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Microplastics (MP) are recognised as emerging anthropogenic contaminants and have been observed in biota including commercial produced bivalve species, however only a few studies assess the efficacy of MP depuration in species from aquaculture production. This preliminary study assessed MP depuration efficacy in Pacific oysters (Magallana gigas, n=50) and European flat oysters (Ostrea edulis, n=50). Four depuration times (24, 48, 72 and 96-h) were considered, with 10 individuals per treatment, and an additional 10 control organisms. Organic tissues were digested using a 10% KOH solution (40 ᵒC for 24-hours). Digested tissue was filtered to be subsequently observed for MP isolation. A subsample (109/539) was used for FTIR polymer identification. A forensic approach to cross-contamination was applied to minimise potential sources. Environmental MP concentrations in edible tissue of M. gigas were 0.6 MP g-1 and 0.4 MP g-1 for O. edulis. These were significantly reduced after a 96-hour depuration for both species: 0.2 MP g -1 for M. gigas and 0.1 MP g-1 for O. edulis, respectively. No statistically significant correlation between MP concentration and weight of edible tissue of oysters were identified. MP isolation retrieved mainly fibres and polymer identification revealed that 51.6% of these were natural. Main outputs of this research showed that increasing depuration time to 96-hour can significantly reduce MP concentrations in edible tissues of farmed oysters. These findings aligned with similar depuration studies that show reduction; however, this is the first trial to demonstrate a significant decrease in MP concentrations over 96-h. These results provide important industry advice and can contribute to policy design, by providing valuable baseline information to stakeholders on MP reduction in bivalves intended for human consumption. Also see: https://micro2022.sciencesconf.org/426370/document, In MICRO 2022, Online Atlas Edition: Plastic Pollution from MACRO to nano

The present study aimed to evaluate the efficacy of a depuration system equipped with UV-irradiation to control Vibrio vulnificus infection such as septicemia (or sepsis) using alive oysters. After 6 h of bioaccumulation of V. vulnificus, Pacific oyster Crassostrea gigas were found to be contaminated by > 8.0 log MPN/g of V. vulnificus cells. After 60 h of depuration, the V. vulnificus cell number significantly decreased to 3.52 log and

Kinetics of hepatitis A virus (HAV) accumulation and depuration from mussels (Mytilus galloprovincialis) was studied in an experimental depuration system. Different parameters likely to influence the rate of virus accumulation and elimination were evaluated. Analyses were carried out by both real-time RT-qPCR and digital PCR. Results demonstrated that the animals start to concentrate the virus already after one hour and reach the maximum level of contamination in 6 h of experiment. With respect to depuration, HAV showed a rapid reduction of the concentration (89%) during the first 24-48 h of experiment and a very slow virus decrement in the following days with a 1% residual RNA at the ninth day of depuration. When process parameters likely to increase the depuration rate (presence of ozone, microalgal feeding, presence of lactic bacteria, pre-treatment with digestive enzymes) were tested, no significant differences in the kinetics were observed. Only treatment with pancreatin seemed to positively affect depuration in the first two days of the experiment.

In urban wastewater treatment plants, bacteria lead the biological component of the depuration process, but the microbial community is also rich in fungi (mainly molds, yeasts and pseudo-yeasts), whose taxonomical diversity and relative frequency depend on several factors, e.g., quality of wastewater input, climate, seasonality, and depuration stage. By joining morphological and molecular identification, we investigated the fungal diversity in two different plants for the urban wastewater treatment in the suburbs of the two major cities in Lombardia, the core of industrial and commercial activities in Italy. This study presents a comparison of the fungal diversity across the depuration stages by applying the concepts of α-, β- and ζ-diversity. Eurotiales (mainly with Aspergillus and Penicillium), Trichosporonales (Trichosporon sensu lato), Saccharomycetales (mainly with Geotrichum) and Hypocreales (mainly with Fusarium and Trichoderma) are the most represented fungal orders and genera in all the stages and both the plants. The two plants show different trends in α-, β- and ζ-diversity, despite the fact that they all share a crash during the secondary sedimentation and turnover across the depuration stages. This study provides an insight on which taxa potentially contribute to each depuration stage and/or keep viable propagules in sludges after the collection from the external environment.

Effect of depuration on content of geosmin in pikeperch (Sander lucioperca) produced in a commercial RAS farm was examined during a 15-day period. Concentrations of geosmin in the fish were related to geosmin content in the water. For depuration, half of the water volume in a 230 m3 production tank was replaced daily with geosmin-free water. After 8 days of depuration and absence of feeding, content of geosmin in the fish was reduced from 710 ± 245 ng/kg to 165 ± 50 ng/kg (mean ± SD, p < .01). Additional depuration for 7 days only reduced the geosmin content to 135 ± 24 ng/kg. Geosmin concentration in the water was initially 34 ng/L but declined to 10 ng/L after 15 days. Changes in geosmin concentrations in water of the depuration tank indicated that geosmin was released by the fish during the depuration. In addition to removal of geosmin, the depuration also decreased concentrations of 28 different volatile compounds from the fish. Sensory analysis showed decrease in intensity of geosmin flavor upon depuration and improved the overall sensory quality of the fish after 2 weeks of depuration. Our study shows that geosmin and other off-flavors in pikeperch from RAS production can efficiently be removed to be a level that is below the threshold to most consumers.

Manganese (Mn) is a ubiquitous trace metal that is essential to living organisms and valued for the production of steels and alloys. However, Mn is potentially toxic to marine organisms at elevated levels. Land-based anthropogenic activities such as mining and dry cell batteries release Mn waste and other associated metals, such as nickel (Ni), that can threaten the health of marine species. A review of the Australian and New Zealand water quality guidelines for Mn in marine waters has identified a chronic toxicity data gap for Cnidarians exposed to Mn. Also, the synergistic and other potential cumulative impacts with other metals such as Ni are unknown. The sea anemone Exaiptasia pallida belongs to the phylum Cnidaria along with coral and jellyfish and is suitable as a model for marine laboratory testing. To understand the effects of Mn on non-calcified cnidarian, I investigated the effects of Mn uptake and depuration in the anemone E. pallida tissue and the endo-symbiotic, dinoflagellate algae - Symbiodinium spp. as well as stress-response, determined by changes in tentacle length and symbionts density. Because Ni coexists with Mn in mine tailings, I also investigated Ni alone and in combination with Mn. The results showed that anemones can accumulate Ni and Mn in the tissue, but higher concentrations were measured in the Symbiodinium spp. after 12-and 24 d of Ni or Mn exposure. Manganese in the anemones did not elicit a significant reduction in the Symbiodinium spp. density after 12- and 24 d, but tentacle retraction was significantly higher in all treatments than in controls. Mn depuration in anemones depended on the exposure concentrations but was more rapid in the symbionts than in the host anemone tissue. These results also showed that E. pallida are more sensitive to Ni after 12 d of Ni exposure alone and in a mixture with Mn. There was significant dose-dependent retraction in tentacle length after 12 d of exposure to Ni alone and when mixed with Mn. Exposure of anemones to a combination of Ni and Mn for 12 d caused a significant reduction in the Symbiodinium spp. Still, no effects on cell density were observed in both single-exposure experiments. The response of anemones to Ni and Mn alone and combined adds to knowledge on the vulnerability of symbiotic cnidarians in metal-polluted environments. Furthermore, these results reveal the importance of testing metal effects in combination before establishing safe limits for marine invertebrates.

Domoic acid (DA) is a potent neurotoxin produced by worldwide distributed diatoms of the genus Pseudo-nitzchia (PSN) and is responsible for Amnesic Shellfish Poisoning (ASP) in humans. King scallop Pecten maximus, a bivalve species of high commercial interest, is regularly subjected to blooms of Pseudo-nitzschia sp., thus accumulating and retaining high levels of DA for extended periods, leading to prolonged fisheries and aquaculture closures and important economic losses following increasingly recurrent toxic PSN blooms. The underlying mechanisms behind this accumulation and long toxin retention remain poorly understood so far. Fishermen and the aquaculture industry ask for methods to accelerate DA depuration in contaminated scallops, which has led to investigate the effect of some substances such as the antioxidant N-Acetylcysteine (NAC), which was previously found to improve up to four-fold DA depuration in P. maximus adductor muscle. Our study investigated the potential of NAC to accelerate DA depuration in all scallop tissues, including the digestive gland (DG), where most of the toxin is accumulated. Twenty-four contaminated adult scallops were collected following a toxic P. australis bloom in the Bay of Brest (France) and half were treated with the antioxidant NAC (250 mg L−1) for 6 days. HPLC toxin quantification analyses did not revealed any significant differences in the DA burdens in the DG between treated scallops and the control group. DA amounts in the adductor muscle and gonads were below the HPLC detection limit in both groups. Our results revealed that NAC does not thus appear as a commercially suitable solution for fisheries and aquaculture industries as DA depuration enhancer in the tested conditions.

Previous toxicokinetic studies have shown that mussels (Mytilus spp.) can readily absorb the three main mammalian sex steroids, estradiol (E2), testosterone (T) and progesterone (P) from water. They also have a strong ability to store E2 and the 5α-reduced metabolites of T and P in the form of fatty acid esters. These esters were shown to have half-lives that were measured in weeks (i.e. they were not subject to fast depuration). The present study looked at the toxicokinetic profile of two other common steroids that are found in water, the potent synthetic oestrogen, (ethinyl-estradiol) (EE2; one of the two components of ‘the pill’), and cortisol, a natural stress steroid in vertebrates. In the first three hours of uptake, tritiated EE2 was found to be taken up at a similar rate to tritiated E2. However, the levels in the water plateaued sooner than E2. The ability of the animals to both esterify and sulphate EE2 was found to be much lower than E2, but nevertheless did still take place. After 24 h of exposure, the majority of radiolabelled EE2 in the animals was present in the form of free steroid, contrary to E2, which was esterified. This metabolism was reflected in a much lower half-life (of only 15 h for EE2 in the mussels as opposed to 8 days for E2 and >10 days for T and P). Intriguingly, hardly any cortisol (in fact none at all in one of the experiments) was absorbed by the mussels. The implications of this finding in both toxicokinetic profiling and evolutionary significance (why cortisol might have evolved as a stress steroid in bony fishes) are discussed.

