Bivalve Anomalocardia Brasiliana Research Articles

Biosurfactant Production using Candida tropicalis URM 1150 and its Application in the Bioremediation of Coast Environments Impacted by Oil Spills

Background: This study aimed to produce, characterize, and apply a biosurfactant as a bioremediation tool for oil-contaminated coastal environments. Methods: The biosurfactant was produced in a medium containing 5.0% corn steep liquor and 1.5% residual frying oil by Candida tropicalis (URM 1150) for 144 hours with 200 rpm agitation. The growth curve and production of the biosurfactant were evaluated. The emulsifying properties and stability of the biosurfactant were tested against pH, temperature, and NaCl variations. Toxicity assays were carried out on seeds, the microcrustacean Artemia salina, and the bivalve Anomalocardia brasiliana. Static and kinetic assays were performed, alongside stone washing to assess the removal capacity. Results: The produced biosurfactant had a surface tension reduction capacity of 70 to 25 mN/m, yielding 7.1 g/L, and a critical micellar concentration (CMC) of 0.4%. During the initial 4-hour cultivation period, the growth curve showed an exponential phase, marked by a constant increase in production. In the final growth stage, biosurfactant production reached its maximum value of 7.1 g/L. After 120 h of cultivation, the maximum biomass output of 9.93 g/L was reached. The biosurfactant was applied in static and kinetic tests with seawater and sand contaminated with oil. The biosurfactant remained stable in the face of the tested variations. The biosurfactant is anionic in nature and showed no toxicity to the microcrustacean Artemia salina, vegetable seeds, or the bivalve Anomalocardia brasiliana, which exhibited 100% survival rates. The biomolecule removed 97% of the contaminated oil on the stone. The biosurfactant proved efficient and biocompatible for the bioremediation of oil derivatives, showing significant removal rates of hydrophobic compounds. Conclusion: These results indicate that the biosurfactant has great potential for application as a remediation agent to clean up oil spills in coastal environments.

Ecotoxicity of the formulated biosurfactant from Pseudomonas cepacia CCT 6659 and application in the bioremediation of terrestrial and aquatic environments impacted by oil spills

Dispersants with a low environmental impact are necessary for oil spill remediation. Thus, the biosurfactant produced by the bacterium Pseudomonas cepacia CCT6659 using industrial waste and formulated using a method of adding food preservative was evaluated for its toxicity against the vegetable Allium cepa and aquatic species such as the freshwater fish Poecilia vivipara and the bivalve Anomalocardia brasiliana. The biosurfactant was also applied in the removal of hydrophobic contaminant in sand and soils, in sea stones, in the dispersion and in the bioremediation of oil in seawater. The surfactant was considered to be of low toxicity for the bioindicators evaluated. As a petroderivative removal agent, the formulated tensoactive reached 76.55 % removal in soil and 84.50 % in sea stones. The biosurfactant was able to disperse 96.00 % of oil in seawater and promoted an increase in the biodegradation of oil by 70.00 % during a bioremediation process carried out in seawater. Therefore, the formulated biosurfactant presents suitable conditions for application as a dispersing agent in the decontamination of terrestrial and aquatic environments impacted by oil spills in substitution of chemical and toxic compounds.

Multivariate taphonomic analysis of mollusk shell concentrations in Holocene deposits of southern Brazil: An integrated approach

Shell concentrations are one of the most distinctive features of the Holocene coastal stratigraphy in the southern portion of Santa Catarina State, southern Brazil. In this paper, we integrated stratigraphic, geochronological, geophysical, and taphonomic data to discuss the processes involved in the genesis of shell concentrations in a siliciclastic and subtropical setting, a useful analogy for ancient shell concentrations in semi-closed environments affected by storms. The data indicated the succession of three facies associations (FA): bay, lagoon, and back-barrier. This succession implies a grain size fining-upward trend that is representative of a gradual shallowing. Interpretation of GPR sections revealed that the passage from the bay to lagoonal deposits occurred by forming a laterally continuous, high-amplitude surface overlain by sigmoidal reflections, which characterized the progressive basinward backstepping of the lagoonal margin. Shell concentrations in bay deposits are an allochthonous product of storm flows in shallow waters. In contrast, accumulations of the bivalve Anomalocardia brasiliana had their valves reworked in the lagoonal margins and transported to the bottom, characterizing a parautochthonous accumulation. In this study, the correlation of taphonomy and grain size indicates that in bay FA, the loss of periostracum is correlated with increased gradients of fine sand, and part of the shell samples correlates to corrosion and abrasion in increased gradients of medium sand and decreased ones of fine sand. Additionally, in the lagoon FA, the loss of periostracum depends on the decrease in mud-enriched sediments and the increase in fine and medium sand, whereas brightness loss and color alteration are related to the increase in fine and medium sand, as well as margin modification. Corrosion was positively correlated to the mud-dominated fraction.

