Maximiliano Cledón

Biomonitoring of TBT contamination and imposex incidence along 4700 km of Argentinean shoreline (SW Atlantic: From 38S to 54S)

The imposex incidence and TBT pollution were investigated along 4,700km of Argentinean coast, including city harbors and proximal zones without marine traffic. We analyzed 1805 individuals from 12 gastropod species, including families Volutidae, Muricidae, Nassariidea, Calyptraidae, Marginellidae, and Buccinidae, and found the imposex phenomenon for the first time in six species. In high marine traffic zones, TBT pollution was registered and the percentage of imposex was high, while these occurrences were null in areas without boat traffic. The species that best reflect the degree of imposex were those inhabiting sandy/muddy or mixed bottoms. TBT determination and imposex incidence indicate that pollution was focused only in ports with high marine traffic or in areas where ship hulls are painted. This is the first report of an imposex-sediment approach to evaluate organotin contamination along the coast of a South American country.

Size and age at sexual maturity in Adelomelon brasiliana (Neogastropoda: Volutidae) off Argentina

Size at first maturity of Adelomelon brasiliana near Mar del Plata, Argentina, was established analysing gonad tissue samples and the secondary sexual characters. Age was determined through growth marks. Gonad matures after development of secondary sexual characters. Minimum shell length at sexual maturity is 107 mm in females and 102 mm in males. The shell length at which 50% of the animals are mature is 115.1 mm in females and 107.25 mm in males (approximatley 7 years of age). In males, penis matures before testis. All animals are mature beyond 125 mm in females and 115 mm in males, respectively (approximatley 8 years of age). The comparative late sexual maturation in this species makes the population quite sensitive to over-fishing.

The effect of temperature on the inhalant siphon regeneration of Amiantis purpurata (Lamarck, 1818) (Bivalvia; Veneridae)

Abstract The purple clam Amiantis purpurata inhabits intertidal and shallow subtidal platforms from San Matías Gulf, Argentina to Santa Catarina, Brazil. This edible bivalve is an important component of the marine trophic webs due to siphon nipping. The present study investigates the influence of temperature on the regeneration of the inhalant siphon tentacle crown of A. purpurata. Under laboratory conditions 140 purple clams were exposed to four different temperatures (12, 15, 20 and 22°C). At each temperature, the distal 0.5 cm of the inhalant siphon was removed from each clam. The length of long tentacles from each group was measured on different days until the tentacles had reached asymptotic growth. Four candidate models were used for each tentacle data set for growth at the four experimental temperatures. The data were fitted to size-increments for the long siphon at different temperatures using maximum likelihood. The von Bertalanffy model was the one that best fitted the data at most experimental temperatures. To evaluate differences in tentacle regeneration in each treatment, the growth parameters were compared using a likelihood ratio test. The two interdependent parameters affecting the regeneration process k (growth constant) and t ip (inflexion point), were clearly influenced by temperature. In the case of k, increasing temperature produces acceleration in the regeneration process while t ip is not dependent on temperature. Regeneration was slower than in any other species previously reported in the literature and decreasing temperature slowed down the process.

BIVALVE CONTRIBUTION TO SHALLOW SANDY BOTTOM FOOD WEB OFF MAR DEL PLATA (ARGENTINA): INFERENCE FROM STOMACH CONTENTS AND STABLE ISOTOPE ANALYSIS

Abstract Two infaunal species, the purple clam Amiantis purpurata and the razor clam Solen tehuelchus, are common species in the 15–20 m sandy bottom sediments between southern Brazil and central Argentina. Both species are food sources for the coastal food web, but the extent of their contribution to this food web is still unknown. Based on stomach content analysis and δ15N and δ15C stable isotope signatures we explored the position of these clams in the food web. Stomach content shows that the ray Sympterigia bonapartei and the white croaker Micropogonias furnieri prey on entire A. purpurata and S. tehuelchus. The stable isotopic analysis confirms this result. The elephant fish Callorynchus callorynchus and the Brazilian codling Urophycis brasiliensis also show values of C and N consistent with those expected from species that are preying on A. purpurata. Based on the prediction from the isotopic analysis the clam A. purpurata is a food source for the shrimps Artemesia longinaris, Pleoticus muelleri, the anemone Antholoba achates and the gastropod Buccinanops monilifer. The gastropods Adelomelon brasiliana, Olivancillaria deshayesiana, Olivancillaria urceus and Zidona dufresnei also show evidence of consuming A. purpurata but with contribution from other species with heavier C content. According to complementary results the razor clam Solen tehuelchus may be this other species. The stable isotopic analysis shows that both clam species are at the base of the consumers in the food web. A. pupurata showed lighter C mark than S. tehuelchus, but the N isotopic mark showed higher value but still being within the same trophic level.

