process of the host cell. This is the mean event in infection pathogenesis generated by N. caninum and other parasites from the phylum Apicomplexa, promoting influence in the parasite biology and the interface between the parasite and its host. Therefore, molecular tools have been developed in order to identify and characterize these possible virulence factors. Thus, the present study sought to establish a specific system of genetic manipulation of N. caninum, searching for the improvement of the genetics manipulation of this parasite. So, we developed genetically depleted N. caninum to Rop9 rhoptry using the pU6-Universal CRISPR-Cas9 plasmid of T. gondii modified by the insertion of Ku80. The Rop9 depleted parasite showed important during initial phase of invasion and replication of the parasite, however it was not characterized as a potential virulence fator for N. caninum. Furthermore, T. gondii proteins were expressed in N. caninum by the use of specific vectors for this parasite, showing an heterologous system for the study of Toxoplasma proteins, due to the fact that Gra15 or Gra24 of type II T. gondii and Rop16 of type I T. gondii were expressed in N. caninum tachyzoites in a stable way and keept its biological phenotype, as already presented the former parasite, that naturaly expresses these proteins. In addition, it was observed that N. caninum induced an inflammasome activation through NLRP3, ASC and Caspase-1. IL-1R/MyD88 demonstrated an indirect pathway in the control of parasite replication. Furthermore, it was observed that this activation is dependent of the potassium efflux and that different strains of N. caninum keep this activation profile. However, T. gondii strains block this activation, making necessary a prior signal in order to active the inflamosome pathway. Type I T. gondii Rop16 was identified as responsible for blocking this activation, in a dependent way to the STAT3 activation. Therefore, the development of molecular tools and their application in N. caninum may prove to be useful to identify and characterize virulent factors involved in the pathogenesis by these two protozoans.

Produção de biomassa e exportação de nutrientes de Eucalyptus grandis e E. urophylla

Scientific research in forest production technology area search techniques that increase production per unit area, with high economic viability and reducing environmental impacts. When dealing with forest plantations, studies are needed in the production of biomass and its nutrient content, and these are data parameters for planning the environmental implications of different intensities of forest harvesting. Given the above, this study aimed to elucidate the production and export of biomass and nutrients for two species of the genus Eucalyptus (E. grandis and E. urophylla) grown in the southwestern region of Parana. For this, it was evaluated: the stock of biomass and nutrients in eucalyptus (wood, bark, branches and leaves) at 60 months of age; the export rate of nutrients; the calorific value and economic viability. The biomass and the largest eucalyptus nutrient stocks are predominantly allocated to the stem (wood + bark). The components of biomass showed different chemical compositions, generally being higher in the leaves and bark and lower in wood and branches components. As for the calorific value, the leaves had its calorific value statistically superior than the other fractions, followed by branches, wood and bark. The organic carbon content (C.O.) is directly connected to the calorific value, and the calorific value increases as its content increase. The wood had the highest nutrient use efficiency values, something highly desirable and of great interest to forestry. The leaves showed smaller nutrient utilization efficiency values, with the exception of Ca and Mg that were smaller in the bark, indicating the importance of maintaining these components in the soil after harvest. The wood fraction presents the biomass lower cost when considering the replacement of nutrients exported by its biomass. On the other hand, the leaf fraction showed NPK higher cost of replacement.

Tipos de adubação para a videira 'BRS - violeta' cultivada em latossolo vermelho no sudoeste do Paraná

The vineyard culture, in the Southwest of Paraná, has faced an evolution in recently years. However, some technical barriers has contained the expression of its full potential. Among which, the lack of scientific and technical support about the fertilization management and the fertility maintenance of production fields, is the most worrying. This fact, allied with the raising on the consumers demand for ecological correct products, are the motivations for the present study, whose main objective was to evaluate the effects of different fertilizer formulations, based on alternative nutrient sources, on grapevine yield and grape fruit quality, aiming at the improvement of those parameters and the maintenance of soil fertility. To achieve this goal, an experiment has been evaluated since 2008, at the experimental area of the Federal Technological University of Paraná, Campus Pato Branco, where ten treatments were being tested, combining or isolating shale derivates from other alternative nutrient sources. Those are the treatments: T1: Gafsa Rock Phosphate (GRP) + K2SO4; T2: GRP + RPB (Rock Powder Bioland®); T3: GRP + K2SO4 + LH (Laying Hen Litter); T4: GRP+ RPB + LH; T5: GRP + K2SO4 + MBR (Matrix Shale 3); T6: GRP + RPB + MBR; T7: GRP + K2SO4 + MBR + LH; T8: GRP + RPB + LH + MBR; T9: TSP (Triple Superphosphate) + Urea + KCl and T10: absolute control. The usage of fertilization, specially the alternative fertilization, improved soil fertility characteristics and also the yield on the last two evaluated harvests. The potassium sulfate improved the potassium availability on soil, while improved yield on the last three harvests. The MBR improved the phosphorus availability, improved post-harvest conservation and improved the yield on the last evaluated harvest.