Production, characterization, evaluation and toxicity assessment of a Bacillus cereus UCP 1615 biosurfactant for marine oil spills bioremediation

In this study, Bacillus cereus was cultivated in a mineral medium composed of 2% frying oil and 0.12% peptone to produce a biosurfactant. The production was scaled up from flasks to 1.2-, 3.0- and 50-L bioreactors, where surface tension achieved 28.7, 27.5 and 32 mN/m and biosurfactant concentration 4.3, 4.6 and 4.7 g/L, respectively. The biosurfactant was characterized as anionic, while nuclear magnetic resonance, thin-layer chromatography and gas chromatography analyses revealed its lipopeptide nature. Toxicity tests showed survival rates of the fish Poecilia vivipara and the bivalve Anomalocardia brasiliana higher than 90% and 55%, respectively, thus suggesting the use of this biosurfactant in marine environment depollution. Moreover, the biosurfactant stimulated the growth of autochthonous microorganisms independently of the presence of motor oil in bioassays performed in seawater. These results demonstrate that the biosurfactant is biocompatible and has potential for industrial-scale production and application to bioremediation of oil spills-polluted marine environment.

An alternative approach to bioaccumulation assessment of methyl-Hg, total-Hg, Cd, Pb, Zn in bivalve Anomalocardia brasiliana from Rio de Janeiro bays

We present an alternative approach for establishing in situ bioaccumulation assessment of methyl-Hg (MeHg), total-Hg, Cd, Pb and Zn in bivalve Anomalocardia brasiliana from four bays of Rio de Janeiro presenting varying degrees of eutrophication, acid volatile sulfides (2–55 μmol g−1), simultaneously extracted metals (SEM) and total metals (TM) in sediments. Using metal concentrations of composite samples from three size classes of bivalve and their incorporation rates (IR = metal concentration / total length), which depend on exposure time, we calculated asymptotic IR and respective consequent metal concentrations. Both IR and the metal concentration presented inverse relationships with total length (excepting MeHg) and bay contamination. Lead and zinc concentrations were above Brazilian legal criteria in the most anoxic and contaminated bay, suggesting significant metal bioavailability (SEM/TM between 8% and 63%).

Meiosis Maturation in the Marine Clam Anomalocardia brasiliana (Veneridae)

ABSTRACT Advances in oyster farming have been achieved with biotechnological applications, such as chromosome manipulations aimed at polyploidy. The bivalve Anomalocardia brasiliana is of considerable importance to artisanal fishing activities and is a potential organism for aquaculture in Brazil. The cytogenetic behavior of polar bodies during meiosis provides essential information for chromosome manipulation directed at the production of triploid organisms. The objective of the present study was to identify postfertilization times in which the polar bodies are expelled and determine the most frequent number of chromosomes in A. brasiliana. Individuals were caught on the coast of the state of Pernambuco, in northeast Brazil, and subsequently induced to release the gametes. Samples of the oocyte solution were taken before and every 2 min after fertilization. The material was fixed in Carnoy's solution, stained with 4′,6-diamidino-2-phenylindole and photographed under an epifluorescence microscope. Among t...

