Data assimilation has been developed into an effective technology that can utilize a large number of multi-source unconventional data. It cannot only provide the initial field for the ocean numerical prediction model, but also construct the ocean reanalysis datasets and provide the design basis for the ocean observation plan. In data assimilation, the estimation of the observation error is of paramount importance, because the quality of the analysis depends on it. In general, the observation error covariance matrix is diagonal or assumed to be diagonal, which means that the observation errors are independent from one another. However, there are indeed correlations in the observation errors. A diagnostic method has been developed, which can estimate a correlated and more accurate observation error covariance matrix. The proposed method combines an ensemble square-root Kalman filter with the diagnostic method, providing an estimation of the observation error covariance matrix. In order to test the performance of the method, the numerical experiments are performed with the Lorenz 96 model and a Shallow water model. The more accurate observation error covariance matrix can be obtained to use in ensemble square-root Kalman filter by using the new method. We could find using the estimated correlated observation error in the data assimilation improves the analysis.
The circulation induced by the wind and the North Brazil Undercurrent (NBU) in and surrounding the Japaratuba submarine canyon on the continental shelf of the basin of Sergipe and Alagoas is described using numerical modeling. The numerical simulations were implemented to determine the canyon influence in the local hydrodynamics and in the volume flow normal to the coast, considering several different scenarios, including a homogeneous and stratified fields of temperature and salinity. Northeast and East winds favor an upward flow in the canyon, while Southeast and South winds privilege subsidence. Winds parallel to the coast cause greater volume flow in the canyon section: 40° winds (relative to true the North, parallel to the coast) caused the highest upward flow, while winds from 215° to 220° caused the highest subsidence. On the other hand, the NBU favors subsidence motion and seems to predominate over the wind forcing.
Mangroves and coral reefs are among the major ecosystems of tropical and subtropical coastlines. The Andaman group of islands, situated at the juncture of Bay of Bengal and Indian Ocean, are one of the richest coastal ecosystems of India in terms of biodiversity. Since the tsunami waves of 2004 affected this region severely, the outer fringes as well as inland areas of these islands faced extensive ecological degradation. Mayabunder is one such place of this region, where corals and mangroves had experienced both natural and anthropogenic threat. Considering the notable vulnerability of this coastal environment, the present study aimed to assess the transformations of the coral and mangrove ecosystems at Mayabunder both in pre-tsunami and post-tsunami periods till the present year using multi-temporal satellite imageries and geospatial techniques. Results showed that the areal coverage of healthy living coral reefs was reduced by 466.56 ha (10.42 %) from 1990 to 2000. Afterwards, the coupled ecosystem had experienced serious degradation again during the 2000−2010 phase. The areal coverage of dense mangroves decreased by 47.37%, whereas the area of dead coral covers showed a significant rise of 55.52%. However, partial restoration of both mangroves as well as healthy corals had also been observed here in recent years. It was raised from the extensive field visits and feedbacks from local inhabitants that this restoration initiative could become more effective if a participatory mode of management is adopted.
Pampus argenteus (Perciformes: Stromateidae) is widely distributed along the coast of China, Indian Ocean, Arabian Gulf and North Sea. Due to overfishing and environmental degradation, its resources reduced year after year. Thus, new management strategies are urgently needed for the sustainable growth and utilization of this species. Characterization of the genetic variation of this fish species is essential for conserving the genetic resource and restraining the population decline. Therefore, it is necessary to have a clear understanding of the intraspecific genetic diversity and population structure of the species. In this study, we assess the genetic diversity and population structure of P. argenteus by using microsatellites. We genotyped 240 P. argenteus individuals from eight wild populations collected from Shidao (SD), Lianyungang (LYG), Lvsi (LS), Zhoushan (ZS), Dongtou (DT), Xiapu (XP), Haikou (HK), and Beibuwan (BBW) along the coast of China using fifteen polymorphic microsatellites. A total of 139 alleles were determined at 15 loci across the eight populations, and a relatively high level of genetic diversity was observed, with observed heterozygosity (Ho) and expected heterozygosity (He) ranging from 0.100 to 1.000, and from 0.669 to 0.934 per locus-location combination, respectively. LS had the highest average allele (number of alleles, A=15.200), and HK the lowest (A=13.000). Hos of P. argenteus are less than Hes, indicating lack of heterozygote within populations. Analysis of molecular variance (AMOVA) showed that most variation (95.66%) occurred within populations, suggesting that this is the main source of total variance. This study will provide useful information for conservation and sustainable exploitation of this important fishery resource.
