Sponges in tropical coral reefs harness photosynthesis to generate roughly 11% of the ecosystem's total productivity, according to research from the University of Amsterdam's Institute for Biodiversity and Ecosystem Dynamics (IBED) published in Functional Ecology.
The study reveals that sponges function as hybrid organisms. While they traditionally filter-feed on other organisms to obtain nutrients, many sponges also contain photosynthetic algae or cyanobacteria living within their tissues. This symbiotic relationship allows sponges to produce energy directly from sunlight, similar to plants.
Researchers at IBED quantified this contribution by measuring the photosynthetic output of sponges across tropical reef environments. The finding that sponges account for roughly one-ninth of reef productivity reshapes understanding of how these ecosystems generate and distribute energy. Coral reefs depend on multiple productive organisms working together—corals themselves, zooxanthellae algae, and now sponges emerge as significant contributors.
The photosynthetic capability of sponges has ecological ramifications beyond coral reefs. Sponges appear in diverse marine settings, from shallow coastal waters to deep ocean environments, suggesting this sun-powered strategy could enhance productivity in other ecosystems where these organisms thrive.
This dual feeding strategy represents an evolutionary adaptation. Sponges can simultaneously filter organic particles from water while capturing solar energy through their symbiotic partners. During periods when food particles are scarce, photosynthesis provides an alternative energy source. During productive periods, filter-feeding supplements photosynthetic nutrition.
The research underscores how overlooked organisms play vital roles in ecosystem function. Sponges, often considered passive filter-feeders, actively contribute to reef energy production. Understanding these contributions becomes increasingly important as coral reefs face mounting pressure from climate change, ocean acidification,