Ancient wooden shipwrecks harbour microbial communities similar to naturally occurring geological seabed structures, according to a new study. Wood and other hard surfaces are often islands of deep-sea life, and microbes are found at the base of ocean food chains. However, little is known about the microbial diversity of human-made habitats also found on the seafloor. The new study is among the first research to show the impact of human activities, like shipwrecks, on these environments. The paper describing the findings was recently published in the journal Frontiers in Marine Science.
Study Is The First To Show Built Habitats Impact Microbial Films
In a statement released by Frontiers, Dr Leila Hamdan, corresponding author of the study, said microbial communities are important to be aware of and understand because they provide early and clear evidence of how human activities change life in the ocean. She added that this work is the first to show that built habitats, which are places or things made or modified by humans, impact the films of microbes coating these surfaces as well. The coatings, called biofilms, are ultimately what enable hard habitats to transform into islands of biodiversity.
The United Nations Educational, Scientific and Cultural Organization estimates that there are three million shipwrecks around the world, most of which are made of wood. For this initial study of the microbial life around such sites, Hamdan and collaborators chose two wooden sailing ships that sank in the Gulf of Mexico in the late 19th century.
Pine And Oak Placed At Different Distances From Shipwreck
The team placed pieces of pine and oak at varied distances between zero and 200 metres from the shipwreck, in order to collect samples of biofilms. The researchers retrieved the samples after four months, and measured all of the bacteria, archaea and fungi using gene sequencing.
The Type Of Wood Had Greatest Impact On Bacterial Diversity
According to the study, the type of wood had the greatest impact on bacterial diversity. Oak was found to be more favourable for bacteria than pine.
However, the link between the type of wood and the impact on microbial diversity was less influential for archaea and fungi. Depending on the proximity of the pine and oak samples to the wreck site, microbial diversity varied.
Samples Closest To Shipwrecks Did Not Show The Most Diversity
Samples taken closest to the shipwrecks themselves did not show the most microbial diversity, the study found. Instead, diversity peaked at about 125 metres from the wreck sites.
The presence of these shipwrecks increased microbial richness in the surrounding area and altered biofilm composition and dispersal, with environmental factors such as the depth of the water and proximity to a nutrient source like the Mississippi River delta determining the distribution of biofilms.
More Research Needed On How Built Habitats Are Changing Deep Sea
The authors note in the study that there are thousands of oil and gas platforms and oil pipelines in the Gulf of Mexico alone, and many more worldwide, and that further research is needed to better understand the impact of these structures as well.
Hamdan said while researchers are aware human impacts on the seabed are increasing through the multiple economic uses, scientific discovery is not keeping pace with how this shapes the biology and chemistry of natural undersea landscapes.
She added that the scientists hope this work will begin a dialogue that leads to research on how built habitats are already changing the deep sea.