scholarly journals Influence of river discharge on phytoplankton structure and nutrient concentrations in four tropical semiarid estuaries

2016 ◽  
Vol 64 (1) ◽  
pp. 37-48 ◽  
Author(s):  
Hortência de Sousa Barroso ◽  
Helena Becker ◽  
Vânia Maria Maciel Melo
Keyword(s):  
Urban Areas ◽  
Rainy Season ◽  
River Discharge ◽  
Inorganic Nitrogen ◽  
Dry Season ◽  
Northeastern Brazil ◽  
Nutrient Concentrations ◽  
Freshwater Species ◽  
Rainy Period ◽  
Phytoplankton Structure

Abstract This study evaluated changes in phytoplankton and nutrients after an increase in river discharge in four estuaries of northeastern Brazil. Samples were taken during a markedly freshwater-deprived period (Nov/2010, dry season), and during a rainy season (May/2011). While two estuaries are located in urban areas (Ceará - CE and Cocó - CO), the others are markedly freshwater-deprived (Pacoti - PAC and Pirangi - PIR). Our findings indicate that increased freshwater had opposing effects on estuaries impacted by anthropogenic discharges (CO, CE and PIR) compared with the other, less impacted (PAC). In CO and CE, the freshwater flow during the rainy period had a nutrient diluting effect and controlled phytoplankton blooms. In PIR, only phosphorus and inorganic nitrogen decreased in the rainy season. In contrast, an increase of all nutrients was observed in PAC, and of TN in PIR, followed by an increase in phytoplankton biomass. In the rainy season, eutrophic freshwater species dominated in all the estuaries. In the dry season, blooms of Cryptomonas/Rhodomonas and Synechocystis aquatilis were, respectively, observed in CE and CO. Also in the dry season, PAC and PIR had a predominance of marine species under a condition of hypersalinity. Canonical correspondence analysis suggested the variation observed for salinity, silica, and TN are the main driver of phytoplankton structure.

scholarly journals Thermal performance and concentration of gases in facilities for pigs in semiarid region from State of Paraiba - Brazil

2012 ◽  
Vol 32 (1) ◽  
pp. 30-37 ◽  
Author(s):  
Dermeval A. Furtado ◽  
Daniele Amancio ◽  
José W. B. do Nascimento ◽  
Josivanda P. Gomes ◽  
Rafael C. Silva
Keyword(s):  
Carbon Monoxide ◽  
Thermal Comfort ◽  
Rainy Season ◽  
Dry Season ◽  
International Standards ◽  
Semiarid Region ◽  
Thermal Discomfort ◽  
Rainy Period ◽  
Globe Temperature ◽  
The Times

The study was conducted in a facility for pigs during the nursery and finishing in the town of 'Montadas', in the semiarid of the state of Paraiba, Brazil, in the rainy and dry season, aiming to evaluate the concentration of oxygen, methane, carbon monoxide and ammonia, and the bioclimatic indexes: ambient temperature (AT), relative humidity (RH) and the index of black globe temperature and humidity (IBGTH). These indexes differed significantly (P>0.05) between the periods and times. The AT in the rainy season was in the thermal comfort zone(TCZ) in most of the times in the nursery; for the finishing phase, thermal discomfort occurred; during the dry season, there was thermal comfort in the nursery phase; in the finishing phase the thermal discomfort occurred at all times. In the rainy season, the IBGTH was in TCZ; in the dry season, it was above the TCZ. The RH in the rainy period was in the TCZ; in the dry season, in most of the times, below the range of the TCZ. The concentration of gases showed no differences (P > 0.05) between periods and between the times, and the carbon monoxide, hydrogen sulfide and methane were below 1.0 ppm, and the ammonia showed a mean of 5.2 ppm. None of the analyzed gases exceeded the limits established by Brazilian and international standards for animals and workers.

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.

scholarly journals Spatial and temporal variation of phytoplankton in a tropical eutrophic river

2016 ◽  
Vol 76 (3) ◽  
pp. 600-610 ◽  
Author(s):  
L. M. Santana ◽  
M. E. B. Moraes ◽  
D. M. L. Silva ◽  
C. Ferragut
Keyword(s):  
River Flow ◽  
Light Availability ◽  
Abundant Species ◽  
Northeastern Brazil ◽  
Spatial And Temporal Variation ◽  
Rainy Period ◽  
Lotic Ecosystem ◽  
Phytoplankton Structure ◽  
Accumulated Rainfall ◽  
Eutrophic River

