Dredging impacts on the toxicity and development of sediment quality values in a semi-arid region (Ceará state, NE Brazil).

Sediment dredging impacts coastal environments by promoting the resuspension of fine particles and remobilization of contaminants that may trigger toxic effects. In this study, we evaluated the sediment quality in harbor areas of Mucuripe bay, a semi-arid ecosystem located in Ceará state (Brazil), which is subject to dredging activities. A sampling survey was conducted right after dredging operations and data compared to another survey performed prior dredging. Sediments were analyzed for fine particles, organic carbon, nutrients, metals, hydrocarbons, and tributyltin (TBT). Toxicity of whole-sediment and liquid phase exposures were also determined. The concentrations of Cd, Cr, Cu, and Zn decreased after dredging, which was confirmed by the geoaccumulation index. Levels of TBT dropped while phosphorus, aliphatic and polycyclic aromatic hydrocarbons increased. Toxic effects persisted, indicating a post-dredging recontamination combined with other sources such as urban runoff, wastewater discharges, harbor activities, and antifouling particles. Data from Mucuripe and Pecém harbors were compiled and site-specific sediment quality values (SQVs) were developed by using multivariate methods. The threshold values proposed by our study were lower and more effective to predict toxicity compared to international guidelines, indicating levels of contamination for this tropical region in which toxic effects may occur. Considering the large geographic area with different sediment characteristics of the Brazilian coast, this study represents a significant contribution to sediment toxicity assessment of dredging activities in semi-arid environments.

Insights into leaded gasoline registered in mud depocenters derived from multivariate statistical tool: southeastern Brazilian coast.

Lead has been widely used since antiquity, but its uses drastically increased during the Industrial Revolution. The global emission of Pb into the environment was mainly due to tetraethyl lead added to gasoline as an antiknock additive. Because of its toxicity and neurological effects, the compound was phased out in the 1980s. Isotopic signatures are widely applied to differentiate sources of Pb; however, this is an expensive and sophisticated analysis compared to elemental analysis. Thus, this study aims to gain insight into leaded gasoline registered in mud depocenters from the southeastern Brazilian coast using multivariate statistical tools on elemental analysis data of trace elements. Seven multiple cores were collected on board the Research Vessel Alpha Crucis. Al, As, Ba, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Ni, P, Pb, Sc, Sr, V and Zn were analyzed by acid digestion and quantified by ICP-OES. Levels and enrichment factors of Pb resulted in homogeneous columns, indicating that small variations in concentrations can be attributed to grain size differences, not presenting contaminated levels. From statistical results, the highest contribution on the first component was represented by a lithogenic source with the leaching of continental rocks. Lead content was notable in its high loadings in other components, which suggests atmospheric deposition. An increase in these components in subsurface samples from vertical profiles between 1935 and 1996 could represent a fingerprint of the consumption of leaded gasoline in Brazil between 1923 and 1989. Thus, statistical analysis of elemental data enabled to infer possible sources and pathways of Pb to the environment, without isotopic analysis.

Transcriptional effects in the estuarine guppy Poecilia vivipara exposed to sanitary sewage in laboratory and in situ.

The urban growth has increased sanitary sewage discharges in coastal ecosystems, negatively affecting the aquatic biota. Mangroves, one of the most human-affected coastal biomes, are areas for reproduction and nursing of several species. In order to evaluate the effects of sanitary sewage effluents in mangrove species, this study assessed the hepatic transcriptional responses of guppy fish Poecilia vivipara exposed to sanitary sewage 33% (v:v), using suppressive subtraction hybridization (SSH), high throughput sequencing of RNA (Ion-proton) and quantification of transcript levels by qPCR of some identified genes in fish kept in a sewage-contaminated environment. Genes identified are related predominantly to xenobiotic biotransformation, immune system and sexual differentiation. The qPCR results confirmed the induction of cytochrome P450 1A (CYP1A), glutathione S transferase A-like (GST A-like) methyltransferase (MET) and UDP glycosyltransferase 1A (UDPGT1A), and repression of complement component C3 (C3), doublesex and mab-3 related transcription factor 1 (DMRT1), and transferrin (TF) in the laboratory experiment. In the field exposure, the transcript levels of CYP1A, DMRT1, MET, GST A-like and UDPGT1A were higher in fishes exposed at the contaminated sites compared to the reference site. Chemical analysis in fish from the laboratory and in situ experiments, and surface sediment from the sewage-contaminated sites revealed relevant levels of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyl (PCBs) and linear alkylbenzenes (LABs). These data reinforce the use of P. vivipara as a sentinel for monitoring environmental contamination in coastal regions.