The latitudinal variations of the Subantarctic Front (SAF) and Southern Hemisphere atmospheric jet were investigated for the period of 1993-2016. Zonal wind velocity, sea surface height and temperature data were used to identify these features over the South Atlantic, South Pacific and Indian Oceans individually. During this period, the atmospheric jet migrated poleward 0.34°S decade-1 in the Atlantic, 0.28°S decade-1 in the Pacific and 0.14°S decade-1 in the Indian oceans. Previous works have shown that the poleward trend is due to the expansion of the tropical belt as a consequence of greenhouse gas increase and cooling of polar stratosphere due to ozone depletion. In addition the atmospheric jet strengthen in all three basins. The SAF represents the Antarctic Circumpolar Current northern boundary and was observed in average at 46.3°S (±0.5°) in the Atlantic, 54.3°S (±0.3°) in the Pacific and 46.6°S (±0.5°) in Indian Oceans. The SAF shows a poleward migration of 0.46°S decade-1 in the Atlantic, 0.20°S decade-1 in the Pacific and 0.27°S decade-1 in the Indian Oceans, which is attributed to the sea level increasing in the Southern Hemisphere due to thermal expansion. The SAF poleward trend is consistent with the positive trend of the Southern Annular Mode during the studied period. Moreover, the jet position is statistically significant correlated to the SAF position in each ocean basin. However, the coefficients are weak: +0.22 for the Atlantic, +0.17 for the Pacific and +0.21 for the Indian oceans. The latitudinal displacement of the SAF in the Pacific is inversely proportional to the El Niño-Southern Oscillations (ENSO). During El Niño years the SAF tend to be more poleward and during La Niña years more equatorward, with maximum correlation of 0.56, with ENSO leading by three months.
Embryonic malformations can be a result of exposure toxic substances (pollution), lack of nutrients, physical restraint, genetic disorders, or infections and diseases. Such malformations can be classified according to severity and offspring survival outside the uterus. Moreover, abnormalities are normally restricted to a small portion of the litter, mostly, to only one embryo. Here, we report a case of congenital malformation dominance in an offspring of the shortnose guitarfish and compare it with other abnormalities commonly reported in batoids in addition to discussing the possible causes involved in the observed deformities.
ABSTRACT Salinity is a key variable for ecological processes in estuaries. Acartia tonsa is a typical estuarine copepod whose responses to salinity have been thoroughly studied in the laboratory. However, results cannot be extrapolated to the field, and formal comparisons between lab and field responses to salinity were not attempted. Here we compare lab-based with field copepod egg production rates (EPR) from the Río de la Plata estuary (RPE), with focus on A. tonsa. Field work was conducted between 2009 and 2011 in the mixing zone of the RPE. Water temperature, salinity and chlorophyll-a varied over ample ranges (temperature: 10.54 - 24.56ºC, salinity: 2.83 - 32.99, chlorophyll-a: 0.62 - 7.27 mg m-3). A. tonsa was the strongly dominant species. EPR ranged between 6.7 and 95.7 eggs female-1 day-1, and correlated to salinity, temperature (weakly), but not to chlorophyll. The relationship between A. tonsa’s EPR (EPRAT) and salinity was consistent with that obtained under laboratory conditions: a humped pattern with a maximum at intermediate salinities. However, differences were also evident, e.g., higher EPRAT was measured in the field. We speculate that discrepancies derive from nutritional differences between field and reference (laboratory) data sets. Besides salinity, food quality and quantity may be first order drivers of A. tonsa’s productivity in the RPE.
