Snails associated with the coral-killing sponge Terpios hoshinota in Okinawa Island, Japan

Hideyuki Yamashiro,Hiroaki Fukumori,Yurika Hirose,Siti Nurul Aini

doi:10.1038/s41598-021-00185-x

Hideyuki Yamashiro, Hiroaki Fukumori + Show 2 more

Open Access

https://doi.org/10.1038/s41598-021-00185-x

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Abstract

Terpios hoshinota is a thin encrusting sponge that overgrows live scleractinian corals and it is linked to coral loss in many reefs. However, our knowledge of the species associated with this sponge species is poor. During a periodical survey of T. hoshinota in 2020, we found tiny snails crawling on the sponge in the subtropical waters around Okinawa Island, Japan. We observed egg capsules inside the sponge tissue and veliger larvae released from the egg capsules. Molecular analyses of both the snails and veliger larvae (cytochrome oxidase I, COI) showed that they were identical and belonged to Joculator sp. (family Cerithiopsidae). There was no direct observation of predation on the sponge by this snail; however, to the best of our knowledge, this is the first report on a close association between a snail and the sponge T. hoshinota.

Highlights

Coral reefs are valuable ecosystems that supply numerous services to humans, and they are home to numerous coral-associated organisms, which are linked to the high levels of biodiversity observed in these ecosystems
Snails crawling on the T. hoshinota sponge, which were overgrowing the branching coral Montipora digitata, were obtained from two sites around Okinawa Island (Nakijin and Odo)
The material was inspected in the marine laboratory and live veliger larvae were collected from a sponge from Nakijin together with sponge larvae using a cup with nylon net

Summary

Introduction

Coral reefs are valuable ecosystems that supply numerous services to humans, and they are home to numerous coral-associated organisms, which are linked to the high levels of biodiversity observed in these ecosystems. Sponges are predicted to be ‘winners’ in future coral reefs and, together with macroalgae, they could replace corals under a changing e nvironment[7]. It is becoming increasingly likely that some sponges could replace corals to create sponge-dominated reefs. Changes from coral- to sponge-dominated reefs are reported in Caribbean, Atlantic, Indo-Pacific, and Pacific reefs. Terpios hoshinota is a thin (< 1 mm thick), encrusting demosponge with numerous symbiotic cyanobacteria in its tissues It grows rapidly on live coral at the rate of 1 mm per day (linear progression rate of 11.5–23.0 mm month–1) in tropical s ites[11,12,25,26]. The aim of this study was to describe the snails found for the first time on T. hoshinota, their sites of occurrence on sponges, and to examine their relationship with T. hoshinota, and identify the snail using molecular DNA barcoding techniques (Figs. 1, 2, 3, 4)

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