Chicken Liver Sponges Thrive in Polluted Costa Brava Harbour, Hinting at Bioremediation Potential

Researchers from the Spanish National Research Council transplanted five native sponge species into Marina Palamós on Spain’s Costa Brava to test their resilience in a polluted port. After 15 months of monitoring, only the chicken liver sponge (*Chondrosia reniformis*) persisted, with almost 92 % of the specimens surviving the contaminated water. The surviving individuals also reproduced asexually, increasing the colony from 24 to 40 specimens.

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The team collected sponges from a site about 30 km south of the harbour and installed them in the port, conducting underwater dives every 20–64 days to photograph and inspect health. Red starfish began colonising the surviving sponges, suggesting that the organisms may create habitat for other marine life. The chicken liver sponge is a high-microbial-abundance species that converts ammonium to nitrate, a trait researchers suspect helps it tolerate pollutants.

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Marine biologist Andreu Santín Muriel (University of Porto) noted that sponges have provided ecosystem services for at least 600 million years and argue they have been under-funded compared with coral restoration. He emphasized their potential for bioremediation despite limited public attention.

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Doctoral researcher David Amptmeijer (Helmholtz-Zentrum Hereon) cautioned that the results are site-specific and may not translate to harbours elsewhere, such as those in Maine, underscoring the need for broader studies.

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Lead researcher Manuel Maldonado highlighted the sponge’s diverse microbiome as a likely factor in its robustness and announced plans to extend monitoring beyond the summer and to explore combined sponge-oyster projects.

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Escarré described the high survival rate as unexpected for the team. Santín Muriel asserted that sponges’ long evolutionary history equips them with inherent resilience, positioning them as promising tools for habitat recovery and pollutant filtration.

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• “So we tested different Spanish species with the idea of finding some that could survive in a harbour environment,” — Manuel Maldonado

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• “It was a surprise for all of us,” — Escarré. Some, of the Earth’s oldest ecosystem engineers

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• “This study shows what we in the sea sponge community have known for years,” — Andreu Santín Muriel

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