Fine-grained sediment production by endolithic sponges on Caribbean coral reefs

Abstract

Endolithic sponges are key players in carbonate cycling on coral reef systems. While their bioerosion of reef framework is relatively well studied, their role in biogenic sediment generation is poorly understood. In this study, the sedimentary attributes and production rates of eight Caribbean endolithic sponge species were characterized. The findings revealed notable species-specific variations in sediment production rates (range: 1.0–6.3 kg CaCO₃ m⁻² yr⁻¹), alongside consistency in sediment characteristics (modal sizes ranging from 39 to 48 μm). The species-specific rates were used to explore reef-scale variations in sponge-derived sediment generation across 50 reef sites in the Mexican Caribbean. Significant between-site variability was observed, with estimated annual sediment production ranging from < 0.01 to 0.84 kg m⁻² of reef. Production was primarily driven by sponge abundance, with discernible spatial variations in the contributions of different species, which could be related to variability in local environmental conditions. The rapidity at which these sediment producers can utilize dead coral substrates, coupled with their positive response to the changing marine environment, highlights the growing importance of these sponges in modern degraded Caribbean reef systems.