Preliminary study of marine sponges (Porifera) in the littoral of Spermonde Archipelago, Indonesia

Previous ecological studies show higher sponge diversity in the Spermonde Archipelago, SW Sulawesi, Indonesia, compared to the World Porifera Database. This study aims to provide an updated checklist of sponges of the Spermonde Archipelago, focusing particularly on the littoral area. Systematic sampling was executed through several observations, with roving techniques, e.g., snorkeling and SCUBA diving. In situ photographs of living sponges were taken using an underwater digital camera. Some specimens were collected and stored at the Naturalis Biodiversity Center, Leiden. Fragments of samples were analyzed using light and scanning electron microscopy. A total of 27 sponges (Calcarea and Demospongiae) were catalogued from the littoral area of the Spermonde Archipelago. Some of these are new records for the Sulawesi Sea/Makassar Strait marine ecoregion, including four potentially novel taxa. Preliminary morphological descriptions of all examined samples are presented. This study highlights the sponge assemblage flourishing in a shallow area characterized by a paucity of live corals and a predominant environment by macroalgae, rocks, and rubble.

Two centuries of sponges (phylum Porifera) taxonomic studies in Indonesia (1820-2021): checklist and bibliography

Sponges in Indonesia have been studied since the 19th century during several historical expeditions and international collaborations. Hundreds of new species were reported from various locations, e.g., Ambon, Ternate, Sulawesi, Aru, and Kei Islands. This study aimed to create a sponge (Porifera: Calcarea, Demospongiae, Hexactinellida, and Homoscleromorpha) species checklist from Indonesia based on World Porifera Database. With a total of 731 species, our checklist comprises approximately 45 species of Calcarea, 566 species of Demospongiae, 115 species of Hexactinellida, and five species of Homoscleromorpha. The number of species are recorded from 12 marine ecoregions across the Indonesian Archipelago and freshwater habitats (Spongillida) between 1820-2021. The species composition indicates higher regional endemism or poorly studied since no other report after the original description. However, several marine ecoregions of Indonesia remain highly overlooked (e.g., Northeast Sulawesi, Papua, Southern Java, Western Sumatra), including freshwater habitats. Therefore, a taxonomic biodiversity baseline study, particularly on Porifera, is necessary to better understand the aquatic and marine biodiversity in the Indonesia Archipelago.

The complete mitochondrial genome of the invasive cyanobacteriosponge Terpios hoshinota (Demospongiae, Suberitida, Suberitidae)

The cyanobacteriosponge Terpios hoshinota occurs on tropical reefs throughout the Indo-Pacific. The species encrusts live coral, and other benthos, and is considered a pest species that can threaten the health and productivity of locally native benthic communities on coral reefs. Here we assemble a complete mitochondrial genome to aid further research into the range expansion of this species. The circular genome was 20,504 bp in length and encoded 14 protein-coding genes, two ribosomal RNA (rRNA) genes, and 25 transfer RNA (tRNA) genes. A phylogenetic analysis based on the concatenated sequences of 14 protein-coding genes of 12 members of the subclass Heteroscleromorpha including the newly sequenced T. hoshinota, suggests further taxonomic revisions within the order Suberitida may be warranted.

Population genetics and demography of the coral-killing cyanobacteriosponge, Terpios hoshinota, in the Indo-West Pacific

The first occurrence of the cyanobacteriosponge Terpios hoshinota was reported from coral reefs in Guam in 1973, but was only formally described in 1993. Since then, the invasive behavior of this encrusting, coral-killing sponge has been observed in many coral reefs in the West Pacific. From 2015, its occurrence has expanded westward to the Indian Ocean. Although many studies have investigated the morphology, ecology, and symbiotic cyanobacteria of this sponge, little is known of its population genetics and demography. In this study, a mitochondrial cytochrome oxidase I (COI) fragment and nuclear ribosomal internal transcribed spacer 2 (ITS2) were sequenced to reveal the genetic variation of T. hoshinota collected from 11 marine ecoregions throughout the Indo-West Pacific. Both of the statistical parsimony networks based on the COI and nuclear ITS2 were dominated by a common haplotype. Pairwise F ST and Isolation-by-distance by Mantel test of ITS2 showed moderate gene flow existed among most populations in the marine ecoregions of West Pacific, Coral Triangle, and Eastern Indian Ocean, but with a restricted gene flow between these regions and Maldives in the Central Indian Ocean. Demographic analyses of most T. hoshinota populations were consistent with the mutation-drift equilibrium, except for the Sulawesi Sea and Maldives, which showed bottlenecks following recent expansion. Our results suggest that while long-range dispersal might explain the capability of T. hoshinota to spread in the IWP, stable population demography might account for the long-term persistence of T. hoshinota outbreaks on local reefs.