Abstract Biological invasions are leading several species to extinction and are projected as a main driver of biodiversity changes in lakes for this century. However, the knowledge of their impacts ...on the Neotropical ichthyofauna over time remains largely incipient, especially when considering the functional diversity of native communities. Here we aim to identify the effects of non-native species, especially the non-native piscivorous Cichla kelberi and Pygocentrus nattereri, on the functional diversity of the native ichthyofauna of the Carioca Lake, Middle Rio Doce basin, state of Minas Gerais. Using fish occurrence data for eight years from 1983 to 2010 combined with an ecomorphological-trait analysis, we found that while the native species richness dropped to 56%, the functional richness is only 27% of that found before introductions. In other words, more than species, the ichthyofauna suffered an impressive decline in the range of functional traits, which can further have severe impacts on ecological processes within that system. When considering all the components of the current ichthyofauna (native and non-native species), neither taxonomic nor functional richness have changed over time. However, even keeping biodiversity levels, non-native species are not able to fully compensate for the extinct native ones in terms of functions.
Resumo Invasões biológicas vêm levando várias espécies à extinção, sendo projetado como o principal causador de mudanças na biodiversidade em lagos neste século. Entretanto, o conhecimento dos impactos sobre a ictiofauna Neotropical ao longo do tempo permanece bastante incipiente, especialmente quando se considera a diversidade funcional de comunidades nativas. Neste estudo, nós procuramos identificar os efeitos das espécies não nativas, especialmente os piscívoros não nativos Cichla kelberi and Pygocentrus nattereri, sobre a diversidade funcional da ictiofauna da Lagoa Carioca, bacia do médio rio Doce, Minas Gerais. Utilizando dados de ocorrência de oito anos entre 1983 e 2010, combinados a uma análise de atributos ecomorfológicos, observamos que a riqueza de espécies decaiu a 56%, enquanto a riqueza funcional é de apenas 27% da encontrada antes das introduções. Ou seja, mais do que espécies, a ictiofauna sofreu um declínio significativo na amplitude de atributos funcionais, o que pode levar a impactos severos em processos ecológicos neste sistema. Ao considerar todos os componentes da ictiofauna atual (espécies nativas e não nativas), as métricas de riqueza não sofreram alterações ao longo do tempo. Entretanto, mesmo mantendo os níveis de biodiversidade, espécies não nativas não são capazes de compensar totalmente as espécies nativas extintas em termos funcionais.
Controlling factors of CH
4
ebullitive flux are still poorly understood within daily timescales in aquatic environments. Here, we explored if
Chaoborus
larvae bioturbation can influence the timing of ...daily CH
4
ebullitive flux and how this emission pathway is affected considering direct observations in a tropical reservoir. For this, we collected CH
4
bubbles on two different days and three sampling periods: 1–4 pm, 4–7 pm and 7–10 pm. In the middle of each period, we collected
Chaoborus
larvae, chemical, and environmental variables and acoustically surveyed the underwater environment. We found similar temporal patterns of CH
4
emissions between the periods in both days. The intervals of higher CH
4
ebullitive flux (1–4 pm and 4–7 pm) appeared to correspond with the exit period of
Chaoborus
larvae from sediment (2:30 pm to 5:30 pm). Furthermore, the density of benthic larvae, a proxy of the bioturbation intensity, was the only variable that significantly correlated with the ebullitive flux, presenting a high and positive relation. Our findings suggest that the stochastic nature of the CH
4
ebullitive flux may not be absolute truth, and this emission pathway might be enhanced daily by a
Chaoborus
-driven physical disturbance.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Worldwide, freshwater environments are impacted by inputs of nutrients and dissolved organic matter from human activities. Yet, the recovery of aquatic systems is usually focused only on nutrient ...management. In our work, we presented the case of an urban and hypereutrophic environment (Pampulha reservoir, Belo Horizonte, Brazil) that receives discharges from several streams and was treated with lanthanum modified bentonite (Phoslock®) and microbial bioremediation (Enzilimp®). Our goals were to evaluate whether the treatment could improve the water quality and characterize the spatiotemporal variation of dissolved organic matter sources and indices according to absorbance and fluorescence measurements from the reservoir and streams post-application months (2018). In our results, the reservoir showed a relative decrease in its phosphorus concentration compared to data from before the treatment. On the other hand, carbon concentrations reached expressive values in the post-application months following a similar pattern found in the streams. Our data showed that the reservoir’s high resistance in its hypereutrophic condition was related to the elevated loading of external inputs coming from the streams. The parallel factor analysis (PARAFAC) identified four main carbon sources, two of them being potential tracers of organic pollution in the Pampulha reservoir and watershed, together with absorbance and fluorescence indices. Our findings suggest that carbon parameters can be essential tools to provide adequate monitoring and optimization of water recovery attempts in complex, polluted environments.
