Transition of neritic and oceanic tintinnid communities in the Northern Gulf of Alaska

Abstract Tintinnids play a key role in marine microbial food webs and are broadly categorized into neritic and oceanic species. While tintinnids have been well studied in the western subarctic gyre of the North Pacific, their occurrence in the eastern subarctic gyre, particularly in the Gulf of Alaska, remains poorly understood. To address this, we investigated the tintinnid community within Prince William Sound and along the Seward Line in the Northern Gulf of Alaska during 12–19 September 2024. Our findings revealed the spatial patterns of neritic and oceanic tintinnid species in this zone. Compared with the western subarctic gyre, oceanic tintinnids in the Northern Gulf of Alaska showed similar dominant oceanic species, suggesting a shared species pool. Twelve common species exhibited specific horizontal and vertical preferences. Different dominant species were found at two nearshore stations: neritic Stenosemella sp. dominated at GAK-1, while oceanic Acanthostomella norvegica was more abundant at PWS-2. Cross-shelf variation in lorica oral diameter correlated inversely with Chl a, reflecting links between morphology and productivity. The occurrence of warm-water Dictyocysta sp. at ~ 57.8°N indicated the possible influence of subtropical water. These findings could serve as baseline data for the eastern subarctic gyre in the context of global change monitoring.