Occurrence of amphidromous atyid shrimps in a small stream on the Boso Peninsula, Japan

The present study aimed to examine the relationship between stream temperature and the occurrence of amphidromous atyid shrimps as a basis for inferring the impacts of global warming on shrimp populations and communities. We investigated the occurrence of amphidromous atyid shrimps from spring 2017 to summer 2019 in the Banda River, a small stream located at near the southern tip of the Boso Peninsula, Japan. Five amphidromous atyids, including Caridina leucosticta, C. multidentata, C. serratirostris, C. typus, and Paratya compressa, were collected. The number of shrimps collected showed a distinct seasonal variation, being high in summer and low in winter. A positive correlation was found between the stream temperature and the number of shrimps collected. A notable reduction in shrimp occurrence was observed at temperatures below 15°C, particularly for C. typus, followed by C. serratirostris. Additionally, interspecific variability in shrimp occurrence was observed, likely due to interspecific differences in larval performance under changing ocean conditions. Global warming and climate change may affect the overwintering success and larval performance of atyids, potentially altering their population dynamics and community structure.