The effects of autotrophic, heterotrophic, and mixotrophic conditions were examined on micro green alga Dunaliella salina (UTEX 200 ) in terms of cell growth, total chlorophyll concentration, and lipid production . Results revealed a minimum growth rate of microalgae in the heterotrophic condition which is not recommended for D. salina . When the cells were cultured in mixotrophic conditions containing different concentrations of acetate or glucose, in 100 mM acetate or 60 mM glucose, the highest levels of growth rate and lipid production were obtained compared with autotrophic culture; however, the chlorophyll concentration decreased. Moreover, a significant correlation between ROS production and lipid synthesis was observed. When the combined acetate and glucose was added to the culture, no increase in growth rate and lipid synthesis was observed. This might be due to substrate inhibition. In the presence of glucose, the acidification of culture and bleaching occurred. Results indicated that lipid production is not affected by acidified conditions. In general, our results confirmed that mixotrophic culture with 100 mM acetate or 60 mM glucose is the most appropriate culture for D. salina concerning high lipid production as well as high growth rate in the shortest period of time.
ABSTRACT This study describes the taxonomic composition and horizontal distribution of Serranidae larvae along the Southeastern Brazilian Bight (SBB, approximately 22°S and 28°S), and investigates how environmental and biological factors influence the larval distribution. Ichthyoplankton samples were collected in 10 oceanographic cruises conducted from 1975 to 1981. Serranidae larvae were identified into 15 species, including 11 genera and four subfamilies. Except for Diplectrum formosum, which was widely distributed throughout the SBB, Hyporthodus spp. and Baldwinella vivanus were distributed in the southern portion of the SBB, while other species were distributed mainly in the northern portion of the SBB, inside the 200 m isobath. Local depth, latitude, distance from the closest island and salinity were factors that influenced significantly on the distribution and abundance of the most abundant taxa D. formosum, Diplectrum spp., Serranus spp. and Mycteroperca spp. Significant progress was made in identifying grouper larvae from the SBB (Epinephelus morio, Epinephelus itajara and Hyporthodus nigritus).
ABSTRACT Studies involving coastal sediment resuspension have shown that trace metals could be released to the water column due to changes in physical-chemical conditions. Therefore, if environmental agencies adopt screening protocols with insufficient evaluations of contaminant mobilization risks for a given area, the prediction of environmental impacts caused by dredging may be limited. This work evaluates the influence of spatial variation on the geochemical mobility of trace metals (Cd, Cu, Ni, Pb, Zn) after artificial sediment resuspension, using as study case the Iguaçu River estuary (Guanabara Bay, Brazil). The Iguaçu River drains the industrial complex of the metropolitan area of Rio de Janeiro State, besides the presence of agriculture and the input of untreated domestic wastes. Surface estuarine sediments were submitted to resuspension experiments in an open system, during 1h and 24h of agitation on local water. A clear tendency of metals’ solubilization was observed after resuspension, especially considering the dissolved concentrations of Cu (average: 8.0 µg L-1) and Zn (average: 0.9 mg L-1), especially for the samples from the transects 2 and 3. However, evaluations of water quality changes due to sediment resuspension are not requested by the legislation regulating the dredging activities. In the sediments, the results suggested a higher geochemical mobility of Cu, indicated by the massive increase on the bioavailable fraction after resuspension, mainly on the transect number 3, on the river’s mouth. The effects of resuspension were distinct between samples, suggesting that even in a small scale, important differences on metals’ mobility are found. Thus, the combined assessment of changes in metal concentrations in water and in the metal partitioning linked to the solid-phase was demonstrated to be a promising tool for predicting the environmental risks of dredging due to changes in the bioavailability of metals.
Energy budgets for juvenile Pacific whiteleg shrimp, Litopenaeus vannamei (1.7-4.0 g) fed with different diets were assessed. The energy partitioning between growth, respiration, ammonia excretion, feces and exuvia was calculated to estimate for total food energy intake. Shrimp oxygen consumption and ammonia excretion were quantified in sealed chambers (25 degrees C, 34 ppt). Energy allocated for growth and feces were obtained from the wet combustion of whole body and feces samples, exuvia was estimated as 10% growth energy. Three diets were tested: 100% chopped fish (Fish), 100% commercial feed (Feed), and 50-50% chopped fish and commercial feed (Mix). Most of the energy from the diets was channeled into respiration (49.7-70.5%). Shrimp fed the Feed diet used more energy in growth (24.4%) than those fed Mix (13.4%) or Fish diets (13.2%), either in absolute (joule) or relative (% of ingested energy) terms. Conversely, energy loss as ammonia excretion was lower in shrimp fed Feed (1.0%) compared to shrimp fed Mix (4.2%) or Fish diets (7.8%). Less energy was lost in feces by shrimp fed Fish diet (7.3%) compared to Mix (20.2%) and Feed diets (22.2%). The calculated energy intake by shrimp fed Fish, Mix and Feed were 0.995, 1.100, and 1.255 kJ ind(-1)day(-1), respectively. According to the O:N atomic ratios (oxygen consumed to nitrogen excreted), protein tented to be the predominant substrate catabolized by shrimp fed Fish (O:N= 16 +/- 5.2), and Mix (O:N= 25 +/- 11.6), with increasing use of carbohydrates and/or lipids in the Feed (O:N= 74 +/- 37.3). Results suggest diet composition may affect energy budget and partitioning differently between metabolism and growth either in absolute or relative terms, as shrimp fed Fish and Mix diets used protein as main substrate for metabolism, whereas shrimp fed Feed diet channeled protein for growth, and lipids and carbohydrates for other metabolic functions.
