Abstract The global warming-induced rise in seawater temperatures has reduced survival rates and sustainability in coastal aquaculture. In this study, we aimed to perform rearing experiments to assess the seedling survival rate and harvest size of kuruma shrimp ( Penaeus japonicus ), an important species for seafood production in Japan, under high-temperature conditions. In addition, we evaluated the reduction in aquaculture-suitable days predicted for future temperature scenarios. Our results demonstrate that kuruma shrimp seedling exposure to 36 °C for 1 day and 34 °C for 10 days reduced the survival rates to 50% and 55–60%, respectively. Furthermore, under the Representative Concentration Pathways 8.5 scenario, the number of aquaculture-suitable days is projected to decrease by 6 and 60 days (median) by 2050 and 2100, respectively, highlighting the significant challenges posed by climate change to the sustainability of shrimp aquaculture. The results of this study underscore the urgent need for adaptive measures to address climate change to ensure kuruma shrimp aquaculture sustainability.

Abstract When groundwater rich in dissolved ferrous ion [Fe(II)] is pumped from wells, iron-oxidizing bacteria can grow and clog the well’s screens, pipes, and pumps, making it difficult for the pump to operate fully. In this study, we employed 16S rRNA gene amplicon sequencing to investigate the types of microorganisms that adhere to a well’s pipes and identified the main bacterial species involved in the microbial mat and clogging process. Deposits from the sampling equipment were collected daily for seven consecutive days and subjected to 16S rRNA gene amplicon sequencing, revealing the continuous presence of a Gallionella sp. We speculated that this species was the initial factor in the microbial mat’s formation and hypothesized that Gallionella forms long thread-like "stalks” and attaches to the pipe’s inner surface; as the stalks accumulate and become intertwined, they create a mat. As the mat continues to grow without detaching from the pipe’s inner surface even under rapid water flow, the pipe eventually clogs.

Abstract We compared the diet of larval Japanese sardine Sardinops melanostictus between the western and eastern areas of the Japanese coastal waters of the Sea of Japan in March–May 2019–2022. Standard lengths of larvae examined for gut contents ranged from 5 to 17 mm; in both areas, the main prey items found in the gut were copepod nauplii and copepodites. However, food incidence was low in eastern areas, and mean prey width differed between the areas. Larvae in the western area in March and April fed on copepods as large as the largest in ambient waters, such as the copepodites of Paracalanus spp. and the nauplii of large Calanoida, whereas the main food for larvae in the eastern area in May was small copepod nauplii such as those of Oithona spp. These differences suggest that the prey environment in the western area in March and April is more favorable for sardine larvae than in the eastern area in May. Understanding such spatial patterns in prey availability and larval diets would be essential for elucidating the survival and recruitment processes of Japanese sardine in the Sea of Japan.