Abstract This study aims to evaluate the environmental factors determining of the changes in phytoplankton structure in spatial (upper, middle and lower course) and seasonal (dry and rainy period) scales in a eutrophic river (Almada River, northeastern Brazil). In the study period, total accumulated rainfall was below of the historic average, resulting in flow reduction, mainly in rainy period. High orthophosphate concentration was found at the sampling sites. Phytoplankton chlorophyll a increased from upstream to downstream. Geitlerinema splendidum (S1) and Chlamydomonas sp. (X2) were the most abundant species in the upper course and several species of diatoms (D), Euglenophyceae (W1, W2) and Chlorophyceae (X1) in the middle and lower course. The functional groups were found to be characteristic of lotic ecosystem, shallow, with low light availability, rich in organic matter and eutrophic environments. We conclude that phytoplankton community structure was sensitive to change of the river flow and nutrient availability in spatial and seasonal scale in a tropical river.

The instantaneous transport of inorganic and organic material in a highly polluted tropical estuary

2013 ◽  
Vol 64 (6) ◽  
pp. 562 ◽  
Author(s):  
Carlos E. D. Noriega ◽  
Marilene Felipe Santiago ◽  
Patrícia Façanha ◽  
Maria da Glória Gonçalves da Silva Cunha ◽  
Rodolfo Araújo da Silva ◽  
...  
Keyword(s):  
Chlorophyll A ◽  
Coastal Area ◽  
Rainy Season ◽  
Phytoplankton Biomass ◽  
Dry Season ◽  
Tropical Estuary ◽  
Liquid Transport ◽  
Water Renewal ◽  
Rainy Period ◽  
Dissolved Inorganic Nutrients

The contribution of the estuarine channel of Recife harbour to the eutrophication of the Recife coastal area was evaluated by quantifying the instantaneous transport of salt, dissolved inorganic nutrients (PO4–, SiOH4, NO3–, NO2– and, NH4+), material in suspension, Chlorophyll-a, pico–nanoplankton and microplankton during the rainy (June 2007) and dry (November 2007) seasons. The results showed that all of the dissolved nitrogenated nutrients, the silicate and the material in suspension had higher concentrations during the rainy season, whereas the phosphate and Chlorophyll-a (both the total and the pico–nanoplankton and microplankton fractions) showed greater concentrations during the dry season. All of the materials considered were exported to the sea except for Chlorophyll-a (pico–nanoplankton and microplankton fractions) during the dry season, when these materials were imported into the area. The total liquid transport in the rainy season was three times higher than that found for the dry season. Silicate represented nearly 85% of the total exported material during the rainy period, whereas during the dry season, phosphate and silicate represented 79% of the total exported material. The stratification and circulation processes indicated a well mixed environment. The water-renewal rate was low, as demonstrated by the input of phytoplankton biomass during November. The area was characterised as eutrophic during the months investigated.

scholarly journals SPATIAL AND TEMPORALVARIATION OF DISSOLVED INORGANIC NUTRIENTS, AND CHLOROPHYLL-α IN A TROPICAL ESTUARY IN NORTHEASTERN BRAZIL: DYNAMICS OF NUTRIENT REMOVAL

2015 ◽  
Vol 63 (1) ◽  
pp. 1-15 ◽  
Author(s):  
Maria Aparecida Macedo Silva ◽  
Marcelo F. L. Souza ◽  
Paulo C. Abreu
Keyword(s):  
Nutrient Removal ◽  
Organic Phosphorus ◽  
Inorganic Nitrogen ◽  
Salinity Gradient ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
River Estuary ◽  
Temporal Distribution ◽  
Northeastern Brazil ◽  
Nutrient Concentrations

Monthly sampling campaigns were carried out between February 2010 and January 2011 to evaluate the spatial and temporal distribution of nutrients (ammonium, nitrite, nitrate, dissolved organic nitrogen, phosphate, dissolved organic phosphorus and silicate) and chlorophyll-α along a salinity gradient in the tropical Cachoeira River estuary, subject to the untreated effluents of a sewage treatment plant (STP). During the study period the lowest and highest river discharge occurred in February and April 2010, respectively. High river outflow promoted increased concentrations of inorganic nitrogen and silicate but did not affect the concentration of phosphate. Based on the chlorophyll-α concentration the estuary may be classified as eutrophic / hypereutrophic in its inner portion and mesotrophic in the lower region. The inner portion is more affected by the nutrient load carried out by the river and STP, while dilution by seawater contributed to the reduction of the nutrient concentrations in the lower reaches of the estuary. The results indicate that nutrient uptake by the phytoplankton is the most effective dissolved inorganic nutrient removal processes, especially for phosphate. Mixing diagrams suggest that the coupling of nitrification and denitrification processes is also responsible for the elimination of nitrogen from this ecosystem.

