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Mercury and selenium concentrations and Se:Hg molar ratio in edible muscle and hepatopancreas of the crab Callinectes arcuatus from coastal lagoons of northwest Mexico were determined using atomic absorption spectrophotometry. The three coastal lagoons were Santa Maria La Reforma (SMLR), Urias (UR), and Huizache-Caimanero (HC); samplings were carried out from December 2016 to October 2017. The mercury ranges in the muscle of C. arcuatus in SMLR, UR, and HC lagoons were 0.31–0.52, 0.15–0.45, and 0.22–0.55 μg g−1, respectively. In hepatopancreas, the values ranged from 0.08 to 0.15, 0.06 to 0.15, and 0.05 to 0.12 μg g−1 in SMLR, UR, and HC lagoons, in that order. For selenium concentrations in C. arcuatus muscle, the ranges 11.64–20.14, 14.88–19.71, and 15.27–29.51 μg g−1 were determined in SMLR, UR, and HC lagoons, respectively. While for hepatopancreas, the ranges were 34.34–44.13, 27.77–40.45, and 15.16–49.80 μg g−1, in that order. No significant relationships (p > 0.05) between mercury and selenium concentrations (in white meat and hepatopancreas) were observed in C. arcuatus carapace width and length. Se:Hg molar ratio values were 98.1 ± 20.8, 171.4 ± 81.6, and 176.8 ± 51.2 for SMLR, UR, and HC lagoons, in that order. This high ratio (> 1) in C. arcuatus edible muscle indicated that selenium concentration was sufficient to neutralize possible mercury toxicity, so it does not represent danger to humans when it is consumed.

The omnipresence of microplastics (MPs) in marine and coastal environments has attracted attention owing to their effects on various organisms, including humans. We present the first study of MPs in the gastrointestinal tract (GT), gills (GI), and exoskeleton (EX) of the farmed whiteleg shrimp Litopenaeus vannamei from commercial aquaculture facilities in northwestern Mexico that have operated semi-intensively for the last two decades. We found that the number of MP items per tissue was 7.6 ± 0.6 in the GT, 6.3 ± 0.9 in the GI, and 4.3 ± 0.9 in the EX, with an average of 18.5 ± 1.2 MP items per shrimp (1.06 items/g, wet weight [ww]). MP concentrations were 261.7 ± 84.5, 13.1 ± 1.8, and 2.6 ± 0.6 items/g (ww) in the GT, GI, and EX, respectively. Microplastics ranged from 30 to 2800 μm in size (360 ± 39 μm) with fibers (∼90.8%), filament-shape (∼93.4%), and transparent (∼47.7%) being the most common ones. Polyethylene (∼54.5%) and polyamide (∼24.2%) were the most commonly identified polymers, although polyesters (∼12.1%), polystyrene (∼6.1%), and nylon (∼3.0%) were also found. The abundance of MPs in farmed L. vannamei may be related to their feeding habits and the availability of MP sources in aquaculture facilities.

The objective of this review is to synthetize knowledge of the relationship between metals and oxidative stress in aquatic crustaceans (mainly shrimp and crabs) to analyze antioxidant responses when organisms are exposed to metals because the direct metal binding to the active site of enzymes inactivates most of the antioxidant systems. This study reviewed over 150 works, which evidenced that: (i) antioxidant defense strategies used by aquatic decapod crustaceans vary among species; (ii) antioxidant enzymes could be induced or inhibited by metals depending on species, concentration, and exposure time; and (iii) some antioxidant enzymes, as superoxide dismutase increase their activity in low metal levels and time exposures, but their activities are inhibited with higher metal concentrations and exposure time.

The present study shows the human health risk of Cd, Cu, Hg and Zn by consumption of clams Megapitaria squalida from Northwest Mexico, collected in 2013. The mean concentration for each metal in the soft tissue was: Zn > Cu > Cd > Hg; and mean values of 68.89 ± 37.59—30.36 ± 27.19, 8.77 ± 1.35—6.80 ± 0.36, 4.47 ± 0.21—3.18 ± 0.63 and 0.99 ± 0.81—0.52 ± 0.16 µg/g, respectively. Clam age was significantly negatively correlated (p

Adult sharpnose sharks (Rhizoprionodon longurio) with a mean total length of 110.93 ± 5.30 cm were obtained from a local fishery in Mazatlan (Southeast Gulf of California, Mexico). The total mercury content in muscle was analyzed by cold vapor atomic absorption spectrophotometry. The minimum and maximum total mercury content were 0.77 ± 0.23 and 2.33 ± 0.57 µg/g (dry weight), respectively. Only 6.6 % of the organisms did show mercury content higher than the permissible limit. No significant relationship was observed between weight and total mercury content in edible muscle of the sharks (r = 0.364, p > 0.05). The Hazard Quotient values for total mercury (0.005–0.015) and methyl mercury (0.022–0.065) indicated no risk by edible muscle consumption of the shark Rhizoprionodon longurio.