Sub-lethal Responses of the Polychaete Armandia agilis in Whole-sediment Toxicity Testing.

The present study assessed biochemical responses as sublethal endpoints in the polychaete Armandia agilis exposed to contaminated sediments to in order to assess its potential use as a test organism. Sediment samples from several locations at a dredging site were obtained and used in whole-sediment exposures. Samples were tested with A. agilis to determine the 10-day toxicity of the 100% sample and the enzymatic activity of catalase (CAT), glutathione-S-transferase (GST) and acetylcholinesterase (AChE) biochemical measurements made in whole-body homogenates of a subset of the surviving organisms. Biochemical responses reported in A. agilis were not statistically different from the reference site sediment, however, the integrated analysis demonstrated that contaminants bound to sediment samples influenced the sublethal effects.

Effects of harbor activities on sediment quality in a semi-arid region in Brazil.

Tropical marine environments are rich in biodiversity and the presence of harbor activities in these areas can harm the coastal ecosystems. In this study, we assessed sediment quality of two harbors from a tropical region in Brazil by applying multiple lines-of-evidence approach. This approach included the integration of results on: (1) grain size, organic matter, organic carbon, nitrogen, phosphorus, trace metals, polycyclic aromatic hydrocarbons, linear alkylbenzenes, and tributyltin; (2) acute toxicity of whole sediments and chronic toxicity of liquid phases; and (3) benthic community descriptors. Our results revealed that the main contaminants detected in sediments from Mucuripe and Pecém Harbors were chromium, copper, nitrogen, zinc, and tributyltin. These toxicants arise from typical harbor activities. However, the changes in benthic composition and structure appear to depend on a combination of physical impacts, such as the deposition of fine sediments and the toxic potential of contaminants, especially in Mucuripe. Thus, apart from toxicants physical processes are important in describing risks. This information may assist in management and conservation of marine coastal areas.

Upregulation of biotransformation genes in gills of oyster Crassostrea brasiliana exposed in situ to urban effluents, Florianópolis Bay, Southern Brazil.

The release of untreated sanitary sewage, combined with unplanned urban growth, are major factors contributing to degradation of coastal ecosystems in developing countries, including Brazil. Sanitary sewage is a complex mixture of chemicals that can negatively affect aquatic organisms. The use of molecular biomarkers can help to understand and to monitor the biological effects elicited by contaminants. The aim of this study was to evaluate changes in transcript levels of genes related to xenobiotic biotransformation in the gills of oysters Crassostrea brasiliana transplanted and kept for 24h at three areas potentially contaminated by sanitary sewage (Bücheller river, BUC; Biguaçu river, BIG; and Ratones island, RAT), one farming area (Sambaqui beach, SAM) and at one reference site (Forte beach, FOR) in the North Bay of Santa Catarina Island (Florianópolis, Brazil). Transcript levels of four cytochrome P450 isoforms (CYP2AU1, CYP3A-like, CYP356A1-like and CYP20A1-like), three glutathione S-transferase (GST alpha-like, GST pi-like and GST microsomal 3-like) and one sulfotransferase gene (SULT-like) were evaluated by means of quantitative reverse transcription PCR (qRT-PCR). Chemical analysis of the sediment from each site were performed and revealed the presence of aliphatic and polycyclic aromatic hydrocarbons, linear alkylbenzenes and fecal sterols in the contaminated areas (BUC and BIG). Water quality analysis showed that these sites had the highest levels of fecal coliforms and other parameters evidencing the presence of urban sewage discharges. Among the results for gene transcription, CYP2AU1 and SULT-like levels were upregulated by 20 and 50-fold, respectively, in the oysters kept for 24h at the most contaminated site (BUC), suggesting a role of these genes in the detoxification of organic pollutants. These data reinforce that gills possibly have an important role in xenobiotic metabolism and highlight the use of C. brasiliana as a sentinel for monitoring environmental contamination in coastal regions.