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CEKLJ, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Cyanobacteria are phytoplanktonic microorganisms that are susceptible to the deleterious effects of pharmaceutical residues in the aquatic environment, which poses a challenge to the environment ...exposed to diverse pharmaceutical products and their potential effects. The objective of this study was to evaluate the effects of the antibiotic substances ciprofloxacin and chlorhexidine in pharmaceutical preparations on the growth and production of chlorophyll of two cyanobacterial strains, Microcystis aeruginosa and Microcystis panniformis, isolated from a lake in a Brazilian environmental protection area. The EC50 and EC10 of chlorhexidine for M. aeruginosa were 206.4 µg/L and 108.5 µg/L, respectively, and for M. panniformis were 171.4 µg/L and 116.6 µg/L, respectively. The EC50 and EC10 of ciprofloxacin for M. aeruginosa were 17.24 µg/L and 3.21 µg/L, respectively, and for M. panniformis were 13.56 µg/L and 1.50 µg/L, respectively. The toxicity of the antibiotic ciprofloxacin (drug) and chlorhexidine (standard solution) to the Microcystis species was demonstrated, and these species were both very sensitive to ciprofloxacin. Our results suggest that the strains of M. aeruginosa and M. panniformis may be affected by exposure to residues of ciprofloxacin (>1.5 µg/L), which may represent a risk to the survival of aquatic species.
As hotspots of the global carbon cycle, lakes can regulate climate change while being regulated by it via a feedback loop. As ecosystem metabolism is considered to be a sentinel to these changes, we ...used high-frequency measurements and the inverse modeling approach to study the temporal dynamic of gross primary production (GPP), respiration (R), and net ecosystem production (NEP) at surface waters of a tropical lake, which lost about 60% of its volume in almost 10 years. This water loss and the return of the average rainfall led to an increased concentration of nitrogen, phosphorus, and dissolved organic carbon and decreased water transparency and light availability. During the post-drought period, epilimnetic GPP increased by 40% compared with the pre-drought period, and R surpassed GPP during the mixing period of the lake. We discuss that this modification results from higher carbon and nutrient concentrations, lower light availability, and a change in the lake stratification pattern. Surface water metabolism changed due to meteorological and hydrological drought, and it may continue to change under the ongoing variation in rainfall patterns, temperature, and human disturbances.
ABSTRACT Cyanobacteria possess metallic ion interaction properties that should be explored with the aim of recovering arsenic (As) contaminated areas. Contamination of As is an issue of worldwide ...concern due to the risk of human chronic intoxication and negative environmental health effects. In this study the potential decontamination of As(III) and As(V) using cyanobacteria cultures was assessed. Microcystis novacekii (Komárek-Compere, 1974) showed normal growth in concentrations of As(V) similar to those found in natural environments contaminated with As, demonstrating its resistance to As(V). Growth rates gradually decreased upon exposure to high As(V) concentrations from 600 to 5630 mg.L-1 while As(III) affected growth from 14.7 - 85.7 mg.L-1. The As(III) EC50 value (41.0 mg.L-1) was 140-fold lower possibly due to differences in As(III) and As(V) absorption pathways. Upon exposure to 14.7 mg.L-1 As(III), 21.2% of As was removed from culture medium. The absorption capacity (12000 mg.kg-1) remained constant with increasing As(III) concentrations in a dose independent effect. The potential of M. novacekii for As decontamination was demonstrated in this study. This microorganism is recommended in As bioremoval studies due to its autotrophic-mixotrophic growth, low nutritional requirements and high As(III) absorption capacity.
