scholarly journals Natural events of anoxia and low respiration index in oligotrophic lakes of the Atlantic Tropical Forest

2012 ◽  
Vol 9 (8) ◽  
pp. 2879-2887 ◽  
Author(s):  
H. Marotta ◽  
M. L. S. Fontes ◽  
M. M. Petrucio
Keyword(s):  
Tropical Forest ◽  
Thermal Stratification ◽  
Tropical Lakes ◽  
Oligotrophic Lakes ◽  
Natural Event ◽  
Deep Waters ◽  
Anoxic Events ◽  
Dry Seasons ◽  
Average Standard Error ◽  
Dry And Rainy Seasons

Abstract. Hypoxia is a well-recognized condition reducing biodiversity and increasing greenhouse gas emissions in aquatic ecosystems, especially under warmer temperatures of tropical waters. Anoxia is a natural event commonly intensified by human-induced organic inputs in inland waters. Here, we assessed the partial pressure of O2 (pO2) and CO2 (pCO2), and the ratio between them (represented by the respiration index, RI) in two oligotrophic lakes of the Atlantic Tropical Forest, encompassing dry and rainy seasons over 19 months. We formulated the hypothesis that thermal stratification events could be coupled to natural hypoxia in deep waters of both lakes. Our results indicated a persistence of CO2 emissions from these tropical lakes to the atmosphere, on average ± standard error (SE) of 17.4 mg C m−2 h−1 probably subsided by terrestrial C inputs from the forest. Additionally, the thermal stratification during the end of the dry season and the rainy summer was coupled to anoxic events and very low RI in deep waters, and to significantly higher pO2 and RI at the surface (about 20 000 μatm and 1.0, respectively). In contrast, the water mixing during dry seasons at the beginning of the winter was related to a strong destratification in pO2, pCO2 and RI in surface and deep waters, without reaching any anoxic conditions throughout the water column. These findings confirm our hypothesis, suggesting that lakes of the Atlantic Tropical Forest could be dynamic, but especially sensitive to organic inputs. Natural anoxic events indicate that tropical oligotrophic lakes might be highly influenced by human land uses, which increase organic discharges into the watershed.

scholarly journals Natural events of anoxia and low respiration index in oligotrophic lakes of the Atlantic Tropical Forest

2012 ◽  
Vol 9 (4) ◽  
pp. 4225-4244 ◽  
Author(s):  
H. Marotta ◽  
M. L. S. Fontes ◽  
M. M. Petrucio
Keyword(s):  
Tropical Forest ◽  
Thermal Stratification ◽  
Tropical Lakes ◽  
Oligotrophic Lakes ◽  
Natural Event ◽  
Greenhouse Gases Emissions ◽  
Deep Waters ◽  
Anoxic Events ◽  
Average Standard Error ◽  
In The Beginning

Abstract. Hypoxia is a well-recognized condition reducing biodiversity and increasing greenhouse gases emissions in aquatic ecosystems, especially under warmer temperatures of tropical waters. Anoxia is a natural event commonly intensified by human-induced organic inputs in inland waters. Here, we assessed the partial pressure of O2 (pO2) and CO2 (pCO2) and the ratio between both (represented by the respiration index, RI) in two oligotrophic lakes of the Atlantic Tropical Forest, encompassing dry and rainy seasons over 19 months. We formulated the hypothesis that thermal stratification events could be coupled to natural hypoxia in deep waters of both lakes. Our results indicated a persistence of CO2 emissions from these tropical lakes to the atmosphere, on average ± standard error (SE), 2.3 (±0.3) mmol m−2 h−1 probably subsided by terrestrial C inputs from the forest. Additionally, the thermal stratification during the end of the dry season and the rainy summer was coupled to anoxic events and very low RI in deep waters, and to significantly higher pO2 and RI at the surface (about 20 000 μatm and 1.0, respectively). In contrast, the water mixing during dry seasons in the beginning of the winter was related to a strong destratification in pO2, pCO2 and RI in surface and deep waters, without reaching any anoxic conditions throughout the water column. These findings confirm our hypothesis, suggesting that lakes of the Atlantic Tropical Forest could be dynamic, but especially sensitive to organic inputs. Natural anoxic events indicate that tropical oligotrophic lakes might be highly influenced by human land uses, which increase organic discharges into the watershed.

