Biochemical changes in the liver and gill of Cathorops spixii collected seasonally in two Brazilian estuaries under varying influences of anthropogenic activities.

In order to understand environmental health by the use of a bioindicator species in estuaries, biochemical responses observed in the catfish Cathorops spixii such as catalase (CAT), glutathione-S-transferase (GST), lipid peroxidation (LPO) and acetylcholinesterase (AChE) were evaluated in liver and muscle. Furthermore, histological changes were also verified in liver and gills preparations. Fish were collected in three sites of the Santos-São Vicente estuary located at São Paulo (Brazil), subjected to varying levels of inputs of pollutants. For a reference site, specimens were sampled at Cananéia estuary at southern coast of São Paulo, a region with low anthropogenic influence. In general, no significant seasonal differences in antioxidant enzymes and lipid peroxidation responses were found in the organisms from the Cananéia estuary. However, in the polluted estuary (Santos-São Vicente), biochemical responses were observed by increases in GST hydroperoxides and decreases in AChE activities in the summer. Inhibition of AChE expression in fish from different areas of the Santos-São Vicente estuary in the summer was also found and can indicate neurotoxic effects in these organisms. Histopathological observation of gill and liver showed severe lesions, such as lamellar fusion and necrosis.

Temporal and spatial toxicogenetic damage in estuarine catfish Cathorops spixii from a marine protected area with evidence of anthropogenic influences.

Taking action to contribute to the preservation of the natural coastal environment, which maintains a diversity of life, is important in today's world. In estuarine ecosystems that are included in marine protected areas (MPA), it is important to conduct biomonitoring over time to monitor the effects of xenobiotics on bioindicator species such as the catfish Cathorops spixii. This study aims to evaluate the toxicogenetic signals in C. spixii from a MPA (Cananéia-Iguape region, Brazilian coast). These genotoxic signals are demonstrated by the presence of micronuclei (MN) and abnormalities in erythrocytes (AE). This study also takes into account the environmental differences signaled by the water's properties (temperature, salinity, pH, DO, dissolved nutrients, and particulate material) over time (2009, 2014, 2017, and 2018). The results show that in the northern region of the estuary, and mainly in 2009, the water properties reveal the influence of the river in the form of the lowest levels of salinity and pH and the highest levels of nutrients. The most significant levels of suspended particulate material and chlorophyll-a are found in the southern region of the estuary, mainly in 2017 and 2018. In general, the C. spixii from the northern region had better well-being than catfish from the more preserved (southern) region. The data on MN and AE show evidence of toxicogenetic damage occurring over time and clastogenic/aneugenic effects mainly in fish sampled in 2018. The presence of a new AE, first recorded in C. spixii sampled in 2018, and named here as double bubbled, is another indicator of toxicogenetic effects. Finally, although the southern region of the estuary has better abiotic properties and conditions for primary production, the obtained toxicogenetic data for C. spixii reinforces the need for - and encourages the implementation of - monitoring actions in this marine protected area using bioindicator species of contamination.

Use of Cathorops spixii as bioindicator of pollution of trace metals in the Santos Bay, Brazil.

In the present study Cathorops spixii, was evaluated as a bioindicator fish for trace metal pollution. Concentrations of cobalt (Co), iron (Fe), selenium (Se) and zinc (Zn) were determined by Instrumental Neutron Activation Analysis in liver. Mercury (Hg) and methyl-mercury (MeHg) were analyzed by Cold Vapor Atomic Absorption Spectrometry in muscles and livers. High concentrations of Co, Fe, Se and Zn were observed in C. spixii from Santos Bay in comparison to fish collected in a non-polluted site in the same Brazilian coast. These trace metal concentrations were out of the permissible levels for human consumption. Although, Hg and MeHg levels were low, the C. spixii could still be used as an effective bioindicator to observe trace metal behaviors in the environment in function of the bioaccumulation process observed mainly by other analyzed trace metals. Thus, the use of this species is strongly recommended to monitor the effects and behavior of trace metal pollution in aquatic ecosystems in Brazil due to its bioaccumulation function.

Biomarkers of exposure to metal contamination and lipid peroxidation in the benthic fish Cathorops spixii from two estuaries in South America, Brazil.

Biomarkers as lipid peroxidation, metallothionein and delta-aminolevulinic acid dehydratase were determined in Cathorops spixii to compare the biological responses of this fish from estuaries with distinct anthropogenic influence. Three areas were selected in two estuaries in accordance with the levels of contamination for the polluted (Santos/São Vicente) and with the hydrodynamic characteristics for the non-polluted (Cananéia) estuary. Water characteristics and mercury levels in C. spixii confirmed a high human influence in the polluted system. In general, the biomarkers showed differences between the estuaries, suggesting disturbances in the specific cell mechanisms due to the presence of multiple xenobiotics in the contaminated system. Therefore, these biomarkers are recommended to promote more accurate information about the exposure to pollutants. Additionally, the study of the effect of the multiple xenobiotics on resident species such as the benthic fish C. spixii can favor a better assessment of the environmental quality of these systems.