Determination of Geochemically Important Sterols and Triterpenols in Sediments Using Ultrahigh-Performance Liquid Chromatography Tandem Mass Spectrometry (UHPLC-MS/MS).

A fast, sensitive, and selective ultrahigh-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method that is able to quantify geochemical biomarkers in sediment is described. A pool of 10 sterols, which can be used as biomarkers of autochthonous (cholesterol, cholestanol, brassicasterol, ergosterol), allochthonous (stigmasterol, ß-sitosterol, campesterol, and stigmastanol) and anthropogenic (coprostanol and epicoprostanol) organic matter (OM), and three triterpenols (lupeol, α-amyrin, and ß-amyrin) were chosen as the analytes. The method showed excellent analytical parameters, and, compared with the traditional GC-MS methods that are commonly applied for the analysis of sterols, this method requires no sample cleanup or derivatization and presents improved values for the LOD and LOQ. UHPLC can separate the diastereoisomers (epicoprostanol, coprostanol, and cholestanol) and the isomers (lupeol, α-amyrin, and ß-amyrin). The method was successfully applied for the quantification of the biomarkers, and thus, it was applied to assess the OM sources and the impacts of anthropogenic activities in sediments from different environments, such as Antarctica and other Brazilian systems (Continental Shelf, São Sebastião Channel, and Santos Estuary). Unique profiles of the biomarkers were observed for the contrasting environments, and ß-amyrin and cholesterol were more predominant in the Santos Estuary and Antarctica samples, respectively. The sterol ratios indicated a higher level of sewage contamination in the Santos Estuary.

Petroleum hydrocarbon ecological risk and changes induced on macrobenthic communities of a microtidal estuary in South America.

The coastal areas of Montevideo-Canelones, Uruguay, are strongly affected by anthropogenic activities. Polycyclic aromatic hydrocarbons (PAHs) are of especial ecological concern due to their acute toxicity. The study aimed to evaluate the relationship between different pollution levels and the ecological structure of macrobenthic communities of the subtidal coastal zone and to assess the ecological risk of the 16 PAHs identified by US EPA for these communities. Communities in Montevideo Bay are under the influence of combined effects of natural oscillations and anthropic pollution, while the adjacent coastal areas communities are strongly influenced by El Niño Southern Oscillation. Toxicity assessments classified two sites in Montevideo Bay as medium to low risk. This study allowed recognizing the complex nature of the responses of benthic organisms to multiple stressors and the importance of considering different approaches.

One century of variations in organic matter inputs in marine Antarctic sediments: Insights from bulk and isotopic data.

The elemental composition and carbon and nitrogen stable isotopes of sedimentary organic matter (OM) are vital geochemical tools for understanding environments, physical and biogeochemical processes, and even paleoclimatic conditions on Earth. Given that the Antarctic Peninsula region is one of the few areas that remain relatively preserved compared to many other regions on Earth, sensitive to climate change, and yet remains the least explored continent, this study aimed to characterise the elemental (total organic carbon and total nitrogen) and isotopic (δ13C and δ15N) composition of marine sediments from various regions of Admiralty Bay, King George Island, Antarctica. This was done to assess potential sources of OM. The sampling included: (i) 17 surface sediment samples collected across the bay in January 2020; (ii) surface sediment samples collected during the 2009-2019 period at three specific inlets of Admiralty Bay; and (iii) three sediment cores collected from each inlet in 2007-2008. TOC and TN varied from 0.09 to 0.99 % and 0.02 to 0.18 %, respectively. The δ13C values ranged from -25.9 to -18.4 ‰, while the δ15N values varied from -12.4 to 22.7 ‰. The C/N ratio values were from 2.5 to 19.3. OM in sediments from Ezcurra Inlet primarily originates from terrestrial plants prevalent in Antarctica, such as mosses and lichens, alongside aquatic plants like algae and phyto- and zooplankton. Similarly, Mackelar Inlet is characterised by substantial contributions from these abovementioned sources. In contrast, Martel Inlet exhibits diverse sources, predominantly influenced by various marine mammals and seabirds and their excrements, in addition to the signals from mosses and lichens. Recent sediments sampled post-2008 in Martel Inlet show a decreased contribution from animal sources, with mosses and lichens emerging as the predominant contributors, corroborating patterns observed in the other inlets. Our findings suggest that climate change is expanding ice-free areas, promoting the growth of terrestrial vegetation, and altering the composition of sedimentary OM in Admiralty Bay, indicating changes over the studied time scale.

