Abstract The bearded fireworm Hermodice carunculata is widely distributed across tropical and subtropical Atlantic and Mediterranean Oceans and was previously considered to be mostly associated with shallow reefs. We provide here data on the distribution, abundance and habitat use of H. carunculata across a euphotic-mesophotic gradient (0-90 m) in the Saint Peter and Saint Paul’s Archipelago (SPSPA, Mid Atlantic Ridge, Brazil). Samples were obtained using SCUBA and a Remote Operated Vehicle (ROV). A total of 189 individuals were observed and a sharp increase in abundance with depth was recorded, particularly from 50 m depth onwards. In the mesophotic zone (50-90 m) individuals were closely associated with branching black-corals (Tanacetipathes spp.) and predation over black-corals and the scleractinian Madracis decactis was commonly sighted. A Boosted Regression Tree model indicated black-coral abundance as the main driver of H. carunculata abundance, suggesting that preference for optimal habitats to hide/forage is more important than depth per se on the bathymetric distribution of the fireworm. The high abundances of H. carunculata in the mesophotic zone, and its predation on keystone benthic cnidarians, suggests that this species play important roles in the dynamics of deep reefs.

Abstract Although we are currently in the Decade of Ocean Sciences for Sustainable Development, Chile seems to be lagging behind in marine education. Research has shown the importance of animal imagery in generating a bond between students and their environment, and strengthening interest in conservation. The objective of this study is to contribute to ocean literacy research in Latin America, by describing coverage of ocean content in the Chilean primary school curriculum and textbooks. Content analysis was undertaken concerning textual and pictorial materials. Learning Objectives of the science primary curriculum were reviewed, and the number and type of fauna species shown in images were recorded. For each textbook, we recorded the number of marine and terrestrial animals, categorized endemic, native, and exotic species, and whether the name of the animal was labeled with the image. The results show that only three Learning Objectives of the primary curriculum explicitly define content associated with the ocean. Of the total animal images, slightly more than twenty percent are marine fauna. The great majority of the marine animals shown are native, however, most of the time the image is not reinforced with the name of the species. Considering that school textbooks are the foundation of formal education, this preliminary study indicates that there is a content deficit when teaching about the relevance of the ocean and its animal species in primary school textbooks in Chile, covering only three ocean literacy principles in the science curriculum. However, this study recognizes that important improvements have been made in prioritizing natural science teaching with images of native species.

Abstract Mangrove forests play a critical role in natural disaster resistance and provide meaningful livelihoods for local communities, especially integrated mangrove shrimp farming (IMSF) systems. Organic shrimp certification actually increases the value chains of shrimp farming in addition to ameliorating mangrove–forest management. Identifying technical issues and assessing environmental risks are the leading concerns when considering organic shrimp production certification. In this study, the technical practices of 30 households were investigated, and surface water and sediment samples were collected in the IMSF models and adjacent rivers in the Thua Duc Forest Management Board area, Ben Tre Province. Data collected from shrimp farming ponds and the environmental background were referred to both the Naturland and National Standards. The results showed that the average mangrove forest and shrimp pond ratio was 56.90:42.70 (%). Two technical issues were highlighted: (i) the use of rotenone, known as a toxin to kill undesirable fish before stocking shrimp, and (ii) annual shrimp pond regeneration causing increased pollution. The data showed that higher concentrations of TSS and P-PO4 3- were detected in surrounding rivers, while surface water in either IMSF ponds or adjacent rivers slightly surpassed the permissible levels of total Fe concentration. All parameters—including heavy metals; toxic and persistent parameters; oil and grease and coliforms analysed in surface water, and sediment samples—were lower than the detection and permissible levels. The results provided evidence that the IMSF’s practices and environmental characteristics were suitable for recommending the Naturland Standards. Recommendations and technical interventions for farmers are necessary to help reduce Fe levels and the safe use of rotenone in IMSF systems. An environmental quality monitoring programme at the target area should be applied when launching organic shrimp production.