Simulations of water quality and oxythermal cisco habitat in Minnesota lakes under past and future climate scenarios

2012 ◽  
Vol 47 (3-4) ◽  
pp. 375-388 ◽  
Author(s):  
Xing Fang ◽  
Shoeb R. Alam ◽  
Heinz G. Stefan ◽  
Liping Jiang ◽  
Peter C. Jacobson ◽  
...  
Keyword(s):  
Water Quality ◽  
Lake Water ◽  
Fish Habitat ◽  
Future Climate ◽  
Climate Scenarios ◽  
Quality Model ◽  
Lake Water Quality ◽  
Oligotrophic Lakes ◽  
Minnesota Lakes ◽  
Average Standard Error

A deterministic, process-oriented, dynamic and one-dimensional year-round lake water quality model, MINLAKE2010, was developed for water temperature (T) and dissolved oxygen (DO) simulations to study impacts of climate warming on lake water quality and cisco fish habitat. The DO model is able to simulate metalimnetic oxygen maxima in vertical DO profiles of oligotrophic lakes. The model was calibrated with profile data from the 28 study lakes in Minnesota; two-thirds of them are deep mesotrophic/oligotrophic lakes that support cisco, a coldwater fish species. The average standard error of estimate against measured data was 1.47 °C for T and 1.50 mg/L for DO. Oxythermal habitat parameter TDO3 (T at DO = 3 mg/L) was determined from simulated daily T and DO profiles under past and future climate scenarios in the 28 study lakes. Average annual maximum TDO3 (TDO3AM) for the 28 study lakes is projected to increase on the average of 3.2 °C under the MIROC 3.2 future scenario, while the occurrence day of TDO3AM is not much different under past and future climate scenarios. Both physical processes (mixing characteristics related to lake geometry ratio) and trophic status control temperature and DO characteristics and then affect cisco habitat in a lake.

scholarly journals Zooplankton biomass of reservoirs in different trophic conditions in the State of São Paulo, Brazil

2006 ◽  
Vol 66 (1b) ◽  
pp. 337-350 ◽  
Author(s):  
S. Sendacz ◽  
S. Caleffi ◽  
J. Santos-Soares
Keyword(s):  
Sao Paulo ◽  
Zooplankton Biomass ◽  
Dry Season ◽  
The State ◽  
Numerical Density ◽  
Calanoid Copepods ◽  
Trophic Conditions ◽  
Density Data ◽  
Dry Seasons ◽  
Dry And Rainy Seasons

This paper reports on a study involving an estimate of the biomass of rotifers, cladocerans, and cyclopoid and calanoid copepods found in reservoirs in different trophic conditions, comparing and relating numerical density data and pointing out differences between the dry and rainy seasons. In terms of numerical densities, both reservoirs were dominated by rotifers, although cladocerans represented a higher biomass in the oligotrophic environment in both seasons. In the eutrophic environment, higher biomass values were found for cyclopoids during the dry season and for cladocerans during the rainy one. Different biomass patterns were observed relating to both the trophic conditions and the rainy and dry seasons.

scholarly journals Cyathostomin larvae: presence on Brachiaria humidicola grass during the rainy and dry seasons of Brazil

2012 ◽  
Vol 21 (1) ◽  
pp. 28-31
Author(s):  
Claudia Navarro dos Santos ◽  
Luciene Soares de Souza ◽  
Vivian Suane de Freitas Vieira ◽  
Jairo Pinheiro ◽  
Maria de Lurdes de Azevedo Rodrigues
Keyword(s):  
Climatic Conditions ◽  
Dry Season ◽  
Southeastern Brazil ◽  
Tropical Region ◽  
Brachiaria Humidicola ◽  
Significant Difference ◽  
Dry Seasons ◽  
The Mean ◽  
Janeiro State ◽  
Dry And Rainy Seasons

The presence of cyathostomin larvae is directly associated to climatic conditions of each region. This study aimed to evaluate the ecology of infective larvae on Brachiaria humidicola during the dry and rainy seasons from October 2007 to September 2008 in a tropical region, Rio de Janeiro state, southeastern Brazil. Stools were collected from the rectum of horses naturally infected with cyathostomins at the beginning of the rainy season (October to March) and dry season (April to September). They were divided into four samples of 500 g and deposited on a grass patch of B. humidicola. Seven days later and every 15 days thereafter samples of feces and grass were collected and processed by the Baermann technique. The mean number of larvae recovered from the grass varied according to the season, with greater recovery of larvae during the peak of the dry season (14,700 L3.kg-¹ DM). There was a statistically significant difference between L3 recovered from feces and grass, but not between L3 recovered from the grass base and apex. These results show that the region’s climate favors the development and survival of infective cyathostomin larvae throughout the year, with a greater number of larvae during the dry season.

