Temporal and spatial variability in the isotopic composition of sea urchins along Portuguese coast.

Paracentrotus lividus is a sea urchin widely distributed throughout Mediterranean basin and Atlantic coast, highly appreciated for its gonads. It is broadly distributed along the Portuguese coast and its exploitation has potential to grow. Nevertheless, fluctuations on nutritional composition and sensory traits of P. lividus according to each habitat and seasonality are still little understood. Stable isotopes analysis has been recognised as a powerful tool for exploring environmental-ecological-biological processes in aquatic systems. It is also useful to give indications on how to improve available diets for the aquaculture of this species, contributing to a sustainable rearing. Herein, such technique was used to assess temporal and spatial differences in isotopic composition of P. lividus' gonads and intestines and to evaluate its application as a management tool for the identification of the most suitable locations and periods of the year to collect organisms with high quality gonads. Sampling campaigns were carried out between 2019 and 2020 in five rocky shores along the Portuguese coast (Viana do Castelo, Figueira da Foz, Peniche, Sines and Guia). Three rock pools were selected in each shore, and five specimens were collected per pool. The gonadosomatic index (GSI, %) was calculated and carbon and nitrogen elemental and isotopic composition were determined in gonads and intestine using isotope ratio mass spectrometry. Significant spatial and temporal fluctuations were registered among urchins collected along Portuguese coast. Such variations may be associated with latitudinal gradients along the coast and variations of environmental and ecological conditions within each area, especially those affecting algal biomass, on which urchins primarily feed. More research must be pursued to maximise the use of stable isotopes analysis as a management tool for supporting sustainable exploitation of natural stocks or even to contribute to nutritional studies with new diets for sea urchin production that consider the feeding of these animals in the wild.

First characterization of the ecotoxicity of paraffin particles: assessment of biochemical effects in the marine polychaete Hediste diversicolor.

Plastics are a widespread environmental problem, particularly in the form of small particles or fragments (microplastics). With the purpose of gradually replacing the use of plastics in cosmetic products (primary microplastics), the use of paraffin in microspheres has recently been applied. Paraffin waxes are composed by organic molecules usually derived from petroleum, thus assumed to be chemically and biologically inert, having a lower (eco)toxicity and residence time compared with plastic particles. However, the low ecotoxicity of paraffin waxes may be somewhat questionable, because some paraffin constituents can be absorbed and catabolized, thus exerting biological effects. The main objective of this study was to understand the potential toxic effects of paraffin microparticles on key physiological processes of the polychaete Hediste diversicolor. To attain this objective, this work assessed the acute and chronic effects of three densities (5, 20, and 80 mg L-1) of four size ranges of paraffin particles (from 100 to 1200 µm) on this epibenthic organism. Although paraffin wax can be generically considered innocuous, the present study was able to demonstrate a significant inhibition in the activity of acetylcholinesterase in acutely exposed organisms and an increase in the activity of glutathione peroxidase, catalase, and glutathione S-transferase under some specific scenarios.

In situ evaluation of the microbial adhesion on a hard acrylic resin and a soft liner used in removable prostheses.

PURPOSE: The purpose of this study was to evaluate, in situ, the initial adhesion of microorganisms to as well as the surface roughness and chemical composition of ProBase Hot (Ivoclar Vivadent), a hard acrylic resin, and Vertex Soft (Vertex-Dental), an acrylic-based soft liner, used in removable dental prostheses. MATERIALS AND METHODS: Equal sized disks of ProBase Hot and Vertex Soft were prepared and polished according to the recommended procedures for clinical use. Two disks of each material were mounted in individual oral splints and exposed for 4 hours to the oral cavities of 15 participants. The microbial adhesion to each material's surface was measured with the pour plate technique using rich and selective growth media. Statistical analysis was performed using the Student t test. Scanning electron microscopy and chemical composition analyses obtained through electron probe radiographic microanalysis of sample disks also were performed. RESULTS: In comparison to ProBase Hot, Vertex Soft presented higher microbial adhesion, namely regarding total aerobes, anaerobes, streptococci, and mutans streptococci (P < .05). Also, Vertex Soft presented higher surface roughness. Differences in the chemical composition of the two materials also were found. CONCLUSIONS: The Vertex Soft liner has been found to be more susceptible to microbial adhesion than the acrylic resin ProBase Hot, probably due to its greater surface roughness. The application of Vertex Soft liner to a hard denture base may lead to a higher risk of oral and systemic infections for patients, highlighting a greater need for plaque control, especially for more susceptible individuals.