Microplastics (MPLs) are contaminants of emerging concern (CECs) ubiquitous in aquatic environments, which can be bioaccumulated along the food chain. In this study, the accumulation of polyethylene (PE), polystyrene (PS) and polyethylene terephthalate (PET) microplastics (MPLs) of sizes below 63 μm was assessed in Mediterranean mussels (Mytilus galloprovincialis spp). Moreover, the potential of mussels to uptake and bioaccumulate other organic contaminants, such as triclosan (TCS) and per- and polyfluoroalkyl substances (PFASs), was evaluated with and without the presence of MPLs. Then, the modulation of MPLs in the human bioaccessibility of co-contaminants was assessed by in vitro assays that simulated the human digestion process. Exposure experiments were carried out in 15 L marine microcosms. The bioaccumulation and bioaccessibility of PE, PS, PET, and co-contaminants were assessed by means of liquid chromatography -size exclusion chromatography-coupled to high-resolution mass spectrometry (LC(SEC)-HRMS). Our outcomes confirm that MPL bioaccumulation in filter-feeding organisms is a function of MPL chemical composition and particle sizes. Finally, despite the lower accumulation and bioaccumulation of PFASs in the presence of MPLs, the bioaccessibility assays revealed that PFASs bioaccessibility was favoured in the presence of MPLs. Since part of the bioaccumulated PFASs are adsorbed onto MPL surfaces by hydrophobic and electrostatic interactions, these interactions easily change with the pH during digestion, and the PFASs bioaccessibility increases.

The increasing demand for healthy aquatic products has contributed to the rapid growth of aquaculture. Despite the many progresses, over the years, in aquaculture production, animal welfare and reduction of the stress induced by captivity remain a challenge in this sector, and overcoming it is fundamental to improve animal growth performance and resilience to environmental threats (e.g., disease outbreaks and/or climate change impacts). To address this challenge, aquafeeds biofortified with natural ingredients with functional properties, such as macroalgae, have emerged as a promising strategy to enhance fish immunity. The present study aimed at evaluating the potential of Laminaria digitata to improve juvenile gilthead seabream (Sparus aurata) physiological status and resilience, through the modulation of immunomodulatory and antioxidant responses. To explore this hypothesis, four independent treatments were carried out in which fish were fed with different experimental aquafeeds: control feed and biofortified feeds with 1.5%, 3% and 6% of whole L. digitata (incorporated as a dried and powdered ingredient). Fish (n=9) were collected from each treatment upon 30 and 60 days of biofortification in order to assess animal growth and condition indexes, haematological parameters, innate humoral parameters (antiprotease (AP) activity, peroxidase (POD) activity and immunoglobulin M (IgM)) and oxidative stress biomarkers (lipid peroxidation (LPO), catalase (CAT) activity, glutathione S-transferase (GST) activity, superoxide dismutase (SOD) activity and total antioxidant capacity (T-AOC)). Significant differences (α = 0.05) between treatments in biomarker responses were tested through a nested-design ANOVA, followed by Tukey HSD multiple comparisons. Pearson correlations between the different endpoints were also explored. Results indicate that a dietary inclusion of 1.5% L. digitata is the most effective biofortification dose, significantly improving antioxidant responses of S. aurata, by increasing levels of CAT, GST and T-AOC, along with the reduction in LPO levels. Additionally, the inclusion of 1.5% L. digitata enhances immunity by increasing the levels of IgM and POD, while maintaining the growth performance and condition indices of the fish. These findings underscore the potential utilization of L. digitata as a functional feed ingredient in aquaculture with relevant immune and antioxidant attributes.

The increasing frequency and duration of marine heatwaves (MHWs) due to climate change pose severe threats to aquaculture, causing drastic physiological and growth impairments in farmed fish, undermining their resilience against additional environmental pressures. To ensure sustainable production that meets the global seafood demand and animal welfare standards, cost-effective and eco-friendly strategies are urgently needed. This study explored the efficacy of the red macroalga Asparagopsis taxiformis on juvenile white seabream Diplodus sargus reared under optimal conditions and upon exposure to a MHW. Fish were fed with four experimental diets (0%, 1.5%, 3% or 6% of dried powdered A. taxiformis) for a prophylactic period of 30 days (T30) and subsequently exposed to a Mediterranean category II MHW for 15 days (T53). Biometric data and samples were collected at T30, T53 and T61 (8 days post-MHW recovery), to assess performance indicators, biomarker responses and histopathological alterations. Results showed that A. taxiformis supplementation improved catalase and glutathione S-transferase activities and reduced lipid peroxidation promoted by the MHW, particularly in fish biofortified with 1.5% inclusion level. No histopathological alterations were observed after 30 days. Additionally, fish biofortified with 1.5% A. taxiformis exhibited increased citrate synthase activity and fish supplemented with 1.5% and 3% showed improved digestive enzyme activities (e.g., pepsin and trypsin activities). Overall, the present findings pointed to 1.5% inclusion as the optimal dosage for aquafeeds biofortification with A. taxiformis, and confirmed that this seaweed species is a promising cost-effective ingredient with functional properties and great potential for usage in a climate-smart context.

This study is aimed at the development of a fermented cashew nut cheese alternative supplemented with Chondrus crispus and Porphyra sp. and the evaluation of the impact of seaweed supplementation through analysis of physicochemical, microbiological, and organoleptic properties of the developed food products. The total lipid content decreased with the supplementation with seaweeds. Crude protein content also slightly decreased, while elemental analysis showed that mineral and trace element (Ca, K, Mg, Na, Fe, I, Se, and Zn) content increased when C. crispus was added to the paste. The analyses of color and textural (TPA) attributes showed that these were significantly influenced by adding seaweeds to the cashew paste. Generally, the microbiological results comply with the different European guidelines for assessing the microbiological safety of ready-to-eat foods placed on the market, except for aerobic mesophilic bacteria and marine agar counts. Flash Profile analysis allowed for distinguishing sample attributes, showing an increased flavor complexity of the plant-based cheese alternatives supplemented with seaweeds. Overall, the study indicates that seaweed enrichment mainly influenced the physicochemical and sensory characteristics of plant-based cheese alternatives.