Abstract Knowledge of the feeding habits of pelagic fishes off the Brazilian coast is scarce, making the analysis of trophic interactions often inaccurate. Here, we investigated the diet and trophic role of 12 pelagic fish species by revisiting samples obtained by the ECOSAR II Program (FURG/IO/IBAMA) between 23°S and 28°40'S, an area also known as South Brazil Bight. In addition, we analyzed their biomass and fisheries landings in order to examine shifts over time. The content of 432 stomachs was analyzed at the lowest taxonomic level possible. The frequencies of occurrence were used to cluster species, revealing three trophic guilds: "Planktivorous Clupeiformes", "Planktivorous Carangiformes", and "Piscivores". Most Carangidae consumed mainly copepods and other small crustaceans, except Selene setapinnis which clustered in the piscivorous guild together with Scombriformes specimens. In terms of biomass, the dominance of Trachurus lathami, Sardinella brasiliensis, and Trichiurus lepturus was evident. The species' trophic levels ranged from 2.98 to 4.5, showing that these fishes occupied intermediate to high trophic position. Comparing fisheries landings in two study periods (1986-2002 and 2003-2019), six species showed a decrease, while three an increase. Correlations between landings of the Brazilian sardine (Sardinella brasiliensis) and other pelagic fishes indicate that when the former's decreases, the catch of alternative species, such as Opisthonema oglinum and Chloroscombrus chrysurus, increases. The intermediate position of small pelagics in the food web may affect the availability of commercial species by controlling the abundance of lower and upper trophic-level organisms. These findings fill essential gaps for ecosystem modeling, suggesting that ecosystembased fisheries management should address multispecies issues of the pelagic realm rather than only singlespecies approaches. Combining past survey data with yield trends provides evidence for both natural and humaninduced ocean changes.

Abstract Studies relating the populational structure of target species to operational and environmental variables contribute directly to the management of the fisheries in these resources. Therefore, this study aimed to provide data on fishing and ecology of the swordfish ( Xiphias gladius) caught by the Brazilian longline fleet operating in the western Atlantic between 2010 and 2016. Generalized additive mixed models were used to evaluate the relationship between explanatory variables and responses based on Catch Per Unit of Effort (CPUE) data. Results show that the Brazilian longline fleet catches the swordfish mostly between latitudes of 5°N to 30°S and longitudes of 20° to 50°W and that the swordfish prefers temperatures under 25°C at depths below 60 meters. The species showed a tendency toward intermediate light intensity, predominating in the crescent moon phase, and a preference for areas with low chlorophyll concentrations. Our findings on operational and environmental interactions with swordfish CPUE suggest areas and times that can be used by fishing fleets and government institutions as a starting point for swordfish management strategies.

Abstract Picoplankton are central global carbon (C) cycling players and often dominate the ocean plankton communities, especially in low latitudes. Therefore, evaluating picoplankton temporal dynamics is critical to understanding microbial stocks and C fluxes in tropical oceans. However, the lack of studies on low-latitude picoplankton communities translates into a common conception that there is an absence of seasonality. Herein, we studied the temporal variation in abundance (measured by flow cytometry), and carbon flux (taking bacterial production and respiration as proxies) of the picoplanktonic community for the first time, as well as their environmental drivers in a low-latitude (05° 59’ 20.7″S 035° 05’ 14.6″W) Atlantic coastal station. We performed monthly samplings between February 2013 and August 2016 in a novel microbial observatory – hereafter called the Equatorial Atlantic Microbial Observatory – established on the northeastern Brazilian Atlantic coast. Our results revealed stability in temporal dynamics of picoplankton, despite a considerable inter-annual variation, with some related to the El Niño (ENSO) event in 2015. However, weak environmental relationships found were not enough to explain the variation in picoplankton’s abundance, which suggests that other factors such as biological interactions may lead to picoplankton abundance variation over time. Heterotrophic bacteria dominated picoplankton during the entire study period and between photosynthetic counterparts, and Synechococcus showed greater relative importance than picoeukaryotes. These results bring a novel perspective that picoplankton may exhibit more pronounced fluctuations in the tropical region when considering inter-annual intervals, and is increasing prokaryotic contribution to carbon cycling towards the equator.

