Post-Tsunami monitoring of the introduced Banggai cardinalfish (Pterapogon kauderni) population in Palu Bay

Abstract

Post-disaster recovery of marine ecosystems and species is still poorly understood. The Banggai cardinalfish (Pterapogon kauderni) is an ornamental fish endemic to the Banggai Archipelago and a few nearby islands. Classified as Endangered in the IUCN Red List, this fish has limited protected status under Indonesian law. Introduced to several sites in Palu Bay in the early 2000’s, two populations had become established by 2006. Until the triple disaster (earthquake, tsunami, liquefaction) in September 2018, these populations were used for research and education as well as the aquarium trade. The tsunami devastated habitat and microhabitat at the Mamboro site; a census in 2019 found 10 surviving juvenile Banggai cardinalfish in one sea anemone. Monitoring in June 2021 revealed signs of ecosystem recovery, especially seagrass. Despite limited microhabitat with few corals and a lack of Diadema sea urchins, there was a substantial increase in Banggai cardinalfish abundance with all life stages present. New recruits were observed in sea anemones and upside-down jellyfish (Cassiopea sp.). These sites present a natural laboratory for P. kauderni population and post-tsunami ecosystem recovery. Lessons learned can be used to inform conservation management of depleted P. kauderni populations in the endemic range of this endangered fish.