Bay In Brazil Research Articles

An effective wetting and drying algorithm for numerical shallow water flow models

This paper presents a simple and effective method to model the wetting and drying of coastal areas by the tide. The approach considers an equivalent "rough-porous layer" (RPL), wetting and drying method. The method can be easily implemented in finite elements, which makes it useful in numerical modeling of natural water bodies with intricate topographies. Some benchmark tests are devised to examine the performance and robustness of the method at extreme conditions, with satisfactory results. Finally, the effectiveness of the RPL is evaluated in modeling the complex Vitoria Bay in Brazil, with its extensive mangrove areas, where the predicted variations in the inundation areas and the velocity fields were reproduced more accurately for different stages of the tide. At field measurement sites, the predicted water levels and velocities agreed favorably with the measured data.

Occurrence of pharmaceutical and personal care products (PPCPs) in marine sediments in the Todos os Santos Bay and the north coast of Salvador, Bahia, Brazil

The Todos os Santos Bay is the largest bay in Brazil and receives drainage from various watersheds. For more than 450 years, it was the main destination for the domestic and hospital sewage from the city of Salvador, Bahia. With the growing concern regarding the presence of pharmaceutical and personal care products (PPCPs) in the environment, an investigation was undertaken to determine the presence and levels of some commonly used drugs (i.e., atenolol, caffeine, carbamazepine, diazepam, diclofenac, erythromycin, ibuprofen) and personal care products (i.e., galaxolide, tonalide), using sediments as an indicator of their presence in the water column. Surficial sediment samples from 17 stations located in the intertidal zone of the Todos os Santos Bay and infralittoral zone along the north coast of Salvador were tested for the presence of some PPCPs using LC-MS/MS (for drugs) and GC-MS/MS (for fragrances). The PPCPs examined were present in all sediment samples at levels of parts per billion of dry sediment. The highest concentrations were found for the fragrances galaxolide (52.5 ng g−1) and tonalide (27.9 ng g−1), followed by caffeine (23.4 ng g−1) and pharmaceuticals ibuprofen (14.3 ng g−1), atenolol (9.84 ng g−1), carbamazepine (4.81 ng g−1), erythromycin (2.29 ng g−1), diclofenac (1.06 ng g−1), and diazepam (0.71 ng g−1). Pharmaceuticals were found to be ubiquitous in the sediments of the study areas. The texture of the sediment was an important factor in PPCPs fixation and deposition. The concentrations of all PPCPs had statistically significant positive correlations with the percentage of clay in the sediments.

Differences in Methylmercury and Inorganic Mercury Biomagnification in a Tropical Marine Food Web

Methylmercury (MeHg), inorganic mercury (Hginorg) and their biomagnification factors (BMF) were evaluated along a non-degraded Brazilian bay food web. Highly significant differences (p < 0.0001) were found between MeHg and Hginorg concentrations among all organisms (microplankton, shrimp, fish and dolphin). MeHg increased with increasing trophic position while Hginorg did not present the same pattern. BMF values for MeHg were higher than 1 for all trophic interactions from source to consumer, indicating that MeHg was transferred more efficiently and biomagnified over the entire web. Only one BMF exceeding one was observed for Hginorg (27) between microplankton and their consumer, planktivorous fish. BMF values for Hginorg were significantly different than those found for MeHg (20) at the base of the food web.

Evaluation of an Efficient Approach for Target Tracking from Acoustic Imagery for the Perception System of an Autonomous Underwater Vehicle