Silagem do bagaço de sorgo sacarino

Brazilian sweet sorghum is used to generate ethanol and the bagasse is burned in industrial boilers or deposited on soil polluting the environment. This study evaluated the performance of sorghum plants and its bagasse silage nutritional value aiming to use it in the ruminant nutrition. Experiments were set up on the UTFPR campus at Dois Vizinhos-PR. The first trial was established on October 2nd, 2012 using the genotypes ADV 2010, Hunnigreen, Sugargraze, Volumax, BR 505, 503, 501 and the second trial at 2013 on November 27th assessing the materials ADV 2010, Sugargraze, Hunnigreen, EX 5110, BR 506, 508, 509 and 511. Experimental was laid out as a randomized block design with three replications. Results were analyzed through ANOVA comparing the averages by Duncan test at 5% error probability. As field variables were evaluated: plant height (Pl hei), green mass production (GM Prod), percentage of leaves, stems and panicles in relation to the plant, stems production without straw (Prod stems with straw), whole stems production (Who stems Prod), stem diameter (Stem diam), juice production (Juice prod) and Brix degree (oBrix). After juice plant extraction, forage bagasse was crushed and packed in silos for 60 days and green matter yield was estimated (GM). In bagasse silage gauged to buffer capacity (BC), dry matter (DM), mineral matter (MM), crude protein (CP), ether extract (EE), total carbohydrates (TC), non-fibrous carbohydrates (NFCH), neutral detergent fiber (NDF), acid detergent fiber (ADF), lignin (LIG ) and digestibility "in vitro" (DIGIV). There was no significant difference (P> 0.05) between genotypes regarding to green matter production and on average, the second crop yield was lower and reflected in the reduction of bagasse production. Bagasse silage DM was of 32.3% and 33.1%; NDF 73% and 65.8%, crude protein 3.8% and 5.9; pH 3.7 and 3.7; TC and 9.8 and 10.7. mg MS-1; the amount of NFCH was 11.1 and 13.5%; DIG of DM 36.9 and 62.4% for the respectively to the bagasse produced from materials grown in the 2012/2013 and 2013/2014 seasons. Hybrid genotypes had a better agronomic performance while the varieties were more efficient in bromatological indexes. And despite the high percentage of NDF and the low protein level, it is possible to feed ruminants with this coproduct.

Estudo comparativo de dois tipos de cultivo: monocultivo (camarões) versus cultivo integrado (algas/camarões)

The integrated culture of seaweed and aquatic animals is an ancient practice in Asian countries. The expansion of this practice to western countries is consequence of the recognition of this system as a sustainable alternative that allows economical diversification and mitigation of environmental impacts generated by effluents of aquaculture. This study evaluated the growth of the seaweed Gracilaria caudata and of the shrimp Litopenaeus vannamei in monoculture (shrimps) and integrated culture (shrimps and algae) systems, and accessed the effect of the seaweed in the water quality. There were two treatments in the experiment: monoculture (shrimps) and integrated culture (shrimps/ algae). The organisms were cultured in 6 aquaria (10L) filled with seawater (35.0±0.0 PSU and 28.1±0.4°C) for 28 days. The nutrients of water (PO43-, NH4+, NO2-, NO3- and DIN), the biomass and the relative growth rate (RGR, % day-1) of seaweed and shrimps were measured weekly. The parameters pH, temperature, salinity and dissolved oxygen were measured daily. The concentration of NH4+ in integrated culture (62.8±25.2µM) was lower (Mann-Whitney p<0.001) than in monoculture (85.6±24.3µM). The mean of PO4- in monoculture (10.4±4.6µM) was markedly higher (Mann-Whitney; p=0.024) than that in integrated culture (8.7±4.1µM). The level of dissolved oxygen in integrated culture (6.0±0.6mg/L) was higher (t-Student; P=0.014) than that in shrimp monoculture (5.8±0.6mg/L). The mean values of the parameters pH, NO2-, NO3- and DIN were 7.5±0.2, 10.1±12.2µM, 24.5±3.2µM and 120.17±30.76µM in monoculture, and 7.5±0.2, 10.5±13.2µM, 27.4±3.5µM and 100.76±49.59µM in integrated culture. There were not differences in these parameters between treatments. The biomass and RGR of seaweed reached 15.0±1.9g and 7.4±2.8% day-1 at the end of the experiment. The performance of shrimp was favorable in monoculture (1.5±0.8g; 5.7±1.6% dia-1) and in integrated culture (1.5±0.7g; 5.2±1.2% dia-1), and the rate of survival was 100% in both treatments. The tolerance and favorable performance of Gracilaria caudata suggest that this seaweed might be integrated into shrimp (Litopenaeus vannamei) culture systems