Distribution and density of the bivalve Anomalocardia brasiliana in the estuarine region of Northeastern Brazil

The objective of this study was to analyze the density and distribution of the bivalve Anomalocardia brasiliana in beaches in the estuarine region of the semiarid in Rio Grande do Norte State, Barra and Pernambuquinho (04°56.978'S and 37°08.961'W and 04°56.792'S and 37°09.375'W, respectively). Samples were collected monthly during 37 months using five transects (300 m long and 400 m apart) laid perpendicularly to the beach line toward the sea. Seven collection points, 50 m apart, were set in each transect, and shellfish and sediment samples were collected. Temperature and salinity were measured in each transect. The results showed a temperature variation of average values ​​of 3 °C; the greatest variation (33.2 °C) was observed in May of 2009. The lowest average salinity values were observed between April and June of 2009 (5, 8.7, and 7.8, respectively). This fact was due to an atypical rainfall in the region, which resulted in a large freshwater inflow into the estuary; the average salinity values ​​were about 40 in the remaining months. The highest precipitation values were observed in April/09, April/10, and April/11; the highest precipitation occurred in April/09 (316.3 mm). The lower average densities of A. brasiliana were observed in April and May/09 when compared to the other months; the lowest value was observed in April/09 (26 ind/m2). The highest densities occurred between November/10 and July/11, with values ​​ranging from 70 to 322 ind/m2. The highest inflow of young individuals (lengths from 2 to 5 mm) was observed between April and June of 2010 and on September/10 while the highest frequency of adults (from 20 to 25 mm) occurred between December of 2010 and April of 2011. Hence, the results of this study show that in the months with the greatest rainfall, salinity and the average density of A. brasiliana showed the lowest values.

Environmental influence on population dynamics of the bivalve Anomalocardia brasiliana

Understanding how species respond to the environment in terms of population attributes (e.g. abundance, growth, mortality, fecundity, and productivity) is essential to protect ecologically and economically important species. Nevertheless, responses of macrobenthic populations to environmental features are overlooked due to the need of consecutive samplings and time-consuming measurements. We examined the population dynamics of the filter-feeding bivalve Anomalocardia brasiliana on a tidal flat over the course of one year to investigate the hypothesis that, as accepted for macrobenthic communities, populations inhabiting environments with low hydrodynamic conditions such as tidal flat should have higher attributes than populations inhabiting more energetic habitats (i.e. areas more influenced by wave energy such as reflective and intermediate beaches). This would be expected because the harsh conditions of more energetic habitats force organisms to divert more energy towards maintenance, resulting in lower population attributes. We found that A. brasiliana showed moderate growth and secondary production at the study area. Moreover the recruitment period was restricted to a few months. A comparison with previous studies showed that, contrary to expected, A. brasiliana populations from areas with low hydrodynamic conditions have lower abundance, growth, recruitment and turnover rate. It is likely that morphodynamic characteristics recorded in these environments, such as larger periods of air exposure and lower water circulation, may affect food conditions for filter-feeding species and increase competition. In addition, these characteristics may negatively affect macrobenthic species by enhancing eutrophication processes and anoxia. Overall, our results suggest that models accepted and applied at the macrobenthic community level might not be directly extended to A. brasiliana populations.

Biosurfactant production from Candida lipolytica in bioreactor and evaluation of its toxicity for application as a bioremediation agent

Abstract This large-scale production, toxicity, characterization and economic analysis of the biosurfactant from Candida lipolytica UCP 0988 produced in the low-medium formulated with animal fat and corn steep liquor was investigated. The biosurfactant was produced in the stationary phase under 200 rpm in the absence of aeration and reduced the surface tension of the medium from 50 to 28 mN/m after 96 h, yielding 10.0 g/L of isolated biosurfactant in a 2 L bioreactor. The production was maximized in a 50 L bioreactor, reaching 40 g/L biosurfactant and 25 mN/m. The cell biomass was quantified and characterized for use in animal nutrition. Chemical structures of the biosurfactant were identified using FTIR and NMR. The crude biosurfactant was not toxic to the bivalve Anomalocardia brasiliana, to the microcrustacean Artemia salina, or three species of vegetables seeds. The biosurfactant stimulated the degradation of motor oil by the seawater indigenous microorganisms. The results obtained indicate that the biosurfactant produced has great potential to be applied as a bioremediation agent for cleaning oil spills.