Biochemical responses in Pacific oysters Magallana gigas (Thunberg, 1793): Tools to evaluate the environmental quality of aquaculture areas.

The discharge of sanitary sewage into the bays of the Florianópolis Metropolitan Area (Southern Brazil), has led to the contamination of oyster farms. Consequently, linear alkylbenzenes (LABs) were quantified in the sediment, and the biochemical responses in gills and digestive gland of oysters from six farms were assessed. Our findings revealed elevated levels of LABs in the sediment of the Imaruim and Serraria farms. Additionally, alterations were observed in the antioxidant enzymes: catalase, glutathione peroxidase and superoxide dismutase in both oyster tissue from the Serraria, Santo Antonio de Lisboa and Sambaqui farms. Furthermore, correlation analyses indicated strong and moderate associations between biochemical responses, organic contaminants, and certain physicochemical parameters. Consequently, our results demonstrated the activation of the antioxidant system in oysters, representing a protective response to the presence of sanitary sewage and other contaminants. Therefore, we propose the utilization of biochemical biomarkers for monitoring the environmental quality of farms.

Gender influences molecular and histological biomarkers in mature oysters Crassostrea gasar (Adanson, 1757) after pyrene exposure.

Oysters are frequently used as sentinel organisms for monitoring effects of contaminants due to their sessile, filtering habits and bioaccumulation capacity. These animals can show elevated body burden of contaminants, such as pyrene (PYR). PYR can be toxic at a molecular level until the whole oyster, which can show reproductive and behavioral changes. Considering that biologic parameters, such as gender or reproductive stage can interfere in the toxic effects elicited by contaminants uptake, the aim of this study was to evaluate some molecular and histological responses in females and males of oyster Crassostrea gasar exposed to PYR (0.25 and 0.5 µM) for 24 h at the pre-spawning stage. PYR concentrations were analyzed in water and in tissues of female and male oysters. Gene transcripts related to biotransformation (CYP3475C, CYP2-like, CYP2AU1, CYP356A, GSTO-like, GSTM-like, SULT-like), stress (HSP70), and reproduction (Vitellogenin, Glycoprotein) were quantified in gills. In addition, histological analysis and histo-localization of CYP2AU1 mRNA transcripts in gills, mantle and digestive diverticulum were carried out. Females and males in pre-spawning stage bioconcentrated PYR in their tissues. Males were more sensitive to PYR exposure. CYP2AU1 transcripts were higher in males (p < 0.05), as well as tubular atrophy was observed only in males exposed to PYR (p < 0.05). As expected, vitellogenin transcripts were lower in males (p < 0.05). Given these results, it is suggested that levels of CYP2AU1 be a good biomarker of exposure to PYR in oyster C. gasar and that it is important to consider the gender for the interpretation of biomarker responses.

Comparative biochemical and molecular responses of biotransformation and antioxidant systems in three species of Crassostrea (Sacco, 1897) oysters exposed to chrysene.