This article describes the core algorithms of the perception system to be included within an autonomous underwater vehicle (AUV). This perception system is based on the acoustic data acquired from side scan sonar (SSS). These data should be processed in an efficient time, so that the perception system is able to detect and recognize a predefined target. This detection and recognition outcome is therefore an important piece of knowledge for the AUVs dynamic mission planner (DMP). Effectively, the DMP should propose different trajectories, navigation depths and other parameters that will change the robot's behaviour according to the perception system output. Hence, the time in which to make a decision is critical in order to assure safe robot operation and to acquire good quality data; consequently, the efficiency of the on-line image processing from acoustic data is a key issue. Current techniques for acoustic data processing are time and computationally intensive. Hence, it was decided to process data coming from a SSS using a technique that is used for radars, due to its efficiency and its amenability to on-line processing. The engineering problem to solve in this case was underwater pipeline tracking for routine inspections in the off-shore industry. Then, an automatic oil pipeline detection system was developed borrowing techniques from the processing of radar measurements. The radar technique is known as Cell Average – Constant False Alarm Rate (CA – CFAR). With a slight variation of the algorithms underlying this radar technique, which consisted of the previous accumulation of partial sums, a great improvement in computing time and effort was achieved. Finally, a comparison with previous approaches over images acquired with a SSS from a vessel in the Salvador de Bahia bay in Brazil showed the feasibility of using this on-board technique for AUV perception.

Stormwater impact in Guanabara Bay (Rio de Janeiro): Evidences of seasonal variability in the dynamic of the sediment heavy metals

Guanabara Bay is one of the most prominent coastal bays in Brazil. This environment is an estuary of 91 rivers and channels, surrounded by the metropolis of Rio de Janeiro. The bay receives considerable amounts of contaminants introduced from sewage effluents, industrial discharge, urban and agricultural runoff, atmospheric fallout, and the combined inputs from the rivers, making Guanabara Bay one of the most polluted coastal environments on the Brazilian coastline. The aim of this work is to study the concentration and fractionation of the heavy metals within the sediments of the bay. In order to understand the possible seasonal influence on the heavy metal fractionation, two campaigns were carried out in two different seasons of the year (rainy and dry). Twelve stations, in four different areas, with different oceanographic characteristics, where chosen. To assess the bioavailability of the metals a selective extraction procedure was used to study the geochemical fractionation and bioavailability of Zn, Cu, Cr, Ni and Pb. The rainy season was very important with respect to variation in the total concentrations of Cr, Ni and Pb and their fractionation within different “operational” phases present in Guanabara Bay sediments. The water-soluble phase showed little importance, with respect to metal adsorption and this would suggest very low mobility of metals in the water column. Nevertheless, the potentially available metals within these sediments showed a high probability for their release and therefore cause contamination of the water column, since different parts of the bay are constantly subjected to dredging projects promoted by the harbor authorities.

PAHs in cultured mussels Perna perna from a Southeastern Brazilian Bay

The presence and distribution of polycyclic aromatic hydrocarbons (PAHs) were evaluated for the first time in cultured mussels at Ilha Grade Bay, the largest mariculture center in the Rio de Janeiro State, Southeast Brazil. Analyses of PAHs on soft tissue were performed in triplicate by GC-MS on composite samples (10 individuals each) collected in 2011 at six mussel farms. The mean concentration of the total PAHs (38 compounds), excluding one farm, was 14.0 ± 8.53 ng g-1, whereas the 16 priority PAHs was 9.51 ± 4.78 ng g-1. These values characterize the farmed mussels analyzed as having low level of PAH contamination. The exception was the farm in Mombaca, where the total PAHs of 584 ng g-1 (16 PAHs of 22.4 ng g-1) and the profile of individual PAHs suggest moderate contamination by petrogenic sources. All the concentrations measured were below threshold values established by environmental and health agencies as limiting to pose risk to humans by mussel consumption.

Distribution and size of the mojarra Diapterus rhombeus (Cuvier) (Actinopterygii, Gerreidae) in a Southeastern Brazilian bay

