Sun-powered sponges generate 11% of productivity in tropical coral reefs

A study published on July 1, 2026, by researchers at the University of Amsterdam reveals that sponges contribute to 11% of the productivity in tropical coral reefs. This groundbreaking research, featured in Functional Ecology, highlights the role of sponges in photosynthesis, challenging the perception of their ecological function.

Understanding Sponge Productivity in Coral Reefs

Traditionally regarded as filter feeders, sponges have now been found to possess photosynthetic capabilities. Michelle Achlatis, a benthic ecologist and lead researcher, explains, "We call them a textbook example of filter feeding and suspension feeding because they are not only filtering, but also absorbing all sorts of edible material from the seawater." This ability allows them to supplement their energy needs through sunlight.

Achlatis and her team assessed 24 common sponge species around Curaçao, focusing on eight species to measure their contribution at the ecosystem level. They discovered that half of the species studied were significant producers of organic compounds, accounting for 11% of gross primary productivity. This finding was unexpected, as Achlatis initially believed that only a smaller fraction of sponges would exhibit photosynthetic traits.

The Role of Symbiotic Microbes in Photosynthesis

Sponges rely on symbiotic microbes that perform photosynthesis, using sunlight to create food and release oxygen. This relationship enhances the sponge's ability to thrive in nutrient-poor environments. Jasper de Goeij, an associate professor at IBED, noted, "Together with their symbiotic microbes, sponges can photosynthesize, just like a plant." This multifaceted role of sponges emphasizes the need for re-evaluating their contributions to marine ecosystems.

The implications of this research extend beyond coral reefs. Achlatis argues that sponge-rich ecosystems should be included in carbon sequestration assessments. "People should be aware that sponges are not only recycling carbon and nutrients that they find on the reef, they also have their own ways of making them, even if they're small amounts, comparatively," she stated.

Wider Implications for Marine Ecosystems

While this study focuses on tropical regions, the findings suggest that sponges in similar ecosystems may share these photosynthetic characteristics. The research calls for a broader understanding of sponges, which do not fit neatly into the traditional classifications of plants and animals. Achlatis emphasizes the need for more comprehensive studies that consider the ecological roles of sponges in various marine environments.

• Sponges contribute 11% to coral reef productivity.
• The study assessed 24 sponge species around Curaçao.
• Half of the tested species were found to be photosynthetic.

As marine ecosystems face increasing threats from climate change, understanding the diverse roles of organisms like sponges becomes crucial for conservation efforts and ecosystem management.