Chrysene (CHR) is among the most persistent polycyclic aromatic hydrocarbons (PAH) in water and a priority compound for pollutants monitoring, due to its carcinogenic, mutagenic and genotoxic potential. Aquatic animals exposed to CHR may present alterations of biomarkers involved in the biotransformation and oxidative stress-related parameters. The aim of this study was to investigate differences in antioxidant and biotransformation (phase I and II) systems of Crassostrea gigas, C. gasar and C. rhizophorae and its effects resulting from CHR exposure. Adult oysters of these species were exposed to 10 µg L-1 of CHR for 24 h and 96 h. In gills, the transcripts CYP1-like, CYP2-like, CYP2AU1-like, GSTO-like, MGST-like, SULT-like were evaluated after 24 h of exposure. The activity of SOD, CAT, GPx, GR and G6PDH were analyzed in gills and digestive glands after 96 h of exposure. CHR bioaccumulated in tissues. Differences in the remaining levels of CHR in water after 96 h were observed in aquaria containing C. gigas or C. gasar oysters and may be associated to the different filtration rates between these species. Downregulate of biotransformation genes were observed in gills of C. gasar (CYP2AU1-like and GSTO-like) and C. rhizophorae (CYP1-like1, CYP2-like, MGST-like and SULT-like), suggesting that biotransformation responses may be species-specific. Differential activity of antioxidant enzymes were observed in gills and digestive gland of oysters exposed to CHR. Biochemical responses suggested that C. gigas and C. gasar are more responsive to CHR. Differential responses observed among the three Crassostrea species can be related to evolutionary differences, ecological niches and adaptation to environment.

Evaluation of tropical water sources and mollusks in southern Brazil using microbiological, biochemical, and chemical parameters.

Florianópolis, a city located in the Santa Catarina State in southern Brazil, is the national leading producer of bivalve mollusks. The quality of bivalve mollusks is closely related to the sanitary conditions of surrounding waters where they are cultivated. Presently, cultivation areas receive large amounts of effluents derived mainly from treated and non-treated domestic, rural, and urban sewage. This contributes to the contamination of mollusks with trace metals, pesticides, other organic compounds, and human pathogens such as viruses, bacteria, and protozoan. The aim of this study was to perform a thorough diagnosis of the shellfish growing areas in Florianópolis, on the coast of Santa Catarina. The contamination levels of seawater, sediments, and oysters were evaluated for their microbiological, biochemical, and chemical parameters at five sea sites in Florianópolis, namely three regular oyster cultivation areas (Sites 1, 2, and oyster supplier), a polluted site (Site 3), and a heavily polluted site (Site 4). Samples were evaluated at day zero and after 14 days. Seawater and sediment samples were collected just once, at the end of the experiment. Antioxidant defenses, which may occur in contaminated environments in response to the increased production of reactive oxygen species (ROS) by organisms, were analyzed in oysters, as well as organic compounds (in oysters and sediment samples) and microbiological contamination (in oysters and seawater samples). The results showed the presence of the following contaminants: fecal coliforms in seawater samples (four sites), human adenovirus (all sites), human noroviruses GI and GII (two sites), Hepatitis A viruses (one site), JC Polyomavirus in an oyster sample from the oyster supplier, Giardia duodenalis cysts, and Cryptosporidium sp oocysts (one site). Among organochlorine pesticides, only DDT (dichlorodiphenyltrichloroethane) and HCH (hexachlorocyclohexane) were detected in some sediment and oysters samples in very low levels; site 4 had the highest concentrations of total aliphatic hydrocarbons, PAHs, and linear alkylbenzenes (LABs) found either in oysters or in sediment samples. The major concentration of fecal sterol coprostanol was found at site 4, followed by site 3. After 14 days of allocation in the four selected sites, there was a significant difference in the enzymes analyzed at the monitored spots. The detection of different contaminants in oysters, seawater, and sediment samples in the present study shows the impact untreated or inadequately treated effluents have on coastal areas. These results highlight the need for public investment in adequate wastewater treatment and adequate treatment of oysters, ensuring safe areas for shellfish production as well as healthier bivalve mollusks for consumption.

Unusual natural polycyclic aromatic hydrocarbons in sediment cores of an Amazon estuary.

Polycyclic aromatic hydrocarbons (PAHs) most likely derived from natural sources were observed in two sediment cores covering the last 100 years in an Amazon estuarine region. A considerable change in the PAHs main source was observed in the 1960s. Before the 1960s, the sources of PAHs seem to be related to biogenic and/or early-diagenetic processes. Concentrations of perylene were higher before the 1960s and suggest that its primary source to the sediments in the Amazon region is linked to a short-term diagenetic transformation of their biogenic precursors. The natural formation of alkylated PAHs in sediments was linked to the methylation of the parental aromatic hydrocarbons due to sediment maturation processes and the dehydrogenation of sterols in the sediments. The relatively rapid reaction occurring in recent sediments of the Amazon region suggests the importance of the microbial community in the transformation of biogenic precursors to alkylated-PAHs in the sediments.