scholarly journals Temporal variation in the phytoplankton community of Acapulco Bay, Mexico

2012 ◽  
Vol 3 (1) ◽  
pp. 4 ◽  
Author(s):  
Agustín A. Rojas-Herrera ◽  
Juan Violante Gonzalez ◽  
Sergio García-Ibáñez ◽  
Víctor M.G. Sevilla-Torres ◽  
Jaime S. Gil-Guerrero ◽  
...  
Keyword(s):  
Species Composition ◽  
Temporal Variation ◽  
Rainy Season ◽  
Phytoplankton Community ◽  
Species Abundance ◽  
Sampling Period ◽  
Dry Season ◽  
Nutrient Concentrations ◽  
Diatom Species ◽  
Oceanic Environments

<p>Species composition and abundance of the phytoplankton community in Acapulco Bay, Mexico, were studied from May to December 2009. Samples were collected at 5 stations (4 coastal and 1 oceanic) at 3 depths (1, 5 and 10 m). Eighty-seven species were identified: 54 dinoflagellates, 32 diatoms and 1 silicoflagellate. The community was structured mainly by adiaphoric species, that is, species adapted to both neritic and oceanic environments. Species abundance and composition varied significantly during the sampling period due to increased nutrient concentrations in the rainy season. Dinoflagellate species were more abundant during the dry season, and diatom species dominated numerically during the rainy season.</p>

scholarly journals Phytoplankton dynamics in a highly eutrophic estuary in tropical Brazil

2010 ◽  
Vol 58 (3) ◽  
pp. 189-205 ◽  
Author(s):  
Marilene Felipe Santiago ◽  
Maria da Glória Gonçalves da Silva-Cunha ◽  
Sigrid Neumann-Leitão ◽  
Kátia Muniz Pereira da Costa ◽  
Gislayne Cristina Borges Palmeira ◽  
...  
Keyword(s):  
Environmental Quality ◽  
Rainy Season ◽  
Diversity Indices ◽  
Dry Season ◽  
Northeastern Brazil ◽  
Species Diversity Indices ◽  
Negative Impacts ◽  
High Level ◽  
Social Area

The port of Recife in northeastern Brazil is an important ecological and social area but little is known about its environmental quality. Observations, sampling and measurements of phytoplankton were performed during spring and neap tides in the dry (January-February, 2005) and rainy (June, 2005) seasons to assess the environmental quality of the port of Recife. The area had chlorophyll-a concentrations ranging from 3.30 to 54.40 mg m-3, the highest values occurring at low tide during the dry season. A total of 129 species were identified: 53 of them in the dry season and 97 in the rainy season. Diatoms were the most diverse group and comprised 75.47% of the phytoplankton collected in the dry season and 60.82% of those collected in the rainy season. The dry season was characterized by Coscinodiscus sp. and Helicotheca tamesis; the rainy season by Oscillatoria sp. and Coscinodiscus centralis. Species diversity indices varied from 1.06 to 3.74 bits cel-1. Low indices were related to the dominance of Helicotheca tamesis, Coscinodiscus centralis, Coscinodiscus sp. and Aulacoseira granulata. Seasonal forcing, rather than the estuarine flux, determined the phytoplankton community structure. The area is exposed to seasonally varying negative impacts due to metropolitan degradation and the high level of eutrophication.

scholarly journals Vertical distribution, nutrient concentration and seasonal changes of fine root mass in a semi-deciduous tropical dry forest and in two adjacent pastures in the Western Llanos of Venezuela

2020 ◽  
Vol 8 (2) ◽  
pp. 93-104
Author(s):  
Ana Francisca González-Pedraza ◽  
Nelda Dezzeo
Keyword(s):  
Vertical Distribution ◽  
Seasonal Changes ◽  
Rainy Season ◽  
Nutrient Concentration ◽  
Fine Root ◽  
Tropical Dry Forest ◽  
Dry Season ◽  
Dry Forest ◽  
Nutrient Concentrations ◽  
Root Mass

