University of Hawaiʻi at Mānoa

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    The Efficacy of Vermicompost in Optimizing Water Quality and Plankton Production in Cemented Aquaculture Ponds

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    Aquaculture is vital for global food security, yet cemented ponds often face challenges related to poor water quality and low natural productivity owing to the absence of bottom soil. This study investigates the use of vermicompost, a nutrient-rich organic fertilizer, to enhance water quality and increase plankton production in aquaculture systems. The experimental design involved four cemented tanks: a control (Without fertilizer) and three treatments with varying vermicompost application rates (5,000, 10,000, and 15,000 kg/ha/yr). Assessments of water quality parameters—including dissolved oxygen, pH, and ammonia levels—were conducted, along with sampling of plankton abundance and species composition. Results indicated improvements in water quality, particularly in DO levels, with the highest rates observed in the treatment receiving 15,000 kg/ha/yr vermicompost. Additionally, plankton diversity (Diversity index) and abundance increased with higher vermicompost applications, notably enhancing phytoplankton groups, particularly Chlorophyta, while maintaining stable zooplankton populations. These findings suggest that vermicompost is a promising sustainable alternative to chemical fertilizers, effectively improving water quality and fostering a healthier aquatic ecosystem, thereby supporting aquaculture productivity. Future research should explore the long-term effects of vermicompost in various aquaculture settings

    Japanese land records. Mariana Island District, Saipan Island.

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    Supplementation of Yellow River carp diet with lutein and ferrous fumarate: Growth performance, digestive enzyme activity, skin pigmentation, and intestinal microbiota

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    In this study, the effect of the diet with lutein and ferrous fumarate on Yellow River carp (Cyprinus carpio) was studied, aiming to evaluate skin pigmentation, intestinal digestive enzymes, intestinal microbial diversity, and growth performance. Three experimental diets, including a control group, a lutein group (150mg/kg lutein), and a lutein and ferrous fumarate mixture group (150mg/kg lutein and 100mg/kg ferrous fumarate), were designed. The carp (N=135; 25.0±2.0g) were fed with experimental diets for 42 days. The results showed that the intestosomatic index (ISI) and viscerosomatic index (VSI) of the carp fed with lutein and ferrous fumarate were increased, accompanied by significant changes in body color, with the higher value of blue (b), color difference (ΔE) and chroma (Ch) compared with control group (P Actinobacteria and Flavobacterium was significantly increased in the carp fed with the mixture group compared with the control group. In conclusion, the addition of lutein and ferrous fumarate to the feed can change the skin pigmentation and intestinal microbial composition of Yellow River carp, thereby enhancing the coloring effect and digestive function of the fish. These findings provide valuable insights for optimizing feed formulation and aquaculture management, which can contribute to the improvement of the quality and farming efficiency of Yellow River carp

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