scholarly journals Interactions between different biological forms of aquatic macrophytes in a eutrophic tropical reservoir in Northeastern Brazil

2017 ◽  
Vol 65 (3) ◽  
pp. 1095 ◽  
Author(s):  
Thainá Alves Lycarião ◽  
Ênio Wocyli Dantas
Keyword(s):  
Aquatic Plants ◽  
Hydrological Cycle ◽  
Submerged Macrophytes ◽  
Correlation Coefficients ◽  
Dry Weight ◽  
Dry Season ◽  
Northeastern Brazil ◽  
Tropical Reservoir ◽  
Emergent Plants ◽  
Floating Macrophytes

The aquatic plants and biological processes have different interactions and their knowledge may contribute to the understanding of environmental dynamics in wetlands. The aim of this study was to report the type of interactions that different biological forms of macrophytes stand in the eutrophic tropical reservoir of Penha reservoir, Northeastern Brazil. Data collection was captured every two months from October 2009 to October 2010, considering the hydrological cycle in one-year period. For this, twelve perpendicular transects (separated by 10 m) at the reservoir’s water edge were defined; each transect had two plots of 625 cm² (25 x 25 cm, separated by one meter) from which samples were obtained. Plants were collected and transported in identified plastic bags for subsequent quantification of the dry weight biomass; additionally, pressed samples were made in the field for identification purposes. The relative interaction index (RII) was used to identify the existence of positive and/or negative interactions between the biomass of the biological forms of aquatic plants. Student’s t-tests were used to analyze variations in the abiotic data and biomass over time, and to determine differences between the dry and rainy seasons. Pearson and Spearman correlation coefficients were calculated to determine correlations between the biological forms and the biomass of the macrophytes, as well as environmental variables and RII. In the dry season, the environment was mainly composed of floating macrophytes (1 013.98 g/m²), with mats of submerged macrophytes (98.18 g/m²) that demonstrated a range of positive (RII= 1.0) to negative (RII= -0.2) interactions. The biomass of emergent macrophytes increased throughout the dry season (4.87 to 106.91 g/m²) due to the nurse plant effect that served as a substratum (RII= 1.0). During the rainy season the biomass of submerged macrophytes was reduced by 97 % due to direct and indirect relationships (RII= -1.0) to other macrophytes. Rainfall and emergent plants contributed to a reduction in the biomass of floating macrophytes (19.16 g/m²). The emergence of a third group of plants (emergent) lead floating plants to occupy other areas and excluded submerged plants. Overall, the interactions among plants within ecosystems were not definite due to stand composition and seasonality.

EMERGENCE AND SEEDLING GROWTH OF INBRED LINES OF CORN AT SUBOPTIMAL ROOT-ZONE TEMPERATURES

1987 ◽  
Vol 67 (2) ◽  
pp. 409-415 ◽  
Author(s):  
A. MENKIR ◽  
E. N. LARTER
Keyword(s):  
Zea Mays ◽  
Seedling Growth ◽  
Root Zone ◽  
Seedling Emergence ◽  
Correlation Coefficients ◽  
Dry Weight ◽  
Inbred Lines ◽  
Root Zone Temperature ◽  
Emergence Percentage ◽  
Zone Temperature

Based on the results of an earlier paper, 12 inbred lines of corn (Zea mays L.) were evaluated for emergence and seedling growth at three controlled root-zone temperatures (10, 14, and 18 °C). Low root-zone temperatures, 10 and 14 °C, were detrimental to emergence, seedling growth, and root growth of all inbred lines. Differential responses of inbred lines were observed within each temperature regime. The differences in seedling emergence among lines became smaller with increasing root-zone temperature, while the reverse was true for seedling dry weight. Simple correlation coefficients showed a significantly (P = 0.05) negative association between emergence percentage and emergence index (rate). Neither of these two emergence traits was significantly correlated with seedling dry weights. Seedling dry weights were significantly (P = 0.01) and positively associated with root dry weights. Two inbred lines exhibited good tolerance to low root-zone temperatures, viz. CO255 and RB214. A significant and positive correlation existed between emergence percentage at a root-zone temperature of 10 °C and field emergence in test with the same genotypes reported earlier. Selection at a root-zone temperature of 10 °C for a high percentage of seedling emergence, therefore, could be effective in identifying genotypes capable of germinating in cool soils. Furthermore, the significantly (P = 0.01) positive relationship between seedling dry weights at all root-zone temperatures and those from the field test suggest that strains with vigorous seedling growth in the field could be identified using low root-zone temperature regimes.Key words: Zea mays, root-zone temperature, cold tolerance

Use of aquatic plants by moose: sodium hunger or foraging efficiency?

