scholarly journals Spatial and seasonal variation of microphytoplankton community and the correlation with environmental parameters in a hypereutrophic tropical estuary - Maranhão - Brazil

2017 ◽  
Vol 65 (3) ◽  
pp. 356-372 ◽  
Author(s):  
Ana Karoline Duarte dos Santos ◽  
Amanda Lorena Lima Oliveira ◽  
Jordana Adorno Furtado ◽  
Francinara Santos Ferreira ◽  
Bethânia de Oliveira Araújo ◽  
...  
Keyword(s):  
Phytoplankton Community ◽  
Skeletonema Costatum ◽  
Tidal Flow ◽  
River Estuary ◽  
Environmental Parameters ◽  
Spatial And Temporal Variation ◽  
Statistical Correlations ◽  
Spatial And Seasonal Variation ◽  
Salinity Water ◽  
Highly Correlated

Abstract The Bacanga River Estuary has a hydrodynamic behavior and its tidal flow is limited by a dam. It is considered as a hypertrophic environment that receives daily high loads of domestic sewage without treatment. This study aimed to evaluate the spatial and temporal variation of phytoplankton community and its relationship with environmental parameters. Bi-monthly sampling campaigns were carried out at six fixed sites between 2012 and 2013. Physical-chemical and biological parameters were collected (chlorophyll a, phytoplankton composition and abundance) to perform the statistical correlations. The results indicate that phytoplankton community is mostly represented by diatoms, with Skeletonema costatum being the dominant species responsible for bloom in April and June of 2012. The dominance of this species is related to the high silicate concentrations, pH and turbidity. Other blooms events as well as the Euglena gracilis and Chlamydomonas sp. were recorded in February 2013, when the total phosphorus concentrations were high and the dissolved oxygen concentrations were higher. Dinoflagellates, cyanobacteria and diatom Thallassiosira sp. were widely distributed in the dry period and highly correlated with salinity, water transparency and nutrients. Hence, the distribution of phytoplankton community is more defined seasonally, rather than spatially.

scholarly journals Phytoplankton Dynamics in the Middle Adriatic Estuary, with a Focus on the Potentially Toxic Genus Pseudo-nitzschia

2020 ◽  
Vol 8 (8) ◽  
pp. 608
Author(s):  
Jasna Arapov ◽  
Mia Bužančić ◽  
Sanda Skejić ◽  
Jelena Mandić ◽  
Ana Bakrač ◽  
...  
Keyword(s):  
Domoic Acid ◽  
Phytoplankton Community ◽  
River Estuary ◽  
Environmental Parameters ◽  
Late Summer ◽  
Diatom Genus ◽  
Human Intoxication ◽  
Stratified Estuary ◽  
Special Environment ◽  
Variable Layer

The Krka River estuary is a karstic, permanently stratified estuary due to the strong freshwater inflow. It is a special environment in which to study the phytoplankton community, especially because this area is an important aquaculture site. Among other potentially toxic phytoplankton species, the diatom genus Pseudo-nitzschia occurs frequently and is a potential source of domoic acid (DA), causing shellfish toxicity and human intoxication. The main objective was to examine the dynamics of the phytoplankton community and, in particular, the genus Pseudo-nitzschia in the upper part of the Krka estuary, through monthly sampling over two years. The phytoplankton community was analysed using light microscopy and scanning electron microscopy to determine the diversity of Pseudo-nitzschia species and characterise the environmental parameters associated with a high abundance of Pseudo-nitzschia species. Seven Pseudo-nitzschia species were identified in the investigation, with higher frequencies and abundances in the less variable layer, at a 7 m depth. Blooms of Pseudo-nitzschia were noted in the late summer/early autumn, dominated by P. delicatissima/arenysensis. Winter assemblages were characterised by P. pseudodelicatissima/cuspidata, P. calliantha, and P. subfraudulenta, and were associated with domoic acid occurrence in shellfish.