Abstract This study evaluated the bioavailability of polycyclic aromatic hydrocarbons (PAHs) in Santos Bay (SB) and the adjacent Santos Continental Shelf (SCS) in Brazil. Biliary metabolites were measured in several fish species to establish a baseline for future monitoring programs. Bile samples from different species of fish were collected monthly from July to December 2005 in SB, and in August 2005 and February 2006 on SCS. Metabolite concentrations were determined using high-performance liquid chromatography with fluorescence detectors. Naphthalene, phenanthrene, and benzo[a]pyrene metabolite concentrations ranged from 24 to 810 µg g -1 of bile, 1.8 to 68 µg g -1 of bile, and below the limit of quantitation to 1.3 µg g -1 of bile, respectively. Despite its high concentrations, the levels of naphthalene metabolites were in regions of low-contamination, while benzo[a]pyrene metabolite were in the same range as those reported in moderately contaminated areas, which may indicate pyrolytic contamination by PAHs. No significant differences in the metabolite concentrations were found between the SB and the SCS samples or during the periods of collection. Future studies with a single biomonitoring species should be conducted, considering age, sex, and feeding condition of the individuals. The metabolite data presented in this study is an important baseline information for this urbanized region, which hosts several sources of contaminants.

Abstract Measurements of the marine carbonate system on tropical and subtropical continental margins are poorly distributed in space and time, with many uncertainties persisting regarding the role of carbon exchanges at the ocean-atmosphere interface in these areas. To calculate sea-to-air CO 2 fluxes in Marine Ecoregions along the Brazilian continental margin (4°N to 34°S), we used data from the Surface Ocean CO 2 Atlas (SOCAT v2020), collected up to 400 km from the coast, at the surface (5 m), between 1991 and 2018, with the aim of investigating the role of ecoregions as potential sinks or sources of atmospheric CO 2. The temperature and salinity of seawater presented variability in the north-south direction mainly because of the broad latitudinal range, reflecting typical patterns of tropical (T = 27.4°C ±1.49; S = 36.4 ±1.91) and subtropical waters (T = 22.8°C ±3.41; S = 35 ±2.91), in addition to the greater or lesser influence of river inputs in each ecoregion. The pCO 2 values in the surface waters varied from 121.81 (Amazon) to 478.92 μatm (Eastern), differing significantly between ecoregions and showing an expected decadal increasing trend, both in the atmosphere and in the seawater. The calculated values of CO 2 fluxes showed non-homogeneous spatio-temporal variations, from -24.37 mmol m-2 d-1 (Rio Grande) to 9.87 mmol m- 2 d-1 (Southeastern). Throughout the analyzed time series, we observed that the Northeast, Amazon and Eastern ecoregions acted predominantly as sources of CO 2 and the Southeastern ecoregions and, mainly, Rio Grande, acted predominantly as sinks of atmospheric CO 2.

Abstract The three-dimensional variability of the subaerial beach is examined for Stanwell Park Beach, New South Wales (NSW), Australia. This embayed environment has previously been studied over long time scales (decades), but not over shorter time scales (days, weeks). Embayed beaches experience rotation events during which opposite accretion and erosion patterns are observed at the extremities of the beach. To analyse this phenomenon, the beach is mapped with 10 Real-Time Kinematic Global Positioning System (RTK-GPS) surveys collected from 10th February 2016 to 14th May 2016. This study aims to examine short-term changes (days, weeks) to the morphology of the subaerial beach of Stanwell Park Beach and any factors that may influence its behaviours. We show that a short-time beach rotation event occurs over one month, caused by a large eastern swell. However, swell with a southern direction generates rip current channels on the subaerial beach face. During this particular event, the amount of sediment transported is lower than during beach rotation events. Furthermore, Stanwell Park Beach has two lagoons that can open to discharge water accumulated in these lagoons. We show that during heavy rainfall, the lagoons open, transporting sediment in surf zone and thus causing erosion. This study provides a clear demonstration of the sensitivity of embayed beaches to short-term variability in wave climate.