Brazil's wealth in water, its distribution, and losses, together with considerations on the challenges posed by the impacts of climate change, the precarious basic sanitation in the country, the ...demands of the agroindustry and the need to invest in new areas/themes through partnerships and integrated actions are the main points discussed in this article. The central proposal is to indicate new arrangements and possibilities for Limnology to face some of the problems that afflict humanity, especially those arising from climate change, loss of biodiversity and lack of basic sanitation, particularly critical challenges for Brazil
Ecotones between tropical forests and lakes compose an ecosystem interconnection with a high abundance of terrestrial invertebrates, which represent an outstanding resource for the aquatic fauna. ...However, there is still little quantitative information on tropical forest contribution in terms of invertebrate inputs into lacustrine systems and the factors controlling this flux.
To quantify the terrestrial invertebrate contribution into tropical lakes, we selected six lakes located in the Atlantic rainforest, south‐eastern Brazil, and used pan traps placed in the lakeshore. We focused on total abundance, biomass, and richness of insect orders. To assess the influence of forest and lake morphometry on terrestrial invertebrate inputs into lakes, we measured the forest–lake distance and considered the morphometric characteristics of each lake.
Distance from forest negatively affected the invertebrate biomass reaching the lakes. The dissimilarity across different ecotones also increased with distance from the forest. Perimeter‐to‐area ratio negatively affected the invertebrate abundance, suggesting that more dendritic lakes receive more invertebrates from the forest.
We estimated that annually, on average 21 tons of terrestrial invertebrates fall into the studied lakes, representing a massive food resource for the aquatic ecosystem. Hence, if the distance from the forest increases due, for instance, to severe drought or deforestation, it will create an herbaceous environment unable to provide such a quantity of insects to the water ecosystems, compromising aquatic and terrestrial trophic webs dynamics.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
We studied the importance of environmental drivers for the seasonal dynamics of gross primary production (GPP), ecosystem respiration (R), and net ecosystem production in surface waters of two ...tropical lakes in southeast Brazil (Carioca—CA; and Dom Helvécio—DH), 2011 and 2012, using high frequency measurements of dissolved oxygen. Metabolic rates were approximately twice as high during the fully mixed winter periods, compared to the summer periods. For both lakes, GPP was approximately 30% lower during the warmer and dryer spring of 2012 compared to 2011. Seasonal changes in GPP and R were negatively correlated to water column stability (GPP r = –0.82, p < 0.001; Rr = –0.80, p < 0.001). Periods with high stability coincided with warm waters which reduced mixing and internal inputs of nutrients from hypolimnetic waters. GPP was accordingly suppressed in both lakes during summer due to a combination of nutrient depletion and photo-inhibition, which was more pronounced during summer. These conditions were more prevailing during the warm and dry year of 2012, indicating ecosystem responses in carbon cycling to the ongoing regional climate changes.
This resource contains a checklist of the benthic macroinvertebrate community sampled biannually from 1999 to 2010 in eight natural lakes from the middle Rio Doce Valley lake system and eight river ...segments in the Piracicaba River basin (sub-basin of Doce river), Minas Gerais State, Brazil. Three of the lakes are located inside a protected state park and are surrounded by preserved vegetation (Atlantic Forest). The other five lakes are in private properties, surrounded by Eucalyptus plantations. The seven stretches of rivers have a distinct degree of anthropogenic impacts. Samples were collected with a kick net and fixed with formaldehyde solution. Four phyla were represented: Mollusca, Annelida, Arthropoda, and Platyhelminthes. For Insecta, 76 families were identified, one family was identified for Crustacea, and nine families were identified for Mollusca. This subproject belongs to the International Long-Term Ecological Research Project (ILTER—Programa de Pesquisas Ecológicas de Longa Duração—PELD) site 4.
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