With the objective to contribute to a better understanding of ecological consequences of deforestation on the below-ground system in the Western Llanos of Venezuela, we evaluated the vertical distribution, nutrient concentration and seasonal changes of total fine root mass (FRM) (<2 mm diameter) in a semi-deciduous tropical dry forest and in 2 adjacent pastures of Cynodon nlemfuensis: a young pasture (YP, 5 years old) and an old pasture (OP, 18 years old) in the Obispo municipality, Barinas State. This evaluation included measurements at the end of the rainy season, during the dry season and during the subsequent early rainy season in 2005/2006. Highest FRM was recorded during the dry season, which probably indicates a plant water-stress response mechanism. The highest proportion (63‒88%) of FRM was concentrated in the 10–20 cm soil layer at all studied sites, probably due to a higher nutrient and moisture content at that depth. Non-significant differences (P>0.05) were observed in the total concentrations of organic carbon, nitrogen, phosphorus, calcium and magnesium in the FRM in soils supporting forest, OP and YP at the evaluated depths. Non-significant changes in the total FRM and nutrient concentrations were observed between the sampling periods and the 3 study sites. YP soils showed a slight increase in FRM that could be associated with the root growth of secondary vegetation, which is considered a weed and is periodically removed. Our results suggest that the land use change from tropical forest to pastures has not significantly affected the mass of fine roots and their carbon and nutrient concentrations. Further studies are needed to determine if these findings apply to other ecosystems.

scholarly journals Mapping Urban and Peri-Urban Land Cover in Zimbabwe: Challenges and Opportunities

Geomatics ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 114-147
Author(s):  
Courage Kamusoko ◽  
Olivia Wadzanai Kamusoko ◽  
Enos Chikati ◽  
Jonah Gamba
Keyword(s):  
Sustainable Development ◽  
Land Cover ◽  
United Nations ◽  
Urban Areas ◽  
Rainy Season ◽  
Dry Season ◽  
Land Cover Mapping ◽  
Urban Centers ◽  
Geospatial Information ◽  
Study Results

Accurate and current land cover information is required to develop strategies for sustainable development and to improve the quality of life in urban areas. This study presents an approach that combines multi-seasonal Sentinel-1 (S1) and Sentinel-2 (S2) data, and a random forest (RF) classifier in order to map land cover in four major urban centers in Zimbabwe. The specific objective of this study was to assess the potential of multi-seasonal (rainy, post-rainy, and dry season) S1, rainy season S2, post-rainy season, dry season S2, multi-seasonal S2, and multi-seasonal composite S1 and S2 data for mapping land cover in urban areas. The study results show that the combination of multi-seasonal S1 and S2 data improve land cover mapping in urban and peri-urban areas relative to only multi-seasonal S1, mono-seasonal S2, and multi-seasonal S2 data. The overall accuracy scores for the multi-seasonal S1 and S2 land cover maps are above 85% for all urban centers. Our results indicate that rainy and post-rainy S2 spectral bands, as well as dry-season S1 VV and VH bands (ascending orbit) are the most important features for land cover mapping. In particular, S1 data proved useful in separating built-up areas from cropland, which is usually problematic when only optical imagery is used in the study area. While there are notable improvements in land cover mapping, some challenges related to the S1 data analysis still remain. Nonetheless, our land cover mapping approach shows a potential to map land cover in other urban areas in Zimbabwe or in Sub-Sahara Africa. This is important given the urgent need for reliable geospatial information, which is required to implement the United Nations Sustainable Development Goals (UN SDGs) and United Nations New Urban Agenda (NUA) programmes.

scholarly journals SEASONAL VARIATIONS OF NUTRIENT BUDGETS IN JAKARTA BAY, INDONESIA

2014 ◽  
Vol 35 (1) ◽  
pp. 9-17 ◽  
Author(s):  
Mochamad Saleh Nugrahadi ◽  
Tetsuo Yanagi ◽  
Iwan G. Tejakusuma ◽  
Seno Aji ◽  
Rahmania A. Darmawan
Keyword(s):  
Suspended Matter ◽  
Rainy Season ◽  
Dry Season ◽  
Nutrient Concentrations ◽  
Nutrient Budgets ◽  
Phytoplankton Abundance ◽  
Dissolved Nutrients ◽  
Carbon And Nitrogen ◽  
Estuarine Coastal ◽  
Nitrogen Phosphorus

This study aims to quantify the fluxes of carbon, nitrogen, phosphorus, and silicate in Jakarta Bay and use these flux data to gain an initial understanding of the biogeochemical processes occurring in the system. We investigated water, suspended matter and sediments fluxes from estuarine, coastal water and outside of the bay. Water samples were analyzed for dissolved nutrients, chlorophyll-phytoplankton abundance, and their composition. Suspended matter and sediment were analyzed for carbon and nitrogen. Nutrient concentrations were high in the rivers or estuaries and then decreased rapidly seaward. Calculation budget results showed that Jakarta Bay is a sink for DIP, DIN and DSi during dry season and rainy season. In the dry season, the system is in the slightly fixation condition ([nfix-denit] = 0.03 mmol N m-2 d-1). In contrast, denitrification exceed nitrogen fixation ([nfix-denit] = -9.74 mmol N m-2 d-1) in the rainy season. Moreover, the bay produced net carbon about 2.6-32 mmol C m-2 d-1.

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