Antioxidant responses in estuarine invertebrates exposed to repeated oil spills: Effects of frequency and dosage in a field manipulative experiment

We have experimentally investigated the effects of repeated diesel spills on the bivalve Anomalocardia brasiliana, the gastropod Neritina virginea and the polychaete Laeonereis culveri, by monitoring the responses of oxidative stress biomarkers in a subtropical estuary. Three frequencies of exposure events were compared against two dosages of oil in a factorial experiment with asymmetrical controls. Hypotheses were tested to distinguish between (i) the overall effect of oil spills, (ii) the effect of diesel dosage via different exposure regimes, and (iii) the effect of time since last spill. Antioxidant defense responses and oxidative damage in the bivalve A. brasiliana and the polychaete L. culveri were overall significantly affected by frequent oil spills compared to undisturbed controls. The main effects of diesel spills on both species were the induction of SOD and GST activities, a significant increase in LPO levels and a decrease in GSH concentration. N. virginea was particularly tolerant to oil exposure, with the exception of a significant GSH depletion. Overall, enzymatic activities and oxidative damage in A. brasiliana and L. culveri were induced by frequent low-dosage spills compared to infrequent high-dosage spills, although the opposite pattern was observed for N. virginea antioxidant responses. Antioxidant responses in A. brasiliana and L. culveri were not affected by timing of exposure events. However, our results revealed that N. virginea might have a delayed response to acute high-dosage exposure. Experimental in situ simulations of oil exposure events with varying frequencies and intensities provide a useful tool for detecting and quantifying environmental impacts. In general, antioxidant biomarkers were induced by frequent low-dosage exposures compared to infrequent high-dosage ones. The bivalve A. brasiliana and the polychaete L. culveri are more suitable sentinels due to their greater responsiveness to oil and also to their wider geographical distribution.

Does mollusc shell debris determine patterns of macrofaunal recolonisation on a tidal flat? Experimental evidence from reciprocal transplantations

Mollusc shells introduce complexity and heterogeneity into soft-sediment habitats and might regulate the structure and functioning of benthic assemblages. Two areas of an unvegetated tidal flat located at the mouth of Paranaguá Bay (southern Brazil) largely differ in substrata characteristics and macrofaunal assemblage structure. Sediments of the inner part of the studied site are structurally more complex than those of the peripheral portion, due to high densities of empty shells of the bivalve Anomalocardia brasiliana. The effects of this biogenic matrix on macrofaunal recolonisation during a three-month period were assessed through a reciprocal transplantation experiment of defaunated sediment between shelled and bare habitats. Hypotheses were tested to distinguish between three possible causes of variation: (i) habitat complexity, (ii) intrinsic factors of each area (regardless of the presence/absence of shells), and (iii) their interaction. Habitat structural heterogeneity provided by empty shells does not explain the large differences between macrofauna in shelled and bare habitats. Assemblages that colonised transplanted sediments became similar to those in controls at the area to which they were moved, but differed from those in controls at the area where they originated. The lack of a consistent response of assemblages to the presence of shells can be explained not only by the extremely fast recovery following small-scale experimental disturbances, but also by the dispersal mechanisms related to reproductive traits of the dominant taxa. Changes in assemblages were greatly influenced by the tanaid Monokalliapseudes schubarti, the numerically-dominant species that showed consistent differences among treatments. The reduced dispersal capacity due to the lack of planktonic larval stages associated with high fecundity, continuous reproduction and fast growth were determinant features for the rapid colonisation of defaunated sediments, regardless of habitat complexity. Despite the well-recognised impact of mollusc shell production on soft-sediment habitats, our study showed that its effects are scale-dependent, both spatially and temporally, and might be regulated by the structure of local assemblages and species-specific responses related to dispersal mechanisms.

Population structure of the bivalve Anomalocardia brasiliana, (Gmelin, 1791) in the semi-arid estuarine region of northeastern Brazil.