Simple Summary Rapid urbanization and industrialization has resulted in substantial contamination of various ecosystems, especially aquatic environments with heavy metals. Heavy metals are classified as either essential (iron, zinc, or copper) or non-essential (cadmium, lead, or mercury) for organisms. Cadmium is a toxic, cancerogenic, and mutagenic metal, occurring as anthropogenic contamination in aquatic environments. The level of cadmium uptake in animals depends on the rate at which they are accumulated and eliminated. Exceeding the permissible levels of cadmium in fish muscle may pose risks for human health in the case of contaminated fish consumption. The aim of the present study was to evaluate the influence of melatonin on cadmium accumulation and elimination in fish muscle. Prussian carps were exposed to two doses of cadmium in the presence or without the melatonin implants. This is the first study to report that melatonin co-administration can effectively protect fish from the accumulation of cadmium in muscle tissue, improve the accumulated cadmium depuration from muscle, and prevent disturbance of the concentration of essential metals in fish body. Abstract The aim of this study was to investigate the bioaccumulation of cadmium in the muscle tissue of Prussian carp during 7 and 13 weeks of exposure to different concentrations of this metal in water (0.4 and 4.0 mg/L), and the depuration of cadmium from muscle during the following 6-week depuration period in the presence of melatonin implants. Furthermore, the relationship between cadmium accumulation and the levels of essential bioelements (copper, zinc, iron) in muscle was evaluated, as well as the bioconcentration factor of cadmium. Heavy metal concentration was determined using atomic absorption spectrometry. Cadmium accumulation in fish muscle increased with the duration of exposure. Cd concentrations exceeded the permissible levels for human consumption in groups exposed to the higher concentration of this metal. Moreover, a significant increase of Zn and Fe levels in the muscle was observed. In the fish that received melatonin implants and were exposed to Cd, its level in the muscle was significantly lower. The depuration of accumulated cadmium depended mainly on the duration of the elimination period. This is the first study to report that melatonin co-administration can effectively protect the fish from the accumulation of cadmium in muscle tissue and changes in trace metal levels.

Depuration is generally the main treatment employed for bivalve mollusks harvested from contaminated sites. Commercial depuration has demonstrated to be effective for removal of bacterial pathogens, although it probably provides only limited efficacy against human enteric viruses. We evaluated the quantitative reduction of norovirus (NoV) genogroups I and II in naturally contaminated oysters after 1, 4, and 9 days of depuration. The process was conducted in an authorized depuration plant, and NoV concentration was determined by RT-qPCR according to ISO 15216-1:2017 method. Regardless of the NoV genogroup, our results showed no significant reduction in NoV concentration after 1 day of depuration. Higher mean reduction (68%) was obtained after 4 days of treatment, while no further increase was observed after 9 days. Overall, reduction was highly variable, and none of the trials showed statistically significant reduction in NoV RNA concentration at the end of each depuration period. Indeed, NoV concentration remained high in 70% of samples even after 9 days of depuration, with values ranging between 4.0 × 102 and 2.3 × 104 g.c./g. These results indicate that an extension of commercial depuration time does not appear to be effective for reducing or eliminating NoV in oysters.

Bivalve mollusks as filter-feeders concentrate in their digestive tissue microorganisms likely present in the harvesting water, thus becoming risky food especially if consumed raw or poorly cooked. To eliminate bacteria and viruses eventually accumulated, they must undergo a depuration process which efficacy on viruses is on debate. To better clarify the worth of the depuration process on virus elimination from mussels, in this study we investigated rotavirus kinetics of accumulation and depuration in Mytilus galloprovincialis experimentally contaminated. Depuration process was monitored for 9 days and virus residual presence and infectivity were evaluated by real time quantitative polymerase chain reaction, cell culture and electron microscopy at days 1, 2, 3, 5, 7, 9 of depuration. Variables like presence of ozone and of microalgae feeding were also analyzed as possible depuration enhancers. Results showed a two-phase virus removal kinetic with a high decrease in the first 24 h of depuration and 5 days necessary to completely remove rotavirus.

A long-term test at a laboratory scale with a closed system (a coral reef aquarium) has been carried out to study the potentialities of photocatalytic ozonation and photocatalysis for the removal of noxious organic compounds in recirculating systems (aquaria and recirculating aquaculture systems) working with a minimum make up of new water. Attention has been focused not only on the depuration capabilities but also on possible negative phenomena, some of which could become apparent only at long times. After having tuned the system by setting appropriate operating conditions and procedures, positive results were obtained. In particular, it was observed that the alternation of photocatalytic ozonation with photocatalysis with definite cycle allowed to severely limit the presence of the organic compounds, which otherwise could accumulate in the system, and at the same time to control the formation of bromate, the ozonation side-product of main concern. In addition, the values of other parameters, which are important for water quality, remained at satisfactory values. It was also verified that the prepared photocatalytic films maintained a good photocatalytic activity even after several months of utilization in seawater. These results demonstrate that photocatalytic ozonation is a good candidate for water purification in recirculating systems in view of sustainable aquaculture.

The oxidative status of the hepatopancreas of Prussian carp females (Carassius gibelio) co-exposed to sublethal cadmium in water and melatonin was studied. The activities of antioxidant enzymes such as glutathione reductase (GR), glutathione peroxidase (GPx), and superoxide dismutase (SOD) as well as the concentration of reduced glutathione (GSH) were measured in homogenates of the hepatopancreas. Furthermore, concentrations of cadmium (Cd), zinc (Zn), copper (Cu), and iron (Fe) in the hepatopancreas were assayed. These females received melatonin implants and were exposed to 0.4 mg/L or 4.0 mg/L Cd in water for either a 13- or a 7-week period, followed by further 6 weeks of purification in clear water. Exposure to Cd influenced the increase in this metal concentration in fish hepatopancreas. In contrast, the fish exposed to cadmium with additional administration of melatonin had a lower accumulation of this metal. Exposure to Cd caused the increase in GSH content and the activity of GR, and a reduction in GPx activity, whereas the SOD activity varies depending on the exposure time on cadmium. In the hepatopancreas of fish treated with Cd alone, the content of Cu and Zn were increased and that of Fe was changed. After melatonin administration to Cd-exposed fish, a decrease in copper and zinc hepatopancreas content was noted. The present findings imply that melatonin co-treatment can effectively protect the fish against the toxic effects of cadmium on endogenous antioxidant status in hepatopancreas tissues and variations in metal concentration, such as Zn, Cu, and Fe.

RESUMEN: En el presente trabajo de fin de Máster se lleva a cabo un análisis operativo y normativo de la puesta en marcha de un nuevo servicio de recogida de residuos provenientes del lavado de tanques de los petroleros, su depurado para convertirlos en combustibles de uso marino y su posterior almacenamiento en una terminal de combustibles marítimos dentro del Puerto de la Luz. Para ello, en primer lugar, se analiza cual es la normativa aplicable tanto desde el punto de vista del buque donde se establecen especiales condiciones para evitar el vertido de productos contaminantes al mar (imponiendo la obligatoriedad de descargar estos vertidos a gestores autorizados en tierra), como desde el punto de la terminal de combustibles donde se pone el foco en aquella normativa que sería de nueva aplicación y las consecuencias que ello conllevaría. A continuación, se analiza el sistema actual de lavado de tanques en buques petroleros y cómo se generan los residuos de dicho proceso, cuál es su composición y que cantidad podemos estimar que se tratará en dicho servicio. 7 Con las herramientas que manejaremos (normativa) y el planteamiento inicial sobre cómo se generan esos residuos en el buque pasaremos a desarrollar los procedimientos que serán el eje central de este trabajo, en concreto: • cómo se descargarán dichos residuos del buque hasta la terminal, coordinación con la consignataria y el buque, proceso de conexión, medidas de seguridad, comunicaciones e intercambio de documentación. • los distintos procesos que deberemos aplicar a estos residuos hasta convertirlos en productos comerciales (combustible de uso marino). • El proceso de almacenaje y, en función de los resultados obtenidos, la elección de los distintos tanques de la terminal. • Una vez que los residuos ya son convertidos y almacenados como combustible, se analizan las gestiones requeridas ante las autoridades portuarias y aduaneras para su comercialización como combustibles marinos. Por último, se realiza un análisis económico (ingresos-gastos) de los costes que la terminal deberá soportar para llevar a cabo estos procesos y los ingresos esperados tras la comercialización de los combustibles generados. Este trabajo termina con las conclusiones del autor sobre la implantación de este nuevo servicio en la terminal de combustibles marinos. ABSTRACT: This final Master project carries out an operative and legal analysis about a new terminal service consisting in the collection of residues from tanks washing, its depuration to convert them into marine fuel oil and the final storage in a bunker terminal at La Luz port. 8 First, we analyse how the residues are generated, their composition and an estimation about the quantity we could process in such new service. Next, we analyse the discharging process from the vessel to the terminal and the depuration process until they become commercial products (marine fuel oil). In the last part of the paper, the storage process and all the formal document management (Port Authority and customs) are shown. This document ends with the author conclusions about the implementation of this new terminal service. Máster en Ingeniería Náutica y Gestión Marítima

This work explored the effects of salinity and temperature on the efficacy of purging V. parahaemolyticus from eastern oysters (Crassostrea virginica). Oysters were inoculated with a 5-strain cocktail of V. parahaemolyticus to levels of 104 to 105 MPN (most probable number)/g and depurated in a controlled re-circulating wet-storage system with artificial seawater (ASW). Both salinity and temperature remarkably affected the efficacy for the depuration of V. parahaemolyticus from oysters during wet-storage. The wet-storage process at salinity 20 ppt at 7.5 °C or 10 °C could achieve a larger than 3 log (MPN/g) reduction of Vibrio at Day 7, which meets the FDA’s requirement as a post-harvest process for V. parahaemolyticus control. At the conditions of 10 °C and 20 ppt, a pre-chilled system could achieve a 3.54 log (MPN/g) reduction of Vibrio in oysters on Day 7. There was no significant difference in the shelf life between inoculated and untreated oysters before the depuration, with a same survival rate (stored in a 4 °C cooler for 15 days) of 93%.