1993 ◽  
Vol 71 (12) ◽  
pp. 2345-2351 ◽  
Author(s):  
James G. MacCracken ◽  
Victor Van Ballenberghe ◽  
James M. Peek
Keyword(s):  
Aquatic Plants ◽  
Habitat Preferences ◽  
Indirect Evidence ◽  
Foraging Efficiency ◽  
Aquatic Habitats ◽  
Forage Production ◽  
Sex Structure ◽  
Emergent Plants ◽  
Terrestrial Habitats ◽  
Emergent Species

Use of submergent aquatic plants by North American moose (Alces alces) has been linked to sodium hunger. Habitat preferences, seasonal diets, forage abundance and quality, and population surveys indicated that emergent plants in small shallow ponds were important to moose on the Copper River Delta, Alaska. However, sodium was abundant in terrestrial browse. We propose that foraging in aquatic habitats, particularly on emergent species, may be highly efficient based on the following habitat attributes and behavioral observations: (i) ponds dominated by either emergent or submergent species produced about 4 times more forage than terrestrial habitats, (ii) emergent and submergent plants were more digestible and had higher concentrations of minerals than browse, (iii) use of aquatic habitats followed trends in forage production over the growing season, (iv) indirect evidence suggested that forage intake rates were greater in aquatic habitats, and (v) use of aquatic habitats by male and female moose was in proportion to the sex structure of the population. These data provide consistent circumstantial evidence that use of emergent species, and possibly submergents, may maximize the intake of nutrients and also reduce conflicts between cropping forage and vigilance during a foraging bout.

scholarly journals Morphofunctional changes of phytoplankton community during pluvial anomaly in a tropical reservoir

2015 ◽  
Vol 75 (3) ◽  
pp. 628-637 ◽  
Author(s):  
FRA Câmara ◽  
O Rocha ◽  
EKR Pessoa ◽  
S Chellappa ◽  
NT Chellappa
Keyword(s):  
Species Diversity ◽  
Dissolved Oxygen ◽  
Oxygen Content ◽  
Phytoplankton Community ◽  
Diversity Index ◽  
Hydrodynamic Instability ◽  
Electrical Conductance ◽  
Northeastern Brazil ◽  
Tropical Reservoir ◽  
Cyanobacterial Species

AbstractThe present study focuses on the structure and function of phytoplankton community during periods of marked changes in hydrological traits, influenced by an atypical climatic event (La Niña) and its impact on Armando Ribeiro Gonçalves Reservoir of Rio Grande do Norte, situated in the Caatinga biome of northeastern Brazil. The main questions addressed were: What are the effects of environmental factors on the temporal variation of Morphologically Based Functional Group (MBFG) of phytoplankton community? How does the composition of cyanobacterial species shift in relation to high and low trends of phytoplankton diversity? The samples were collected monthly during 2008-2009 and analyzed for pH, temperature, electrical conductivity, dissolved oxygen content and the nutrients, such as, nitrate-nitrogen, ammoniacal nitrogen, total nitrogen and orthophosphate. Phytoplankton samples were collected for both qualitative and quantitative analyses to evaluate species richness index and species diversity index. The data was divided into two distinct hydrodynamic periods of instability and stability. The results demonstrate considerable changes in dissolved oxygen content, water transparency and nitrogen nutrients, which directly influenced the MBFG of phytoplankton community in space and time. The instability of reservoir water was caused by heavy rainfall, which exerts atypical external disturbances. The seasonal variation of MBFG demonstrates a change in cyanobacterial composition and their diversity during instability and stability periods. MBFG VII, composed by colonial cyanobacteria with mucilage, was associated with reduced values of electrical conductance and alterations in pH. The predominance of filamentous species with heterocyst (MBFG III) occurs only during the hydrodynamic stability period and did not show significant association with analyzed parameters. The co-dominance of MBGFs III, V and VII along with high species diversity of phytoplankton community occurred during the second hydrodynamic instability period which was associated with the reduction in water temperature. It is concluded that the decrease in cyanobacterial species dominance and the general increase in the diversity of phytoplankton community are influenced by pluvial anomaly. The higher water level during the period of pluvial anomaly resulted in nutrient pulse and the mixing of water column in the reservoir, which determined the MBPG phytoplankton community distribution.