This study investigated acute arsenic toxicity and bioconcentration capacity in Litopenaeus vannamei because it has been frequently exposed to lower salinities than its isosmotic point (25 g L−1). Juveniles (9.9 ± 0.4 g) were exposed to low (5–10 g L−1) and isosmotic salinity (25 g L−1) levels; As values were 30.8, 20.2, 16.8 and 13.9 mg L−1 at 5 g L−1; 30.4, 19.1, 16.8 and 14.8 mg L−1 at 10 g L−1; 31.5, 19.0, 15.0 and 11.9 mg L−1 at 25 g L−1 at 24, 48, 72 and 96 h LC50, respectively. No significant differences were found among As LC50 values calculated for different salinity levels and same exposure times, concluding that low salinity did not affect shrimp sensitivity to As. Likewise, no significant differences were observed in As bioconcentration in shrimp exposed to the same waterborne As and distinct salinity, supporting the results of acute toxicity. Bioconcentration factors of As maintained a relatively stable tendency where all values (0.8 ± 0.2 to 1.7 ± 0.4) were statistically comparable to 1, indicating that As was accumulated in a similar proportion to waterborne As concentration at three salinity levels. This study proposed 135.3 ± 12.1 μg L−1 for salinities from 5 to 25 g L−1 as provisional safe As concentration. According to these results, the hypothesis that sustains an effect of low salinity on As acute toxicity and its bioconcentration capacity cannot be acceptable. Therefore, the information provided allows knowing the threshold levels of As in water to avoid ecological and economic losses.

The aim of this work was to determine the best conditions for biomass production of the bacterium Enterobacter cloacae and for Cd and Pb retention by adsorption on the cell walls or by absorption and accumulation in the bacterial biomass. Suspended and immobilized cultures of this bacterium, acclimated to both metals, were grown for 24 h at pH 6, 7 and 9, in trypticase soy (TS) medium added with 2.73 mg/L of Cd or 16.8 mg/L of Pb. Immobilized cultures at pH 7 and 9 had the highest biomass production. Percentages of Cd retention by adsorption and absorption increased with increasing pH, but adsorption was higher in suspended while absorption was higher in immobilized cultures. Possibly because of different affinity of bacterial cells for these metals, the percentages of Pb retention were higher than those of Cd. In percentage, the highest Pb adsorption on cell walls was at pH 9, while retention by biomass decreased with increasing pH. The amount of metal retained by one g of bacterial biomass, efficiency was higher at pH 6, possibly because of the presence of dead or dying bacterial cells.

Litopenaeus vannamei juveniles were exposed to sublethal levels (2.33-18.03 µg/L) of inorganic mercury. Time of exposure (0, 24 and 168 h) was a source of DNA damage. Mean comet tail length not changed significantly with mercury concentrations and exposure time, and this parameter cannot be used to assess DNA damage in this shrimp. Total hemocyte count showed a trend to decrease according to the increase of mercury concentrations, although no significant difference between treatments with mercury was observed. The phenoloxidase (PO) activity was not influenced by the time of exposure. At the end of the experiment, the PO in organisms exposed to 18.03 µg/L was different from the control. The time of exposure has a more important influence in superoxide dismutase than the concentration of mercury. According to these results, a suitable criterion of water quality for long-term exposure of L. vannamei should be lower than 2 µg/L of mercury.

Nutrient flux, net metabolism, and N 2 fixation and denitrification processes were estimated and compared in two semi-arid subtropical coastal lagoons in the Gulf of California: El Soldado (ES), where no wastewater is discharged, and El Rancho (ER), where shrimp farm effluents are regularly discharged. Biogeochemical processes were evaluated with the LOICZ model. Flushing time was 2 fixation in the spring, autumn, and winter, but heterotrophic metabolism and denitrification in the summer. Denitrification dominated in ER (−2.21 mmol m 2 day −1 ) and values were higher than those estimated in ES (−0.45 mmol m 2 day −1 ). The comparative analysis between ES and ER evidenced the significant changes in its biogeochemical performance caused by the input of anthropogenic nutrients, and can orient the environmental management of coastal lagoons.

This study analyzed the effects of cadmium (Cd) and lead (Pb) on growth, sexual couples, and histological structures of Artemia franciscana exposed to individual concentrations of these metals and combined. No histological effects were observed at tissue level in digestive, respiratory, nervous, and reproductive systems (i.e., necrosis, loss of regular structure) in individual and mixed applications on A. franciscana for 20 days of exposure. No significant differences (p0.05) were determined in final size and growth rate among the organisms exposed to Cd and those of control. For Pb, only the final size (3.59 ± 0.59 mm) of organisms exposed to the highest concentration was significantly lower (p0.05) than those of the control (4.53 ± 0.34 mm) group, whereas for the combined experiment, no significant differences (p0.05) were observed in final size and growth rate. At all Cd concentrations, mean sexual couples were significantly lower (p0.05) than those of the control, as well as for Pb. For the combined experiment (8 μg/L of Cd + 8 μg/L of Pb), sexual couples were not observed, indicating synergism and negative reproduction effects. The results showed that Cd and Pb aquatic environmental regulations (as the Criterion of Continuous Concentration) proposed by the US Environmental Protection Agency (EPA) should include their interactions with other metals.

Juveniles of the shrimp Litopenaeus vannamei (3.3 ± 0.4 g) were exposed separately to nitrite (0.0, 1.1, 2.6, and 5.3 mg/L nitrogen as nitrite [NO2−-N]) and nitrate (0, 90, 225 and 400 mg/L nitrogen as nitrate [NO3−-N]) concentrations equivalent to 0, 10, 25, and 50% of the LC50-96 h value of NO2−-N and NO3−-N in low salinity water (3 g/L). Shrimps responded to nitrite and nitrate according to changes in oxyhemocyanin, glucose, lactate and ion levels in the hemolymph after 6, 12, 24, and 48 h of exposure. Oxyhemocyanin levels decreased with increasing nitrite and nitrate levels and were higher at 50% exposure to the contaminants. Compared to the control, glucose and lactate increased significantly at 50% exposure to nitrite and nitrate, particularly at 12 and 24 h. Na+ in the hemolymph changed with nitrite and nitrate, while K+ only changed ˜with nitrite.