The king scallop Pecten maximus retains the amnesic shellfish poisoning toxin, domoic acid (DA), for a long time. Most of the toxin is accumulated in the digestive gland, but this organ contains several cell types whose contribution to the accumulation of the toxin is unknown. Determining the time-course of the depuration by analyzing whole organs is difficult because the inter-individual variability is high. A sampling method, using biopsies of the digestive gland, has been developed. This method allows for repetitive sampling of the same scallop, but the representativeness of the samples obtained in this way needs to be validated. In this work, we found that the distribution of DA in the digestive gland of the scallops is mostly homogeneous. Only the area closest to the gonad, and especially its outer portion, had a lower concentration than the other ones, probably due to a transfer of the toxin to the intestinal loop. Samples obtained by biopsies can therefore be considered to be representative. Most of the toxin was accumulated in large cells (mostly digestive cells), which could be due to differences during the toxin absorption or to the preferential depuration of the toxin from the small cells (mostly secretory).

After the first outbreak of viral haemorrhagic septicaemia virus (VHSV) in Finnish brackish water rainbow trout Oncorhynchus mykiss farms, infection spread rapidly between the farms. The infrastructure of fish farming did not take into account spreading of infectious fish diseases. To show the presence of VHSV in the environment, we tested seawater, sediment and wild blue mussels Mytilus edulis from VHSV-infected fish farms, and liquid waste from a processing plant that handled infected rainbow trout. Additionally, blue mussels were bath-challenged with VHSV (exposed to cultivated virus or naturally infected rainbow trout). To detect VHSV, virus isolation in cell culture and real-time reverse transcriptase polymerase chain reaction (qRT-PCR) were used. The virus or viral RNA was detected in sea water and in liquid waste from processing plants during wintertime when water temperature is close to 0°C and sunlight is sparse. VHSV did not appear to replicate in blue mussels in our study. Therefore, blue mussels were not considered relevant carriers of VHSV. However, traces of viral RNA were detected up to 29 d post challenge in mussels. Contact with water from processing plants handling VHSV-infected fish populations increases the risk of the disease spreading to susceptible fish populations, especially during cold and dark times of the year.

Máster en Ingeniería Industrial

Microcystins (MCs) are produced by certain bloom-forming cyanobacteria that can induce toxicity in various organs, including renal toxicity, reproductive toxicity, cardiotoxicity, and immunosuppressive effects. It has been a significant global environmental issue due to its harm to the aquatic environment and human health. Numerous investigators have demonstrated that MC exposure can induce a widespread epidemic of enterogastritis with symptoms similar to food poisoning in areas close to lakes. Both in vivo and in vitro studies have provided evidence of positive associations between MC exposure and gastrointestinal toxicity. The toxicity of MCs on the gastrointestinal tract is multidimensional. MCs can affect gastrointestinal barrier function and shift the structure of gut microbiota in different gut regions. Furthermore, MCs can inhibit the secretion of gastrointestinal digestive enzymes and the release of inflammatory cytokines, which affects the expression of immune-related genes in the intestine. The damage of the intestine is closely correlated to MC exposure because the intestine is the main site for the digestion and absorption of nutrients. The damage to the gastrointestinal tract due to MCs was summarized from different aspects, which can be used as a foundation for further exploration of molecular damage mechanisms.

Bivalves are filter feeders that can accumulate and concentrate waterborne contaminants present in the water in which they live. Biotoxins, pathogenic bacteria, viruses, and heavy metals present in the aquaculture environment constitute the main hazards for human health. The most common method employed for combating waterborne pollutants in bivalves is depuration with purified seawater. Although this method is effective at increasing the microbiological quality of bivalves, in most cases, it is ineffective at eliminating other risks, such as, for example, viruses or heavy metals. Biological (bacteriocins and bacteriophages), physical (UV light, ozone, and gamma-irradiation), chemical (metallothioneins and chitosan), and other industrial processing methods have been found to be useful for eliminating some contaminants from seawater. The aim of this work was to provide a review of academic articles concerning the use of treatments complementary to conventional depuration, aiming to improve depuration process efficiency by reducing depuration times and decreasing the levels of the most difficult-to-erase contaminants. We conclude that there are different lab-tested strategies that can reduce depuration times and increase the food safety of bivalve produce, with possible short- and long-term industrial applications that could improve the competitivity of the aquaculture industry.

Oysters contaminated with norovirus present a significant public health risk when consumed raw. In this study, norovirus genome copy concentrations were determined in Pacific oysters (Magallana gigas) harvested from a sewage-impacted production site and then subjected to site-specific management procedures. These procedures consisted of relocation of oysters to an alternative production area during the norovirus high-risk winter periods (November to March) followed by an extended depuration (self-purification) under controlled temperature conditions. Significant differences in norovirus RNA concentrations were demonstrated at each point in the management process. Thirty-one percent of oyster samples from the main harvest area (Site 1) contained norovirus concentrations > 500 genome copies/g and 29% contained norovirus concentrations 500 genome copies/g. In addition, 60 and 88% of oysters samples contained norovirus concentrations

International audience; To reduce the exposure of the French West Indies population to the organochlorine insecticide chlordecone (Kepone; CLD), the contamination of currently consumed foodstuffs must be reduced. Depuration of contaminated animals before slaughter could be a strategy to obtain safe animal products. The aim of this study was to characterize and quantify CLD elimination in contaminated ewes during depuration process. Experiments A and B consisted in a single intravenous (i.v.) administration of CLD (n = 5) and CLDOH (chlordecol; n = 3) followed by a 84-d and 3-d depuration period respectively with collection of blood, faeces and urine samples. After CLD administration, CLD and conjugated-CLDOH (CLDOH-C) were quantified in serum and urine and CLD and CLDOH were quantified in faeces. Based on calculations of faecal, urinary and body clearances of CLD and CLDOH-C, faeces appeared as the major route of CLD excretion with 86 % of the CLD administered dose eliminated in faeces, either as CLD (51 %) or as CLDOH (35 %).

The recurrent emergence of infection outbreaks associated with shellfish consumption is of extreme importance for public health. The present study investigated the potential application of phages AH-1, AH-4, and AH-5 to inactivate Aeromonas hydrophila, a causative agent of infections in humans associated with bivalve shellfish consumption. The inactivation of A. hydrophila was assessed in vitro, using a liquid culture medium, and in vivo, using artificially contaminated cockles with A. hydrophila ATCC 7966. In the in vitro experiments, all phages were effective against A. hydrophila, but phage AH-1 (with a maximum reduction of 7.7 log colonies forming units CFU/mL) was more effective than phages AH-4 and AH-5 (with reductions of 4.9 and 4.5 log CFU/mL, respectively). The cocktails AH-1/AH-4, AH-1/AH-5, AH-4/AH-5, and AH-1/AH-4/AH-5 were slightly more effective than the single phage suspensions. The phages presented a low emergence rate of phage-resistant mutants. When artificially contaminated cockles were treated in static seawater with phage AH-1, around 44% of the added A. hydrophila (1.0 log CFU/g) was inactivated. The results of this study suggest that phage therapy can be an effective alternative to control human pathogenic bacteria during depuration.

This study established that geosmin depuration from European eel is not affected by the water renewal rate of depuration tanks. A general fish bioaccumulation model extended with terms that account for effects of tank water renewal rate and system losses of chemicals, predicted strong effects of the water renewal rate of depuration tanks on geosmin depuration from European eel. Model predictions were validated in a depuration experiment with geosmin-loaded European eel (n = 95) with a mean (SD) individual weight of 134.4 (5.0) g and a mean (SD) lipid content of 33.7 (2.8) % (w/w). Fish were depurated for 24, 48 or 72 h at three different tank water renewal rates (0.3, 3.3 and 33 day-1). Treatments were installed by three different mean (SD) water flow rates (13.8 (1.3), 143.5 (9.2) and 1511 (80) L kg fish-1 day-1) over 30-L tanks. Eels eliminated geosmin from their bodies, but unlike the model predicted, this was independent of the water renewal rate of the depuration tanks. Although being eliminated from the fish, geosmin hardly appeared and certainly did not accumulate in the water of the depuration tanks as the model predicted. This observation may be explained by geosmin being eliminated from eel as metabolite rather than the parent compound. Geosmin elimination from eel seems not to occur according to the generally accepted passive diffusion mechanism for excretion of lipophilic chemicals, and geosmin biotransformation by the eel seems indicated. Clearly geosmin depuration from European eel cannot be enhanced by increasing water renewal rates of depuration tanks.

European whitefish Coregonus lavaretus has increasingly become an important species for aquatic food production, especially in the Nordic countries. Whitefish is produced in traditional cage and pond operations, and in recirculating aquaculture system (RAS) in which, unfortunately, off-flavors and odors, mostly caused by geosmin (GSM) and 2-methylisoborneol (MIB), can accumulate in fish flesh from the circulating water. GSM and MIB have very low human sensory detection limits and, therefore, often disliked by consumers even at low concentrations. In this study, concentrations of GSM and MIB in RAS farmed European whitefish were studied by an analytical method based on headspace solid phase microextraction and gas chromatography–mass spectrometry. Concentrations were determined in different parts of fish: fillet, neck, belly, and tail during a depuration period and in depuration water. The highest initial concentrations were on average 32 ng g−1 (GSM) and 24 ng g−1 (MIB) in European whitefish fillet and 128 ng L−1 (GSM) and 94 ng L−1 (MIB) in water, respectively. After a depuration period of 16 days, concentrations decreased to below the detection limits, indicating the importance of the depuration period. Electronic supplementary material The online version of this article (10.1007/s13197-019-03910-7) contains supplementary material, which is available to authorized users.

