Coral recruitment is impacted by the presence of a sponge community

Abstract

As coral cover has declined on Caribbean reefs, space has become occupied by other benthic taxa, including sponges, which may affect the recruitment of new corals, thereby affecting the ability of reefs to recover to coral-dominated states. Sponges may inhibit coral recruitment by preempting potential recruitment space, overgrowing recruits, or through allelopathy. This study examined coral recruitment across six coral reef sites surrounding St. Thomas, US Virgin Islands, and the impact of one species of sponge and the sponge community as a whole on coral recruitment. To test the effect of a single species of sponge on coral recruitment, fragments of living or non-living Aplysina cauliformis were attached to terracotta recruitment tiles and deployed at all six sites, along with unoccupied tiles as controls. At two of the sites, a community-level experiment consisted of deploying recruitment tiles in 1 m 2 plots that were either cleared of the entire sponge community or control plots where no sponges were removed. Recruitment rates showed a consistent difference among sites over multiple years and experiments. Results of the species-specific experiment showed that the proximity of live or dead A. cauliformis did not affect coral recruitment. However, results of the community-level experiment found greater coral recruitment rates in plots cleared of sponges, suggesting that the presence of the sponge community negatively affected coral recruitment. This study is one of the first to experimentally test and find a significant impact of sponges on coral recruitment, and highlights the need for additional research in this area.

Effects of the Stony Coral Tissue Loss Disease Outbreak on Coral Communities and the Benthic Composition of Cozumel Reefs

“…Coral mortality resulting from SCTLD is clearly consistent with the side-in model of reef degradation that invokes perturbations causing coral mortality as the primary factor favoring the rapid colonization of available space by non-accretional organisms (Precht et al, 2020). Furthermore, it may also prevent coral recruitment and thus the recovery of populations that are highly affected by SCTLD (e.g., Birrell et al, 2005;Arnold et al, 2010;Brandt et al, 2019;Tebbett and Bellwood, 2019); a scenario that may worsen if stressors become more frequent and/or severe. In addition, the loss of highly susceptible coral species may also trigger an abrupt decrease in the accretion (growth) of the reef framework (Estrada-Saldívar et al, 2020), as most of the highly susceptible species to SCTLD are also important reef builders.…”

Impacts of Hurricanes Irma and Maria on Coral Reef Sponge Communities in St. Thomas, U.S. Virgin Islands

“…Macroalgae and EAC are the major benthic constituents on shallow reefs in St. Thomas and likely occupy space or produce allelochemicals that inhibit invertebrate larval recruitment (Ritson-Williams et al 2009;Paul et al 2011). In a 2015-2016 study, coral recruitment on these reefs was low relative to earlier studies in the USVI (Brandt et al 2019). Historically, one of the main effects of hurricanes on coral reefs was to provide open space for invertebrate, particularly coral, recruitment (Hughes and Connell 1999).…”

Sponge community (Porifera) in coral reef ecosystem in Sabang, Aceh Province, Indonesia

“…On the other hand, when it comes to high diversity regions, consisting of hundreds of species, detailed/specific types of morphology are more representative. Previous studies have claimed that sponges are the main competitors with corals in reef habitats, affecting the growth, recruitment, and mortality of corals (Chadwick and Morrow 2011;Chaves-Fonnegra and Zea 2011;Brandt et al 2019). However, the result of this study indicates that the interaction between the sponge variables (cover and species richness) and corals was not statistically significant.…”

“…Sponges compete with corals for space to grow; when sponges are abundant, the stable state of coral-dominated reefs may be compromised. In this situation, sponges can kill corals by overgrowing their colonies, and by hindering coral recruitment as a result of occupying potential recruitment space (González-Rivero et al 2011;Turicchia et al 2018;Brandt et al 2019). Considering these issues, it is necessary in poorly studied areas, to develop an understanding of the interaction between sponges and corals, as well as with their substrates.…”