Microplastic ingestion by Atlantic chub mackerel (Scomber colias) in the Canary Islands coast.

In recent years, due to the increasing concerns about their negative impact on wildlife and possible toxicity to living organisms (including humans), microplastics have become the subject of intense investigations. In the ocean, microplastics can be easily ingested by numerous marine organisms because of their small size (<5 mm). The Northwest African upwelling system is an important fishery area, and the present study is the first one in the region to reveal the presence of microplastic particles in the digestive tract of Atlantic chub mackerel (Scomber colias). From the 120 examined fish gastrointestinal tracts, 78.3% contained some type of microplastics, 74.2% contained fibres, 17.5% plastic fragments, and 16.7% paint. More studies are needed on fish, but S. colias is a candidate for being a good indicator of microplastic contamination in the region.

Microplastic and tar pollution on three Canary Islands beaches: An annual study.

Marine debris accumulation was analyzed from three exposed beaches of the Canary Islands (Lambra, Famara and Las Canteras). Large microplastics (1-5mm), mesoplastics (5-25mm) and tar pollution were assessed twice a month for a year. There was great spatial and temporal variability in the Canary Island coastal pollution. Seasonal patterns differed at each location, marine debris concentration depended mainly of local-scale wind and wave conditions. The most polluted beach was Lambra, a remote beach infrequently visited. The types of debris found were mainly preproduction resin pellets, plastic fragments and tar, evidencing that pollution was not of local origin, but it cames from the open sea. The levels of pollution were similar to those of highly industrialized and contaminated regions. This study corroborates that the Canary Islands are an area of accumulation of microplastics and tar rafted from the North Atlantic Ocean by the southward flowing Canary Current.

Effects of inorganic mercury on the respiration and the swimming activity of shrimp larvae, Pandalus borealis.

In order to test the sensitivity of respiration (physiological and potential) to mercury (Hg) contamination, larval shrimp Pandalus borealis were exposed to inorganic Hg (0-160 ppb) for 27 h in the laboratory. Oxygen consumption rates (RO2), potential respiration (determined by respiratory electron transfer system activity, ETSA), protein content, and swimming activity for zoeae III and zoeae V stages were measured. For both zoeae stages, ETSA and protein content remained constant after 27 h exposure to 160 ppb Hg whereas RO2 and swimming activity decreased. This study revealed the impact of different Hg levels and different exposure times on RO2 of shrimp larvae. After 10 h exposure to 160 ppb Hg, the RO2 decreased by 43 and 49% in zoeae III and zoeae V stages, respectively. Exposure time of 27 h to 80 ppb Hg and higher, induced paralysis in nearly 100% larvae. Surprisingly, the paralysed larvae displayed almost 50% of the control's RO2. The results showed that Hg disturbs a part of the respiration process without modifying the maximum activity of the enzymes involved in the ETSA assay. Therefore, the ETSA assay can not be used as a sublethal bioanalytic probe to detect Hg in short-term exposures. The decline of the RO2/ETSA ratios reported here, indicates an inability of contaminated larvae to adapt their metabolism to physiological stress caused by Hg.

NADP-Isocitrate dehydrogenase from Pseudomonas nautica: kinetic constant determination and carbon limitation effects on the pool of intracellular substrates.

Variations of intracellular concentrations of isocitrate and NADP+ were measured throughout all growth phases of the marine bacterium Pseudomonas nautica. The intracellular isocitrate concentration tracked the intracellular protein concentration throughout all phases of growth. It rapidly increased in early exponential phase to a maximum and fell to nearly zero in parallel with pyruvate exhaustion in the culture medium. The intracellular NADP+ and protein concentrations increased in parallel during the exponential phase but were poorly correlated. Even after carbon exhaustion, the intracellular NADP+ concentration stayed high, as did protein levels. The results demonstrated that the intracellular isocitrate concentration, but not the intracellular NADP+ concentration, was affected by the carbon availability in the culture. They also suggest that, because of its variability, isocitrate, but not NADP+, plays the larger role in the control of the respiratory CO2 production rate (RCO2). From initial rate studies, bisubstrate Michaelis constants and the dissociation constant were determined for NADP+-specific isocitrate dehydrogenase (IDH) from P. nautica. These studies support the hypothesis that the mechanism of IDH's activity involves the ordered addition of the substrates, D-isocitrate and NADP+. Furthermore, the results support the use of a bisubstrate enzyme kinetic equation to model RCO2 in P. nautica.

The effects of a multimodal intervention with attention-deficit hyperactivity disorder children: a 9-month follow-up.

Using a double-blind, placebo design, we evaluated 96 attention-deficit hyperactivity disordered children for the effects of methylphenidate alone and in combination with behavioral parent training plus child self-control instruction. Seventy one of the children completed the treatment protocol. As reported previously, main effects were found for medication at posttest; however, there was no evidence of additive effects. Nine months after the termination of the behavioral interventions and the withdrawal of the stimulant medication, we found limited support for the hypothesis that the combined conditions would produce greater maintenance of treatment gains than would medication alone.

Additive effects of psychostimulants, parent training, and self-control therapy with ADHD children.

Utilizing a double-blind, placebo design, the effects of a high (0.8 mg/kg) and a low (0.4 mg/kg) dose of methylphenidate alone and in combination with behavioral parent training plus child self-control instruction were evaluated with 96 attention deficit hyperactivity disorder children. No evidence of the superiority of the combined conditions relative to medication alone was found. Some limited support was found for the hypothesis that the effects of a high dose of psychostimulant medication could be achieved by combining the low dose with a behavioral intervention. The importance of the latter finding is highlighted by the fact that both the benefits and untoward effects of the psychostimulants appear to increase with the dose.

High Nitrite Levels off Northern Peru: A Signal of Instability in the Marine Denitrification Rate.

During February and March 1985, nitrite levels along the northern (approximately 7 degrees to 10 degrees S) Peruvian coast were unusually high. These accumulations occurred in oxygen-deficient waters, suggesting intensified denitrification. In a shallow offshore nitrite maximum, concentrations were as high as 23 micromoles per liter (a record high). Causes for the unusual conditions may include a cold anomaly that followed the 1982-83 El Niño. The removal of combined nitrogen (approximately 3 to 10 trillion grams of nitrogen per year) within zones of new or enhanced denitrification observed between 7 degrees to 16 degrees S suggests a significant increase in oceanic denitrification.