Recording different geometries of 2D hexagonal photonic crystals by choosing the phase between two-beam interference exposures.

2D hexagonal patterns can be generated by the superimposition of two or three fringe patterns that have been formed by two-wave interference and that have rotations of 60 degrees between them. Superimposing three exposures solves the problem of asymmetry in the cross section of structures, which is caused by double exposure. The resulting structure, however, depends on the phase shift of the third fringe pattern in relation to the previous two. We propose a method for controlling the phase shift, and we demonstrate that three different lattice geometries of hexagonal photonic crystals can be recorded when the phase is chosen.

Simulation of the enhancement factor from an individual 3D hemisphere-on-post field emitter by using finite elements method.

This paper presents a 3D computational framework for evaluating electrostatic properties of a single field emitter characterized by the hemisphere-on-post geometry. Numerical simulations employed the finite elements method by using Ansys-Maxwell software. Extensive parametric simulations were focused on the threshold distance from which the emitter field enhancement factor (γ) becomes independent from the anode-substrate gap (G). This investigation allowed demonstrating that the ratio between G and the emitter height (h) is a reliable reference for a broad range of emitter dimensions; furthermore, results permitted establishing G/h ≥ 2.2 as the threshold condition for setting the anode without affecting γ.

Reconnaissance of submarine groundwater discharge at Ubatuba coast, Brazil, using 222Rn as a natural tracer.

Submarine groundwater discharge (SGD), which includes fresh groundwater and recycled seawater, has been recognized as a widespread phenomenon that can provide important chemical elements to the ocean. Several studies have demonstrated that SGD may approach or even exceed freshwater sources in supplying nutrients to coastal zones. This work reports preliminary results of a study carried out in a series of small embayments of Ubatuba, São Paulo State, Brazil, covering latitudes between 23 degrees 26'S and 23 degrees 46'S and longitudes between 45 degrees 02'W and 45 degrees 11'W. The main aims of this research were to set up an analytical method to assess 222Rn and 226Ra activities in seawater samples and to apply the excess 222Rn inventories obtained to estimate SGD. Measurements made during the summer of 2001 included 222Rn and 226Ra in seawater, 226Ra in sediment, seawater and sediment physical properties, nutrients and seepage rates. A continuous 222Rn monitor was also used to determine in situ collection of data to study short-term changes at one location. All methods indicated significant inflow of subsurface fluids at rates in excess of several cm per day.

Tracing latitudinal gradient, river discharge and water masses along the subtropical South American coast using benthic Foraminifera assemblages.

More than 30% of Buccella peruviana (D'Orbigny), Globocassidulina crassa porrecta (Earland & Heron-Allen), Cibicides mackannai (Galloway & Wissler) and C. refulgens (Montfort) indicate the presence of cold Sub Antarctic Shelf Water in winter, from 33.5 to 38.3º S, deeper than 100 m, in the southern part of the study area. In summer, the abundance of this association decreases to less than 15% around 37.5-38.9º S where two species (Globocassidulina subglobosa (Brady), Uvigerina peregrina (Cushman) take over. G. subglobosa, U. peregrina, and Hanzawaia boueana (D'Orbigny) are found at 27-33º S in both seasons in less than 55 m deep in the northern part, and are linked with warm Subtropical Shelf Water and Tropical Water. Freshwater influence was signalized by high silicate concentration and by the presence of Pseudononion atlanticum (Cushman), Bolivina striatula (Cushman), Buliminella elegantissima (D'Orbigny), Bulimina elongata (D'Orbigny), Elphidium excavatum (Terquem), E. poeyanum (D'Orbigny), Ammobaculites exiguus (Cushman & Brönnimann), Arenoparrella mexicana (Kornfeld), Gaudryina exillis (Cushman & Brönnimann), Textularia earlandi (Parker) and thecamoebians in four sectors of the shelf. The presence of Bulimina marginata (D'Orbigny) between 34.1-32.8º S in the winter and 34.2-32.7º S in the summer indicates that the influence of the Subtropical Shelf Front on the sediment does not change seasonally, otherwise, the presence of Angulogerina angulosa (Williamson) in the winter, only in Mar del Plata (38.9º S), show that Malvinas currents are not influencing the sediment in the summer.

Diffractive structures holographically recorded in amorphous hydrogenated carbon (a-C:H) films.

We propose and demonstrate the direct recording of submicrometer relief gratings in amorphous hydrogenated carbon (a -C:H) films by reactive ion etching (RIE) for use as diffractive optical components. The high refractive index of this film and its transparency in the IR make such structures promising candidates for IR-transmission diffractive optical components. The structures are holographically recorded in photoresist and then transferred to a thin aluminum layer that is used as a mask for RIE of the a -C:H films. The diffraction measurements of the structures recorded in these films demonstrated the feasibility of using the materials as diffractive optical components.