La ausencia de tratamiento adecuado de las aguas residuales constituye un problema global que afecta a todos los territorios según su realidad geográfica, demográfica y socioeconómica, y al mar. Sólo un 20% de las aguas residuales son tratadas previamente a su vertido al cauce (UNESCO, 2017). Los problemas asociados son reconocidos e inciden directamente sobre la salud de las personas y del medioambiente, contaminando acuíferos y destruyendo ecosistemas. Situación que se agrava por la incidencia del cambio climático.Son diversas las técnicas utilizadas en el tratamiento de aguas residuales y su éxito o fracaso se visibiliza en la continuidad de uso y requiere del análisis particular de la instalación. Las principales causas de fallo son: la pérdida de funcionalidad, los errores de diseño, el rápido deterioro de los materiales, la falta de adaptabilidad, la imprevisión de controles y mantenimiento, especialmente por el coste económico que suponen.Es por ello que la propuesta de solución va más allá de la tecnología y ha de adaptarse a la realidad social y territorial en donde va a ser implantada, especialmente en pequeñas poblaciones, caso de referencia en este artículo. Por tanto, la innovación en saneamiento y depuración requiere de sinergias que favorezcan la adaptación de las instalaciones a las diferentes coyunturas de su ciclo de vida, garantizando su continuidad sostenible de uso.Estas propuestas están recogidas como tecnologías “no convencionales” y se caracterizan por ser soluciones económicas y sostenibles a una realidad territorial. Mientras que a nivel internacional estas propuestas están ampliamente implantadas, en España, y pese a la crisis económica, estas han caído en desuso. El objeto de este artículo es plantear de nuevo un debate que ha sido relegado y pospuesto, pese a los importantes incumplimientos de España con respecto a la UE en pequeñas poblaciones.AbstractThe lack of adequate wastewater treatment is a global problem that affects all territories depending on their geographical, demographic and socio-economic reality, and also the sea. Only 20% of wastewater is treated before the discharge into rivers (UNESCO, 2017). The associated problems are widely recognized and affect the health of people and the environment, contaminating aquifers and destroying ecosystems; moreover, this situation is aggravated by the impact of climate change.Various techniques are used in wastewater treatment and their success or failure is visible in the continuity of use and requires the particular analysis of the installation. The main causes of failure are: loss of functionality, design errors, early deterioration of materials, lack of adaptability, and unforeseen control and maintenance especially due to their economic cost.That is why the proposed solution goes beyond technology and has to be adapted to the social and territorial reality where it is going to be implemented; especially in small towns, the case of reference in this article. Therefore, innovation in sewerage and wastewater treatment requires synergies that favour the adaptation of the facilities to the different junctures of their life cycle, making sure their sustainable continuity of use. These proposals are included as "non conventional" technologies and are characterised by being ecological and sustainable solutions to a territorial reality. While at an international level these proposals are widely implemented, in Spain, and despite the economic crisis, they have fallen into disuse. The purpose of this article is to once again raise a debate that has been neglected and postponed, in spite of Spain's important failures to comply with the EU in small towns.

The king scallop Pecten maximus retains the amnesic shellfish poisoning toxin, domoic acid (DA), for a long time. Most of the toxin is accumulated in the digestive gland, but this organ contains several cell types whose contribution to the accumulation of the toxin is unknown. Determining the time-course of the depuration by analyzing whole organs is difficult because the inter-individual variability is high. A sampling method, using biopsies of the digestive gland, has been developed. This method allows for repetitive sampling of the same scallop, but the representativeness of the samples obtained in this way needs to be validated. In this work, we found that the distribution of DA in the digestive gland of the scallops is mostly homogeneous. Only the area closest to the gonad, and especially its outer portion, had a lower concentration than the other ones, probably due to a transfer of the toxin to the intestinal loop. Samples obtained by biopsies can therefore be considered to be representative. Most of the toxin was accumulated in large cells (mostly digestive cells), which could be due to differences during the toxin absorption or to the preferential depuration of the toxin from the small cells (mostly secretory).

9 pages, 6 figures, Nanoplastics (NPs) have become one of the most serious environmental problems nowadays. The environmental issues linked to NPs are attributed to the effects after ingestion in marine organisms. Due to the incipient and controversial information about the effects of PS NPs on the feeding of organisms, the aim of this work is to assess (i) digestion dynamics of Artemia franciscana when exposed to PS NPs as the lowest concentration of PS NPs reported in toxicity test [0 (control), 0.006 and 0.6 mg·L-1] and possible interferences in the ingestion of microalgae and (ii) the accumulation and depuration of PS NPs by A. franciscana. Artemia were subjected to ingestion experiments [24 h and 3.5 h], in which the organisms were exposed to PS NPs or to PS NPs + microalgae. Post-exposure feeding (24 h exposure and 2 h feeding) and depuration (24 h exposure and 24 h of depuration) were also carried out. More than 90% of the PS NPs were ingested by Artemia and bioaccumulated in the mandible, stomach, gut, tail gut and appendages after 24 h. The ingestion of microalgae was not affected by the presence of the PS NPs. Data of post-exposure feeding indicated that Artemia previously exposed to plastic and/or microalgae presented similar microalgal ingestion (around 70%); the highest microalgal consumption (around 90%) was recorded in the treatment in which Artemia were previously starved (no plastic and no microalgae). The presence of PS NPs in the gut after the depuration experiments indicates that 24 h was not enough to eliminate the PS NPs, Marta Sendra is grateful to CEI·MAR for their support of the CEIJ-C06.1 project. This research has been funded by the Spanish National Research Plan MINECO (CTM2016-75908-R). C.V.M. Araújo is grateful to the Spanish Ministry of Science, Innovation and Universities for a Juan de la Cierva contract (IJCI-2014-19318)

Several species of the dinoflagellate genus Dinophysis produce toxins that accumulate in bivalves when they feed on populations of these organisms. The accumulated toxins can lead to intoxication in consumers of the affected bivalves. The risk of intoxication depends on the amount and toxic power of accumulated toxins. In this review, current knowledge on the main processes involved in toxin accumulation were compiled, including the mechanisms and regulation of toxin acquisition, digestion, biotransformation, compartmentalization, and toxin depuration. Finally, accumulation kinetics, some models to describe it, and some implications were also considered.

International audience; Subcellular cadmium (Cd) partitioning was investigated in the liver of two marine fish species, the European sea bass Dicentrarchus labrax and the Senegalese sole Solea senegalensis, dietary exposed to an environmentally realistic Cd dose for two months followed by a two-month depuration. Cd exposure did not modify Cd cellular partitioning for either species, refuting the spillover hypothesis. Both species contained most of the Cd in the detoxifying fraction but displayed different handling strategies. Cd was largely bound to heat stable proteins (HSP) including metallothioneins (MT) in sea bass while Cd was more linked to metal rich granules (MRG) in sole. Whole liver concentrations and subcellular partitioning were also determined for essential elements. The greatest impairment of essential metal homeostasis due to Cd exposure was found in sole. These elements followed the Cd partitioning pattern, suggesting that they are involved in antioxidant responses against Cd toxicity. Cd consumption diminished sole growth in terms of body weight, probably due to lipid storage impairment. During the depuration period, the two species showed contrasting partitioning patterns, implying different pathways for Cd elimination from the liver. In sea bass, MT-bound Cd would be excreted through bile or released into blood, crossing the cell membrane via a protein transporter. In sole, MRG-bound Cd would be sequestered by organelles before being released into the blood via vesicular exocytosis. These distinct strategies in cellular Cd handling in the liver might account for differential sensitivity to Cd toxicity and differential Cd excretion pathways between the two marine fish species.

Surf clams, Mesodesma donacium, were shown to accumulate toxins from Dinophysis acuminata blooms. Only pectenotoxin 2 (PTX2) and some of its derivatives were found, and no toxins from the okadaic acid group were detected. PTX2 seems to be transformed to PTX2 seco-acid (PTX2sa), which was found in concentrations more than ten-fold those of PTX2. The seco-acid was transformed to acyl-derivatives by esterification with different fatty acids. The estimated amount of these derivatives in the mollusks was much higher than that of PTX2. Most esters were originated by even carbon chain fatty acids, but some originated by odd carbon number were also found in noticeable concentrations. Some peaks of toxin in the bivalves did not coincide with those of Dinophysis abundance, suggesting that there were large differences in toxin content per cell among the populations that developed throughout the year. The observed depuration (from the digestive gland) was fast (more than 0.2 day−1), and was faster for PTX2 than for PTX2sa, which in turn was faster than that of esters of PTX2sa. PTX2 and PTX2sa were distributed nearly equally between the digestive gland and the remaining tissues, but less than 5% of the palmytoyl-esters were found outside the digestive gland.

The influence of temperature on the bioaccumulation, toxicokinetics, biotransformation and depuration of pyrene was studied in the arctic marine amphipod Gammarus setosus. A two-compartment model was used to fit experimental values of total body burden, total metabolites and parent pyrene concentrations and to calculate toxicokinetic variables derived for two experimental treatments (2 and 8 °C). No statistically significant differences were observed with temperature for these toxicokinetic variables or bioconcentration factors. Contrarily, the Q10 values suggested that the toxicokinetic variables ke and km were temperature-dependent. This may be explained by the high standard deviation of the Q10 values. Q10 is the variation in the rate of a metabolic reaction with a 10 °C increase in temperature. Depuration rate constants were calculated from linear best fit equations applied to measured pyrene concentrations over time during the depuration phase of the experiment. During depuration, the parent pyrene was eliminated in two stages with faster elimination observed at 8 °C compared to 2 °C. This finding was also indicated by the Q10. No changes in total body burdens of metabolite concentrations were observed during the monitoring of depuration over a period of 96 h. The biotransformation pathway of pyrene in G. setosus was also investigated in this study with two main phase II biotransformation products discovered by liquid chromatography. These products are conditionally identified as the sulphate and glucose conjugates of 1-hydroxy-pyrene. Overall, the study contributes new knowledge to the understanding of the fate of PAHs in arctic biota. In particular, the study provides valuable insight into the bioaccumulation and biotransformation of an important PAH and its metabolites in a species that serves as both a predator and prey in the arctic ecosystem.

