Short Communication: Diversity of sponges associated in seagrass meadows at coastal area of Pacitan District, East Java, Indonesia

Setiawan E, Chodiantoro MR, Insany GF, Subagio IB, Dewi NK, Muzaki FK. 2021. Short Communication: Diversity of sponges associated in seagrass meadows at coastal area of Pacitan District, East Java, Indonesia. Biodiversitas 22: 3105-3112. Sponges are sessile organisms and aquatic filter feeders that play an important role in marine ecosystems. They are also secondary metabolite compounds that exhibit promising novel properties. Indonesia has been categorized as a hot spot for sponge diversity. Despite this fact, some Indonesian coastal areas, especially in the southern area of East Java, have not yet been comprehensively explored to understand its diversity and potential value. For this reason, we investigated species richness of sponges associated with seagrass meadows in the southern coastal area of Pacitan District, in East Java. Seagrass meadows are important coastal areas that have been recognized as buffer zones for sustainable marine conservation because it provides safe shelter and acts as a nursery for many fishes and other invertebrates, including sponges. We identified 16 genera out of 12 families from two selected beaches in Pacitan. Boring sponges belonging to the Clionaidea family were dominant in those areas, covering more than 20 percent of the total recorded specimens. Moreover, conspicuous boring sponges in this study can be used for further environment alert since this group plays a vital role and negatively impacts destroying the calcium carbonate of marine organisms.

Relationships between boring sponge assemblages and the availability of dead coral substrate on Mexican Pacific coral reefs

Boring sponges are an important component of bioeroder assemblages in tropical coral reefs. They are considered as a potential threat for coral reef health, and the increase of dead corals is expected to promote their abundance. The relationship between the availability of dead coral substrata and the development of boring sponge assemblages was evaluated during El Niño 2015–16 at five reefs from Zihuatanejo, Guerrero, Mexico. Environment and substrate quality were assessed. Overall, environment conditions remained normal in relation to previous studies in the area. Only water temperature showed unusually high records at all sites and coincided with bleaching and mortality of corals, possibly caused by the effects of the El Niño event. Abundance of boring sponges in dead corals and coral rubble was lower than during previous studies. Although sponge abundance was not directly related to cover of both dead corals and coral rubble, cover of dead corals showed a high correlation with the variation in the structure of sponge assemblages across sites.Cliona vermiferadominated sponge assemblages at all sites, and its abundance was high under conditions of high cover of live corals and low cover of bleached corals. Since overall sponge abundance responded in a similar way, these results suggest that boring sponge assemblages dominated byC. vermiferaare enhanced by conditions favourable for corals. Our results imply that El Niño events in the Mexican Pacific are not likely to cause immediate population outbreaks of boring sponges.

Range expansion of a fouling species indirectly impacts local species interactions

We investigated how recent changes in the distribution and abundance of a fouling organism affected the strength of interactions between a commercially important foundation species and a common predator. Increases in the abundance of boring sponges that bioerode the calcified shells of oysters and other shelled organisms have been attributed to increased salinization of estuarine ecosystems. We tested the hypothesis that fouling by boring sponges will change the interaction strength between oysters and a common predator (stone crabs). We generated five oyster density treatments crossed with two sponge treatments (sponge and no sponge). We contrasted the interaction strength between stone crabs and fouled and non-fouled oysters by comparing the parameters of fitted functional response curves based on Rogers random predation model. We found that fouled oysters suffered higher predation from stone crabs, and that the increased predation risk stemmed from a reduction in the handling time needed to consume the fouled oysters. These findings highlight the importance of understanding the effects of abiotic changes on both the composition of ecological communities, and on the strengths of direct and indirect interactions among species. Global climate change is altering local ecosystems in complex ways, and the success of restoration, management, and mitigation strategies for important species requires a better appreciation for how these effects cascade through ecosystems.

New species of excavating sponges (Porifera: Demospongiae) on coral reefs from the Mexican Pacific Ocean

Three new species of coral reef boring sponges were found in remote coral reefs from Revillagigedo Island, an archipelago that is 386 km from the continent.Cliona medinaesp. nov. is a sponge with orange-yellow papillae characterized by short almost straight spirasters.Cliona tropicalissp. nov., is a yellow papillate sponge with a spicule complement similar to the species included in theCliona viridiscomplex. However, the new species differs from the rest of the species mainly in its external morphology and by differences in the size and shape of spicules.Thoosa purpureasp. nov. is characterized by its purple colour, and the spicular complement formed by tylostyles, two amphiaster categories, bi- tri- and tetra-radiate oxyasters and smooth or microspined centrotylote oxeas. In addition,Cliothosa tylostrongylatasp. nov. is also described from coral reefs from the southern Mexican Pacific Ocean. This is a light red species, with tylostyles and tylostrongyles as megascleres and ramose and nodulose amphiasters as microscleres. The four species were found exclusively excavating skeletons of live or dead corals of the genusPocillopora. This study increases the number of boring sponges known from the Mexican Pacific Ocean to 22 species and it is the first study on marine sponge fauna from the Revillagigedo archipelago.