Microplastics and linear alkylbenzene levels in oysters Crassostrea gigas driven by sewage contamination at an important aquaculture area of Brazil.

The levels of linear alkylbenzenes (LABs) and the occurrence of microplastics (MPs) in the oysters Crassostrea gigas were evaluated in six farming areas in southern Brazil. The results revealed higher concentrations of LABs in oyster tissue from the Serraria (1977 ± 497.7 ng g-1) and Imaruim (1038 ± 409.9 ng g-1) sites. Plastic microfibers were found in oysters from all locations with values from 0.33 to 0.75 MPs per oyster (0.27-0.64 MPs per gram) showing the ubiquitous presence of this contaminant in the marine environment, which could be considered a threat to farming organisms. In addition, elements such as Ti, Al, Ba, V, Rb, Cr, and Cu were found in the chemical composition of the microfibers, suggesting MPs as vectors of inorganic compounds. A positive correlation between LABs and thermotolerant coliforms suggests that sewage discharges are the main source of contamination in these oysters cultured for human consumption. The present study highlights the need for efficient wastewater treatment plants and the implementation of depuration techniques in oysters from farming areas.

Molecular changes in oysters Crassostrea gigas (Thunberg, 1793) from aquaculture areas of Santa Catarina Island bays (Florianópolis, Brazil) reveal anthropogenic effects.

Anthropogenic activities in coastal regions cause risks to the environmental and human health. Due to the carcinogenic and mutagenic potential, polycyclic aromatic hydrocarbons (PAH) are considered priority for monitoring. Most of the Brazilian production of Crassostrea gigas oysters are placed in the Bays of Santa Catarina Island. The aim of this study was to evaluate molecular responses (phase I and II of biotransformation and antioxidant defense) of C. gigas from six oyster farming areas potentially contaminated by sanitary sewage in Florianópolis Metropolitan (SC, Brazil): Santo Antônio de Lisboa, Sambaqui, Serraria, Caieira, Tapera, Imaruim. We evaluated the transcript levels of CYP1A1-like, CYP2-like, CYP2AU2-like, CYP356A1, GSTA1A-like, GSTO.4A-like, SULT-like, SOD-like and CAT-like by qRT-PCR. Only oysters from Caieira showed levels of thermotolerant coliforms allowed by the law. Chemicals analyses in soft tissues of oysters showed low to average levels of PAH in all monitored areas. Enhanced transcript levels of phase I (CYP1A1-like, CYP3564A1-like, CYP2-like and CYP2AU2-like) were observed in oysters from Serraria and Imaruí, suggesting higher biotransformation activity in these farming areas. Regarding phase II of biotransformation, GSTO.4A-like was up-regulated in oysters from Imaruí compared to Caieira and Santo Antônio de Lisboa. An upregulation of SOD-like and CAT-like were observed in oysters from Imaruí and Serraria, suggesting that oysters from these sites are facing higher prooxidant conditions compared to other areas. By integrating the biological and chemical data it is suggested that human-derived contaminants are affecting the oyster metabolism in some farming areas.

Polycyclic aromatic hydrocarbons in marine mammals: A review and synthesis.

Most marine mammal species and populations are listed as endangered, threatened, or depleted under the Endangered Species Act and the Marine Mammal Protection Act. Organic contaminants such as polycyclic aromatic hydrocarbons from anthropogenic activities are part of the threat to marine mammals. The evaluation of the potential bioaccumulation of these compounds by marine mammals is a tool for adoption of policies to reduce polycyclic aromatic hydrocarbons discharges to the marine environment, where important players such as the oil and gas industries, maritime transport and sewage companies operate. This review seeks to present a bibliographic survey covering all published peer reviewed works of the contents of polycyclic aromatic hydrocarbons in biological tissues of marine mammals. It intended to compare the sampling protocols, procedures for preservation of the tissues, and the analytical method applied to quantify the polycyclic aromatic hydrocarbons, no to criticize any of them but to review the data and discuss how they can be compared.