A Real-Time Mathematical Model for Three-Dimensional Tidal Flow and Water Quality

1991 ◽  
Vol 24 (6) ◽  
pp. 171-177 ◽  
Author(s):  
Zeng Fantang ◽  
Xu Zhencheng ◽  
Chen Xiancheng
Keyword(s):  
Mathematical Model ◽  
Water Quality ◽  
Real Time ◽  
Control Volume ◽  
Tidal Flow ◽  
Three Dimensional ◽  
River Estuary ◽  
Pearl River Estuary ◽  
Practical Application ◽  
The Pearl River

A real-time mathematical model for three-dimensional tidal flow and water quality is presented in this paper. A control-volume-based difference method and a “power interpolation distribution” advocated by Patankar (1984) have been employed, and a concept of “separating the top-layer water” has been developed to solve the movable boundary problem. The model is unconditionally stable and convergent. Practical application of the model is illustrated by an example for the Pearl River Estuary.

scholarly journals Preliminary assessment of the potential for mangrove oyster cultivation in Piraquê-açu river estuary (Aracruz, ES)

2006 ◽  
Vol 49 (1) ◽  
pp. 163-169 ◽  
Author(s):  
Luciana Alvarenga ◽  
Rosebel Cunha Nalesso
Keyword(s):  
High Salinity ◽  
Shell Height ◽  
River Estuary ◽  
Oyster Shell ◽  
Preliminary Assessment ◽  
High Salinity Water ◽  
Salinity Water ◽  
High Predation ◽  
Fouling Organisms ◽  
Oyster Cultivation

At Piraquê-açu river estuary, Aracruz, ES, the technical viability of Crassostrea rhizophorae cultivation was determined through monthly measures in shell length and weight. Seeds of C. rhizophorae were put in cages and suspended in rafts. Increase in height and weight (flesh and dry) of the oysters was measured. During ten months (July/98 to May/99), oyster shell reached an average of 37.6 mm in shell height and 3.0 g in flesh weight (the whole animal). High mortality rates were registered and could be related to the high salinity water and to high predation observed, especially by flatworms Stylochophana divae and snails Cymatium parthenopeum, as well as fouling organisms such as barnacles, Serpulidae polychaetes and seed of the same species.

scholarly journals Longitudinal Study of Total and Pathogenic Vibrio parahaemolyticus (tdh+ and/or trh+) in Two Natural Extraction Areas of Mytilus chilensis in Southern Chile

2021 ◽  
Vol 12 ◽  
Author(s):  
Cristina Bacian ◽  
Cristobal Verdugo ◽  
Katherine García ◽  
Josu Perez-Larruscain ◽  
Ignacio de Blas ◽  
...  
Keyword(s):  
Water Temperature ◽  
Vibrio Parahaemolyticus ◽  
River Estuary ◽  
Environmental Parameters ◽  
Economic Losses ◽  
Pcr Analysis ◽  
Potential Hazard ◽  
Detection Rates ◽  
Pathogenic Vibrio ◽  
Interaction Factor

Vibrio parahaemolyticus is the leading cause of seafood-associated bacterial gastroenteritis worldwide. Although different studies have focused on its pattern of variation over time, knowledge about the environmental factors driving the dynamics of this pathogen, within the Chilean territory, is still lacking. This study determined the prevalence of total and pathogenic V. parahaemolyticus strains (tdh and/or trh genes) in mussels (Mytilus chilensis) collected from two natural growing areas between 2017 and 2018, using selective agar and PCR analysis. V. parahaemolyticus was detected in 45.6% (93/204) of pooled samples from the Valdivia River Estuary. The pathogenic strains carrying the tdh and/or trh gene were detected in 11.8% (24/204): tdh in 9.8% (20/204), trh in 0.5% (1/204), and 1.5% (3/204) presented both genes. In Reloncaví Fjord, V. parahaemolyticus was detected in 14.4% (30/209) of the samples, pathogenic V. parahaemolyticus carrying the trh gene was detected in 0.5% (1/209) of the samples, while the tdh gene was not detected in the samples from this area. The total count of mauve-purple colonies typical of V. parahaemolyticus on CHROMagar was positively associated by multivariate analysis with area, water temperature, and salinity. Similarly, V. parahaemolyticus detection rates by PCR had a positive correlation with the area and water temperature. The chances of detecting total V. parahaemolyticus in the Valdivia River Estuary are significantly higher than in the Reloncaví Fjord, but inversely, during spring-summer months, the interaction factor between the area and temperature indicated that the chances of detecting V. parahaemolyticus are higher in the Reloncaví Fjord. Interestingly, this period coincides with the season when commercial and natural-growing shellfish are harvested. On the other hand, pathogenic V. parahaemolyticus tdh+ was significantly correlated with an increase of water temperature. These environmental parameters could be used to trigger a warning on potential hazard, which would influence human health and economic losses in aquaculture systems.