Moon phases influence the molting process of shrimp, which affect other physiological processes as immune response. This study analyzed some parameters of immune response: total hemocytes counts (THC), hemolymph clotting time and superoxide anion (O2−) production, total protein concentration, superoxide dismutase activity, and the presence of Vibrio spp. in Litopenaeus vannamei at different moon phases. The highest percentage of organisms in intermolt stage was observed in the first quarter moon phase (95%). The highest THC was observed at new moon phase, which was significantly different (p 0.05) between different moon phases. The higher (p

Experiments were carried out to verify the existing information on the LC50 of waterborne Hg for L. vannamei postlarvae and determine that of juveniles. Additionally, the structure of different tissues of the organisms which survived the acute toxicity test was examined. The experiment with juveniles was performed after addition of 1.00, 0.75, 0.50, 0.25 and 0.10 mg/L of Hg (using HgCl2). For postlarvae, additions were 0.5, 0.4, 0.3, 0.2, 0.1 and 0.01 mg/L. Acute toxicity tests determined that, after 96 h of exposure to Hg, the respective LC50 values for juveniles and postlarvae of Litopenaeus vannamei were 0.50 and 0.25 mg/L. Although lower that the only value of LC50 known for L. vannamei postlarvae, these lethal concentrations are one order of magnitude higher than those known for larval and juvenile stages of other crustaceans, suggesting that L. vannamei has a high resistance to the toxic effects of waterborne Hg. The only histological damages in survivors to 96 h of exposure were observed in nervous tissues and consisted in the presence of necrotic cells. The degree of damage severity was related to the concentration of dissolved Hg, and the numbers of necrotic cells decreased progressively with increasing distance from the nerve ganglia. A safe level of mercury exposure for L. vannamei postlarvae would be 2.5 μg/L.

Distincts methods are used to evaluate acute toxicity and generate different values of LC50. However, the static with renewal (100% renewal every 24 h) and feeding method is the more utilized. This study was developed to determine the differences between the LC50 obtained and define which method is most adequate for testing acute toxicity of nitrite in shrimp. Litopenaeus vannamei postlarvae (PL18) were exposed to different concentrations of nitrite-N (nitrite as nitrogen) at 3 g/L of salinity, using two different strategies of renewal solution and feeding trials: treatment Ts/nf/1 (static (no water renewal) + not feed), Tsr/f/2 (static with renewal + feed), Tsr/nf/3 (static with renewal + not feed) and Ts/f/4 (static + feed). Different values of LC50 nitrite-N for 96 h values were generated for the four distinct treatments (Tsr/f/2 > Tsr/nf/3 > Ts/nf/1, Ts/f/4). However, significant differences (p Tsr/nf/3). Considering the magnitude and variation of the LC50 values, it is recommended the static with renewal method and feeding method which generates higher values of LC50 and lowest variation, results suggesting that this method is more adequate to evaluate in shrimps nitrite and other nitrogen compounds acute toxicity.

We evaluated the total Hg concentration in different tissues of squalid callista Megapitaria squalida in order to measure Hg distribution in tissue and to estimate human health risk. Samples were obtained by free diving in the SW Gulf of California, Mexico. Concentrations are given on a wet weight basis. A total of 89 squalid callista specimens were obtained, presenting an average Hg concentration of 0.07 ± 0.04 µg g−1. There were no significant differences (p > 0.05) in Hg concentration between tissues (visceral mass = 0.09 ± 0.08 µg g−1; mantle = 0.06 ± 0.07 µg g−1; muscle = 0.06 ± 0.04 µg g−1). The low Hg values found in squalid callista and its low risk quotient (HQ = 0.03) suggest that the consumption of squalid callista does not represent a human health risk. However, HQ calculated using MeHg was > 1, it which could indicate a potential risk related to consumption of clams.

Shrimp aquaculture has been the fastest growing and diversifying food production industry in the world. On the other hand, basil is an important herb moderately salt-tolerant, which is among the most main crops which essential oils stand out for the quality and chemical diversity. This paper evaluates the performance of an aquaponic shrimp (Litopenaeus vannamei)-basil (Ocimum basilicum) system in terms of water quality, water use, and nutrient removal. This aquaponic system consists of three units (aquaculture; water conditioning; and hydroponic) coupled in a recirculation system using low-salinity water: well water (WW) and diluted seawater (DSW). The experiment was conducted over 78 days to characterize the performance of the proposed system, which reduces ~73% and 76% of the organic suspended solids, 23% and 18% of the total phosphorous (TP), and 24% and 21% of total nitrogen (TN) for WW and DSW, respectively. The reduction of TN and TP in the system implies a great efficiency in the use of nutrients, and consequently a low environmental impact. The water use by the shrimp biomass was 2.7 and 3.0 m3 kg−1 for WW and DSW, respectively, while by the total biomass (shrimp + basil) was 0.5 and 0.8 m3 kg−1 for WW and DSW, respectively. These results evidence that aquaponic shrimp-basil system remove N and P from water, improve water quality, enable efficient use of water and nutrients, reduce effluent discharge to the environment, as well as increase production.

Cholinesterases (ChE) have been suggested as biomarkers of the presence of organophosphorus insecticides (OP). The activities of these enzymes were determined in abductor muscle, gills and labial palps of oysters collected during the rainy and the dry seasons at eight points of the coastal zone of Nayarit state (NW Mexico), aiming to determine if their variability is related to geographic and seasonal differences in the use of OP. At all stations, ChE mean activity was lower in the dry than in the rainy season, and the muscle had consistently lower values than gills and labial palps. Lower activities were found in Bahia de Banderas, in the southern part of the state, than in the northern stations. This may be explained by the year-round use of OP insecticides in the southern part of the state, whereas herbicides are the most common pesticides used in agricultural areas draining into the northern stations during the rainy season.