Classification and ecological relationships of seed dormancy in a seasonal moist tropical forest, Panama, Central America

2007 ◽  
Vol 17 (2) ◽  
pp. 127-140 ◽  
Author(s):  
Adriana Sautu ◽  
Jerry M. Baskin ◽  
Carol C. Baskin ◽  
Jose Deago ◽  
Richard Condit
Keyword(s):  
Tropical Forest ◽  
Seed Dormancy ◽  
Tree Species ◽  
Panama Canal ◽  
Physical Dormancy ◽  
Ecological Relationships ◽  
Morphophysiological Dormancy ◽  
Large Size ◽  
Physiological Dormancy ◽  
Dry Seasons

AbstractThis is the first study to determine the class of seed dormancy (or non-dormancy) of a large number of native tree species in a tropical forest, the seasonal moist tropical forest of the Panama Canal Watershed (PCW), or to test the relationships between class of dormancy (or non-dormancy) and various seed and ecological characteristics of the constituent species. Fresh seeds of 49 of 94 tree species were non-dormant (ND), and 45 were dormant (D). Seeds of 23 species had physiological dormancy (PD), 13 physical dormancy (PY), two morphological dormancy (MD), 7 morphophysiological dormancy (MPD) and none combinational dormancy (PY+PD). Seeds with PY were significantly smaller ( < 0.1 g) and drier (moisture content < 16%) at maturity than those that were ND or in the other D classes. Seeds of 62, 42 and 53% of species dispersed in the early rainy, late rainy (LRS) and dry seasons, respectively, were ND. The majority (61%) of species with PD seeds, but only 17% of those with PY seeds, were dispersed in the LRS. The proportion of species with ND seeds was higher in large-size (63%) than in mid-size (35%) and understorey (17%) trees, but differed only slightly between non-pioneers (58%) and pioneers (54%). The proportion of species with D seeds increased only slightly through a precipitation gradient of about 3100 to 1900 mm in the PCW; however, PY increased from 19 to 32% and PD decreased from 63 to 44%.

scholarly journals Occurrence of Four Dengue Virus Serotypes and Chikungunya Virus in Kilombero, Tanzania during Dengue Outbreak in 2018

2020 ◽  
Author(s):  
Beatrice Chipwaza ◽  
Robert David Sumaye ◽  
Maja Weisser ◽  
Winfrid Gingo ◽  
Nicholas Kim-Wah Yeo ◽  
...  
Keyword(s):  
Large Scale ◽  
Age Groups ◽  
Cross Sectional Study ◽  
Cross Sectional ◽  
Denv Serotypes ◽  
First Occurrence ◽  
Dry Seasons ◽  
Dengue Virus Serotypes ◽  
And Gender ◽  
Dry And Rainy Seasons

AbstractBackgroundDengue and Chikungunya viruses can cause large-scale epidemics with attack rates exceeding 80%. In Tanzania, there have been repeated outbreaks of dengue fever, the most recent one in 2018 and 2019 mostly reported in coastal areas. Despite its importance, there is limited knowledge on epidemiology of dengue (DENV) and chikungunya (CHIKV) in Tanzania. This study was conducted to investigate the prevalence of DENV and CHIKV in Kilombero district, South-Eastern Tanzania.MethodsA cross-sectional study was conducted at Kibaoni Health Center, in Kilombero district, in the rainy and dry seasons of 2018. Febrile patients of any age and gender were enrolled. Blood samples were taken and screened for DENV and CHIKV viral RNA by real-time RT-PCR assays.ResultsA total of 294 patients were recruited. Most were females (65%), and aged between 14⍰25 years (33%). DENV and CHIKV were detected in 29 (9.9%) and 3 (1.0%) patients, respectively. DENV was detected across all age groups and during both dry and rainy seasons. Although all four DENV serotypes were detected, serotypes 1 and 3 dominated and were present in 14 patients (42.4%) each. Additionally, the study showed DENV-1 and DENV-3 co-infections.ConclusionThis study reveals the co-circulation of all four DENV serotypes and CHIKV in Kilombero district. Importantly, we report the first occurrence of DENV-4 in Tanzania. Unlike previous DENV outbreaks caused by DENV-2, the 2018 outbreak was dominated by DENV-1 and DENV-3. Occurrence of all serotypes suggests the possibility of having severe clinical outcomes in future DENV epidemics in Tanzania.

scholarly journals Seasonal and microclimatic effects on leaf beetles (Coleoptera, Chrysomelidae) in a tropical forest fragment in northeastern Mexico

ZooKeys ◽  
2022 ◽  
Vol 1080 ◽  
pp. 21-52
Author(s):  
José Norberto Lucio-García ◽  
Uriel Jeshua Sánchez-Reyes ◽  
Jorge Víctor Horta-Vega ◽  
Jesús Lumar Reyes-Muñoz ◽  
Shawn M. Clark ◽  
...  
Keyword(s):  
Tropical Forest ◽  
Rainy Season ◽  
Close Association ◽  
Dry Season ◽  
Great Sensitivity ◽  
Heat Index ◽  
Forest Fragment ◽  
Leaf Beetles ◽  
Northeastern Mexico ◽  
Dry Seasons