ABSTRACT The ocean bottom morphology, depth, sediment grain size, sediment sorting, carbonate content, and water depth are used to compose seafloor maps as support for biological studies. Sediments are reworked by waves and currents and accumulate according to the hydrodynamic level on the continental shelf. In contrast, sediments are accumulated by pelagic settling, mass wasting, turbidity flows, and boundary currents on the slope. Sea level oscillations during the Quaternary also played an important role in modifying the shelf seabed's morphology and sedimentary mosaic composition. The work addresses these topics in the Santos Basin based on extensive bathymetric data, shallow seismic records, and stratified bottom sediment samples in water depths ranging from 25 to 2,400m, as part of The Santos Basin Regional Environmental Characterization Project (PCR-BS). The main objective is to provide broad background information on the sedimentology and morphology of Santos Basin, focusing on the continental shelf. The morphology, sediment supply, shelf orientation, and ocean climate imprint the Santos Basin's characteristics. The Northern shelf sector is the most dynamic because of the narrow shelf, steep gradient, and East-West shoreline orientation, providing conditions for storm waves to approach and mobilize sediment in the ocean bottom shallow than 50 m water depth. The Southern sector of the shelf is much broader than the Northern sector; it displays a gentler gradient, and its orientation is Northeast-Southwest; therefore, less subject to storm waves than the Northern sector.

Abstract We evaluate how the concentrations of inorganic nutrients and chlorophyll a vary in a heterogeneous area (Equatorial SW Atlantic), covering a gradient from stations closer to the coast to others more distant associated or not with turbid-zone reefs. Vertical temperature (27.9 ± 0.10 °C; mean ± standard deviation) and salinity (36.2 ± 0.14) profles showed that the water column is well mixed (0-30 m depth). The oligotrophic condition was marked by low concentrations of phosphate (0.30 ± 0.22 µM) and dissolved inorganic nitrogen (0.64 ± 0.74 µM). Moreover, dissolved reactive silicon (DSi) was low in most samples (< 2.0 µM), but higher (>10 µM) in nearshore stations, probably related to continental runoff and/or resuspension of the bottom sediments. The pelagic phytoplankton biomass indicated that chlorophyll a (0.25 ± 0.08 µg L-1) was low, positively correlated with light and negatively correlated with nutrients, indicating possible phytoplankton uptake. Chlorophyll a concentrations were lower in stations closer to the coast and higher in some stations near the reefs, indicating that the latter could be more prone to phytoplankton development and depletion of nutrients, especially DSi. Therefore, although oligotrophy is present along this coast, we found some unexpected heterogeneity of nutrient and chlorophyll a distributions, which were probably infuenced by benthic-pelagic coupling due to the presence of extensive reefs, sponge gardens (18-30 m depth), and the proximity to the coast. These results highlight the importance of understanding the heterogeneity of ocean productivity, especially in lesser known low-latitude areas, which showed distinct nutrient and chlorophyll a levels related to the occurrence of tropical reefs that are capable of supporting important fsh stocks and unique biological communities.

Abstract Activities related to the marine exploration of oil and gas reservoirs tend to cause a concentration of natural radionuclides in related materials. As such, knowledge regarding the distribution of radionuclides in sedimentary basins with current oil operations is essential for modeling radiological hazards and possible risks of site contamination. This study investigated the distribution of 226Ra and 228Ra, radioisotopes from the 232U and 232Th decay chains in bottom sediment of the Santos basin. Sediment samples were collected from sites in a sampling grid based on depth contours and were analyzed through high-resolution gamma spectrometry. A distribution model of the spatial variation of these isotopes, the frst of its kind for the Basin, supported the interpretation of similar tendencies in their distribution. From studying the spatial trends of the mean levels of the isotopes with descriptive statistics and variance analysis, latitudinal and bathymetric diferences in the content of radionuclides emerged. These diferences are probably derived from the distinct sources of these elements, as 226Ra originates in the deep ocean from the decay of parent 230Th and from the patterns of sedimentation driven by open ocean circulation, while 228Ra is supplied by terrigenous materials transported by the northward-fowing Brazilian Coastal Current.