The Gulf of California (GC) is an unique large ecosystem characterized by its rich biodiversity, high biological productivity and endemism of marine life. However, as many other large ecosystems worldwide, it is subject to diverse anthropogenic pressures (overfishing, climate change, losses of biodiversity and habitats, and pollution). We reviewed over 150 studies dealing with contaminants in water, sediments and representative organisms from the GC, and here we discuss the main issues associated to the presence of metals, metalloids, persistent organic pollutants (POPs, including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), brominated diphenyl ethers (deca tri-a) (PBDEs), and several other pesticides), plastics, nutrients and algal blooms. The GC ecosystems have been subject to a wide range of pollution sources. Nevertheless, the pollution levels remain relatively low to moderate depending on the location and contaminant type. Contamination hotspots are found i) for metals and metalloids, in sites where mining spills have occurred and ii) for nutrients and pesticides, in wetlands that receive discharges from intensive agricultural and shrimp farming. We also identified sites where harmful algal blooms (HABs) have been observed. However, numerous coastal environments in GC, affected by pollution sources and events have yet been poorly studied. More detailed, extensive and comprehensive studies on the pollution levels and trends, transfer and toxic effects are still needed.

The aim of this work was to determine the amounts of copper, zinc, cadmium and lead which enter the tanks of the maternity section of a Mexican commercial hatchery, and those that are discharged to the environment. The most important inputs of Cu were chemicals for water treatment and disease prevention, feeds and the metal dissolved in influent water. Suspended solids and feeds were the two most important inputs of Zn, and feeds and chemicals were the main sources of Pb and Cd. Most metal concentrations may be considered safe for shrimp culture, but the concentrations of Cd of three formulated diets were close or above safe levels. The annual 2013 output of this hatchery was approximately 1.3x109 post-larvae, and the estimated metals discharged to the environment by the maternity section were 351 g of Cu, 1,190 g of Zn and 1.35 and 0.02 g of Pb and Cd, respectively. The amounts of Pb and Cd are equivalent to those of the fertilizers spread on between 0.5 and 1.5 ha of the agricultural land of Sinaloa State.

This research was to evaluate the load and mobility of Cu in juvenile Litopenaeus vannamei after exposure (48 h) to sublethal concentration of nitrite (5.3 mg/L NO2−-N) at a salinity of 3.0 g/L. The hypothesis is that such exposure causes a Cu mobility in the tissues of shrimp. The Cu concentration in exoskeleton, hepatopancreas, muscle and hemolymph in the control group were 38.9 ± 3.0, 2478 ± 256, 11.9 ± 0.2 µg/g (dw) and 95.4 ± 19.1 µg/mL, while in the nitrite exposure, were 46.0 ± 0.1, 1546 ± 173, 11.3 ± 0.3 µg/g (dw) and 118.2 ± 10.5 µg/mL, respectively. Only hepatopancreas exhibited a significant (p

Mercury and selenium were assessed in Mustelus henlei, which is a carnivorous predatory shark that is important for the coastal communities of the northern Mexican Pacific (NMP). Sixty-two individuals were sampled; muscle and liver were isolated and analyzed by atomic absorption spectrophotometry. The mean Hg concentrations (wet weight) obtained for muscle (0.08 ± 0.10 μg g−1) and liver (0.09 ± 0.26 μg g−1) were below the allowed limits (

With the aim of determining the benefit from consumption of dolphinfish Coryphaena hippurus from La Paz and Cabo San Lucas in the southern area of the Gulf of California, mercury (Hg) and selenium (Se) were measured in liver and muscle of specimens (n = 362) collected between 2006 and 2013. Mean levels of Hg in muscle (0.61 μg g-1) and liver (0.42 μg g-1) of all individuals from La Paz were significantly higher (p < 0.05) than in fish from Cabo San Lucas; in the case of Se, mean concentrations in liver (1.54 μg g-1) of all individuals from La Paz were significantly higher (p < 0.05) than in fish from Cabo San Lucas. Hg levels in muscle were positively and significantly (p < 0.05) correlated with fork length and weight of fish; in liver, Hg and Se were significantly (p < 0.05) correlated with fork length and weight of specimens. Levels of Hg and Se in muscle and liver among years varied significantly (p < 0.05); although there was not a defined pattern of temporal fluctuations for both elements, the lowest Hg levels occurred in 2009 when surface water temperatures were the highest for the sampled years. With respect to the Se health benefit value (HBVSe), results were positive and above the unit in all cases; it implies that consumption of dolphinfish in the southern Gulf of California is beneficial.

Information on toxicity of nitrogen compounds for Litopenaeus vannamei in coastal ecosystems and culture under low salinity is scarce. Acute toxicity trials were conducted in L. vannamei to determine the single and combined effects of ammonia, nitrite and nitrate at a salinity of 3 g/L. The 96 h-LC50 was 29.0 mg/L for total ammonia nitrogen (TAN); 10.6 mg/L for nitrogen as nitrite (NO2−-N); and 900 mg/L for nitrogen as nitrate (NO3−-N). The joint effects of ammonia, nitrite and nitrate exposure were antagonistic at 24–72 h; and additive from 72 to 96 h. The proposed safety levels of single exposure to TAN, NO2−-N and NO3−-N for L. vannamei are 1.45, 0.53 and 45.0 mg/L, respectively. When in mixture, the proposed level of TAN/NO2−-N/NO3−-N is 0.05 TU (Toxicity Unit) corresponding to 0.48, 0.08 and 14.6 mg/L of TAN, NO2−-N and NO3−-N, respectively.