Diapterus rhombeus is one of the most abundant fish species in the Sepetiba bay, which is a 520 km² semi-closed coastal area in Southeastern Brazil. The size and distribution of this species have been described in order to assess the use of the area as a rearing ground in both spatial and temporal (seasonal) dimensions. A fish sampling program was conducted monthly by using an otter trawl between October 1998 and September 1999, in three bay zones (outer, middle and inner), defined according to depth and salinity gradient. Highly significant differences were found for CPUEs (number and biomass) among seasons and zones. Size ranged from 50 to 230 mm TL, and three size-groups were defined according to a maturation scale (n = 1435): 1 - immature (&lt; 80 mm Total Length - TL); 2- individuals at the first maturation (L50) (80-90 mm TL), and 3 - adults (L100) (&gt; 100 mm TL). Immature and L50 individuals were more abundant (number and biomass) during Autumn in the inner zone, while adults (L100) predominated during Summer in the outer zone. Evidences of movements of young-of-the-year (50-90 mm TL) individuals from the inner to the outer zone were detected as they reach larger sizes (180 mm TL) in the second year of life. Condition (k) was higher in larger sized individuals in the outer zone during Spring, when they are apt to start the reproductive process. Two cohorts were detected according to modal progression: the first (smaller size) showing faster growth than the second, evidencing a slower growth rate as they reach larger size. Distinct size classes occupying different bay zones suggest that the age-groups optimize their coexistence by partitioning the available resources, avoiding intra-specific competition.

Spatial and size feeding niche partitioning of the rhomboid mojarra Diapterus rhombeus (Cuvier, 1829) in a tropical Brazilian Bay

We examined the stomach contents of 287 individuals of rhomboid mojarra Diapterus rhombeus collected between June 1999 and May 2000 in three zones (inner, middle and outer) of a Brazilian tropical bay. Fish were grouped in five size-class (Total Length1 ≤ 80 mm; TL2=81–110; TL3=111–140; TL4=141–170; and TL5 ≥ 171). The aim was to assess whether intraspecific spatial and size-feeding niche partitioning occurs and to describe the strategy used to explore the available resources. Crustacea and Polychaeta were the most important trophic categories and Harpacticoida (Index of Relative Importance, IRI = 66.9%) was the most preferred prey throughout all zones and size classes. The smallest individuals (TL≤140 mm) occurred exclusively in the inner zone and fed mainly on Harpacticoida, Calanoida, sedentary Polychaeta and Nematoda, while the largest individuals (TL>140 mm) fed mainly on Harpaticoida and Ostracoda. In the outer zone, the largest individuals feed mainly on Harpacticoida and Caprella. A high within-phenotype contribution to the niche width and a generalist zoobenthivore feeding strategy were detected. Partitioning the food items along space and growth seems to be the mechanism used by this species to decrease intraspecific competition.

Migratory flows and foraging habitat selection by shorebirds along the northeastern coast of Brazil: The case of Baía de Todos os Santos

Large numbers of Nearctic shorebirds migrate and winter along the coast of northeastern Brazil, but there is little information on their migratory flows, foraging ecology, and on the structure of the species assemblages that they form with resident shorebirds. We studied these issues on intertidal flats of Baía de Todos os Santos (Bahia), the second largest bay in Brazil. During a full year cycle we carried out weekly bird counts in an intertidal area of 280 ha divided in sectors, where we also measured environmental parameters. The analyses of weekly counts resulted in a detailed phenology of use of the area by shorebirds. Five species were resident and ten were Nearctic migrants. Several of the latter had clear peaks in numbers in March and October, revealing the use of the bay as a stopover during both the north-bound and south-bound migration flows. A canonical correspondence analysis of the relationship between environmental parameters and bird numbers indicated that the foraging bird assemblage could be divided into five main groups, occupying distinct ecological gradients in the study area. The most important factors driving this structure were invertebrate prey abundance, percentage of fine sediments, area of mangrove cover and distance to channels. Our findings imply that maintenance of the diversity of intertidal habitats in this bay is crucial to satisfy the particular habitat requirements of resident and migrant shorebirds using the northeastern coastal regions of Brazil.

Isotope Source Signatures for a Primary Lead Smelter Located Close to Todos os Santos Bay, Brazil