Influência da profundidade e dos parâmetros ambientais sobre o desenvolvimento de Gracilaria birdiae (Rhodophyta, Gracilariales) em viveiro de camarão

This study evaluates the influence of depth and environmental parameters on the development of Gracilaria birdiae Plastino & Oliveira (Gracilariaceae Rhodophyta) in an organic shrimp pound (Litopenaeus vannamei) under euthrophical conditions. PVC structures (module) witch four ropes laden with 150 g of macroalgae each, were kept during 35 days at three different depths (surface, 10 and 20 cm depth). Wet biomass weighing and environmental parameters (temperature, salinity, turbidity, pH, transparence, precipitation, evaporation, insolation, accumulated solar radiation, nitrite, nitrate, ammonium and orthophosphate) were measured weekly. At all three proposed depths, the macroalgae displayed a higher biomass at the end of experiment than at the initial inoculations. The module kept at a 10 cm depth presented the greatest average biomass (186,3), followed by that kept at 20 cm (180,4 g) and the surface module (169,9 g). Biomass variations showed algae to suffer the direct effects of depths. Biomass loss was associated with the factors that influence light penetration, such as sediment deposits above the thallus, rate of evaporation and precipitation. The smallest loses occurred in the algae kept on surface (0,16%), followed by the algae kept at 20 cm (0,20%) and 10 cm (0,22%). The specific growth rate (SGR) of G. birdiae showed no significant difference between the three depths nor the sample periods. Nevertheless, the modules kept at 10 and 20 cm depths presented similar growth evolution, both growing 0,38%·per day-1, while the module kept on surface had an average SGR of 0,36%·day-1. The models related to growth rate demonstrated temperature, salinity, pH, orthophosphate, ammonium, precipitation and turbidity as the principal environmental parameters influencing the development of G. birdiae

Dieta do ouriço-branco, Tripneustes ventricosus (Lamarck, 1816), no Arquipélago de Fernando de Noronha, PE

Sea urchins are benthic macroinvertebrates that inhabit shallow coastal waters in tropical and temperate zones. Urchins are usually classified as generalists or omnivores as they can adjust their diet according to the food resources available in the environment. Due to the strong grazing pressure they may exert, urchins have an important role in marine ecosystems, occupying different trophic levels and stimulating the intensification of the dynamics of communities where they occur. In 2004, a monitoring program focused on the population dynamics of the white sea urchin, Tripneustes ventricosus, has been initiated in the Fernando de Noronha Archipelago. At the same time, a surprisingly lack of information on the species biology has been noted, despite their wide geographical distribution and economic importance in many parts of its range. Hence, this work was developed to provide information on the feeding habits of T. ventricosus in the archipelago. Ten specimens were collected between December 2006 and July 2007 at two sites of the archipelago, Air France and Sueste Bay for biometrics and analysis of gut contents. Test diameters ranged from 9.19 cm (± 1.1) to 10.08 cm (± 0.58). Calculated stomach repletion index (IRE) was higher (p <0.05) in the Air France site and also during January and July. The IRE was not correlated to the gonad index. Fifteen different species of algae were detected in a total of 120 stomachs examined: 4 Chlorophytas, 4 Phaeophytas and 6 Rhodophytas. Food diversity (p <0.05) was higher in December 2006 and January 2007. Although several items had a high frequency of occurrence, they were low represented in terms of weight, and consequently, had a low level of relative importance. The brown algae Dictyopteris spp and Dictyota spp, followed by the green algae Caulerpa verticillata accounted for the greatest importance in T. ventricosus diet, comprising about 90% of the consumed items

Análise do comportamento e crescimento do camarão branco Litopenaeus vannamei (Boone, 1931) em diferentes substratos inconsolidados