scholarly journals Temporal influence on foraging strategies, territoriality and nomadic tendencies of Snail Kite, Rosthramus sociabilis (Viellot, 1817) in an urban Neotropical wetland

2012 ◽  
Vol 72 (2) ◽  
pp. 235-241 ◽  
Author(s):  
SR Posso ◽  
FB Cintra ◽  
J Frias
Keyword(s):  
Energy Demand ◽  
Correlation Coefficients ◽  
Dry Season ◽  
Foraging Strategies ◽  
Wet Season ◽  
Snail Kite ◽  
Foraging Area ◽  
Temporal Influence ◽  
Site Tenacity ◽  
Rainfall Variations

The foraging, territoriality and displacement of the Snail Kite were studied over 232 hours of observations in an urban lake during the dry and wet seasons. The temperature and rainfall variations were used to correlate with predation rates and the correlation coefficients were 0,39 and 0,34, respectively. Snail Kites spent more time foraging during the wet than the dry season when perching is more frequently recorded. The higher predation in the wet season can be explained by the higher abundance of apple snails and the energy demand for reproduction. In the wet season, the territories were smaller and the conspecific conflicts decreased as prey were more available. However, due to the lack of food in the dry season, intra-specific conflicts and expansion of male territories were observed and the female and immatures were expelled from their foraging area to another location. In this way, site tenacity of Snail Kites should be interpreted in relation to the variations on food and dominance gradients according to the temporal changes (time) and foraging sites (space).

Invasive Aquatic Species

2018 ◽  
pp. 338-358 ◽  
Author(s):  
Julie A. Coetzee ◽  
Martin P. Hill ◽  
Andreas Hussner ◽  
Ana L. Nunes ◽  
Olaf L.F. Weyl
Keyword(s):  
Northern Hemisphere ◽  
Native Species ◽  
Submerged Macrophytes ◽  
Economic Impacts ◽  
Freshwater Ecosystems ◽  
Aquatic Species ◽  
Anthropogenic Influences ◽  
Freshwater Invasions ◽  
Geographical Bias ◽  
Floating Macrophytes

Freshwater ecosystems are particularly susceptible to invasions by invasive non-native species (INNS) across a range of taxa, largely as a consequence of anthropogenic influences on these systems, with a number of ecological and socio-economic impacts. This chapter reviews freshwater invasive non-native species across the globe, focusing on fishes, invertebrates, floating macrophytes, and submerged macrophytes emphasising the knowledge gaps in particular that have resulted in biases inherent in assessments of freshwater invasions. These include an ecological bias because the majority of studies focus on terrestrial invasions; a geographical bias as most studies are focused on temperate northern hemisphere systems; and a taxon bias where fish invasions, populate the literature. This chapter highlights some of the approaches needed to survey, monitor, and manage INNS.

scholarly journals Limnological characteristics of a reservoir in semiarid Northeastern Brazil subject to intensive tilapia farming (Orechromis niloticus Linnaeus, 1758)

2014 ◽  
Vol 26 (1) ◽  
pp. 47-59 ◽  
Author(s):  
Luis Artur Valões Bezerra ◽  
Walt Disney Paulino ◽  
Danielle Sequeira Garcez ◽  
Helena Becker ◽  
Jorge Iván Sánchez-Botero
Keyword(s):  
Chlorophyll A ◽  
Rainy Season ◽  
Dry Season ◽  
T Test ◽  
Northeastern Brazil ◽  
Human Consumption ◽  
Temperature Conductivity ◽  
Sampling Locations ◽  
Chemical Variability ◽  
Physical And Chemical