Aiming to detect possible impacts of human activities on the characteristics of the sediments of the Urias lagoon, which is a lagoonal system surrounded by the urban area of Mazatlan (NW Mexico), we determined the mean percentages of the main particle fractions, pH, CO 3 2– , organic carbon and total arsenic content in the surficial sediments of six different zones of the Urias lagoon. Sand was the dominant size fraction throughout the whole system. The highest organic matter and the lowest pH values were found in adjacent sites to industrial activities, especially to fish processing. Most arsenic concentrations were within the values of the natural local background (12.6-27.3 mg/kg), with the possible exception of sediments close to the industrial area, especially those nearby the fish processing plants, where the mean As (45.2 ± 9.3 mg/kg) exceeded the level which may have adverse effects on marine organisms (41.6 mg/kg). However, it is not excluded that such levels are results rather from the combined effect of the hydrodynamic and sediments dynamic of sediment associated to local enrichments background of the region.

This study evaluated low salinity effect on acute Hg toxicity and bioconcentration capacity in L. vannamei juveniles (8.4 ± 0.7 g), because this species is frequently exposed to hypo-osmotic environments in its natural habitat, and in farming ponds. Hg LC50 values were 1723, 1272, 983 and 536 μg L−1 at salinity of 5 ppt (parts per thousand); 2203, 1740, 1340 and 873 μg L−1 at 10 ppt; and 7013, 5693, 1759 and 1534 μg L−1 at 25 ppt for 24, 48, 72 and 96 h, respectively. After 96 h, acute Hg toxicity in shrimp was significantly higher in salinity of 5 ppt than in 25 ppt; likewise, Hg bioconcentration in shrimp exposed to different Hg treatments was statistically greater in salinity of 5 ppt than in 25 ppt. The chemical speciation calculated in experimental waters suggested that neutral chemical Hg species (HgCl2 and HgClOH) were the most bioavailable because their fractions (51–62%) increased when salinity decreased. Therefore, the inverse relationship between Hg toxicity and salinity was due to osmotic stress and the neutral chemical Hg species fractions that increased at lower salinities. Hg bioconcentration factors indicated that the higher Hg waterborne concentrations were the most saturated uptake and storage mechanisms in shrimp. Thus, Hg concentrations in organisms did not increase in proportion to waterborne Hg concentrations in the three salinities. These results support the hypothesis of an effect of low salinity on Hg toxicity and bioconcentration capacity in L. vannamei. The safe Hg concentrations 5.4, 8.7 and 15.3 μg L−1 were proposed for shrimp exposed to salinity of 5, 10 and 25 ppt, respectively. This information allows recognizing risky environments for both wild and cultured healthy growth of these shrimp, which can help decision makers on coastal management and shrimp pond managers to have better water quality.

With the aim of knowing annual variations of Hg concentrations in muscle and liver of blue marlin (Makaira nigricans) from the southern Gulf of California, fish were collected between 2005 and 2012 in three areas. In general, Hg levels were more elevated in liver than in muscle. Variations of Hg concentrations in muscle and liver among the studied years were not significant. Hg levels in muscle and liver increased significantly with length and weight of fish. In comparison to other studies, Hg levels in muscle and liver were lower. With respect to maximum permissible limits (1.0 µg g−1 wet weight) of Hg in Mexico, the average concentration (1.91 µg g−1 wet weight) in the edible portion (muscle) of blue marlin was over the legal limit; this issue is worth research efforts in relation to the rate of ingestion of this species and the co-occurrence of selenium in the edible portion.

The mercury content of mullets and black mojarras of Urías lagoon (NW Mexico) were determined every second month from November 2012 to September 2013, to determine differences related to season or to trophic levels. The Hg contents of the muscle were significantly higher in mojarras, confirming that Hg contents tend to increase along the food chain, while the levels in liver were higher in mullets, suggesting different Hg storage strategies of these species. In mullets, the content of muscles did not vary seasonally and was significantly lower than in the liver. In black mojarras there were no significant differences between muscle and liver, and the lowest mean values were in May in both tissues. Given the low Hg contents, both species are safe for human consumption, but care should be taken in traditional fishing communities.

The nitrite toxicity was estimated in juveniles of L. vannamei. The 24, 48, 72 and 96 h LC50 of nitrite-N on juveniles were 8.1, 7.9, 6.8 and 5.7 mg L−1 at 0.6 g L−1; 14.4, 9.6 8.3 and 7.0 mg L−1 at 1.0 g L−1; 19.4, 15.4, 13.4 and 12.4 mg L−1 at 2.0 g L−1 of salinity respectively. The tolerance of juveniles to nitrite decreased at 96 h of exposure by 18.6% and 54.0%, when salinity declined from 1.0 to 0.6 g L−1 and from 2.0 to 0.6 g L−1 respectively. The safe concentrations at salinities of 0.6, 1.0 and 2.0 g L−1 were 0.28, 0.35 and 0.62 mg L−1 nitrite-N respectively. The relationship between LC50 (mg L−1), salinity (S) (g L−1) and exposure time (T) (h) was LC50 = 8.4688 + 5.6764S – 0.0762T for salinities from 0.6 to 2.0 g L−1 and for exposure times from 24 to 96 h; the relationship between survival (%) and nitrite-N concentration (C) for salinity of 0.6–2.0 g L−1, nitrite-N concentrations of 0–40 mg L−1 and exposure times from 0 to 96 h was as follows: survival (%) = 0.8442 + 0.1909S – 0.0038T – 0.0277C + 0.0008ST + 0.0001CT–0.0029SC, and the tentative equation for predicting the 96-h LC50 to salinities from 0.6 to 35 g L−1 in L. vannamei juveniles (3.9–4.4 g) was 96-h LC50 = 0.2127 S2 + 1.558S + 5.9868. For nitrite toxicity, it is shown that a small change in salinity of waters from 2.0 to 0.6 g L−1 is more critical for L. vannamei than when wider differences in salinity occur in brackish and marine waters (15–35 g L−1).

