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The positive effects of biodiversity on the functioning of ecosystems are well demonstrated in laboratory microcosms but the precise mechanisms underlying higher ecosystem process rates in natural assemblages are less well understood. We investigated, under semi-natural conditions (field enclosures), the potentially interactive effects of species identity and trophic function (i.e., feeding guild) on consumer growth, using a fish assemblage in a tropical stream. We tested the relative importance of species identity and trophic function on consumer growth by placing 2 fish of either (i) the same species, (ii) different species but of similar trophic function, or (iii) different species of different trophic functions in each of 72 stream enclosures for 48 days and measuring biomass change, individual diet composition and behavior. We predicted that if functional diversity had a larger impact than species diversity, then fish growth would be highest for pairs of species from different functional groups (i.e., those with the highest diet complementarity), intermediate for different species within a guild, and lowest for the same species (those with the lowest complementarity and highest niche overlap), such that functional variation between species in different guilds would exceed functional differences within guilds. Our results show that functional heterogeneity rather than species diversity per se had the greatest impact on food resources used complementarily, leading to higher biomass accrual. Mechanistically, higher growth rates were driven by concomitant increases in resource intake and reductions in antagonistic interactions. Together, these results underscore the importance of functional diversity on macroconsumer production in natural assemblages. [ABSTRACT FROM AUTHOR]

The present study evaluated changes in an estuarine fish community caused by blooms of the dinoflagellate Akashiwo sanguinea. Samples were collected before, during and after the red tide using seine nets and surface and bottom nets in three areas near the affected area. The area was around the mouth of the Paraguaçu River. A total of 144 samples were collected, containing 1,989 individuals, with a total weight of 51.4 kg, belonging to 42 species in 29 families. During the red tide, fish density, richness and biomass decreased significantly. Atherinella brasiliensis and Sphoeroides greeleyi were the most abundant species during the red tide, indicating some possible resistance to the effects of the red tide. One month after the red tide, there was a rapid recovery of the density, biomass and richness of fish, and Cetengraulis edentulus was the most captured species. An important result of the present study is the finding that the dynamics of small populations of fish are often influenced by fortuitous events, and stochasticity may dominate. The establishment of a continuous and adequate monitoring program in the area may contribute to understanding the effects of red tides on fish population dynamics. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

The article presents the results of a study which investigated the effects of weight training on postmenopausal women in terms of preventing bone loss. An overview of related previous research is provided, along with details of the experimental protocol. It was found that bone mineral density was not significantly affected by these exercises during the course of the 24-week study. Exercises included hip adductions and abductions, knee extensions, arm curls and sit-ups.

Abstract: Tropical regions’ economy is usually based on agriculture, which involves an intensive use, and even frequent overuse, of pesticides. Nevertheless, not much research has been done on the impact of pesticides on tropical aquatic ecosystems which are often contaminated by runoff-related pesticide inputs due to unpredictable and torrential rainfalls. This study aimed to: (i) adapt and evaluate a short-term sublethal in situ assay using post-exposure feeding as an endpoint, to the tropical cladoceran species Diaphanosoma brachyurum (collected at the Pedra do Cavalo dam in the Paraguaçu River basin, Bahia, Brazil), and, (ii) assess the role of the standard species Daphnia magna as an adequate laboratory surrogate. Lethal and sublethal (post-exposure feeding) responses were assessed for the two species. To evaluate these responses under environmentally realistic exposure conditions, a runoff event was simulated in an agricultural area previously contaminated with different deltamethrin concentrations. The resultant runoff water was used to set up microcosms with different dilutions, simulating the entrance of runoff water in an adjacent lentic system. An in situ assay with D. Brachyurum was performed inside the microcosms, allowing to discriminate the effects due to deltamethrin from those due to other potential stressors associated with the experimental design (e.g. organism handling, load of suspended particles, microcosm design). Water samples were collected from microcosms to conduct a laboratory assay with D. Magna. The in situ methodologies revealed to be suitable to conduct assays with D. Brachyurum under tropical conditions, since all exposed organisms were successfully retrieved from the chambers. Furthermore, none of the potential stressors associated with the experimental design influenced the daphnids’ performance. The tropical cladoceran species, exposed under more realistic conditions, revealed to be more sensitive than the laboratory standard species: lethal effects were only observed for D. Brachyurum and sublethal effects were noticed at a lower deltamethrin concentration for this species than for D. Magna. [Copyright &y& Elsevier]