From 1960 to 1993, a primary lead smelter operated in the Santo Amaro region, close to Todos os Santos Bay in Brazil, using the classical sinter-roasting process followed by smelting and refining. A high lead content was found in the sediments from Todos os Santos Bay, which has a large circulation and receives the discharge from three rivers. Lead stable isotope ratios provide information about the ore mineralization and can be used to evaluate the origin and fate of the lead pollution. The objective of this study is to identify the isotopic signature of the major effluents of this lead smelter and correlate it with the origin of the galena concentrate that generated it. The X-ray microanalysis confirms that the lead occurs in the slag in the metallic state. The soil has a high lead content (about 0.90%) of oxidized lead. The lead isotopic ratios indicated that the slag isotopic ratios (208Pb/204Pb = 34.8; 207Pb/204Pb = 15.3; 206Pb/204Pb = 15.1) are close to the soil value (208Pb/204Pb = 36.2; 207Pb/204Pb = 15.9; 206Pb/204Pb = 16.4) and both agree with the values for the galena from the Boquira mine region (208Pb/204Pb = 34.6±1.1; 207Pb/204Pb = 15.3±0.4; 206Pb/204Pb = 14.7±0.2). These results indicate that no isotopic fractionation occurred in the roasting-smelting process, therefore the original Boquira isotope ratios can be used as the isotopic signature of the lead dispersed from the Santo Amaro smelter.

Characterization of organic matter in sediment cores of the Todos os Santos Bay, Bahia, Brazil, by elemental analysis and 13C NMR

The impact of human activity on the sediments of Todos os Santos Bay in Brazil was evaluated by elemental analysis and 13C Nuclear Magnetic Resonance (13C NMR). This article reports a study of six sediment cores collected at different depths and regions of Todos os Santos Bay. The elemental profiles of cores collected on the eastern side of Frades Island suggest an abrupt change in the sedimentation regime. Autoregressive Integrated Moving Average (ARIMA) analysis corroborates this result. The range of depths of the cores corresponds to about 50years ago, coinciding with the implantation of major onshore industrial projects in the region. Principal Component Analysis of the 13C NMR spectra clearly differentiates sediment samples closer to the Subaé estuary, which have high contents of terrestrial organic matter, from those closer to a local oil refinery. The results presented in this article illustrate several important aspects of environmental impact of human activity on this bay.

Bioinvasion in a Brazilian Bay: Filling Gaps in the Knowledge of Southwestern Atlantic Biota

BackgroundBiological invasions are a major cause of global species change. Nevertheless, knowledge about the distribution and ecology of introduced species is regionally biased, and many gaps in knowledge exist for most developing countries.Methodology/Principal FindingsTo study the zoobenthos on the hard substratum of the Ilha Grande Bay, a survey was conducted on both natural and artificial substrata at three depths and seven sites. The species recorded were classified as native, cryptogenic or introduced. Multivariate analyses were conducted to assess the prevalence of introduced species in these communities and to compare the distribution of species on natural and artificial substrata of this bay to identify possible discrepancies in habitat use. Of the 61 species, 25 were cryptogenic, 10 were introduced and 26 were native. Similar numbers of introduced species were found on both natural and artificial substrata, though the community composition was significantly different between them. We also compared the species composition of the Ilha Grande Bay survey to other inventories taken around the world. The highest similarities were found between the Ilha Grande Bay inventory and the Atlantic coastal region (Tampa Bay, USA and the Gulf of Mexico), American Samoa and Pearl Harbor (USA) inventories.Conclusions/SignificanceThis study presents the first published comprehensive list of hard substratum sessile marine invertebrate species in a Brazilian bay. The high percentage of cryptogenic species reveals gaps in both zoological records and information on introduced species for the Brazilian coast. The introduced species successfully colonized different sites in the Ilha Grande Bay, including both natural and artificial substrata. In addition, we find that artificial structures may not be good surrogates for natural rocky shores and may represent an ecological threat. Comparisons with other inventories suggest a history of broad-scale invasion, though more evidence is needed to support this conclusion.

Non indigenous ascidians in port and natural environments in a tropical Brazilian bay