Abstract The degradation of tropical coastal lagoon systems in urban areas of the least developed countries has been associated with an increase in impermeable areas and poor domestic sewage treatment, increasing land-based runoff of nutrients and suspended solids from catchments. This study aimed to assess the biogeochemical changes caused by human interventions through the analysis of the spatial distribution of sedimentary phosphorus (P) and its mass balance in the Itaipu lagoon, located on the east coast of the state of Rio de Janeiro. Human intervention in the Itaipu lagoon system has caused severe imbalances in biogeochemical cycles over the past decades. Watercourses have been channeled to normalize the hydrological regime and increase hydraulic energy, improving sediment transport capacity. In this context, the increase in runoff from the coastal urban basin into the Itaipu lagoon has buried an increasing amount of phosphorus in the sediment. Recently, a regional increase in storm events caused a series of landslides and floods, which have been reported as possible consequences of global climate change. In recent decades, the synergy between landslides and river channeling has increased TP loads, accelerating phosphorus settling and changing P spatial distribution in surface sediments. This has accelerated siltation of the lagoon with an accumulation of nutrients and organic matter, leading in some cases to sediment anoxia. The lagoon has undergone strong eutrophication, changing its trophic state from meso- to hypertrophic in less than 30 years, even though P loads are not as high as in other coastal lagoons. Our findings confirm that human intervention impacts nutrient loads, which in turn disrupt the balance of biogeochemical cycles, compromising coastal water resources. This leads to the collapse of ecosystem services, another step towards degrading planetary boundaries.

Abstract This study analyses the feeding ecology of Brevortia aurea (Brazilian menhaden) larvae during a reproductive season in the Río de la Plata estuary (RPE), and explores its changes along larval development. Data were obtained from stomach content analyses of 205 individuals collected with a Bongo net during spring 2001. Larvae were discriminated into preflexion (PF), flexion (F) and post-flexion (PsF) stages. Feeding was described using complementary metrics like Feeding incidence (FI), the Relative Importance of different prey types consumed (IRI), the Degree of prey digestion (E) and Diet overlap (D), which were estimated and compared between stages. Also, larval morphometric relationships (body length, BL vs mouth width, MW) and between MW and maximum prey width (Wmax) were established for the range of observed larval sizes. The overall FI was 46.3% and increased with the development stage: 40.4% PF, 63.3% F, 78.6% PsF. Feeding occurred mainly during sunlit hours but no clear daily cycle could be established. Copepods and in particular Acartia tonsa were well represented among ingested preys, followed by invertebrate eggs and nauplii. Prey diversity and overlap between stages tended to decrease as development progressed. B. aurea exhibited isometric growth of MW in relation to BL. Average Wmax was 222.5 µm ± 100.9 SD, and increased non-linearly with both BL and MW. Gape size alone did not seem to be the limiting factor for prey choice (size), and we hypothesize that factors involved in the feeding mechanism other than mouth gape and linked with capture performance substantially influence the feeding ecology of this species in the RPE.

Abstract This study evaluated the effects of biogenic structures (tree roots and crab burrows) on sediment carbon (C), sulfur (S), and iron (Fe) biogeochemistry during the wet season in the Olaria mangrove forests near the city of Cananéia, São Paulo state, Brazil and the Nobrega mangrove forest approximately 2 km from the city. Anaerobic C oxidation pathways were assessed from sediment profiles and anaerobic incubations and related to the abundance of biogenic structures in the form of pneumatophores and crab burrows. Porewater depth profiles of dissolved inorganic carbon (DIC) and SO42- were less steep in the presence than absence of biogenic structures. While Fe(II) appeared unaffected by biogenic structures, Fe(III) levels were significantly higher in the upper 4 cm of the sediment in the presence than absence of vegetation and bioturbation. Surprisingly, the concentration of Fe(III) in this layer was 2-6 times higher in the Nobrega forest (6-13 µmol cm-3) than in the Olaria forest (1.5-6.5 µmol cm-3). Accordingly, depth integrated sulfate reduction (SR) tended to be highest at Olaria, while iron reduction (FeR) was highest at Nobrega. SR accounted for 54-83% of DIC production, with no diference between forested sites, while FeR accounted for 8-24% of DIC production, with a 2-3 times higher contribution in the Nobrega versus the Olaria forest. The results suggest that mangrove roots and crab burrows in mangrove sediments only promote FeR at the expense of SR in the Nobrega forest. It appears that anthropogenic discharge from Cananéia city may have overridden the impact of biogenic structures on sediment redox conditions at Olaria, thereby diminishing the role of FeR without strong stimulation of overall C oxidation rates.