Threats to a Temperate Kelp Forest Species, Ecklonia cava, through Tropical Fish Herbivory Associated with Sea Surface Warming in the East China Sea

Abstract

Kelp forests in Korean waters, mainly consisting of Ecklonia cava, provide ecologically and economically important ecosystems. However, they are severely threatened by increasing sea surface temperature (SST). In 2023, an unusually high SST was observed in the northern East China Sea, where the average SST from August to November 2023 was found to be 1.1 °C higher than the average SST during the same period over the last two decades. Our photo images and videos reveal increasing feeding on E. cava populations by tropical herbivore rabbitfish (Siganus canaliculatus, Siganus fuscescens) associated with the impact of increasing SST. Given the fall reproductive peak of E. cava population, increased herbivory by tropical rabbitfish could have a significant adverse impact on the composition of temperate kelp forests.