The aim of this study was to test the sediment preference of L. vannamei shrimp. It was observed shrimp visit frequency, swimming and burying behaviour at different sediment compositions for 24h. Juvenile (0.93 ± 0.29g) and sub-adult shrimps (10.0 ± 1.18g) were obtained from the aquaculture station at Universidade Federal Rural do Semi-Árido UFERSA, and held in a plastic tank (water volume 500 L) supplied with aerated water and kept at constant temperature, pH, and salinity. Shrimp was fed by commercial shrimp dry food. The experimental substrates were composed by A: medium sand + thick sand + very thick sand + gravel; B: very fine sand + fine sand; and C: silt + clay. Thus, six different substrate combinations were tested: A, B, C, A+B, A+C, B+C. To test preference, it was used a cylindrical tank (40 l) divided into six differently substrate compartments. A single shrimp was introduced each tank and the frequency at which this shrimp visited each compartment was recorded over a 24h study period. It was tested 54 shrimp (18 sub-adult males, 18 subadult females and 18 juveniles). For each trial, sediment and water were changed to avoid pheromones and residues influence. Shrimp were weighted and sub-adults were divided by sex: males present petasma and females present thelycum. Data were collected on the experimental day at 19:30; 20:30; 00:30; 1:30; 05:30; 06:30; 13:30 and 14:30 h. At each time point, shrimp were observed for 20-min periods, in which we noted down which compartment the shrimp was occupying at 2-min intervals. Thus, for each period we had eleven observations (88 observations per day). For observations at night, it was used dim red light that did not affect shrimp behaviour. At each 20-min period, it was observed visit frequency in each substrate, if shrimp was burred or not or if it was swimming. There was not significant difference between light and dark burry activity for females. Swimming activity was significantly higher at night, mainly at 00:30 and 01:30 h. All L. vannamei shrimp showed preference for sediment B. This animal presents cyclic activity, spends the day light period buried and swims at night

Eutrofização do reservatório Engenheiro Armando Ribeiro Gonçalves, no Rio Grande do Norte: implicações para o abastecimento público e para a piscicultura intensiva em tanques-rede

This study aimed to describe the spatial and temporal patterns of variation in trophic state and its relation with the structure and dynamics of planktonic community of a large reservoir located in semi-arid tropical region of Northeast Brazil. The reservoir Armando Ribeiro Gonçalves is the biggest reservoir of the Rio Grande do Norte State and is responsible for about 53% of all surface water accumulated in the State. The samples of water and plankton were taken monthly in 10 points distributed throughout the longitudinal axis of the reservoir and over a full hydrological cycle. The samples were collected to determine concentrations of total phosphorus, total nitrogen, chlorophyll a and suspended solids (fixed and volatile) and for determining the composition and abundance of phytoplanktonic and zooplanktonic species. During the study period, the reservoir was characterized as eutrophic and there was no trend of increasing the trophic state of the reservoir in the period of drought. The concentrations of total phosphorus and suspended fixed solids decreased towards the dam while the N:P ratios increased in the same direction due to the reduction in the phosphorus concentrations and relative constancy in the nitrogen concentrations. The N:P ratios observed were indicative of greater limitation by phosphorus than by nitrogen. However, as concentrations of both nutrients were high and the water transparency was very low, with secchi depth usually lower than one meter, it seems likely that the planktonic primary production of the reservoir is more limited by the availability of light than the availability of nutrients. High nutrient concentrations coupled with low availability of light may explain the continuing dominance of filamentous cyanobacteria such as Cylindrospermopsis raciborskii in the plankton of the reservoir.These cyanobacteria are potentially toxic and pose a serious environmental problem because it compromises the water quality for public supply, recreation and fishing when present in high densities as in this study. The mesozooplankton of the reservoir was dominated by the calanoid Notodiaptomus cearensis and the cladoceran Diaphanosoma spinulosum. In general, the structure of zooplankton community seems to be particularly influenced by the spatial variation of cyanobacteria. The results of the regression analyses show that both the chlorophyll a concentrations and the cyanobacteria biovolume were more strongly correlated with the nitrogen than with phosphorus and that the water transparency was more strongly correlated with algal biomass than with other sources of turbidity. The maximum load of phosphorus to attain the maximum permissible concentration of total P in the reservoir was estimated in 63.2 tonnes P/ year. The current external P load to the reservoir is estimated in 324 tonnes P / year and must be severely reduced to improve the water quality for water supply and allow the implementation of aquaculture projects that could contribute to the socio-economic development of the region

Efeitos da tilápia do Nilo (Oreochromis niloticus) e do enriquecimento por nutrientes sobre a comunidade planctônica em um lago artificial no semi-árido brasileiro