Depuration has been mandatory to eliminate microorganisms in bivalve molluscs, but not to eliminate toxic chemicals, since there is still shortage of scientific evidence about the efficacy of depuration to decrease the levels of toxic chemicals in bivalves. This study aims to assess the effects of depuration on the levels of toxic, macro and trace elements in three bivalve species ( Ruditapes philippinarum- RP, Mytilus galloprovincialis -MG and Scrobicularia plana -SP), taking into account their condition. During depuration, a significant reduction of elements occurred in RP (Fe, Pb, Cu, Rb, Br, Hg, Cd and As), MG (Cl, Sr, Fe, Pb and Br) and SP (Fe, Pb, Cu and Rb), while an increase was registered for other elements in RP (Cl and Sr), MG (S and Zn) and SP (Cl, Zn, Br and Sr). After two days of depuration, Pb in SP had decreased to levels below the permissible limits, thus allowing this species to be acceptable for human consumption as far as toxic elements are concerned. SP revealed the highest glycogen levels compared to the other species indicating different physiological requirements. However, in this species glycogen levels significantly decreased after two days of depuration and mortality increased. In contrast, in MG and RP glycogen and mortality did not vary significantly during depuration. Therefore, SP should be only depurated for a maximum period of two days. Overall, the results of this study are particularly useful to retailers to ensure high quality bivalve products for consumers. Additionally, glycogen can be used as a suitable biomarker of healthy status of bivalve species during depuration.

a b s t r a c t Fish cultured within water recirculating aquaculture systems (RAS) can acquire "earthy" or "musty" off- flavors due to bioaccumulation of the compounds geosmin and 2-methylisoborneol (MIB), respectively, which are produced by certain bacterial species present in RAS biosolids and microbial biofilms. Fish cultured in RAS are generally transferred to separate depuration systems that are flushed with water in a single pass or operated with limited water recirculation (with no biofilter), in order to purge these unpalatable flavors. Technologies and standard operating practices that optimize purging kinetics for Atlantic salmon Salmo salar and other species cultured in RAS are needed to improve the consistency and efficacy of depuration. A 2 × 2 factorial trial was conducted to evaluate techniques to mitigate off-flavor from Atlantic salmon cultured to 3-5 kg in a semi-commercial scale freshwater RAS. Twelve replicated depuration systems (0.5 m3) were used to evaluate four combinations (n = 3) of the following standard operating procedure and system design parameters: (1) disinfection of depuration systems as a 1 h static treatment using 250 mg/L hydrogen peroxide (H2O2) prior to stocking fish, (2) no disinfection prior to stocking fish, (3) presence of water aeration media within gas transfer columns of depuration systems, and (4) absence of water aeration media within gas transfer columns of depuration systems. Food-size Atlantic salmon were stocked within the depuration systems and kept off feed for 10 days. Six salmon were harvested from the original RAS on Day 0 and fileted for baseline assessment of off-flavor concentrations. Thereafter, filet samples (n = 3-4) were taken on Days 3, 6, and 10 to evaluate off-flavor kinetics. Hydrogen peroxide disinfection of depuration systems resulted in significantly reduced off-flavor in salmon filets during the depuration period. Results also indicated that the presence of high-surface-area water aeration media shielded biofilms from complete disinfection, resulting in less and slower off-flavor removal from Atlantic salmon filets; while depuration systems void of media resulted in greater and more rapid off- flavor reduction. Thus, water aeration media should not be used in depuration systems because of the challenges posed for effective cleaning, disinfection, and inactivation of off-flavor producing bacteria that may be present, and unit processes and locations that are difficult-to-clean should be excluded. In addition, a wide range of off-flavor concentrations were measured within individual salmon, indicating that one salmon is not a representative sample size to determine market suitability.

Bivalve shellfish such as oysters and mussels can concentrate human pathogens when grown in areas impacted by municipal wastewater. Under EU regulation this risk to consumers is controlled by determining the sanitary quality of bivalve shellfish production areas based on the concentration of Escherichia coli present in shellfish flesh. The authors present a modelling approach to simulate an uptake of E. coli from seawater and subsequent depuration by Mytilus edulis. The model that dynamically predicts E. coli concentration in the mussel tissue is embedded within a 3-D numerical modelling system comprising hydrodynamic, biogeochemical, shellfish ecophysiological and the newly proposed microbial modules. The microbial module has two state variables, namely, the concentrations of E. coli in water and in the mussel tissue. Novel formulations to calculate the filtration rates by mussels and the resulting uptake of bacteria are proposed; these rates are updated at every computational time step. Concentrations of E. coli in seawater are also updated accordingly taking into account the amounts ingested by mussels. The model has been applied to Bantry Bay in the south-west of Ireland. The results indicate that the model is capable of reproducing the official classification of shellfish waters in the bay based on monthly sampling at several stations. The predicted filtration rates and ratios of E. coli in water and mussels also compare well with the literature. The model thus forms a tool that may be used to assist in the classification of shellfish waters at much greater spatial and temporal detail than that offered by a field monitoring programme. Moreover, it can also aid in designing an efficient monitoring programme. The model can also be utilised to determine the contribution of individual point sources of pollution on the microbial loading in mussels and, when incorporated into an operational framework, it can provide a short-term forecasting of microbial contamination in a shellfishery. Also, the model can be easily extended to include other shellfish and pathogen species., EU Interreg IVB Atlantic Area Programme

Texto completo. Acesso restrito. p. 429–436 Submitted by Santiago Fabio (fabio.ssantiago@hotmail.com) on 2013-06-26T13:40:29Z No. of bitstreams: 1 33333333333.pdf: 703092 bytes, checksum: bef1d011e9cf6671684ec12b8dc9eb66 (MD5) Approved for entry into archive by Alda Lima da Silva(sivalda@ufba.br) on 2013-06-27T21:02:05Z (GMT) No. of bitstreams: 1 33333333333.pdf: 703092 bytes, checksum: bef1d011e9cf6671684ec12b8dc9eb66 (MD5) Made available in DSpace on 2013-06-27T21:02:05Z (GMT). No. of bitstreams: 1 33333333333.pdf: 703092 bytes, checksum: bef1d011e9cf6671684ec12b8dc9eb66 (MD5) Previous issue date: 2013 The streams from municipal wastewater treatment plants (WWTP) have been considered a valuable medium for mass cultivation of algal biomass. The aim of this work is to test and compare the performance of Chlorella vulgaris on several streams from five stages, from two different WWTP. The results showed biomass yields ranging from 39 to 195 mg dry-weight l 1 days 1. The best performance as biomass production was obtained with the centrate (effluent from drying the anaerobic sludge). After testing a wide range of N/P ratios with centrate, the highest productivity and growth rates were obtained with the original N/P ratio (2.0) of this stream. The highest removal rates were of 9.8 (N) and 3.0 (P) mg l 1 - days 1, in the centrate. Finally, this research also suggests that microalgal production seems to be a promising process when coupled to wastewater treatment. Salvador

Made available in DSpace on 2018-11-26T16:56:23Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-08-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Understanding the mechanism of phenanthrene (PHE) biotransformation and related cellular responses in bivalves can be an important tool to elucidate the risks of polycyclic aromatic hydrocarbons (PAHs) to aquatic organisms. In the present study it was analyzed the transcriptional levels of 13 biotransformation genes related to cytochrome P450 (CYP), glutathione S-transferase (GST), sulfotransferase (SULT), flavin-containing monooxygenase and fatty acid-binding proteins by qPCR in gill of scallops Nodipecten nodosus exposed for 24 or 96 h to 50 or 200 mu g L-1 PHE (equivalent to 0.28 and 1.12 mu M, respectively), followed by depuration in clean water for 96 h (DEP). Likewise, it was quantified the activity of catalase (CAT), glutathione peroxidase (GPx), superoxide dismutase (SOD), glutathione reductase (GR), glucose 6 phosphate dehydrogenase (G6PDH), GST and levels of lipid peroxidation. Increased transcriptional levels of CYP2U1-like, CYP2D20-like, CYP3A11-like, GSTomega-like, SULTIBI-like genes were detected in organisms exposed to PHE for 24 or 96 h. In parallel, GR and GPX activities increased after 96 h exposure to 200 mu g L-1 PHE and G6PDH activity increased after 24 h exposure to 50 mu g L-1 PHE. This enhancement of antioxidant and phase I and II biotransformation systems may be related to the 2.7 and 12.5 fold increases in PHE bioaccumulation after 96 h exposure to 50 and 200 mu g L-1 PHE, respectively. Interestingly, DEP caused reestablishment of GPX and GR activity, as well as to the transcript levels of all upregulated biotransformation genes (except for SULTIBI-like). Bioaccumulated PHE levels decreased 2.5-2.9 fold after depuration, although some biochemical and molecular modifications were still present. Lipid peroxidation levels remained lower in animals exposed to 200 mu g L-1 PHE for 24 h and DEP. These data indicate that N. nodosus is able to induce an antioxidant and biotransformation-related response to PHE exposure, counteracting its toxicity, and DEP can be an effective protocol for bivalve depuration after PHE exposure. (C) 2016 Elsevier B.V. All rights reserved. Univ Fed Santa Catarina, Dept Biochem, Lab Biomarkers Aquat Contaminat & Immunochem, Florianopolis, SC, Brazil Univ Fed Santa Catarina, Aquaculture Pathol Res Ctr NEPAQ, Florianopolis, SC, Brazil Univ Sao Paulo, Oceanog Inst, Lab Marine Organ Chem, Sao Paulo, Brazil Univ Fed Santa Catarina, Ctr Agr Sci, Dept Aquaculture, LMM, Florianopolis, SC, Brazil UNESP, IBILCE, Dept Chem & Environm Sci, Sao Jose Do Rio Preto, SP, Brazil UNESP, IBILCE, Dept Chem & Environm Sci, Sao Jose Do Rio Preto, SP, Brazil

Several species of the dinoflagellate genus Dinophysis produce toxins that accumulate in bivalves when they feed on populations of these organisms. The accumulated toxins can lead to intoxication in consumers of the affected bivalves. The risk of intoxication depends on the amount and toxic power of accumulated toxins. In this review, current knowledge on the main processes involved in toxin accumulation were compiled, including the mechanisms and regulation of toxin acquisition, digestion, biotransformation, compartmentalization, and toxin depuration. Finally, accumulation kinetics, some models to describe it, and some implications were also considered.

