Antipredator defenses of bloom-forming cyanobacteria species maximize their fitness but can reduce carbon and energy transfer efficiency to higher trophic levels, making them a key regulator of plankton communities in eutrophic waters. We investigated the grazing responses of the tropical cladoceran Moina micrura to different strains of the cyanobacteria Microcystis aeruginosa and Planktothrix isothrix, using a good food source (green algae Mono-raphidium capricornutum) as a control. Both Microcystis strains grow as unicellular and are microcystins producers; however, this cyanotoxin was not detected on the filamentous Planktothrix strains. M. micrura ingested all cyanobacteria at reduced rates compared to single diets with Monoraphidium. In mixed diets, food type had a significant effect on grazing responses, which differed interspecifically. Planktothrix was more grazed than Microcystis strains. Feeding selectivity on Monoraphidium was negatively affected by the increase of cyanobacteria in the diet. We observed varied responses across treatments, ranging from feeding inhibition to different degrees of tolerance toward cyanobacteria, particularly in non-microcystin-producing species. We also highlight the selectivity of small tropical cladocerans, a pattern that is not yet well documented. These findings emphasize that studies incorporating phyto- and zooplankton with a history of coexistence can provide more meaningful insights into natural ecosystem dynamics.

Microplastics (MPs) are solid microscopic fragments of plastic materials and are widely distributed in water, soil, air, and biota. MPs cause damage and accumulate in animals such as aquatic organisms, including edible fish, and reach human systems through the food chain (biomagnification). MPs have been found in human blood and lungs, and food exposure requires particular priority. The comprehension of mechanisms by which MPs enter the human body is still scarce. Thus, considering the indirect exposure of food to MPs and the potential to affect human health, this chapter will present current knowledge about the main MP characteristics, levels, and the ways they affect human health through food, especially seafood consumption. <!----> <!----> <!----> <!---->

The 2019 oil spill in Guanabara Bay, among the most significant in Brazilian history, has reinforced how persistently PAHs move through food webs significant to artisanal fishing communities. However, low-cost tools for tracking these contaminants in key sentinel species, such as bivalves, remain scarce, especially for matrices that resist conventional extraction protocols. In this sense, this study developed a dual-extraction method combining Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) and solid-phase extraction (SPE) clean-up to quantify multiple PAHs in Perna perna mussels sampled from Guanabara Bay, Brazil overcoming matrix interference to deliver faster, cheaper and more actionable contamination data for a subsistence food source. A total of 210 mussels were collected across four artisanal fishing communities in Guanabara Bay, a socially and ecologically critical estuary, 2 to 3 years after the spill. The method achieved strong linearity ( r ² > 0.995) and acceptable recovery (51.1–109.0%) for 15 of 18 target PAHs. Only five compounds were quantified above the Limit of Quantification, with special focus on benzo(a)pyrene, with a high-molecular-weight and predominantly pyrogenic signature pointing to a diffuse, combustion-derived background rather than a lingering trace of the spill. This finding highlights the value of the proposed method, of a practical, affordable tool that is extensible to oil-impacted tropical estuaries worldwide for routine PAH biomonitoring.