Larval production of giant river prawn Macrobrachium rosenbergii and water quality in a commercial hatchery using a closed recirculation system (RAS) with artificial seawater, considering water used during 240 days (E1) and freshly prepared water (E2), was evaluated. An average of 100 larvae L⁻¹ (zoea I) was stocked in four tanks of 1000 L; in both treatments, they were fed Artemia and egg custard. Survival and larval stage index (LSI) were estimated, every 5 days. Temperature, salinity and pH were monitored daily, while nitrogen compounds and ions were monitored every 5 days. Spearman and Pearson correlations were performed between larval survival and ion concentration and Mg/Ca ratio. Final larval survival differed significantly between treatments E1 (32% ± 7.5%) and E2 (50% ± 7.5%). Larval cycle lasted 23 and 21 days for E1 and E2 respectively. LSI did not differ significantly between the treatments. Water quality parameters were appropriate for the specie, although nitrate (NO₃) increased to 500 mg L⁻¹ in E1 treatment. Reused water showed a depletion of magnesium (~half of it) when compared to freshly prepared water. Magnesium and potassium concentrations decreased in both treatments during E1 cycle. A positive correlation was found between larval survival and magnesium (r = 0.54) and potassium (r = 0.78) in E1, but the same was not observed in E2. Mg/Ca ratio in E1 showed an average of 1.2, whereas, in E2, the average ratio was 2.1. The depletion of magnesium and potassium ions, through the continuous use of the water in RAS, could affect the survival of larvae.

This study investigates the trophic interactions and As and Cd transfer along seven marine ecosystems in Peru. Five of these ecosystems are driven by aquaculture of the Peruvian scallop Argopecten purpuratus. A southward increased gradient of δ¹⁵N was observed among the three examined regions along the Peruvian coast. The stable isotope analysis in R (SIAR)‐stable isotope mixing models helped to clarify the feeding ecology of A. purpuratus and its important predators (e.g., Bursa ventricosa, Romaleon setosum). The food items of A. purpuratus can be ranked in decreasing order of importance: seston > sediment > particulate organic matter (POM) > brackish‐and‐fresh water POM input, while A. purpuratus itself was found to be the main prey item for predators. The highest trophic magnification factors (TMFs) were 1.46 and 1.07 for As and Cd, respectively, and were both found at the location in front of the Illescas Reserve Zone (northern Peru). Metal biomagnification and non‐biomagnification effects were found in the Peruvian marine food webs, but A. purpuratus always fitted the trophic metal magnification or bio‐dilution regression model as intermediate consumer and/or prey. The TMFs and linear metal relationships implied that As contamination is a serious concern in marine ecosystems in Peru.

Se realizaron pruebas de toxicidad con elutriados de sedimentos marinos provenientes de las bahías Los Chimus, Tortugas y Casma, en Perú, empleando las microalgas marinas Isochrysis galbana y Nannochloropsis oceanica. Las muestras de sedimento marino se colectaron en los meses de marzo y agosto de 2016. Estas pruebas de toxicidad se realizaron siguiendo los protocolos estandarizados, mediante pruebas estáticas a 96 h de exposición. Previamente, se determinó la sensibilidad de ambas cepas de microalgas al sulfato de cobre (CuSO4·5H2O) como sustancia de referencia. La Concentración de Inhibición media (CI50) obtenida en este ensayo demostró que I. galbana fue más sensible que N. oceanica. Los elutriados de los sedimentos marinos, provenientes de las zonas de estudio, presentaron diferentes niveles de toxicidad, tales como “no toxicidad” (CI50 = 90% - 100%), “moderada toxicidad” (CI50 = 59% - 81%) y “alta toxicidad” (CI50 < 59%) al emplear la microalga I. galbana; mientras que, para el caso de N. oceanica solo se presentó el de “no toxicidad” (CI50 = 90% - 100%) frente a las mismas muestras de elutriados de sedimentos. Estas pruebas de toxicidad demuestran que la microalga I. galbana detecta diferentes niveles de toxicidad, por lo que se podría emplear para evaluar ambientalmente muestras de sedimento marino como complemento a pruebas químicas, ya que no se discrimina el origen de la toxicidad.

The Peruvian anchoveta fishmeal industry generates wastewater (pumping water) during the transport of fish from boats to production plants. This study represents the first evaluation in Peru of Moringa oleifera (MOD) and chitosan as bio-coagulants specifically applied to the coagulation–flocculation treatment of pumping water, providing a direct comparative analysis against traditional ferric sulfate under identical experimental conditions. The effluent is characterized by an extreme turbidity of 5,683 NTU, total suspended solids (TSS) at 3359.3 mg/L, and oils and fats at 451.3 mg/L, and it was treated using optimized doses: 4.0 g/L for MOD and 0.2 g/L for chitosan. The results demonstrate that natural alternatives achieve turbidity removal exceeding 97.5%, matching the efficiency of inorganic salts. Notably, chitosan achieved 88.59% TSS removal with no significant statistical difference (p > 0.05 according to the Kruskal–Wallis test) from ferric sulfate, while MOD excelled in oil reduction (37.84%) compared with chitosan. Beyond treatment efficiency, this research fills a gap in circular economy data by identifying that the resulting sludge, containing >4% non-toxic nitrogen, is suitable for composting. These findings establish a new renewable benchmark for the Peruvian fishing industry’s transition toward sustainable, zero-waste water management.