Surf clams, Mesodesma donacium, were shown to accumulate toxins from Dinophysis acuminata blooms. Only pectenotoxin 2 (PTX2) and some of its derivatives were found, and no toxins from the okadaic acid group were detected. PTX2 seems to be transformed to PTX2 seco-acid (PTX2sa), which was found in concentrations more than ten-fold those of PTX2. The seco-acid was transformed to acyl-derivatives by esterification with different fatty acids. The estimated amount of these derivatives in the mollusks was much higher than that of PTX2. Most esters were originated by even carbon chain fatty acids, but some originated by odd carbon number were also found in noticeable concentrations. Some peaks of toxin in the bivalves did not coincide with those of Dinophysis abundance, suggesting that there were large differences in toxin content per cell among the populations that developed throughout the year. The observed depuration (from the digestive gland) was fast (more than 0.2 day&minus, 1), and was faster for PTX2 than for PTX2sa, which in turn was faster than that of esters of PTX2sa. PTX2 and PTX2sa were distributed nearly equally between the digestive gland and the remaining tissues, but less than 5% of the palmytoyl-esters were found outside the digestive gland.

The objective of this study was to identify a possible effect of food on the acceleration of decontamination in blue mussels, Mytilus edulis, containing diarrhetic toxins belonging to the okadaic acid (OA) structural group. An experimental protocol was designed to describe and compare the decontamination kinetics and detoxification rates of naturally OA-contaminated mussels that had either received or not received food for three weeks. The protocol was applied in two trials (in June 2006 and June 2007, called Ker06 and Ker07), conducted one year apart on samples of mussels collected in the same area, at the same season. Okadaic acid (OA), the main lipophilic toxin produced by the toxic alga Dinophysis acuminata, was analysed over the course of the decontamination, in hydrolysed (total OA) and non hydrolysed (free OA) digestive gland extracts, in order to estimate acyl-esters (7-O-acyl-ester derivatives of OA) concentrations. OA analyses were also made for toxin presence in biodeposits and in the aqueous phase. Bivalve physiological status was evaluated by biomass measurements (dry weight of flesh) and two biochemical compounds (total lipid and glycogen concentrations). Measured physiological parameters showed that mussels did not suffer under experimental conditions. Both trials showed that the food accelerated the elimination of free and total OA. This effect cannot be attributed to a dilution of the toxin in the tissue, as results expressed in toxin burden led to the same conclusion. The kinetic models of decontamination differed between the two experiments: the model was linear for Ker06, provided that the values corresponding to the first two days were discarded, whereas data fitted a decreasing exponential curve better in Ker07. Detoxification rates increased as the food supply increased. After three weeks of experimentation, the detoxification rates for total OA in Ker06 and Ker07 were 52 and 61%, respectively, in unfed mussels and 90 and 89% in fed mussels (with the highest level in Ker07). Comparisons between the free OA and esters showed that detoxification rate was higher for free OA than for esters, whatever the level of food supply. The results of this study suggest that food increase probably accelerates elimination of OA and OA-esters but the latter are eliminated at a lower speed.

In the latest years, blooms of toxic Cyanobacteria have intensified worldwide, causing serious problems to human health. The edible crayfish Procambarus clarkii is known to accumulate the toxins (microcystins) produced by Microcystis aeruginosa. Our aims here were to (1) quantify microcystin-LR in P. clarkii's organs/tissues; (2) analyse differences in its content between size classes and between sexes; (3) develop protocols for the depuration of the toxin from crayfish; and (4) assess the quality of the crayfish abdominal muscle during depuration. The study was composed of two phases. In the first, the concentration of microcystin-LR in the hepatopancreas, stomach, intestine, and abdominal muscle of 102 crayfish was measured by the means of ELISA and was compared between small and large individuals and between sexes. In the second phase, 136 crayfish (64 males and 64 females) were subject to depuration for a maximum period of 21 days under two feeding regimes (ad libitum, i.e. fed every day or restricted, i.e. once every third day). Sixteen crayfish were sacrificed at different times from the start of the treatment (3, 6, 9, 14, 17, and 21 days). Microcystin-LR was measured in the intestines and in the abdominal muscles of the treated crayfish and was compared to the values obtained from individuals sacrificed immediately upon capture. The abdominal muscle was also analysed for its quality by quantifying colour, water holding capacity, and composition (qualitative and quantitative) of the total lipids and fatty acids. The results showed that (1) P. clarkii accumulates more toxin in the intestine and less in the abdominal muscle (the edible part); (2) microcystin-LR is less abundant in large (the marketable size) than in small individuals; and (3) its content differs between sexes in the hepatopancreas only. Besides, (4) microcystin-LR content decreased in the abdominal muscle, but not in the intestine, after a short period of depuration in the two feeding regimes and (5) depuration did not reduce the overall quality of crayfish meat.

An acute toxicity experiment was conducted by intraperitoneal injection with a sublethal dose of extracted microcystins (MCs), 50 μg MC-LR (where L = leucine and R = arginine) equivalent/kg body weight (BW), to examine tissue distribution and depuration of MCs in crucian carp (Carassius carassius). Liver to body weight ratio increased at 3, 12, 24, and 48 h postinjection compared with that at 0 h (p< 0.05). MC concentrations in various tissues and aquaria water were analyzed at 1, 3, 12, 24, 48, and 168 h postinjection using liquid chromatography coupled with mass spectrometry (LC-MS). The highest concentration of MCs (MC-RR + MC-LR) was found in blood, 2–270 ng/g dry weight (DW), followed by heart (3–100 ng/g DW) and kidney (13–88 ng/g DW). MC levels were relatively low in liver, gonad, intestine, spleen, and brain. MC contents in gills, gallbladder, and muscle were below the limit of detection. Significant negative correlation was present between MC-RR concentration in blood and that in kidney, confirming that blood was important in the transportation of MC-RR to kidney for excretion. Rapid accumulation and slow degradation of MCs were observed in gonad, liver, intestine, spleen, and brain. Only 0.07% of injected MCs were detected in liver. The recovery of MCs in liver of crucian carp seemed to be dose dependent.

Mercury (Hg) bioaccumulation and depuration potential was assessed in the glass eel Anguilla anguilla over a 30-day period, through a mesocosm experiment. During exposure period, glass eels exhibited a significant increase in Hg concentration compared with the control ones, revealing great accumulation capability. Distinct bioaccumulation kinetics were observed depending on the exposure concentrations: a saturation model and a linear accumulation model were achieved for low and high Hg levels, respectively. After 72 h of depuration, glass eels lost around 2 and 10 % of the Hg previously accumulated; however, until the end of the experiment, they never reached the original baseline condition. Most importantly, organisms exposed to high Hg concentrations still retained contaminant levels exceeding the European threshold regulating human food consumption. This may raise serious health concerns, due to the species’ rising interest in the international cuisine.

This study investigated the distribution of Pb, Cd, Cr, Fe, Cu and Zn in the whole tissues of oysters (Saccostrea cucullata) and mussels (Perna viridis) collected from the three river basins of the coastal area in Chanthaburi Province, Thailand. The heavy metal concentrations in oysters followed the order: Zn>Fe>Cu>Cd>Cr>Pb, whereas in the mussels it was: Fe>Zn>Cu>Cr>Cd>Pb. The concentrations of Cu and Zn in the oysters were higher than the permission standard, and the bioconcentration factor (BCF) study revealed the ability of the oysters to accumulate the heavy metals. The results of depuration found that Cu and Zn levels in both oysters and mussels were below the permission standard after the end of the process. The time of depuration was related to the levels of Cu and Zn with the higher r values and the relationship of the depuration study obtained from the results of multiple regression analysis.

The bioaccumulation and depuration capabilities of mercury by the edible bivalve Scrobicularia plana was studied in a coastal lagoon (Ria de Aveiro, Portugal) through a transplantation experiment. Little information on this topic is available in the literature, especially concerning different tissues' responses to contaminant exposure, but the present study is one of the few works that can surpass this knowledge gap. Organisms from a reference area were transplanted to two different contaminated areas in the Ria de Aveiro. In both areas, the bivalves (i.e., entire organism, digestive gland and the rest of the organism) presented a similar saturation model of mercury accumulation, the digestive gland being the tissue that reached the highest concentrations after 25 days of exposure to the contaminant. During this short uptake period, the transplanted organisms reached 20–30% of the concentrations observed in resident contaminated organisms. After the exposure period, the organisms were transplanted to a clean area for more than 25 days of depuration. At the end of the transplantation period, organisms lost approximately 50% of their mercury body burden (60%: the entire organism and digestive gland; 35%: gills and 40%: the rest of the organism) and the ones from the least contaminated site almost reached the concentrations recorded in the reference area. So, the results suggest that S. plana is a promising biomonitoring species, since it accumulates the contaminant in a considerable extent quite rapidly and at the same time it has a low metal retention capacity (low biological half-life) when exposed to clean sediments.