Cellular and humoral responses were evaluated in Litopenaeus vannamei juveniles when exposed to malathion, endosulfan, and their mixture. Each experiment was performed in the hemolymph collected at each exposure time (5 and 96 h) in duplicate; total hemocyte count, coagulation time, hemocyanin concentration, phenoloxidase (PO) and superoxide dismutase (SOD) activities were quantified. Survival was not affected by pesticides applied individually and mixed. Clotting time did not show significant differences concerning increase of concentration percentage of the pesticides tested. In organisms exposed to the pesticide mixture, hemocyanin decreased at 5 h of exposure as the concentration increased. Only in the malathion experiment did exposed shrimp to 10 and 50% of the LC50-96 h show significantly (p

Shrimp of Farfantepenaeus californiensis (78 groups) and Litopenaeus stylirostris (14 groups) were caught in the northwestern fishing zones in Mexico during the 2014–2015 fishing season (September–February); both shrimp species have high commercial value. Muscle, hepatopancreas and exoskeleton were analyzed to determine their metal contents. For F. californiensis, the highest Cd, Pb and Zn contents were determined in specimens caught off the State of Baja California Sur (BCS) with 22.4 ± 8.9 (hepatopancreas), 2.83 ± 4.63 (muscle), and 748.5 ± 1567 (muscle) µg/g, in the regions off Mulege, Los Cabos and Los Cabos, respectively. For L. stylirostris, the fishing zone of Comundu (BCS) showed higher Cd (12.3 ± 11.5 µg/g), Cu (569.1 ± 646.5 µg/g) and Zn (549.7 ± 400.7 µg/g) contents; all values were determined in the hepatopancreas. Regarding the hazard quotient and total hazard quotient calculated in this study, the consumption of marine shrimp caught off NW Mexico does not represent a risk to human health (both

Shrimp farming in low salinities waters is an alternative to increasing production, and counteracting disease problems in brackish and marine waters. However, in low-salinity waters, toxicity of nitrogen compounds increases, and there is no available data of its acute toxicity in shrimp postlarvae. This study determined the acute toxicity of ammonia, nitrite and nitrate in Litopenaeus vannamei postlarvae in 1 and 3 g/L salinity, as well as the safety levels. The LC50 confirms that nitrite is more toxic than ammonia and nitrate in low salinity waters, and that its toxicity increases with a decrease in salinity. The safe levels estimated for salinities of 1 and 3 g/L were 0.54 and 0.81 mg/L for total ammonia–N, 0.17 and 0.25 mg/L for NO2–N, and 5.6 and 21.5 mg/L for NO3–N, respectively.

The reproductive cycle in oysters has been the subject of several studies in temperate zones. However, little information is available for tropical and subtropical species. This study describes the seasonal changes in the gonadic index (GI) of two species of oysters, Crassostrea iridescens and Crassostrea corteziensis, which differ markedly in their hàbitad and time of reproduction. Both oysters were sampled at 45 days intervals in the Northwest coast of Mexico between November 1989 and October 1990. Gonadal and somatic tissue per individual were dried for three days at 90°C, weighed and recorded. The gonadic index (GI) applied in this work was calculated from: GI = Wg/ws. Were WG is the average gonadal tissue dry weight, and Ws is the average somatic tissue dry weight. Seasonal variations in the gonadal state were evident for the two species. C.iridescens exhibited only a single maximum in the year, while C. corteziensis two peaks. This situation is presumably related to the contrastable environmental conditions that prevail in the sites where each species inhabit. El ciclo reproductivo en ostras ha sido objeto de varios estudios en zonas templada. Si embargo, poca información está disponible para especies tropicales y subtropicales. Este estudio describe los cambios estacionales en el ídice gonádico (GI) de dos especies de ostras, Crassostrea iridescens y Crassostrea corteziensis, la cuaes diferen signifcativamnte en su hábitat y tiempo de reproducción. Abas ostras fueron muestradas a intervalos de 45 días cada uno en la costa noroeste de México entre noviembre de 1989 y octubre de 1990. El tejido gonádico y somático por organismo fue secado por tes días a 90·c, pesados y registrados. El índice gonádico (GI) usado en este trabao fue calculado de: Gl= Wg/ws. Donde Wg es el peso seco promedio del tejido gonáico, y Ws el peso seco promedio del tejido somáico. Las varaciones estacionaes en el estado gonádico feron evidentes para las dos especies. C iridescens presentó sólo un máximo en el año, mientra que C. corteziensis presentó dos máximos. Posiblemente esta situación es relacionada con las contrastables condicones ambíentales que prevalecen donde cada especie habita.

Dos poblaciones de Crassostrea iridescens fueron muestreadas en la zona coster¡l de la ciudad de Mazatlan y en una zona libre de actividad antropogénica. Los bivalvos fueron colectados de febrero de 1992 a febrero de 1993. Concentraciones de Cd, Co, Cr, Cu, Fe, Mn, Ni y Zn fueron 4etenninados por espectrofotome!ria de absorción atóIJrica. Los valores medios anuales en la estación de muestreo de la ciudad de Mazatlán fueron mayores en Co, Cu, Fe, Mn, Ni y Zn que los determinados en la zona libre de actividad antropogénica; sin embargo, las diferencias no fueron significativas a! nivel de confianza del 95%. Una conclusión es que las descargas urbanas en la zona costera en frente de Mazatlán no tiene, o tiene, bajas concentraciones de metales pesados disueltos o particulados.