Sources and depositional changes of aliphatic hydrocarbons recorded in sedimentary cores from Admiralty Bay, South Shetland Archipelago, Antarctica during last decades.

Organic biomarkers, as aliphatic hydrocarbons, are present in sedimentary organic matter and have been largely applied to the evaluation of recent environmental changes in the marine environment around the globe, including the Antarctic continent. Five sediment cores were taken in the Admiralty Bay, South Shetland Archipelago, Antarctica to evaluate changes in the signature of aliphatic hydrocarbons such as n-alkanes (n-C10 to n-C40) and isoprenoids as pristane and phytane, over the last decades. The total n-alkanes concentration ranged from 0.17 to 1.67 µg g-1 (mean = 0.74 ± 0.42) which is considered low and similar to pristine sediments. Aliphatic hydrocarbons present in the sedimentary pool came mostly from terrestrial sources as Antarctic lichens and mosses, and from marine sources as the macroalgae forest debris and emergent macrophytes. Anthropogenic inputs of aliphatic hydrocarbons (e.g., petroleum and their by-products) may be neglected based on the multi-proxy approach used to distinct sources of these organic compounds. In general, no significant changes in the sources of aliphatic hydrocarbons were observed along the sediment cores; however, an increased aliphatic hydrocarbons input registered between 1975 and 1992 may be related to the increase in meltwater runoff and the relatively high abundance of marine producers more adapted to increased sea temperatures.

Anthropogenic and natural inputs of polycyclic aromatic hydrocarbons in the sediment of three coastal systems of the Brazilian Amazon.

Polycyclic aromatic hydrocarbons (PAHs) were measured in 32 surface sediment samples collected around three cities (Barcarena, Belém, and Santana) located on the coast of the Brazilian Amazon. The concentration of total PAHs ranged from lower than detection limit to 33,101 ng g-1 in a sample from Barcarena and was related to a large aluminum industrial complex and port activities. In Belém, which is the most populated area in the Amazon region, PAHs were probably derived from untreated sewage discharge and inputs from a large municipal landfill. Pyrogenic PAHs were predominant in both cities, with a smaller contribution of petrogenic PAHs. Low alkylated PAH levels may be associated with small boats and ship traffic. Santana had low total PAH concentrations, with a predominance of unusual alkylated PAHs, probably related to diagenetic transformations of organic matter in the sediment. In general, PAH concentrations in the samples were low and may reflect baseline levels for this Amazon estuarine system.

Isolated and combined effects of thermal stress and copper exposure on the trophic behavior and oxidative status of the reef-building coral Mussismilia harttii.

Global warming and local disturbances such as pollution cause several impacts on coral reefs. Among them is the breakdown of the symbiosis between host corals and photosynthetic symbionts, which is often a consequence of oxidative stress. Therefore, we investigated if the combined effects of thermal stress and copper (Cu) exposure change the trophic behavior and oxidative status of the reef-building coral Mussismilia harttii. Coral fragments were exposed in a mesocosm system to three temperatures (25.0, 26.6 and 27.3 °C) and three Cu concentrations (2.9, 5.4 and 8.6 µg L-1). Samples were collected after 4 and 12 days of exposure. We then (i) performed fatty acid analysis by gas chromatography-mass spectrometry to quantify changes in stearidonic acid and docosapentaenoic acid (autotrophy markers) and cis-gondoic acid (heterotrophy marker), and (ii) assessed the oxidative status of both host and symbiont through analyses of lipid peroxidation (LPO) and total antioxidant capacity (TAC). Our findings show that trophic behavior was predominantly autotrophic and remained unchanged under individual and combined stressors for both 4- and 12-day experiments; for the latter, however, there was an increase in the heterotrophy marker. Results also show that 4 days was not enough to trigger changes in LPO or TAC for both coral and symbiont. However, the 12-day experiment showed a reduction in symbiont LPO associated with thermal stress alone, and the combination of stressors increased their TAC. For the coral, the isolated effects of increase in Cu and temperature led to an increase in LPO. The effects of combined stressors on trophic behavior and oxidative status were not much different than those from the isolated effects of each stressor. These findings highlight that host and symbionts respond differently to stress and are relevant as they show the physiological response of individual holobiont compartments to both global and local stressors.