A sponge of the Cliona viridis complex invades and excavates corals of the Gulf of Mannar, south-eastern India

Abstract

Sponges play an important role in biogenic coral-reef degradation, and it is acknowledged that elevated levels of sponge erosion commonly indicate poor health of coral-reef environments. An increase in the abundance of coral-excavating sponge has been reported from several locations, a development that may move coral-reef carbonate budgets increasingly towards net erosion. The role of coral-excavating sponges on Indian reefs has not been studied in as much detail as elsewhere. The present paper describes the observation of a coral-excavating sponge from the family Clionaidae. This brown, endolithic sponge formed a coherent thin layer over the surface of the substratum and had a spicule complement of tylostyles and spirasters. Therefore it belongs to the Cliona viridis species complex, which, as a group, is widely distributed and commonly displays high bioerosion rates. Accurate identification will require molecular studies and is presently deferred. The sponge was found excavating only Turbinaria mesenterina colonies of Gulf of Mannar. Within the surveyed area of 60m2, 38.58% of T. mesenterina colonies were found to be invaded by the sponge. Targeted long-term studies across a larger spatial scale are warranted to assess the role of this sponge in more detail, and whether its abundance changes over time.

The coral-killing red sponge Clathria (Microciona) aceratoobtusa (Porifera: Demosponigiae) invades various coral communities of Gulf of Mannar Marine National Park, southeast India

“…Corals in the Gulf of Mannar were affected significantly by coral bleaching in 2016 and are under significant stress (Edward et al 2018). Hence, we may interpret the widespread occurrence of overgrowth of the coral excavating sponges as a consequence of the most recent bleaching event occurring in the Gulf of Mannar as evident from recent studies (Ashok et al 2018;Edward et al 2018;Raj et al 2018). Sponges have been reported to be comparatively more capable of 146-(175 ± 1.5)-160.5 × 4 µm 143-(234 ± 1)-188.5 × 1.8 µm 9.2-(9.9 ± 1.2)-10.8 µm 30.5-(47.25 ± 1)-64 µm Benzoni et al 2008 97.5-(160.4 ± 14.6)-308.6 × 5 µm 42.5-(57.4 ± 11)-87.5 × 2.5-(3 ± 0.8)-3.7 µm 137.5-(172.2 ± 40)-242.5 × 2 µm 9-(9.5 ± 3)-10.6 µm 20-(48 ± 10.5)-75 µm thriving in changing climatic conditions and have better regeneration capacity (Miller et al 2010;Runzel 2016).…”

“…Turbinaria was the coral genus more covered by the sponge, but it was not the only; in 2008, on the contrary, Benzoni et al found C. (M.) aceratoobtusa to be highly selective for Porites lutea in Yemen; in Mannar, the plate-like life form of this coral might have favoured the sponge overgrowth over it, even if a clear specificity is not demonstrable, considering that infected and not infected colonies may have the same pattern of growth (Table III) In the recent period, records about sponges threating coral reefs are numerous (Table I). Since (Coles & Bolick 2007;Benzoni et al 2008) and to spread out across Indo-Pacific Ocean, enlarging their area of distribution (Ávila & Carballo 2009;Shi et al 2012;de Voogd et al 2013;Rossi et al 2015); in particular, in the most recent period, there is an increasing number of records of T. hoshinota spreading throughout the Indo Pacific negatively affecting coral reefs (Ashok et al 2018;Raj et al 2018;Yang et al 2018;Fromont et al 2019).…”

“…Though coral reefs have been widely studied around the words, the interaction between corals and sponges is not well understood (Peyrot-Clausade et al 1995;Carreiro-Silva & McClanahan 2001;Zahir et al 2002;Ashok et al 2019). There are several reports on the sponges of the family Clionaidae (Marulanda-Gómez et al 2017;Ashok et al 2018), Suberitidae (Rützler 1971;Raj et al 2018;Fromont et al 2019), Chalinidae (Rossi et al 2015) and Poeciloscleridae (Coles & Bolick 2007;Benzoni et al 2008) (Table I) which can excavate or smother corals. Poecilosclerida is the largest order in the phylum Porifera with vast diversity (Bergquist & Formont 1988;Hajdu et al 1994).…”

Opportunistic spongivore fishes in a reef of Gulf of Mannar, India

“…Many studies report the proliferation of sponges in GoM after the 2016 bleaching episode (Raj et al 2018a(Raj et al , 2019Ashok et al 2018;GOMBRT Report 2021) which makes way for opportunistic sponge feeders (Raj et al 2019). Prevalence of coral colonies affected by sponges increased from 13.11 to 17.19% between 2018 and 2021 in the nearby Koswari Island (GOMBRT Report 2021).…”

Report on an outbreak of coral-killing sponge Clathria (Microciona) aceratoobtusa in an unprotected reef of the Gulf of Mannar, India

“…Schönberg & Ortiz 2008. Climate change has worsened this competition as the heat-stressed corals are often overpowered by sponges (Ashok et al 2018.…”