Spatial distribution patterns (both horizontal and vertical) of meiofauna, with special focus on nematodes, on a tropical macrotidal beach across different climatic periods were analyzed in this study. Samplings were carried out at five stations in the intertidal zone in June (rainy season) and December (dry season), 2011. At each station, three samples were taken using a corer with 3cm diameter, which was thrust 10cm into the substrate and stratified in 0-2, 2-5, and 5-10cm. Meiofauna was comprised of 16 groups and Nematoda was the dominant. Meiofauna density during rainy season was higher at the central intertidal station and during dry season it was lower near the high tide mark, followed by an increasing trend towards the low tide mark. Meiofauna was more concentrated in the upper sediment layer during rainy season. However, during dry season, the highest density occurred in the lower sediment layer at both stations near the high tide mark. Nematoda association was comprised of 72 genera, with Daptonema and Theristus (both from the family Xyalidae) as the dominant ones in most stations and strata. The genera richness and diversity increased towards the low tide mark, with lower richness in the upper stratum at most stations. Non-selective deposit-feeders predominated during rainy season, while at dry season there was an alternation of dominance between non-selective deposit-feeders and epistrate feeders. Significant differences were found in the meiofauna community, as well as in the Nematoda association in regard to the months, stations, and sediment layers. The distribution patterns of interstitial organisms found in this study, in part, follow what is already known for microtidal beaches but other differential aspects were observed even if compared to environments of macrotidal beaches in temperate regions.
In this study, we describe morphometric analyses of Orbulina universa morphotypes presently found in the Western South Atlantic, and their relation to the upper water thermohaline indexes. We also investigate this relationship under glacial and interglacial conditions between 7.2 and 32 kyr BP. Ten plankton samples distributed between 32 degrees 55' and 26 degrees 20'S were selected for the analyses of modern O. universa specimens. Core SIS188 was retrieved at 29 degrees 22'S, 47 degrees 28'W enabling the analysis of 21 fossil samples. Shell diameter, pore diameter, pore density and porosity were measured using SEM images. Chronology of core SIS188 is based on four AMS C-14 ages and the planktonic foraminifera oxygen isotope curve. Planktonic foraminifera relative abundances were converted into SST data using the Modern Analog Technique (MAT). Correlations between the morphometric parameters and temperature and salinity of surface Waters (modern samples) or paleotem-perature (fossil samples) were calculated. Morphological characteristics of the analyzed shells allowed to differentiate two morphotypes of O. universa, namely Caribbean and Mediterranean in the studied region. For the Caribbean morphotype, the large pore density showed a negative correlation with both temperature and salinity. For the Mediterranean morphotype, no significant correlations were found. For fossil samples, no significant correlations were found between summer SST (0-50m) and morphometric parameters for the Caribbean or the Mediterranean morphotypes. Possibly, other genotypes do exist in the fossil record, so modern and fossil morphotypes would not have the same behavior. Another explanation for the absence of correlation in fossil samples are errors associated with the SST estimates. Furthermore, fossil samples could represent distinct and more complex oceanographic conditions compared to current configuration, with Plata Plume Water and Brazil Malvinas Confluence migration playing a most significant role in the past.