Surface treatment of fiber-reinforced posts can increase adhesion, especially on the post/resin cement interface. The purpose of this in vitro study was to evaluate the effect of different surface treatments on fiber post cemented with a self-adhesive system. Sixty fiberglass epoxy resin posts were cleaned, dried and divided into 6 groups (n = 10): Control (no surface treatment), silane (silane coupling agent was applied homogeneously on surface), 24% hydrogen peroxide (H 2 O 2 ) (immersion during 1 min), blasting (blasting with aluminum oxide for 30 s), NH 3 plasma (plasma treatment for 3 min) and HMDSO plasma (plasma treatment for 15 min). After the treatments, posts were inserted into a silicon matrix that was filled with the resin cement RelyX U200. Afterwards, the post/cement specimens were cut perpendicularly to the long axis of the posts into six 1.0 mm thick discs and submitted to a push-out bond strength (POBS) test. Failure pattern was classified in 5 types: type I: cohesive in post; type II: cohesive in cement; type III: cohesive post and cement; type IV: adhesive post/cement; and type V: mixed (association between cohesive and adhesive). Data were analyzed by one-way ANOVA and Tukey HSD post hoc test (α = 0.05). Silane (15.94 ± 6.5), blasting (13.13 ± 3.6), NH 3 plasma (14.44 ± 4.0) and HMDSO plasma (13.23 ± 5.3) showed higher POBS when compared to control (p < 0.05) and similar among them. H 2 O 2 (9.40 ± 4.0) treatment showed POBS values statistically similar to control (9.65 ± 3.6). Failures were predominantly cohesive post and cement, type III, in all groups. In conclusion, surface treatments influenced in the adhesion of fiberglass post with the self-adhesive cement RelyX U200. Silane, blasting with aluminum oxide and plasmas (NH 3 and HMDSO) showed results superior to 24% hydrogen peroxide. [ABSTRACT FROM AUTHOR]

The aim of the study was to compare maximal and submaximal cardiorespiratory responses between progressive tests on a treadmill on land (TRE), and stationary running on land (SRL) and in water (SRW), while also comparing two methods of determining the second turn point (ST) (ventilatory curve and heart rate deflection point). The study sample consisted of nine active women (23 ± 1.94 years) that performed three maximal protocols in separate days. Heart rate (HR) and oxygen uptake (VO2) were measured in all sessions. The data were analyzed using repeated-measures ANOVA and two-way repeated measures ANOVA with post-hoc Bonferroni test. Greater values of maximal HR (HRmax) and HR at ST (HRST) were observed during exercise performed on TRE and during the SRL, compared to the SRW (p < 0.05). The results for maximal VO2 (VO2max) and VO2 at ST (VO2ST) showed greater and significant values on TRE compared to STL and STW (p < 0.05). Furthermore, the HR and VO2 corresponding to the ST showed similar values between the two methods. Thus, the main conclusion of the present study was that the HR deflection point seems to be a simple and practical alternative method for determining the ST in all protocols analyzed. [ABSTRACT FROM AUTHOR]

Abstract: The rehabilitation of a pond after approximately 20years of strong acidified conditions due to industrial and domestic waste deposition in its catchment basin is reviewed. We describe in this study the acidification process that occurred in a tropical pond in Northeast Brazil (Dunas Lake), the rehabilitation plan for the pond and the subsequent monitoring conducted over two decades. After the contamination assessment by the late 80s, a rehabilitation plan was carried out in the early 90s, in which the contaminated soil and water have been removed and reduced, respectively. No further attempt to neutralize the water or any remediation has been carried out. A toxicity monitoring plan based on toxicity assays with the fish Poecilia reticulata was employed to verify the natural rehabilitation of the pond. The data on toxicity, pH, conductivity, sulphate and dissolved iron recorded from 1994 to 2010 were also compiled and discussed. The collected data in 2003 and 2004 indicated changes in water quality and from them complementary management actions, namely improvement in the containment plant, were conducted in 2005. Results for toxicity assays and pH results indicated interannual changes in the water quality similar to rainy-dry periods. Moving average approach using pH data clearly showed the recovery process of Dunas Lake as well as the importance of the containment plan to reduce the contamination. Finally, a summary of the recent situation after two decades of rehabilitation is provided. [Copyright &y& Elsevier]