AIM: There is currently no consensus regarding the physical and chemical variability of tropical reservoirs. In semiarid Northeastern Brazil, reservoirs are among other things used for human consumption, industrial water supply and intensive fish farming, all of which can impact water quality. The objective of this study was to evaluate the physical and chemical variability of the water in Sítios Novos, a reservoir in semiarid Northeastern Brazil, comparing samples collected in areas of intensive tilapia (Oreochromis niloticus) farming to samples from areas not directly impacted by aquaculture, in both the dry and the rainy season. METHODS: Between October 2010 and July 2011, data were collected on temperature, conductivity, pH, turbidity, salinity, chlorophyll a, dissolved oxygen, oxygen demand, total phosphorus and total nitrogen levels in the water column using a multiparametric probe at four different sampling locations. Physical and chemical differences between the four locations were evaluated with the Kruskal-Wallis (KW) test and Dunn's post test, while the t test, followed by Welchʼs correction, was used to compare samples collected in different seasons. RESULTS: No influence of intensive aquaculture was detected when comparing sampling locations near fish farms (180C and 300C) to locations not directly impacted by aquaculture (LIMN1, near the dam, and LIMN2, near the debouch of the São Gonçalo river). However, the sampling locations differed significantly (p<0.05) with regard to conductivity, pH, turbidity and chlorophyll a levels. CONCLUSIONS: The physical and chemical variability was greater between seasons than between locations when the data were analyzed with the t test. That analysis showed significant differences for 22 of 40 comparisons between the 10 physical and chemical parameters in the two seasons at the four sampling locations. In conclusion, the physical and chemical variability registered for the Sítios Novos reservoir throughout the study period indicates morphometric, meteorological and hydrological heterogeneity, with emphasis on the differences between LIMN2 and the other three sampling locations and between the rainy season and the dry season. According to the calculated trophic status index, the reservoir is supereutrophic in the rainy season and supereutrophic to hypereutrophic in the dry season.

Nitrogen and Phosphorus Removal from Simulated Wastewater with Aquatic Macrophytes

2012 ◽  
Vol 518-523 ◽  
pp. 2597-2603
Author(s):  
Na He ◽  
Zhan Xiang Sun ◽  
Yu Long Zhang ◽  
Ming Da Liu
Keyword(s):  
Aquatic Plants ◽  
Phosphorus Removal ◽  
Aquatic Macrophytes ◽  
Nitrogen And Phosphorus ◽  
Nitrogen And Phosphorus Removal ◽  
Emergent Plants ◽  
N Removal ◽  
Significant Difference ◽  
Simulated Wastewater ◽  
Floating Plants

This study focused on the comparisons between nitrogen and phosphorus removal rates from the simulated wastewater using various kinds of aquatic plants (4 emergent and 3 floating plants). Results showed that aquatic plants has a significant effect on the removal of NO3--N and TP, but has a less effect on NH4+-N. Among the four emergent plants, the order of NO3--N removal capacities was: S. sagittifolia > S. tabernaemontani > T. latifolia > A. calamus. But for TP, the order was: T. latifolia > A. calamus > S. tabernaemontani > S. sagittifolia. To the floating plants, the order of NO3--N and TP removal capacities were: E. crassipes > P. stratiotes. The ANOVA analyses showed that there was a significant difference between planted treatments and unplanted treatment for the removal of NO3--N and TP. The study suggests that the treatment of simulated wastewater using the aquatic macrophytes was effective in the removal of nutrients.

Incidence of Salmonella on Beef Carcasses Relating to the U.S. Meat and Poultry Inspection Regulations

1999 ◽  
Vol 62 (5) ◽  
pp. 467-473 ◽  
Author(s):  
JOHN N. SOFOS ◽  
SHERRI L. KOCHEVAR ◽  
J. O. REAGAN ◽  
GARY C. SMITH
Keyword(s):  
Correlation Coefficients ◽  
Total Coliform ◽  
Dry Season ◽  
Wet Season ◽  
Regulatory Requirements ◽  
E Coli ◽  
Beef Carcasses ◽  
Plate Counts ◽  
Dry Seasons ◽  
The U.S