For several decades, the bivalve mollusk Anomalocardia brasiliana has been extracted in estuarine areas in the semi-arid region of northeastern Brazil. However, information on both dynamics and abundance of their populations are missing. In this context, the present study, therefore, investigated several aspects of the population structure of A. brasiliana on beaches near the estuary of the Apodi River in Northeast Brazil. The aims were to determine the population density of A. brasiliana during different times of the year, to estimate population parameters, and to relate species density and distribution to the abiotic characteristics of the region. Sampling was performed from March/2007 and May/2008, we collected samples of sediments and mollusks along 180 m transects in the intertidal area on the beaches Barra and Pernambuquinho, Grossos - RN. At each sampling site, samples of sediments and mollusks were collected in the intertidal area along 180 m transects. The highest and lowest average densities on Pernambuquinho beach were 1148 (April/2007), and 100 individuals.m-2 (May/ 2008), respectively. On Barra beach, the highest and lowest densities were 1813 (April/2007) and 951 individuals.m-2, (November/2007), respectively. The densities of A. brasiliana on both beaches were significantly different only in the months of January, April and May/ 2008. Length of the individuals ranged from 1 to 28 mm, with most individuals measuring between 22 and 24 mm. Length growth rate parameters for A. brasiliana were L∞ = 28.68 mm and k = 0.61 year-1 on Barra beach, and L∞ = 29.87 mm and k = 0.48 year-1 on Pernambuquinho beach. The growth rate curves for A. brasiliana suggest the presence of three well defined cohorts, thus pointing to a continuous reproduction cycle with peak recruitment between October/2007 and March/2008. A. brasiliana density decreased predominantly during the heavy rains of 2008, probably due to an accumulation of sediments and decreasing salinity. This disturbance probably affected population of this species in the region.

Evaluation of the concentration the cadmium, cupper, iron, manganese, nickel and zinc in Anomalocardia brasiliana (Gmelin, 1791) distributed in mangrove areas of São Francisco do Conde and Madre de Deus, Recôncavo Baiano, BA

Cadmium (Cd), cupper (Cu), iron (Fe), manganese (Mn), nickel (Ni) and zinc (Zn) concentrations had been investigated in specimens of the mollusc bivalve Anomalocardia brasiliana (Gmelin, 1791), distributed at nine stations situated in mangroves zones, located at the Baía de Todos os Santos, Bahia, Brazil. Collection sites were selected based on the existence of antropic sources. The analyses had been carried through the atomic absorption spectrometry after drying and digestion of the sample. The concentrations of Cd, Fe, Mn and Ni had differed statistical (p < 0.05) at the different areas. The sites with strong industry influence, Coqueiro Grande at the northeast part of the Baía de Todos os Santos, and Fazenda Cajaíba located at the northern part, had presented the highest concentrations for metals in study. Despite the high concentrations found none of the analysed metals were above the limit established of the Brazilian legislation for human consumption.

Effects of sediment disturbance on the structure of benthic fauna in a subtropical tidal creek of southeastern Brazil

An experimental analysis of benthic response to sediment disturbance by the blue crab Callinectes danae was carried out in an unvegetated flat adjacent to a salt marsh of the tidal Perequ& Creek (Paranagua Bay, SE Brazil). In order to mimic the natural pits dug by C. danae, we made randomly arranged holes, which were subsequently sampled together with undisturbed control sites on 6 different sampling dates, up to 18 d after disturbance. Analyses of variance were performed to determine if significant differences in macrobenthic population densities and abiotic parameters existed at different sampling times, and between control and disturbed areas. Apart from water content, physical variables did not differ significantly between disturbed and control areas, suggesting that adaptive strategies of the organisms themselves were the maln structuring factor of the recolonization process. We provide evidence that active immigration, together with passlve deposition, is a major colonization vector for the fauna of local low-energy tidal flats. Recolonization rates of the local fauna paralleled the mobility degrees of individual species or taxa. The numerically dominant surface crawler Heleobia australis and the burrower Lumbrineris tetraura, which are the more mobile species of local macrofauna, also exhibited the more rapid recolonization. There was no evidence that the catchment action of pits actually concentrated food resources, since sediment organic content was essentially similar between disturbed and control sites. Evidence for passive deposition was shown for the sedentariate species Laeonereis acuta, Capitella capitata and an unidentified nematode, whose recolonization rates were moderate and followed the sediment infill of pits. The only species to exhibit evidence of exploiting conditions created by pit simulation was the suspension-feeding bivalve Anomalocardia brasiliana that exhibited fast recolonization rates and higher abundance at disturbed sites. The infaunal predator Sigambra grubji was the only species present at significantly lower densities in pits throughout the experiment, probably due to the removal of its putative food source. Disturbances made by blue crabs, though short-lived, are abundant and frequent enough actually to maintain high densities of species that are otherwise scarce in similar tidal habitats. Such biogenic disturbances can be considered as a mechanism that allows for the persistence and numerical dominance of opportunistic species in tidal flats of local tidal creeks.