Despite limited natural dispersal, some species of ascidians can be transported vast distances via oceanic petroleum platforms, ship hulls and ballast water and therefore may be good indicators of bioinvasion. Usually non indigenous species (NIS) are abundant in harbors. This is caused in part because of the higher propagule delivery rate in these areas. An alternative explanation of why invasion is enhanced in harbor and marinas is that environmental degradation commonly found in these habitats favors the establishment of NIS. Most surveys for introduced species were not comprehensive and targeted mainly ports and marinas. Angra dos Reis is an excellent system that provides an opportunity to compare the potential distribution of introduced and native species of Ascidiacea between port and natural environments. Here, we compared the colonization of experimental subtidal plates placed in harbors and marinas with the colonization of plates placed in nearby natural areas. With 27 taxa (15 identified to species), species richness was greater in port environments (25 versus 8). Six taxa were common to both environments while 19 taxa were exclusively found in ports. Among the identified species in ports, three were introduced, five were cryptogenic and only one was native. Only three species were found exclusively in the natural sites and all were cryptogenic. The presence of introduced species only in the port areas of Angra dos Reis reinforces the need for continued, periodic monitoring in the region for early detection of new, potentially invasive, species as well as for better understanding of abnormal population growth of the already known species. Management to reduce the transfer of exotics to natural habitats must be implemented.

Oceanographic characteristics of Baía de Todos os Santos, Brazil

Based on a vast set of in situ data, a first comprehensive overview of the oceanographic characteristics of Baía de Todos os Santos (BTS) is provided. BTS is the second largest coastal bay in Brazil (maximum area of 1223 km² and average depth of 9.8 m), and is located in the northeast Brazil, in the vicinity of Salvador city. The circulation inside the bay is mostly tidally driven and does not vary significantly throughout the year. On the other hand, the wet (winter) and dry (summer) seasons does alter significantly the distribution of water properties inside the BTS. During summer, the waters inside the bay have oceanic characteristics, with Tropical Water (TW) penetrating along the whole region, except for the mouth of Rio Paraguaçu. The water temperature inside the bay is higher than in the coastal zone, and variations can be up to 3°C, reaching a maximum of nearly 30°C. During winter, with the increase of freshwater inflow, salinity variations of about 4 are observed between the innermost stations inside BTS and the adjacent coastal region. Salinity values inside the bay can be as low as 32.3, inhibiting the penetration of TW into the BTS, which is totally occupied by a locally formed Coastal Water (CW). An evaluation of the flushing time is also provided and shows that during summer, a 60-fold increase can be observed compared to winter (38 days). While the circulation does not vary seasonally inside the bay, the associated inner shelf is characterized by two different scenarios. During summer, the upwelling favorable easterlies drive a southwestward flow, while during winter the more frequent occurrence of cold fronts (southerly winds) tend to reverse the circulation.

Stomatopod and decapod crustaceans from Camamu Bay, state of Bahia, Brazil

Camamu Bay, located on the central coast of the state of Bahia, Brazil (13°47’ to 14°10’S), is the third-largest Brazilian bay. It is included in a zone that perhaps constitutes the last unexplored frontier on the Brazilian coast, situated between Todos os Santos Bay in Bahia, and the city of Vitória in Espírito Santo. Moreover, this zone coincides with an area of remarkable zoogeographical interest, the transition zone between the Brazilian and Paulista provinces. Camamu Bay contains a wide diversity of marine environments such as sandy beaches, rocky substrata, and mangroves, and it is still in a good state of preservation compared to other large Brazilian bays. The objective of this study was to survey the fauna of Crustacea (orders Stomatopoda and Decapoda) in Camamu Bay. The material analyzed was collected by trawling from July 2003 to September 2005. Voucher specimens were deposited in the collections of the Universidade Estadual de Santa Cruz and the Universidade Estadual do Sudoeste da Bahia, located in the cities of Ilhéus and Jequié (state of Bahia, Brazil), respectively. A total of 93 species, belonging to 35 families, was collected. The order Stomatopoda was represented by 3 families and 4 species; the order Decapoda was represented by 31 families and 89 species. The most important family in terms of number of species was Alpheidae, with 11 species. Of the total number of species, 88 are recorded from Camamu Bay for the first time, while 10 species are cited from the state of Bahia for the first time. The southern geographical distributional limits in the western Atlantic for the caridean Synalpheus pandionis and the brachyurans Macrocoeloma laevigatum and Elamena gordonae are extended.

