A Tropic and Subtropics 2oC Difference Affecting the Spatiotemporal Distribution of Small Demersal Fish Assemblages - Central Western Taiwan Example

Abstract

Abstract Two OR3 research vessel cruises were conducted at seven nearshore sites from north to south in the western coastal waters off Taiwan in May (late spring) and November (late autumn) 2019 in order to gain insights into the 2oC difference in the tropical-subtropical fish fauna. Totally, 37 families, 72 genera, and 99 taxas were recorded for the 1,809 fishes. Three fish assemblages, the North, South, and Fall-Zhuoshui River (ZRf) groups, were identified as eurythermal, stenothermal, and croaker communities. Their dominants, in rank order, were Tarphops oligolepis, Liachirus melanospilosa, Ostorhinchus fasciatus, and Trachinocephalus myops for the Northern eurythermal group, Arnoglossus tenuis, Eubleekeria splendens, and O. pleuron for the Southern stenothermal group, and Johnius taiwanensis, Chrysochir aureus, and Pennahia macrocephalus for the croaker-ZRf group. Their distribution was markedly correlated with the bottom water temperature, seafloor grain size and concentration of suspended solids. The influence of a 2oC difference on the tropic and subtropics demersal fish that could foresee the climate change of rising temperatures shaping fish communities. A flatfish, Liachirus melanospilos was distributed northward by 0.5oN and is suggested to be considered as an ecological indicator of the tropicalization of subtropical marine ecosystems in the future.