The major aim of this study was to test the hypothesis that the introduction of the Nile tilapia (Oreochromis niloticus) and the enrichment with nutrients (N and P) interact synergistically to change the structure of plankton communities, increase phytoplankton biomass and decrease water transparency of a semi-arid tropical reservoir. One field experiment was performed during five weeks in twenty enclosures (8m3) to where four treatments were randomly allocated: with tilapia addition (T), with nutrients addition (NP), with tilapia and nutrients addition (T+NP) and a control treatment with no tilapia or nutrients addition (C). A two-way repeated measures ANOVA was done to test for time (t), tilapia (T) and nutrient (NP) effects and their interaction on water transparency, total phosphorus, total nitrogen, phytoplankton and zooplankton. The results show that there was no effect of nutrient addition on these variables but significant fish effects on the biomass of total zooplankton, nauplii, rotifers, cladocerans and calanoid copepods, on the biovolume of Bacillariophyta, Zygnemaphyceae and large algae (GALD ≥ 50 μm) and on Secchi depth. In addition, we found significant interaction effects between tilapia and nutrients on Secchi depth and rotifers. Overall, tilapia decreased the biomass of most zooplankton taxa and large algae (diatoms) and decreased the water transparency while nutrient enrichment increased the biomass of zooplankton (rotifers) but only in the absence of tilapia. In conclusion, the influence of fish on the reservoir plankton community and water transparency was greater than that of nutrient loading. This finding suggests that biomanipulation should be a greater priority in the restoration of eutrophic reservoirs in tropical semi-arid regions

Caracterização limnológica e determinação da capacidade suporte do reservatório mendubim, (Rio Grande do Norte) para o cultivo de peixes em tanques-rede

The aims of this study were: i) assessing the trophic state of the Mendubim reservoir (semi-arid, Rio Grande do Norte, Brazil; 05° 38 99,0 S 36°55 98,0 W) based on chlorophyll-a, total phosphorus and nitrogen concentrations and water transparency; ii) relating the patterns of temporal variation of zooplankton and phytoplankton to the trophic state of the reservoir and iii) investigating the carrying capacity of the reservoir for cage fish farming. The samplingwas done monthly from July 2006 to July 2007 in three stations at the reservoir: next to the dam (barrage), in the central region and in the mouth of the main tributary. The abiotic and biotic variables analyzed were: Secchi depth, volatiles and fixed suspended solids, chlorophyll-a, total phosphorus and nitrogen, TN:TP ratio and mesozooplankton and phytoplankton composition and biomass. The results showed that the reservoir can be considered as mesotrophic with mean concentrations of total nitrogen, phosphorus and chlorophyll-a equal to 1711, 1 μg.L-1, 30,8 μg.L-1 and 5,62 μg.L-1 respectively. The Cyanophyceae class was the most representative in terms of density, with the presence of potentially toxic species such as Microcystis aeruginosa, Planktothrix planctonica, Cylindrospermopsis raciborskii, Aphanizomenon sp. ,Aphanocapsa delicatissima and Pseudanabaena acicularis. Among the zooplankton, the genus Notodiaptomus presented the largest biomass values. Overall, our results show that the light limitation should explain the weak relationship between chlorophyll-a and total phosphorus and nitrogen concentrations. We concluded that the water of Mendubim reservoir is suitable for intensive fish cage aquaculture. Based on the carrying capacity calculations for this reservoir, we found that the maximum sustainable yield of tilapias in cages in the reservoir is 126 ton per year assuming a factor of food conversion of 1.5: 1.0 and a phosphorus content in the fish food of 1%

Distribuição e abundância da malacofauna epibentônica no Parracho de Maracajaú, RN, Brasil

The mollusks present a great taxon variety and life habits in coral reefs being good environmental indicators. It is important to know the distribution pattern of the mollusks and the processes that influence it, so that disturbances in sea ecosystems could be monitored. The present study aims to accomplish the inventory and distribution of epibenthic mollusks in the Parracho of Maracajaú. 23 sites in different habitats of the Parracho were settled: 11 in the reef habitat, 3 in the sandy bottom and 9 in the seagrass bed. Qualitative and quantitative samplings have been done through snorkeling and scuba diving. Three band transects (10m²) were sampled in each site and the data were obtained to each m² of the transect, where the species were counted and the environmental variables (rugosity and recovery of the substratum) were valued. The data were submitted to multivariate analyses in order to find possible distribution patterns that could be associated to the substratum variables. The diversity indexes were calculated for each reef sites and compared with each other. A number of 46 species were registered. The reef habit at should to be the richnest area while the sandy bottom was poorest one. In the reef habitat, the mollusks were associated to rugosity and recovering of frondose algae and zoanthids, while for the seagrass bed, the animals exhibited a richness variation associated to the muddy and sandy sediment. There were found 3 species economically explored, what requires an appropriate management for the maintenance and conservation of the area resources in a sustainable way