The influence of environmental parameters on the phytoplankton community of two tropical reservoirs

2021 ◽  
Vol 26 (4) ◽  
Author(s):  
Jessica Chappell ◽  
Stefanie Whitmire ◽  
David Sotomayor‐Ramírez ◽  
Gustavo Martínez
Keyword(s):  
Phytoplankton Community ◽  
Environmental Parameters ◽  
Tropical Reservoirs

Spatial and temporal variation of soil moisture in dependence of multiple environmental parameters in semi-arid grasslands

2011 ◽  
Vol 340 (1-2) ◽  
pp. 73-88 ◽  
Author(s):  
Katrin Schneider ◽  
Ulrich Leopold ◽  
Friederike Gerschlauer ◽  
Frauke Barthold ◽  
Marcus Giese ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Temporal Variation ◽  
Environmental Parameters ◽  
Spatial And Temporal Variation ◽  
Arid Grasslands ◽  
Semi Arid

Spatial and temporal variation in lipid and fatty acid profiles of western rock lobster pueruli at first settlement: biochemical indicators of diet and nutritional status

2009 ◽  
Vol 60 (8) ◽  
pp. 810 ◽  
Author(s):  
A. J. Limbourn ◽  
R. C. Babcock ◽  
D. J. Johnston ◽  
P. D. Nichols ◽  
B. Knott
Keyword(s):  
Fatty Acid ◽  
Nutritional Status ◽  
Spatial And Temporal Variation ◽  
Lipid Levels ◽  
Rock Lobster ◽  
Important Species ◽  
Fa Composition ◽  
Lipid Fatty Acid ◽  
Spatial And Seasonal Variation ◽  
Panulirus Cygnus

Rock lobster species are found worldwide and have a life history that includes development through a planktonic phyllosoma followed by a nektonic non-feeding puerulus that relies on stored energy during recruitment into near-shore habitats. Recruitment to adult populations of western rock lobster (Panulirus cygnus) is highly variable and is likely to be strongly influenced by shelf width and oceanic conditions affecting cross-shelf transport and nutrition. Since the nutritional status of newly settled pueruli will reflect the phyllosoma feeding environment and distance swum, we studied levels of lipid, fatty acid (FA) and protein of 422 pueruli and 79 first instar juveniles from four Western Australian locations. Lipid levels generally were inversely related to shelf width but were variable, suggesting pueruli may travel complex trajectories to coastal settlement. Lipid and FA composition of pueruli were consistent with spatial and seasonal variation in Leeuwin Current and coastal productivity regimes. Seasonal differences in FA composition occurred regardless of the year of settlement. Pueruli had lower lipid levels during ENSO years, when recruitment tends to be lower also. Measures of puerulus nutritional status appear to provide valuable insights into the processes underpinning recruitment in Panulirus cygnus and other commercially and ecologically important species.

Nutrient limitation of phytoplankton in the upper Swan River estuary, Western Australia

1996 ◽  
Vol 47 (4) ◽  
pp. 659 ◽  
Author(s):  
PA Thompson ◽  
W Hosja
Keyword(s):  
Nutrient Limitation ◽  
Chlorophyll A ◽  
Phytoplankton Community ◽  
River Estuary ◽  
Early Summer ◽  
Phosphate Silicate ◽  
Cell Densities ◽  
And Control ◽  
Swan River ◽  
Second Peak

During 1993-94 the phytoplankton community in the upper Swan River estuary had a peak chlorophyll a concentration of 57 mg m-3 during early summer (December 1993) and a second peak of 35 mg m-3 during late autumn (May 1994). Mid summer was characterized by low cell densities and low chlorophyll a concentrations. The potential of the phytoplankton community for nutrient limitation was assessed with dilution bioassays given nutrient mixes deficient in one of the following: nitrogen, phosphate, silicate, iron, trace metals, chelators, or vitamins. During the mid-summer period of low phytoplankton abundance, nitrogen was the nutrient with the greatest potential to limit algal biomass. During mid summer, ambient N:P ratios tended to be near unity and bioassays indicated that the available pool of N was up to 20 times more limiting to biomass development than was available P. Also during mid summer, bioassay treatments given no nitrogen and control treatments given no nutrients showed little growth, reaching chlorophyll a concentrations -1/30th of those given a full suite of nutrients. Chlorophyll a concentrations in the bioassay control treatments given no nutrients were correlated (r2 = 0.74) with measured surface nitrate concentrations; this suggested that nitrate inputs may be a major factor controlling phytoplankton biomass in this ecosystem. The correlation between surface nitrate concentration and rainfall (r2 = 0.69) further suggests that rainfall may be the most important mechanism supplying nitrate to the surface waters of this estuary.

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