This article is part of a major study designed to collect baseline contamination data by sampling beef carcasses in seven slaughtering plants (four steer–heifer and three cow–bull plants) during both a dry season (November to January) and a wet season (May to June). Samples (n = 30) were excised from each of three carcass anatomical sites (brisket, flank, and rump) at each of three points in the slaughtering chain (pre-evisceration, following final carcass washing, after 24-h carcass chilling). A total of 3,780 samples (100 cm2 each) were analyzed for presence of Salmonella; aerobic plate counts, total coliform counts, and Escherichia coli counts were also made. After 24-h chilling, average incidence (expressed as a percentage) of Salmonella in the brisket, flank, and rump samples, respectively, for steer–heifer carcasses was 0.8 ± 1.7, 0, and 2.5 ± 5.0 for the wet season and 0.8 ± 1.7, 0, and 0 for the dry season; the corresponding percentages for cow–bull carcasses were 4.4 ± 2.0, 2.2 ± 3.9, and 1.1 ± 1.9 for the wet season and 2.2 ± 3.9, 1.1 ± 1.9, and 0 for the dry season. Depending on plant and season, ranges of probabilities of chilled steer–heifer carcasses passing the U.S. regulatory requirements for Salmonella contamination were 0.24 to 1.0 for the brisket, 1.0 for the flank, and 0.002 to 1.0 for the rump; the corresponding ranges for the chilled cow–bull carcasses were 0.25 to 1.0, 0.25 to 1.0, and 0.70 to 1.0. When the number of positive brisket, flank, and rump samples were combined, the probabilities of passing the regulatory requirements were 0.242 to 1.0 and 0.772 to 1.0 for the wet and dry seasons, respectively, in steer–heifer plants and 0.368 to 0.974 and 0.865 to 1.0 in cow–bull plants. Correlation coefficients of aerobic plate counts, total coliform counts, and E. coli counts with Salmonella incidence were higher (P ≤ 0.05) for cow–bull samples that had increased incidence of the pathogen when compared to steer–heifer samples.

scholarly journals Seasonal dynamics of cyanobacteria in a eutrophic reservoir (Arcoverde) in a semi-arid region of Brazil

2012 ◽  
Vol 72 (3) ◽  
pp. 533-544 ◽  
Author(s):  
MC. Bittencourt-Oliveira ◽  
SN. Dias ◽  
AN. Moura ◽  
MK. Cordeiro-Araújo ◽  
EW. Dantas
Keyword(s):  
Phytoplankton Community ◽  
Climatic Factors ◽  
Principal Component ◽  
Taxonomic Composition ◽  
Dry Season ◽  
Northeastern Brazil ◽  
Cylindrospermopsis Raciborskii ◽  
Physical And Chemical Variables ◽  
Semi Arid Region ◽  
Cyanobacterial Biomass

Environmental conditions favor the predominance of dense populations of cyanobacteria in reservoirs in northeastern Brazil. The aim of this study was to understand cyanobacterial population dynamics in the rainy and dry seasons at two depths in the Arcoverde reservoir. Microalgae and cyanobacteria samples were collected during 24 hours with intervals of 4 hours (nycthemeral) at sub-surface and 10 m using a van Dorn bottle and a determined biomass. Physical and chemical variables were obtained and the data were analyzed using the principal component analysis (PCA). No nycthemeral variations in the taxonomic composition or distribution of the populations of cyanobacteria were found between the different times of day in either the rainy or dry season. In both seasons, the greatest biomass of the phytoplankton community was made up of cyanobacteria at two depths and all times of the day. Cylindrospermopsis raciborskii (Woloszynska) Seenayya et Subba Raju was dominant at all times of the day on both the surface and at the bottom. In the rainy season, the differences in cyanobacterial biomass between the surface and bottom were less significant than in the dry season. The differences in cyanobacterial biomass between surface and bottom were less pronounced than those found in the dry season. We concluded that a) physical variables better explain the alterations of species in the phytoplankton community in an environment dominated by cyanobacteria throughout the year; b) seasonal climatic factors associated to periods of stratification and de-stratification are important for alterations in the community and variations in biomass and, c) the turbidity caused by rainfall favored the emergence and establishment of other cyanobacteria, especially Planktothrix agardhii (Gomont) Anagnostidis & Komárek.

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