Toxic potential of the pH reduction to fingerlings of Poecilia reticulata, through acute toxicity bioassays, as well as the influence of increased pH on the toxicity were assessed. Acid lake samples (Dunas Lake) were collected during 19 months, and assessed with following treatments: water at local pH (±3.0) and samples with modified pH to 3.5, 3.8, 4.0, 4.3, 4.6, 5.0, 5.5, 6.0, and 6.5. Culture water samples with pH reduced to 3.0 were also assessed. Newborn P. reticulata were exposed during 96h, and dead/immobile organisms were counted at various time intervals during exposure (short intervals in the beginning and long towards the end). Mean results of LT50 and confidence intervals from the Dunas Lake and control water with reduced pH were 1.36 (±0.48)h, and 1.03 (±0.50)h, respectively, with no statistical difference. Samples with increased pH showed a significant reduction in toxicity, with no toxicity detected at pH 6.0 and higher. Relationship between pH and lethal toxicity for fingerlings of P. reticulata demonstrated that pH exerted a strong effect on the survival of this species at the Dunas Lake, explaining about 80% of the toxicity observed. [Copyright &y& Elsevier]

Abstract: The suitability and viability of acute in situ bioassays were investigated in the biomonitoring program of an acidic lake contaminated with sulphur residues. Responses of organisms observed in laboratory and in situ bioassays were also assessed to determine whether or not they were similar and comparable, regarding accuracy and precision. Newborn Poecilia reticulata were employed as test organisms and exposed to the same water samples under in situ and laboratory conditions. Mortality/immobility was the endpoint assessed and dead/immobile organisms were counted at various time intervals during exposure. The mean calculated LT50 values and 95% confidence intervals were 1.61 (1.36–1.87) h in the laboratory bioassays and 0.72 (0.55–0.89) h in the in situ bioassays. Statistical comparison of these values revealed a significant difference (p <0.05). In situ bioassays were more accurate than those carried out in the laboratory, demonstrating higher sensitivity and better reproduction of what occurs in nature, while laboratory bioassays were more precise. [Copyright &y& Elsevier]

Abstract: The treatment efficiency, as toxicity removal, of complex effluents from the Industrial District of Camaçari (BA, Brazil), after biological treatment with activated sludge was evaluated using Microtox®. Samples of the equalised effluent (EE) were collected prior to treatment together with samples of the treated effluent (TE), which remained 24h in the treatment plant. Rehydrated colonies of Vibrio fischeri were exposed to sequential dilutions of EE and TE to assess luminosity interference. Values for EC50 were calculated, together with the respective toxicity units. In all, twenty assays of each effluent type were carried out and the mean toxicity removal was 92.71%, while the chemical oxygen demand (COD) presented mean reduction of 83.04%. There was a variability of an order of magnitude between the Microtox® results for the two types of effluents. The mean EC50 values were 2.12 for EE and 47.78% for TE. In spite of its weakness in some conditions, the Microtox® system demonstrated to work adequately in assessing effluent toxicity removal in this treatment plant and therefore can be used for further toxicity removal programs. [Copyright &y& Elsevier]

This study proposes assays with a freshwater chironomid, Chironomus xanthus, distributed over South America, based on subindividual (acetylcholinesterase activity) and individual (survival and postexposure feeding) level endpoints. Sediment and aquatic-rooted floating macrophyte assays were developed, due to the importance of both substrates for toxicant exposure in subtropical/tropical environments. Assays were evaluated under realistic exposure scenarios by simulating a runoff over an agricultural field dosed with deltamethrin. In situ assays were performed within microcosms to discriminate the effects of deltamethrin from those of additional potential stress factors (organism handling and caging, microcosms, use of aquatic roots, and runoff per se). A laboratory sediment assay based on feeding was conducted with samples from the microcosms. In all assays, both sublethal endpoints were responsive to deltamethrin and more sensitive than survival. Survival and feeding were more sensitive in situ than in the laboratory. In the in situ sediment assays, both sublethal endpoints were within a similar range of sensitivity; they were significantly inhibited as of the lowest Decis dose, from approximately 20 to 70%. In situ feeding was more sensitive in the sediment than in the macrophyte assay, where it was inhibited significantly only at the two highest Decis doses (up to 60%). Larval performance was not influenced significantly by any of the other potential stress factors. [ABSTRACT FROM AUTHOR]