Survival, clotting time, hemocyanin concentrations, total hemocyte counts, phenoloxidase activity (PO), and superoxide dismutase (SOD) of Litopenaeus vannamei juveniles (11.7 g) exposed for periods of 5, 48, and 96 h to copper (Cu) concentrations equivalent to 0.008, 1, 10, and 50% of the LC50–96 h for L. vannamei postlarvae showed that survival was similar in all treatments, but clotting time was significantly higher with the two highest Cu concentrations. Hemocyanin had lower values after 5 h with the two highest Cu concentrations, but this difference disappeared with longer times of exposure. The mean number of hemocytes varied widely but with no clear relation to Cu concentration or period of exposure. Differences in PO were related to period of exposure but not to Cu concentrations. SOD mean values did not show significant variation throughout the experiment. Apart from an increase in clotting time, the overall mean values of the stress indicators used in this study show that this particular shrimp s...

The main objective of this study was to evaluate the total mercury content in hepatopancreas and edible muscle of the whiteleg shrimp Litopenaeus vannamei cultured along the NW coast of Mexico, and to evaluate the potential human health risk due to their consumption. Samples were obtained between May and June 2010 in 26 shrimp farms from the three most important shrimp-producing states of NW Mexico, and total Hg was analyzed after reduction with SnCl 2 in a mercury analyzer. The ranges of Hg concentrations of the hepatopancreas were 0.101 ± 0.03–0.184 ± 0.13 μg g −1 in Sonora, 0.077 ± 0.055–0.813 ± 0.363 μg g −1 in Sinaloa and 0.139 ± 0.037–0.791 ± 0.33 μg g −1 in Nayarit. In the muscle, values were from 0.078 ± 0.02 to 0.539 ± 0.09 μg g −1 in Sonora, 0.154 ± 0.03–0.861 ± 0.423 μg g −1 in Sinaloa and 0.121 ± 0.041–1.48 ± 0.44 μg g −1 in Nayarit. Considering the concentrations of Hg in the muscle and the national consumption rate, shrimp farmed in NW Mexico does not represent a risk for human health (HQ

Total mercury (Hg) concentrations were determined by atomic absorption spectrophotometry in muscles and liver of composite samples of Mugil cephalus and M. curema collected during November 2013 and in January, April, and July 2014 from the coastal lagoons Altata-Ensenada del Pabellón (AEP), Ceuta (CEU), and Teacapán-Agua Brava (TAG) of Sinaloa State. The mean Hg contents and information on local consumption were used to assess the possible risk caused by fish ingestion. Mean total mercury levels in the muscles ranged from 0.11 to 0.39 μg/g, while the range for liver was 0.12-3.91 μg/g. The mean Hg content of the liver was significantly (p 0.001) higher than that of the muscles only in samples collected from AEP. Although total Hg levels in the muscles were lower than the official permissible limit, the HQ values for methyl mercury calculated for the younger age classes of one fishing community were1, indicating a possible risk for some fishing communities of the Mexican Pacific coast.

In this work we compared the cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn) contents of muscle, liver and placenta of gestating females of the viviparous shark Rhizoprionodon longurio and of muscle, liver and umbilical cord of their respective embryos. The higher values of the essential Cu and Zn were in embryonic or embryo-related tissues (placenta and umbilical cord). Maternal muscle and liver had the highest values of Pb and Cd, respectively. There were significant direct correlations between the Zn and Cd concentrations of placenta and umbilical cord, as well as between maternal muscle and embryonic livers for Pb and Cd, but the relation between these tissues was inverse in the case of Zn. All correlations between the metal content of embryonic tissues and size of the embryos were negative, suggesting an inverse relation between the rate of mother-to-embryo metal transfer and embryonic growth.

The aim of this work was to survey the discharges of dissolved and particulate Cd, Cu, Fe, Mn, Pb and Zn of the eight main rivers of Sinaloa State to the Mexican coastal environment. Zn was the most abundant dissolved metal and Fe was the most abundant particulate (8.02-16.90 and 51.8-1,140.3 μg/L, respectively). Only particulate Mn had significantly (p = 0.028) higher values in summer-fall (rainy season), whereas the significantly (p = 0.036) higher values of dissolved Zn were observed in winter and spring. The highest annual total discharges to Sinaloa coastal waters were those of the rivers San Lorenzo and Piaxtla (2 × 10(3) m.t.) and the lowest those of rivers Baluarte and El Fuerte (349 and 119 m.t., respectively). Pb concentrations may become of concern, because they are higher than the value recommended for the welfare of aquatic communities of natural waters.

We determined total Hg and Se contents of hepatopancreas, exoskeleton, and muscle, and the Se:Hg molar ratios in the muscle of shrimps Farfantepenaeus californiensis and Litopenaeus stylirostris caught in NE Pacific Mexican waters. Total Hg mean values in muscle, hepatopancreas, and exoskeleton were 0.31 ± 0.26, 0.28 ± 0.29, and 0.24 ± 0.06 μg g-1, and 0.46 ± 0.46, 0.41 ± .034, and 0.24 ± 0.06 μg g-1 for F. californiensis and L. stylirostris, respectively. In all tissues, the mean concentrations of Se tended to be close to one order of magnitude higher than the respective Hg values. In F. californiensis, the hepatopancreas of the larger commercial size had significantly (p

