Anthropopause positively influenced Red Sea Clownfish (Amphiprion bicinctus) populations but not the host sea anemone (Actiniaria spp.) in Eilat, Israel

The anthropopause, when humans were restricted to their homes because of the COVID-19 pandemic, allowed wildlife to reoccupy areas that were previously used by humans. The coral reef at Eilat has been deteriorating for the past 50-years, and includes the sea anemones, that have symbiotic associations with clownfish. The lack of appropriate niches in the form of sea anemones has also resulted in a drastic decline in the endemic Red Sea Clownfish (RSCF). We surveyed 7500 m of the reef to quantify the number of sea anemones and RSCF on five tourist frequented beaches. The pre-pandemic survey was conducted in 2019 and the post-pandemic in 2021. Overall, the average number of sea anemone per sample plot was 0.23/100 m (range 0–6); and there was no significant difference between the years. However, the mean number of RSCF per 100 m was 0.15 (range 0–6); and there were significant differences between the years with on average double the individuals in 2021. We found a significant positive correlation between the number of anemones and RSCF recorded on transects. In both years, 50 RSCF were in sea anemones; 39 (78 %) adults and 11 (22 %) juveniles. All adults and two juveniles populated the bulb/digitiform-tentacle sea anemones Entacmaea quadricolor, while 9 juveniles were in the leathery anemone Heteractis crispa. Our study demonstrates that the COVID-19 closures for the past two years were conducive to the RSCF and resulted in an increase in their numbers.