Blistering Barnacles! Boat detritus boost for marine conservation

Nobody likes biofouling. Even the word sounds unpleasant.

But the periodic cleaning of barnacles, algae and other growths from boat hulls, piers and offshore platforms and rigs may have a surprising upside – for the health of the oceans.

New research suggests that a type of ‘glass sponge’ routinely scrapped or power-hosed off moorings is a treasure trove of scientific information; it literally hoovers up the DNA of species that drift its way.

“These sponges are like underwater CCTV; they can tell us a huge amount about what lives in the ocean below,” explained Professor Stefano Mariani, a conservation biologist at Liverpool John Moores University.

“Surveying marine animals CAN be intrusive and is often like looking for the proverbial needle in a haystack, so having data locked up in biofouling is a bonus for conservationists and marine sustainability.”

Collecting environmental DNA (eDNA) has become a core approach in marine biodiversity research, and typically involves the collection of water or sediment samples.

Professor Mariani’s research has proven that sponges as filter-feeding organisms, are natural eDNA samplers.

This latest study, published in Science of the Total Environment, examined biofouling that colonizes the moorings of the world's largest curtain of hydroacoustic receivers off the coast of Nova Scotia.

By sequencing eDNA extracted from 51 sponges Vazella pourtalesii retrieved during routine biofouling maintenance, the team detected 23 species of marine fish and mammals, including cod, haddock, herring, bluefin tuna, halibut, pilot whale and basking shark.

The sponges outperformed water samples collected at the same sites at the surface and from the sea floor, which detected 19 and 15 species respectively.

So-called ‘natural sampling’ from the sponges captured greater species richness, with the sponges detecting all the species found when sampling the ocean floor and others, including Atlantic mackerel (Scomber scombrus) and Atlantic saury (Scomberesox saurus) were detected more frequently in sponges than in surface water. The long-finned pilot whale (Globicephala melas) was only found by the biofouling.

The scientists also say that by comparing data from biofoulings removed from set locations – pier, moorings over time, they can better track species health over time.

“It’s neat,” adds Professor Mariani. “Here we have routine maintenance coupled with cutting-edge marine biomonitoring tools, helping us assess the health of marine populations without harming marine life in its natural habitat.”

The paper Biofouling sponges as natural eDNA samplers for marine vertebrate biodiversity monitoring is published in Science of the Total Environment and features researchers from Museo Nacional de Ciencias Naturales (CSIC), Madrid; the Chinese Academy of Sciences; Bedford Institute of Oceanography, Canada; Dalhousie University, Canada; the Natural History Museum, London; and the Freshwater Biological Association, Cumbria.