During 2008, the pond surfacededicated to its semi-intensive culture in Mex-ico was 71,611 ha, which yielded close to 132,414 tons (CESA 2008).Among the wide variety of bioactive com-pounds used in shrimp culture, copper sulfateis commonly used in Mexican shrimp farms tocontrol macroalgae and bivalve growth (Lyle-Fritch et al. 2006).Copper is essential for normal growth anddevelopment (Li et al. 2007). However, mostMexican shrimp farms use low water exchangerates (Miranda et al. 2009), which may resultin high concentrations of dissolved Cu andin its accumulation in the farm sediments. Inthese cases, Cu may reach toxic levels andcause genotoxic effects (Guecheva et al. 2001;Arkhipchuk and Garanko 2005).In view of this possibility, this study aimedto assess DNA damage in the hemocytes ofjuvenile

This investigation sought to assess the biological responses to Pb along a simplified four-level food chain, from the primary producer, the microalgae Tetraselmis suecica, grown in a control medium with

The increasing order of the mean concentrations of Cd, Cu, and Zn in the tissues of Mugil cephalus of seven coastal lagoons of Sinaloa State (NW Mexico) was liver > gills > muscle, while for Pb it was gills > muscle ≥ liver. There were no differences between the mean concentrations of Cd and Pb of the three tissues determined in the samples of the seven lagoons and, although there were some significant differences, there was no indication of a latitude-related trend in the distribution of Cu and Zn: the Cu content of the muscle tended to be higher in the northern than in the southern lagoons, although in the case of the gills the highest and lowest mean values indicated an opposite trend, with the highest and lowest values in one southern and one northern lagoon. In the case of the liver, there were no differences and no indication of a regional trend. There were no differences in the mean Zn contents of muscle and gills; in the case of the liver, one of the lagoons of the central part of the state had a significantly higher value than one of the southern lagoons and all the rest had similar values. In addition, there was no clear indication of season-related differences in any of the three tissues. According to our results, the metal contents of the muscle of this species are not of concern for human health, since the allowable ingestion would be in the order of 0.9 kg/day.

El plomo y el cadmio pueden afectar la salud de los ecosistemas y de los consumidores de alimentos con alto contenido de estos metales, que son entre los mas ampliamente utilizados en diferentes actividades humanas y que ademas son entre los principales productos mineros de Mexico. La principal actividad de Sinaloa es la agricultura, por lo cual fertilizantes y plaguicidas son fuentes importantes de contaminacion por estos metales. En este articulo, despues de revisar las posibles fuentes naturales y las principales actividades humanas que aportan estos metales a las aguas marinas costeras del Estado de Sinaloa, se resumen los resultados de las investigaciones realizadas en las dos decadas mas recientes sobre el contenido de cadmio y plomo en los tejidos comestibles de varios organismos acuaticos de los cuerpos de agua costeros del Estado. En el caso del cadmio, las mayores concentraciones se encontraron en el sistema lagunar Altata-Ensenada del Pabellon, posiblemente a causa de las actividades agricolas del valle de Culiacan. Las concentraciones de plomo en los tejidos blandos de bivalvos parecen indicar una tendencia a la disminucion, posiblemente relacionado con el uso de gasolina sin plomo, aunque esto no coincide con los valores encontrados en el tejido comestible de camarones. Ademas, todos los valores de plomo son superiores a los valores que indican la presencia de impactos ambientales. En cuanto a posibles riesgos para los consumidores de pescados y mariscos, no se encontraron valores superiores a los niveles de riesgo en el musculo de crustaceos y peces, mientras que exceden los recomendados en el caso del contenido de cadmio de algunos bivalvos. Lead and cadmium in organisms of commercial importance in the coastal zone of Sinaloa, Mexico: 20 years of studies Lead and cadmium may affect the health of ecosystems and of the consumers of food items d with these metals, which are widely used in several human activities and are, in addition, among contaminate the most important products of Mexican mining activities. Agriculture is the main activity in the State of Sinaloa, and for this reason pesticides and fertilizers are important sources of contamination with both metals. In this article we revise the possible natural sources and the main human activities which may contribute these metals to the coastal waters of the Mexican State of Sinaloa, and summarize the results of the investigations of the latest two decades on the lead and cadmium contents of the edible tissues of several aquatic organisms of its coastal water bodies. The highest cadmium concentrations were those found in the Altata-Ensenada del Pabellon lagoonal system, possibly as a result of the agricultural activities of the Culiacan plains. Lead concentrations in bivalves seem to indicate a tendency to lower values, possibly due to the use of unleaded gasoline, although this does not coincide with the values found in shrimp muscles. In addition, all lead values are above the level indicating the presence of environmental impact. The cadmium content of some bivalve exceed the level of risk for human health, whereas the lead and cadmium contents of fish and crustacean edible tissues are below the level of concern.

The metal contents in tissues of fish species: M. cephalus, Diapterus sp., Scomberomorus sierra and Oreochromis aureus, were determined in order to evaluate if their consumption might become a health risk. The liver and gills of M. cephalus and Diapterus sp. had the highest values of Cu, Fe and Pb. In the muscle, there were no interspecific differences in the Cd, Cu and Pb contents (0.27-0.32, 0.96-1.30 and 2.12-2.80 microg/g dw, respectively). Cd and Pb may be of concern, since their mean contents in the edible muscle of the four species are higher than the limits of the European Community.

Survival of juvenile Litopenaeus vannamei exposed to five Cu concentrations ranging from 10 to 0.003% the 96 h median lethal concentration, which were supposed to be safe in the long term, was 0% after 1, 5 and 6 weeks for Cu concentrations of 3.512, 1.756 and 0.877 mg L − 1 (10, 5 and 2.5% the 96 h LC50). With these three concentrations there were severe time- and dose-dependent structural damages, such as necrosis, loss of regular structure and infiltration of hemocytes in the gill tissues, as well as atrophy, necrosis and irregular tubular structure in the hepatopancreas. After 9 weeks of exposure, only minor histological changes were observed with the two lower concentrations.