Quantification of chemical and mechanical bioerosion rates of six Caribbean excavating sponge species found on the coral reefs of Curaçao

Abstract

Excavating sponges are among the most important macro-eroders of carbonate substrates in marine systems. Their capacity to remove substantial amounts of limestone makes these animals significant players that can unbalance the reef carbonate budget of tropical coral reefs. Nevertheless, excavating sponges are currently rarely incorporated in standardized surveys and experimental work is often restricted to a few species. Here were provide chemical and mechanical bioerosion rates for the six excavating sponge species most commonly found on the shallow reef of Curaçao (southern Caribbean): Cliona caribbaea, C. aprica, C. delitrix, C. amplicavata, Siphonodictyon brevitubulatum and Suberea flavolivescens. Chemical, mechanical and total bioerosion rates were estimated based on various experimental approaches applied to sponge infested limestone cores. Conventional standing incubation techniques were shown to strongly influence the chemical dissolution signal. Final rates, based on the change in alkalinity of the incubation water, declined significantly as a function of incubation time. This effect was mitigated by the use of a flow-through incubation system. Additionally, we found that mechanically removed carbonate fragments collected in the flow-through chamber (1 h) as well as a long-term collection method (1 wk) generally yielded comparable estimates for the capacity of these sponges to mechanically remove substratum. Observed interspecific variation could evidently be linked to the adopted boring strategy (i.e. gallery-forming, cavity-forming or network-working) and presence or absence of symbiotic zooxanthellae. Notably, a clear diurnal pattern was found only in species that harbour a dense photosymbiotic community. In these species chemical erosion was substantially higher during the day. Overall, the sum of individually acquired chemical and mechanical erosion using flow-through incubations was comparable to rates obtained gravimetrically. Such consistency is a first in this field of research. These findings support the much needed confirmation that, depending on the scientific demand, the different approaches presented here can be implemented concurrently as standardized methods.

Extreme spatial heterogeneity in carbonate accretion potential on a Caribbean fringing reef linked to local human disturbance gradients

“…only sand). The contribution of sponges to gross bioerosion was determined using species‐specific erosion rates for chemical and mechanical erosion per unit of infested substrate as defined by De Bakker et al (). Cover for all excavating sponges was measured within 50 cm on both sides of the transect line (10 m 2 in total).…”

Bleaching-driven reef community shifts drive pulses of increased reef sediment generation

“…This knowledge gap has significant implications for ecosystem and coastal management because of the critical importance of reef-derived sediment for sustaining shorelines and reef islands [10], especially in localities where sediment generation is dominated by a restricted suite of taxa [11]. Reefal sediments derive largely from the following sources: (i) the biological erosion (or bioerosion) of reef framework, most commonly by specific species of fish (especially parrotfish), sea urchins and endolithic taxa (including excavating sponges) [12][13][14]; (ii) from direct inputs by carbonate secreting taxa, such as molluscs and foraminifera [15], and (iii) through the growth and breakdown of calcareous red (e.g. crustose coralline algae) and green algae (e.g.…”

Coral recruitment is impacted by the presence of a sponge community

“…Coral reefs once dominated by living coral are now more likely dominated by macroalgae and other benthic organisms, particularly sponges, which can represent significant diversity and biomass on Caribbean reefs (Wilkinson and Cheshire 1990;Gochfeld et al 2007;Maliao et al 2008;Norström et al 2009). As a result of a multitude of stressors affecting coral reef communities and changing reef community structure, competition between reef-building corals and sponges is becoming increasingly common worldwide (Chadwick and Morrow 2011;Bell et al 2013; Some sponges, such as those belonging to the genera Cliona and Aka, opportunistically colonize corals and use chemical and mechanical means to excavate the coral skeleton, resulting in direct mortality of coral tissue and bioerosion of the reef structure (Sullivan et al 1983;Rützler 2002;Chaves-Fonnegra and Zea 2007;González-Rivero et al 2016;de Bakker et al 2018). The enhanced presence of sponges on reefs may affect not only the organisms currently on the reef, but also the ability of coral larvae to recruit and settle (Aronson et al 2002;Vermeij 2006).…”