Mud in the surf: Nature at work in a Brazilian bay

Massive discharge of mud from coastal rivers is a well‐documented phenomenon. However, in areas with limited historical and instrumental records it is often difficult to assess the nature and history of the process. This article looks at Tijucas Bay, in southern Brazil (Figure 1a) (an area that was the landfall region in March 2004 for South America's first recorded hurricane [Bossack, 2004]), to examine the time frame for extensive deposition of fluid muds in the nearshore (Figure 1b).The new geological data suggest that whereas recent human activities (e.g., massive sand mining) along the Tijucas River may be important in increasing the suspended sediment discharge, the shift to a mud‐dominated regime was part of the natural evolution of this coastal plain.

Embryonic development time of Penilia avirostris Dana, 1852 in a tropical bay in Brazil

Development time of embryos in the brood pouch of the cladoceran Penilia avirostris Dana, 1852, was estimated by collecting zooplankton daily for 15 days in surface water of Guanabara Bay, Brazil. Each day the maturity stage of embryos of 90 parthenogenic females was noted. Total development time (egg to birth) varied from 2 to 3 days, the immature phase (stages I to IV) being generally longer (2 days) than intermediate and mature phases (1 day, stages V to XII). Similar results were obtained from Bottrell's equation, which takes water temperature into account.

Zinc detoxification by a cyanobacterium from a metal contaminated bay in Brazil

We describe here the trapping of zinc in polyphosphate granules of the cyanobacterium Synechocystis aquatilis NPBS-3. Cells were cultured in 25 µM of zinc chloride and prepared for electron microscopy and energy-dispersive X-ray analysis. Some ultrastructural features were changed by zinc exposure, the increase of glycogen granules number being the main change. The polyphosphate granules contained phosphorus, sulphur, calcium, iron and zinc. The trapping of zinc in polyphosphate granules seemed to be an effective way of detoxifying the metal and surviving in the bay. As a non-specific mechanism, these polyphosphate granules could also be effective in trapping other metals in excess.

The Vertical Migration Behaviour of Two Calanoid Copepods, Acartia Tonsa Dana, 1849 and Paracalanus Parvus (Claus, 1863) in a Stratified Tropical Bay in Brazil

The diel vertical migration pattern of the copepods, Acartia tonsa and Paracalanus parvus was studied in Guanabara Bay, Brazil. Samples were taken at a fixed station at three depths, at three-hour intervals, and for three days. During the study period, the water column was stratified with warm, low-salinity water from the inner bay at the surface and cold, high-salinity deep-ocean water below. The individuals of both species were identified and counted, with no sex or stage distinction. The results confirmed that A. tonsa and P. parvus have a different migratory behaviour. A. tonsa maintains itself in the surface water layer during the night. This species does not seem to be affected by the presence of a sharp thermocline. P. parvus shows a vertical migration pattern based on a 12-hour cycle and it is limited to deeper waters, below the thermocline. This peculiar behaviour may help P. parvus to avoid being carried into the inner, polluted part of the bay. Le modele de migration journaliere verticale des copepodes Acartia tonsa et Paracalanus parvus a ete etudie dans la baie de Guanabara au Bresil. Des echantillons ont ete preleves a une station fixe, a trois profondeurs, toutes les trois heures et pendant trois jours. Au cours de cette periode, la colonne d'eau etait stratifiee, avec des eaux de surface chaudes et de faible salinite provenant de l'interieur de la baie et au-dessous, des eaux froides de forte salinite provenant des eaux profondes de l'ocean Atlantique. Les individus des deux especes etudiees ont ete identifies et comptes, sans distinction de stade ou de sexe. Les resultats confirment que A. tonsa et P. parvus ont un comportement migratoire different. A. tonsa se maintient pendant la nuit dans les eaux de surface. Cette espece ne semble pas etre affectee par la presence d'une forte thermocline. P. parvus presente une migration verticale fondee sur un cycle de 12 heures, et limitee aux eaux plus profondes, au-dessous de la thermocline. Ce comportement particulier peut aider P. parvus a eviter les eaux polluees de l'interieur de la baie.

Decadal Changes in a Polluted Bay As Seen from Its Seaweed Flora: The Case of Santos Bay in Brazil

Decadal Changes in a Polluted Bay As Seen from Its Seaweed Flora: The Case of Santos Bay in Brazil