Leaf beetles (Coleoptera: Chrysomelidae) constitute a family of abundant, diverse, and ecologically important herbivorous insects, due to their high specificity with host plants, a close association with vegetation and a great sensitivity to microclimatic variation (factors that are modified gradually during the rainy and dry seasons). Therefore, the effects of seasonality (rainy and dry seasons) and microclimate on the community attributes of chrysomelids were evaluated in a semideciduous tropical forest fragment of northeastern Mexico. Monthly sampling was conducted, between March 2016 and February 2017, with an entomological sweep net in 18 plots of 20 × 20 m, randomly distributed from 320 to 480 m a.s.l. Seven microclimatic variables were simultaneously recorded during each of the samplings, using a portable weather station. In total, 216 samples were collected at the end of the study, of which 2,103 specimens, six subfamilies, 46 genera, and 71 species were obtained. The subfamily Galerucinae had the highest number of specimens and species in the study area, followed by Cassidinae. Seasonality caused significant changes in the abundance and number of leaf beetle species: highest richness was recorded in the rainy season, with 60 species, while the highest diversity (lowest dominance and highest H’ index) was obtained in the dry season. Seasonal inventory completeness of leaf beetles approached (rainy season) or was higher (dry season) than 70%, while the faunistic similarity between seasons was 0.63%. The outlying mean index was significant in both seasons; of the seven microclimatic variables analyzed, only temperature, heat index, evapotranspiration and wind speed were significantly related to changes in abundance of Chrysomelidae. Association between microclimate and leaf beetles was higher in the dry season, with a difference in the value of importance of the abiotic variables. The results indicated that each species exhibited a different response pattern to the microclimate, depending on the season, which suggests that the species may exhibit modifications in their niche requirements according to abiotic conditions. However, the investigations must be replicated in other regions, in order to obtain a better characterization of the seasonal and microclimatic influence on the family Chrysomelidae.

scholarly journals Diversity of robber flies (Diptera: Asilidae) in a tropical deciduous forest of central Mexico

2020 ◽  
pp. 1-13
Author(s):  
Frida Alejandra Bello-Morales ◽  
César Antonio Sandoval-Ruiz ◽  
Alejandro Estrada
Keyword(s):  
Deciduous Forest ◽  
Tropical Deciduous Forest ◽  
Central Mexico ◽  
Ecological Interactions ◽  
Ecological Role ◽  
Important Group ◽  
Robber Flies ◽  
Insect Populations ◽  
Dry Seasons ◽  
Dry And Rainy Seasons

Robber flies are an important group in ecosystems, because of their ecological role as predators, thus contributing to maintain a balance in insect populations. Nevertheless, little is known about their diversity and ecological interactions in Mexico. In this study, we analyzed the structure of a community of robber flies collected during three years in a tropical deciduous forest of central Mexico. In this type of vegetation, the dry and rainy seasons are contrasting and generate drastic biotic and abiotic changes that could impact on robber fly populations. Therefore, we compared the structure of the robber fly community across three seasons: cold, dry, and rainy. We collected a total of 191 individuals which included eight species and 21 morphospecies. The rainy season presented higher species richness and diversity, as well as a species composition that differed from that of the cold and dry seasons. However, abundance did not vary significantly across seasons. We also record 14 genera and ten species previously unregistered in the state of Puebla.

scholarly journals Diversity of Ordo Lepidoptera In Mangkok Resort, Sebangau National Park, Central Kalimantan

2018 ◽  
Vol 2 (2) ◽  
Author(s):  
Achmad Faqih
Keyword(s):  
Relative Abundance ◽  
Forest Restoration ◽  
National Park ◽  
Diversity Index ◽  
Butterfly Species ◽  
Diversity Analysis ◽  
Central Kalimantan ◽  
Average Value ◽  
Dry Seasons ◽  
Dry And Rainy Seasons

The diversity of the butterfly in Sebangau National Park, particularly in the Mangkok Resort area has different morphological features in each species. The differences distinguish each species between families. Steps to know the diversity species or populations can be measured and identified based on similarities or differences in Shannon-Wiener's diversity analysis. This research was conducted by random purposive sampling using insect net and food trap. Observation and sampling were conducted in the area of natural forest and forest restoration during the dry and rainy seasons. The results showed, the species obtained and identified as many as 25 species from 4 families namely Papilionidae, Nymphalidae, Pieridae and Lycaenidae. Butterflies obtained from food trap are 24 individuals from 5 species. The level of diversity, evenness and richness of the species of butterflies in each region during the rainy and dry seasons which are the location of the study are included in the "medium" category with the average value of the diversity index, the evenness and the richness of the butterfly species of 2.502. The relative dominance and relative abundance of the butterfly species in the Mangkok resort shows no species communities that are extreme dominant from species other.

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