Polybrominated diphenyl ethers (PBDEs) are a class of global flame retardants whose residues have markedly increased in fish and human tissues during the last decade. They belong to persistent and toxic contaminants which needmore attention and toxicological study as their degradation in the environment is not well understood. This study characterizes 2,2′,4,4′- tetrabromodiphenyl ether (BDE-47) bioconcentration, elimination and biotransformation in juvenile turbot Psetta maxima, in order to evaluate the risk of its bioaccumulation in the marine environment. During this study, juvenile turbot were exposed to environmentally relevant BDE-47 concentrations from 0.001 to 1 μg/L for 16 days via aqueous exposure. This study found that juvenile turbot bioconcentrated and biotransformed BDE-47. There was no difference in standard length or weight between control and exposed fish. Uptake and elimination of BDE-47 by the turbot during exposure were examined in controlled laboratory experiments. Bioconcentration of BDE-47 was similar in fish from all treatment groups. Bioconcentration was rapid and increased with exposure time, since the bioconcentration factor (BCF) was higher. However, elimination was slower in comparison and low elimination was detected after 10 days in clean water. BDE-47 concentration in water influences the BCF. Half-life ranged between 37 and 108 days and theoretical times t90 could range from 120 to 358 days. The present study demonstrates a stepwise debromination of BDE-47 to BDE-28. MAE-PCI Versión del editor

The cyanobacterial toxin Cylindrospermopsin (CYN), a potent protein synthesis inhibitor, is increasingly being found in freshwater bodies infested by cyanobacterial blooms worldwide. Moreover, it has been reported to be implicated in human intoxications and animal mortality. Recently, the alteration of the activity and gene expression of some glutathione related enzymes in tilapias (Oreochromis niloticus) exposed to a single dose of CYN has been reported. However, little is known about the effects induced by repeated doses of this toxin in tilapias exposed by immersion and the potential reversion of these biochemical alterations after two different depuration periods (3 or 7 days). In the present study, tilapias were exposed by immersion to repeated doses of a CYN-containing culture of Aphanizomenon ovalisporum during 14 days, and then were subjected to depuration periods (3 or 7 days) in clean water in order to examine the potential reversion of the effects observed. The activity and relative mRNA expression by real-time polymerase chain reaction (PCR) of the antioxidant enzymes glutathione peroxidase (GPx) and soluble glutathione-S-transferases (sGST), and also the sGST protein abundance by Western blot analysis were evaluated in liver and kidney of fish. Results showed significant alterations in most of the parameters evaluated and their recovery after 3 days (GPx activity, sGST relative abundance) or 7 days (GPx gene expression, sGST activity). These findings not only confirm the oxidative stress effects produced in fish by cyanobacterial cells containing CYN, but also show the effectiveness of depuration processes in mitigating the CYN-containing culture toxic effects

Tez (Doktora) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2013, Thesis (PhD) -- İstanbul Technical University, Institute of Science and Technology, 2013, Besin zincirinde PAH biyobirikimi ve transferinin modellenmesi çalışmasında, Akdeniz midye türü olan Mytilus galloprovincialis ve deniz mikroalglerinden Phaeodactylum tricornutum kullanılarak laboratuvar koşullarında, bir besin zinciri oluşturulmuştur. Laboratuvar deneyleri birikim ve arınım süreçleri olmak üzere iki aşamada gerçekleştirilmiştir. Birikim aşamasında, seçilen alg türü P. tricornutum, iki farklı halka sayısına sahip poliaromatik hidrokarbonlara (PAH) maruz bırakılmıştır. Laboratuvar deneylerinde kullanılmak üzere, iki halkalı PAH olarak fenantren (PHE) ve üç halkalı PAH olarak benzo(a)antrasen (BaA) seçilmiştir. Toksisite çalışmalarında biyo kullanılabilirlik açısından önemli olması nedeniyle deneylerde kullanılacak PAH konsantrasyonları, sudaki çözünürlük limitlerinin altında kalacak şekilde belirlenmiştir. BaA?in sudaki çözünürlük limiti 11 µg L-1 civarında ve PHE?nin sudaki çözünürlüğünün 1200 µg L-1 civarında olması nedeniyle, deneylerde kullanılmak üzere BaA için 3, 6 ve 9 µg L-1 ve PHE için 250, 500 ve 1000 µg L-1 konsantrasyonları çalışma konsantrasyonları olarak belirlenmiştir. Mikroalg ve midyeler, belirlenen konsantrasyonlara BaA için 15 ve PHE için 11 gün boyunca maruz bırakılmış, hemen ardından sırasıyla 14 ve 11 gün boyunca herhangi bir PAH?a maruz bırakılmadan temiz deniz suyu içinde arınmaya bırakılmışlardır. Birikim ve arınma aşamalarından oluşan deney sistemi kısaca şöyle açıklanabilir: Deney düzeneğinde, maruz bırakılacak her bir PAH konsantrasyonu için farklı bir akvaryum oluşturulmuştur. Belirlenen PAH konsantrasyonlarına ek olarak deney sistemine, BaA ve PHE için ayrı birer kontrol akvaryumu eklenmiştir. Belirlenen konsantrasyonlardaki PAH?lar, besin kaynağı olarak kullanılan alg hücrelerine yeterince nüfus etmesi amacıyla 24 saat öncesinden alglerle birlikte karanlık bir ortamda tutulmuş, takip eden gün PAH?a maruz bırakılmş algler akvaryumlardaki midyelere besin kaynağı olarak verilmiştir. Maruz bırakılma süresince bu işlem, her bir akvaryum için günlük olarak tekrar edilmiştir. Arınım sürecinin deney düzeneği açısından tek farkı, besin kaynağı alglerin PAH?lara 24 saat öncesinden maruz bırakılmaması ve akvaryumlara her gün temiz deniz sularının eklenmesi olmuştur. Yürütülen çalışmada, iki farklı ölçekte birikim ve arınım deneyleri gerekleştirilmiştir: büyük ve küçük ölçekli birikim ve arınım deneyleri. Bu deneylerdeki işlemler aynı sırayı takip etmekle birlike tek farkları midye sayısının ve deniz suyu hacminin 1/5 oranında azaltılmış olmasıdır. Azaltılan değişkenler dışında, maruz bırakılan PAH ve alg konsantrasyonlarında herhangi bir değişiklik yapılmamıştır. Büyük ölçekli birikim ve arınım deneyleri esnasında, her üç ya da dört günde bir akvaryumlardan midye örnekleri alınarak midye dokularında biriken PAH konsantrasyonları, GC-MS (gaz komatografisi-kütle spektrofotometresi) ile analiz edilmiştir. Bu analizler sonucunda, midyelerin birikim ve arınım dönemleri için kinetik hız sabitleri belirlenmiştir. Hız sabitlerinin belirlenmesinde, birinci derece diferansiyel denklemler kullanılmıştır. Daha sonra, belirlenen birikim ve arınım kinetik hız sabitleri, geliştirilen PAH biyobirikimi ve transferi model çalışmasında girdi verisi olarak kullanılmıştır. Büyük ölçekli deney sisteminden alınan midye örneklerine aynı zamanda iki farklı biyogösterge deneyi de uygulanmıştır. Bu deneyler filtrasyon hızı ve lizozomal membran stabilitesidir. Midyelerin maruz bırakıldıkları PAH konsanstrasyonuna verdikleri fizyolojik tepkiler, filtrasyon hızı biyogösterge deneyi ve hücresel tepkiler lizozomal membran stabilite biyogösterge deneyi ile gözlemlenmiştir. Küçük ölçekli deney sisteminde ise midyelerin filtrasyon hızları, içinde bulundukları akvaryumlardan her 24 saatte belirli aralıklarla alınan su örnekleri kulanılarak takip edilmiş ve hesaplanan filtrasyon hızı değerleri, geliştirilen model çalışmasında girdi verisi olarak kullanılmıştır. Deniz ortamında yaşayan midyelerin, besin (algler) ve çevrelendikleri ortam (deniz suyu) aracılığıyla PAH?lara maruz bırakılması sonucunda dokularında biriken PAH konsantrasyonlarının belirlenmesi amacıyla matematiksel bir model oluşturulmuştur. Bu model, temel olarak laboratuvarda gerçekleştirilen birikim ve arınım deneylerine dayandırılmıştır. Kinetik hız sabitleri ve filtrasyon hızı gibi daha önce bahsedilmiş olan model girdi verilerine ek olarak akvaryumlardaki midye sayısı, midye ağırlığı, besin olarak kullanılan alg hücreleri sayısı, akvaryumlardaki deniz suyu hacmi ve her bir akvaryuma eklenen ve her biri deniz suyu çözünürlük limitlerinin altında kalmak üzere belirlenmiş PAH konsantrasyonları da modelin diğer girdi verilerini oluşturmaktadır. Geliştirilen model, temel olarak her biri farklı bir bölmeyi temsil eden üç farklı diferansiyel denklemden oluşmaktadır. Bu bölmeler, maruz bırakılan organizma (midye), çevreleyen ortam (deniz suyu) ve organizmanın besin kaynağını (alg) temsil etmektedir. Her bir diferansiyel denklem, deney sistemi göz önünde tutularak ve her bir bölmenin birbirlerine kinetik hız sabitleri ve filtrasyon hızı ile bağlantılı olması düşünülerek formüle edilmiştir. Böylece, birbirleri ile etkileşimli; ancak dış etkenlere kapalı bir model oluşturulmuştur. Modelin, dış etkenlere kapalı çevrim sistemi düşünülerek oluşturulmasıyla, midyedeki PAH birikimi, arınımı ve transferi tahminleri için temel bir model çalışması gerçekleştirilmiştir. Böylece midyede birikebilecek en yüksek konsantrasyon oranları gözlemlenebilecektir. Buharlaşma ve bozunma gibi dış etkenler neticesinde oluşabilecek PAH konsantrasyonlarındaki olası azalmaların, denklemlere eklenecek çeşitli parametreler ile temsil edilmesi ve bunların daha sonraki model çalışmalarına ilave edilmesi düşünülmektedir. Temel olarak, girdi verileri, diferansiyel denklem sistemi ve çıkış grafiklerinden oluşan model; bilim, mühendislik ve matematik konularında kullanılmakta olan hesaplama yazılımlarından Mathematica yazılım programında yazılmıştır. Diferansiyel denklem sistemi, seçilen yazılım programında var olan 4. derece Runge-Kutta sayısal entegrasyon yöntemi ile çözülmüş ve yine aynı programın eğri uydurumu özelliği ile grafik olarak elde edilebilmiştir. Bu özellikler aynı zamanda yazılım programı seçimi konusunda da etkili olmuştur. Yazılan program kodu öncelikle başarılı bir şekilde çalıştırılmıştır ve maruz bırakılan konsantrasyonun günlere bağlı değişimleri görsel olarak elde edilmiştir. Ardından, teorik değerlere dayanarak elde edilmiş olan PAH konsantrasyonu-gün grafikleri, deneysel verilerle karşılaştırılmıştır. Bu karşılaştırma işlemi, üç farklı konsantrasyon ve iki farklı PAH türü olmak üzere toplamda altı kez olmak üzere her bir akvaryum için ayrı ayrı yapılmıştır. Daha sonra, her bir PAH için elde edilen sonuçlar bir araya getirilerek tek bir grafik altında toplanmıştır. Tüm teorik hesaplamalar deneysel verilerle aynı grafik üzerinde karşılaştırılmış ve modelin, temelde PAH birikimi, arınımı ve transferini temsil edebilecek nitelikte olduğu görülmüştür. Bu nedenle, aynı model kodu kullanarak farklı senaryolar üzerinde çalışılmıştır. Bu senaryolar sırayla şöyle özetlenebilir: Öncelikle besin kaynağı olarak kullanılan alglerin sayısındaki değişimin etkisi araştırılmıştır. Saha çalışmaları sırasında yapılan deniz suyundaki parçaçık sayımlarından görece yüksek olan sonuçlardan biri model girdisi olarak denenmiştir. Ölçülen deniz suyu parçacık miktarı, deneydeki alg sayısının yaklaşık üç katı olmasına rağmen sonuçlarda belirgin bir farklılık olmamıştır. Bir diğer senaryo ise farklı türde deniz alglerinin midyelerin besin kaynağı olarak kullanılması üzerine gerçekleştirilmiştir. Literatür çalışmalarından altı farklı türde deniz algine ait biyokonsantrasyon değerleri hesaplanmış ve model girdisi olarak bu değerler kullanılmıştır. Deneylerde kullanılan alg sayısında hiçbir değişim yapmadan model kodu farklı alg türleri için çalıştırılmıştır. Tüm sonuçlar karşılaştırıldığında farklı biyokonsantrasyon faktörlerinin, sonuçları farklı şekillerde etkilediği gözlenmiştir. Bu gözlemler ile üç halkalı PAH?lardan olan BaA ve iki halkalı PAH?lardan olan PHE?in farklı birikim eğilimleri gösterdiği anlaşılmıştır. Alglerle yapılan model senaryoları sonucunda, alglerin biyokonsantrasyon değerlerinin artmasıyla BaA?in dokularda birikme oranının azaldığı, diğer yandan alglerin biyokonsantrasyon değeri arttıkça PHE?in dokularda birikme oranının arttığı sonucuna varılmıştır. Seçilen PAH?ların kimyasal özellikleri incelendiğinde, bu farklılığın sudaki biyolojik kullanılabilirlik farklılıklarından ve sudan uzaklaşma özelliklerinden meydana geldiği anlaşılmaktadır. Algler dışında değiştirilebilecek başka bir parametre olan midye sayıları ile de çeşitli senaryolar gerçekleştirilmiştir. Aynı deney koşulları altında, sadece midye sayıları tüm deney boyunca hiç değişmeden (ara örneklemeler yapılmadan) olduğunun iki katına çıkarıldığında elde edilen PAH konsantrasyonlarında yaklaşık %30-35 oranında azalma göstermiştir. Tüm bu senaryo değişkenlerine ek olarak, birikim ve arınım dönemlerinin süreleri de modelde değiştirilebilecek parametrelerdendir. Gün sayıları, deneylerdeki gün sayılarının iki ve dörder katına çıkarılmış ve model sonuçları elde edilmiştir. Sadece gün sayısı arttırılarak yapılan denemelerde, midyelerdeki BaA konsantrasyonu seviyesinin PHE konsantrasyonu seviyesine kıyasla 1/3 oranında daha yavaş bir hızla kararlı duruma ulaştığı gözlenmiştir. Laboratuvar ortamında gerçekleştirilen deney sistemine dayanan matematiksel model, midyedeki PAH birikim, transfer ve arınımını göstermek açısından eksiksiz değildir. Tamamlanması gereken noktalardan en göze çarpanı uzun süreli maruz bırakma deneyleri için eklenmesi gereken midyelerin büyüme oranı parametresidir. Bunun dışında, PAH?ların buharlaşması ve bozunması gibi parametreler de modele eklenebilir. Bu gibi eksikler tamamlanmak üzere daha sonraki çalşmalara bırakılmıştır. Sonuç olarak, oluşturulan model çalışması, her seferinde yeniden deney yapma ihtiyacını azaltmış, elde edilen sonuçlar potansiyel senaryolar için midyelerde biriken PAH konsantrasyonu seviyelerinin ve ardından arınma süreci sonucu ulaşılabilecek konsantrasyon seviyelerinin tahmini için bir öngörü aracı olarak kullanılabileceğini göstermiştir., In this study, a basic food chain of aquatic environment was formed with Mediterraneaen mussel species Mytilus galloprovincialis fed with marine diatom Phaeodactylum tricornutum. P. tricornutum was exposed to polyaromatic hydrocarbons (PAHs) during the uptake stage of the experiments. Two different kinds of PAHs were selected in order to represent two and three ring PAHs; phenanthrene (PHE) for two ring and benzo(a)anthracene for three ring PAH. Mussels were exposed to three different concentrations of selected PAHs under solubility limits through the routes of food (algae) and surrounding environment (seawater). Exposed concentrations were 3, 6 and 9 µg L-1 for BaA and 250, 500 and 1000 µg L-1 for PHE. Durations of the uptake stages were 15 days for BaA exposure and 11 days for PHE exposure. This period was followed by depuration stage as 14 days for BaA and 11 days for PHE exposures. Two different scales of experiments were performed with the same exposure concentrations: large and small scale uptake and depuration experiments. Exposure concentrations remained same whereas the number of exposed mussels and the volume of seawater were reduced in the small scale experiments. Mussels were sampled at each three or four days of the uptake and depuration periods of the large scale experiment. PAH concentrations in sampled mussel tissues were determined with GC-MS (gas chromatography-mass spectrophotometry). Kinetic rate constants of mussels were calculated with the first order differential equations during the uptake and depuration periods. These kinetic rate constants were used as input parameters of the developed model. In addition, two biomarker methods were applied to the sampled mussels during the large scale experiment. These biomarkers were filtration rate and lysosomal membrane stability. Physiological and cellular effects of exposed PAH concentrations were observed with filtration rate and lysosomal membrane stability biomarkers, respectively. In the small scale uptake and depuration experiment, filtration rates of mussels were observed during 24 hours and used as input parameters of the developed model. Additional to the kinetic rate constants and filtration rate measurements, parameters such as mussel number, mussel weight, algae number, seawater volume and exposed PAH concentration were also used as input parameters of the developed model. A mathematical model was developed by using the previously stated input parameters. Three differential equations were used to represent each compartment (seawater, algae and mussel compartments) of the model. The model was developed to determine the concentration levels of exposed PAHs in the mussel tissues. The model code was written in Mathematica software, and the output graphs were represented in the same software workbook. After the execution of the model code, PAH concentration - exposure day graphs were generated as outputs of the model. After the correctly execution of the model code, developed model was verified wih the experimental data. Although the model was developed as a closed system omitting evaporation and degradation of PAHs, experimental and model data had a good match with each other. Thus, new scenarios were generated using the same model code. These new sceanarios were generated by changing the input parameters of the model code. Input parameters of the new scenarios were different algae number, different types of marine algae, increased mussel number and increased duration of uptake and depuration periods. Input parameters were selected from field measurements and literature data for different algae number and different types of marine algae. All scenarios were successfully generated and the results indicated that the developed model can be evaluated as a prediction tool of PAH concentration levels in Mytilus glloprovincialis in the aquatic environment., Doktora, PhD