Prey preference of the stone crab Platyxanthus crenulatus (Decapoda: Platyxanthidae) in laboratory conditions

The preference for a particular type of prey implies an active behavioral choice of the predator. The present work deals with the prey preference of the large stone crab Platyxanthus crenulatus among similar sized gastropods and bivalves of different substrates using a recent proposed methodology based on a two-stage approach. In laboratory, crabs received different mollusk species separately to determine the consumption in number of each species when choice was not possible. Further, crabs were offered the same mollusc species but together to record differences of specific consumption when choice was possible. Results were then compared to assess prey preferences. Platyxanthus crenulatus is able to effectively attack and consume the majority of the sympatric mollusk species, although preferred the dominant species Brachidontes rodriguezii over the others. Such preference seems to be driven by shell shape and thickness which may be a common pattern in prey preference among large stone crab species.

Cosmetic Nanomaterials in Wastewater: Titanium Dioxide and Fullerenes

AbstractThe rapid growth in the cosmetic industry across the world is mainly due to the application of nanoingredients in cosmetics to enhance their properties and invention of new nanomolecules. Also, the weaker regulations on the application of nanoparticles as cosmetic ingredients and no safety assessment of cosmetics before release into the market has led to uncontrolled production and usage. Unavoidable release of a considerable amount of cosmetic nanoparticles into wastewater introduces them into the environment via treated wastewater effluent and sludge. This paper briefly gives the information about behavior of cosmetic nanomaterials, mainly titanium dioxide (TiO2) and fullerenes (C60), within the wastewater-treatment plant and current research on their characterization and toxicity. Considering the current analytical methods for evaluating the behavior of these nanomaterials in the wastewater, there is still a need to advance these technologies. Furthermore, a better understanding and modeling of...

Regeneration of the Inhalant Siphon of Mesodesma mactroides (Deshayes, 1854) (Mollusca: Bivalvia)

et al., 1970) and birds (Zwarts, 1986). Siphon cropping has been reported for several bivalve species (Trevaillon, 1971; Hodgson, 1982; Peterson & Quammen, 1982; Zwarts, 1986). Many bivalve species have siphons, which can be seen as a renewable resource, if they regenerate after cropping (Penchaszadeh, 1983; Pekkarinen, 1984; Riera, 1995; Luzzatto & Penchaszadeh, 2001). Such processes function as secondary production to higher trophic levels in food webs. However, regeneration occurs at the expense of somatic growth and

Intertechnique Comparisons for Nanoparticle Size Measurements and Shape Distribution

AbstractThere are a number of techniques for measuring and characterization of nanoparticle (NP) size. One of the main problems in the field of NP analysis is in producing reliable and reproducible characterization data for nanomaterials (NMs). There is no one technique or method that is best suited for every situation, therefore the chosen methodologies improve results from a given sample matrix to produce the needed information in the shortest time and most cost-efficient way. A straightforward monitoring method may simply detect the presence of NMs; others may quantify the size distribution, surface area, or the number of the NPs. The interest in the development of wastewater treatment procedures is growing, therefore several clean-up technologies are being proposed in wastewater treatment that apply NMs as nanosorbents and photocatalysts. This review briefly introduces and compares the fundamental principles of routinely used NP size distribution measurements using both single particle (electron and s...

Engineered Nanoparticles Associated Metabolomics

AbstractNanotechnology is of great economic importance due to rapid growth in industrial and household applications and their continuous release into environmental matrices has increased the concerns regarding its potential impact on human and environment. To evaluate the potential toxicity of nanoparticles (NPs), the impact on humans and ecosystems needs to be understood from mechanistic insight by metabolomics. The analytical methods and omics technologies are particularly well-suited to evaluate these two dimensions in environment and both in vitro and in vivo systems, respectively. In this paper, the currently most effective methods for sampling and detection are presented together for future standardization of protocols providing profiles of NPs and associated metabolomics. All these approaches are designed without compromising the reliability and quality of the analytical results for their application in understanding the metabolomics and chemistry of NPs in the environmental matrices. Among samplin...

Nanomaterials in Surface Water and Sediments: Fate and Analytical Challenges

AbstractNanomaterials (NMs) present some interesting properties that may be tailored; for this reason, they are being used in different fields, which leads to their entry into the environment, whether by normal use or intentional delivery. Once in water and sediments, they undergo different transformations that might be difficult to predict. NMs are also difficult to characterize because the methods for this are recently developed. Currently, the most plausible approach is to combine separation and measurement techniques; one of the most versatile integrations is field-flow fractionation with inductively coupled plasma mass spectrometry (ICP–MS) or ICP optical emission spectrometry. In the same way, toxicity assays must be adapted to these emerging contaminants because they behave neither as chemical compounds nor their bulk counterparts, which produces different results. Nevertheless, several adverse effects of NMs exposure on organisms have been reported, including DNA damage, mortality, oxidative stres...