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Cleaning up our planet’s dirty ports could one day get a boost from a creature with a very dirty nickname. Meet the chicken kidney sponge, a true ecosystem engineer that could use its filter-feeding power to clean up degraded habitats in and around busy ports. The process is detailed in a study published today in the journal Frontiers in marine sciences.
Filter feeders for dirty water
While necessary to boost the global economy, ports are very dirty. Oil, garbage, toxins and even invasive species can accumulate in closed ports. Organisms that reach fresh or salt water contained in a ship’s ballast tanks can displace a region’s native wildlife, while dredging, sonar, and propellers cause noise pollution.
Sponge populations offer a possible natural way to clean these dirty ports. They filter thousands of gallons of seawater per day, removing heavy metals, pathogenic bacteria, viruses and organic particles. At the same time, this filtration recycles nutrients back into the water. This improves water quality and also returns energy and organic matter to the food web. Sea sponges also provide habitat for worms, crustaceans and juvenile fish.
A sponge reef
In this new study, a team in Spain tested sponges to find which would be the most tolerant to pollution in Mediterranean ports. They used Marina Palamós, a recreational port in the province of Girona, Spain, to test five species of sponges:corticium candelabra, crambe crambe, Scalarispongia scalaris, Ircinia goldsand the chicken kidney cake Reniform chondrosia. These species are distantly related, but have different functional and anatomical traits. Some have exoskeletons while others do not, while others are made of different minerals and harbor different populations of microbes within their tissues.
The team took the sponges to the Blanes Marine Research Center (also in Girona) and fixed them on ceramic plates in 132-gallon tanks of unfiltered tap seawater. Between 2024 and 2025, they transplanted these plates with a total of 42 sponges to artificial reefs. The reefs were formed by metal grids and covered with calcium carbonate, and were then fixed to the Marina Palamós underwater dock. The only species that failed to reach the artificial reef was C. candelabra, since they died in the laboratory.
queen chicken kidney
Chicken kidney cake C. reniformis stood out among all the sponges tested as the best candidate for future cleaning experiments. It thrived in the harbor, reproduced asexually, and 91.7 percent of the original animals survived throughout the 455-day monitoring period. In comparison, crambe, S.scalarisand I pray It gradually shrank and lived between 20 and 165 days before dying.
“Unlike many sponges, the chicken kidney sponge can ‘sneak away’ if local conditions deteriorate, for example when nearby organisms compete,” Dr. Manuel Maldonado, study co-author and biologist at the Blanes Center for Advanced Studies, said in a statement. “It can also move from the exposed top surface of a rock, where it is subjected to ultraviolet radiation, contaminated sediments and predators, to protected crevices where these stresses are greatly reduced. It also reproduces asexually by fission: this allows populations to expand rapidly and then reproduce sexually, increasing the chances of successful fertilization.”
In future studies, the team plans to monitor sponges transported from the port for several years. In particular, they want to track the microbial communities present in the chicken kidney sponge to see if these microscopic organisms help them tolerate contaminants.
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