8 páginas, 8 figuras, 1 tabla, Mussel-processing wastes, which contain glycogen (~ 10 g/litre) as their main component, can be used as a culture medium for several species of amylolytic yeasts and microfungi useful as single cell protein (SCP) sources. In addition, cell-free media from these cultures (with COD reduced to -~ 10% of its initial vahte) could, in principle, be used for the hydrolysis of greater volumes of the same effluent, which could then be concentrated, converting it into a more versatile microbial substrate. With this objective in mind, the optimal reaction conditions, stability and kinetics of postincubates from several amylolytic species with distinct growth features when cultured on the effluent, were examined. Some of the mechanisms involved in the regulation of amylolytic activity are also discussed, as well as some of the methodological problems often associated with this kind of study., To CICYT for its financial support (project ALl 90-0789).

Background Conventional wisdom regarding exposures to persistent organic chemicals via breast-feeding assumes that concentrations decline over the course of lactation and that the mother’s body burden reflects her cumulative lifetime exposure. Two important implications stemming from these lines of thought are, first, that assessments of early childhood exposures should incorporate decreasing breast milk concentrations over lactation; and, second, that there is little a breast-feeding mother can do to reduce her infant’s exposures via breast-feeding because of the cumulative nature of these chemicals. Objectives We examined rates of elimination and milk/serum partition coefficients for several groups of persistent organic chemicals. Methods We collected simultaneous milk and blood samples of 10 women at two times postpartum and additional milk samples without matching blood samples. Results Contrary to earlier research, we found that lipid-adjusted concentrations of polybrominated diphenyl ethers, polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins and furans, and organochlorine pesticides in serum and milk do not consistently decrease during lactation and can increase for some women. Published research has also suggested an approximate 1:1 milk/serum relationship (lipid adjusted) on a population basis for 2,3,7,8-tetrachlorodibenzo-p-dioxin; however, our results suggest a more complex relationship for persistent, lipophilic chemicals with the milk/serum relationship dependent on chemical class. Conclusions Decreases in concentration of lipophilic chemicals on a lipid-adjusted basis during lactation should no longer be assumed. Thus, the concept of pumping and discarding early milk as means of reducing infant exposure is not supported. The hypothesis that persistent lipophilic chemicals, on a lipid-adjusted basis, have consistent concentrations across matrices is likely too simplistic.