The wave energy potential on the Brazilian coast is estimated using in-situ buoy data and model data. The results present a greater potential on the southern-southeastern coast than on the northeastern coast, but the variance is also larger. These seem to be associated with the different atmospheric regimes. While in the northeastern portion the trade winds determine the wave regime, in the south the passage of cold front systems plays a major role. For almost all regions and throughout the year, the energy potential oscillates between 10 and 30 kW/m, the most efficient range to implement wave energy converters. The occurrence of sea states is also assessed, showing that the passage of cold front systems also creates different sea states in the S-SW area. Finally, the most common sea states and energy flux are estimated, showing a shift towards longer periods and higher waves for the latter. On the S-SW coast, although the most frequent sea states have waves with periods around 8 s, the energy flux has a more balanced distribution between these and the waves with periods around 11s, the common period for waves generated by cold front systems. This result shows that the most common sea state is not necessarily the one that should be considered when planning wave energy converters for the region.
The susceptibility of coastal environments to shifts in the biogeochemical cycles of carbon and nutrients driven by anthropogenic pressure and climate change is a real challenge for the scientific community. This paper evaluated the effects of an extreme rainfall event over the nutrients and carbonate parameters in two polluted tropical estuaries. Surface water samples were taken seasonally along a salinity gradient in the Capibaribe and Barra de Jangadas estuaries m order to investigate the spatial and seasonal variability of dissolved nutrients, chlorophyll-a, dissolved oxygen, total alkalinity, inorganic carbon, partial pressure of C0(2) (pC0(2)) and C0(2) fluxes. The increased riverine influence caused by the fluvial flooding during the extremely rainy season augmented the nitrogen concentrations in the plumes, which also presented reduced salinity, alkalinity and dissolved oxygen values In the Capibaribe plume it has also shifted the mean C0(2) flux value of - 4.01 mmolC m(-2) d(-1) during the dry season, to a positive mean flux of + 5.7 mmolC m(-2) d(-1) during the rainy season. Within the estuaries the BOD5,20 and dissolved phosphorus values were higher during the dry season (p<0.0001), they showed positive correlation with the phytoplanktonic blooms that reached a chl-a value of 85 mg m(-3) in the Capibaribe. The high alkalinity found in both estuaries, with mean values between dry and wet seasons respectively from 1808 to 1373 mu mol kg-1 in the Capibanbe estuary and 1616 to 1058 mu mol kg-1 in Barra de Jangadas estuary, may act as a buffer to the process of coastal acidification due to eutrophication. The increased rivers discharge lead to a greater transport of organic matter and nutrients to the coast, decreasing the oxygen availability and shifting the metabolic status of the estuarine plume to heterotrophic, whereas increased the water quality within the estuaries due the flushing promoted by the extreme rainfall event.
The freshwater-influenced region of the Patos Lagoon discharge to the Southern Brazilian Shelf (SBS) is a region of complex fluid dynamics. Seasoning and synoptic variable winds and coastal current conditions create an alternating flow pattern. The aim of this paper was to investigate the occurrence of persistent coherent structures in this environment. A numerical approach was chosen to describe the main hydrodynamic features of the region during a climatological year. The open-source finite-element code Telemac-Mascaret was applied to the three-dimensional domain. In addition the two-equation k-epsilon model described the turbulence mechanisms. The presence of persistent high-turbulent structures was identified within the study area. These occur as a strong curvilinear disturbance characterized by higher turbulent production and dissipation rates, which increase local mixture. As a result, upward circulation flow was observed, which may be due to irregularities in bottom topography associated with wind-induced stress forces. These results increase the information about the circulation structures of the study area by means of numerical modelling analysis.
1 Centro de Estudo do Mar da Universidade Federal do Paraná UFPR (Av. Beira-mar, s/n. Caixa Postal: 61 Pontal do Paraná PR 83255-000 Brazil) 2 Instituto de Geociências da Universidade Federal da Bahia UFBA (Rua Barão de Jeremoabo, s/n Ondina Salvador BA 40170-115 Brazil) 3 Instituto de Oceanografia da Universidade Federal do Rio Grande FURG (Av. Itália, km 8 Bairro Carreiros Rio Grande RS 96203-900 Brazil) 4 Faculdade de Oceanografia do Estado do Rio de Janeiro UERJ (Rua São Francisco Xavier, 524 Rio de Janeiro RJ 20550-900 Brazil) 5 Brazilian Ocean Acidification Network (BrOA www.broa.furg.br, broa@furg.br) (Rio Grande RS 96203-900 Brazil)
