A new study in which Diego Kersting, a researcher at the Higher Scientific Research Council (CSIC) at the Torre de la Sal Aquaculture Institute (IATS-CSIC), participates, has found, for the first time, contaminants from the burning of fuels fossils in coral skeletons.
The discovery, involving the participation of University College London and the University of Leicester in the United Kingdom, occurred in coral skeletons from the bay of Illa Grossa, in the marine reserve of the Columbretes Islands (Castellón). The work, published this Friday in the journal Science of the Total Environment, offers the scientific community a new tool to trace the history of pollution, as reported by the entity in a statement.
Corals are a natural archive commonly used for paleoclimatic studies for their measurable growth rates. Like tree rings, their long life and slow, regular growth provide scientists with annual, monthly, or even weekly environmental data going back years.
Until now, they have been “largely” used to reconstruct and measure past climate conditions, such as temperature or water chemistry, but this is the first time polluting particles, apart from microplastics, have been detected in corals.
The discovery of this type of contamination, known as ‘fly ash’ or ‘spheroidal carbonaceous particles’ (SCPs), is considered “an indicator of the presence of human influence on the environment, and a historical marker of the beginning of the geological epoch of the Anthropocene proposed by the scientific community,” the entity noted.
In the opinion of Diego Kersting, IATS-CSIC researcher, “the presence of these contaminants in coral skeletons extends over decades and shows a clear image of how extensive human influence is on the environment. It is the first time that this type of contaminant is detected in corals, and its presence in these Mediterranean corals is parallel to the historical rate of combustion of fossil fuels in the region,” he stated.
These corals, small invertebrates that live in colonies, ingest pollutants from surrounding waters, incorporating them into their calcium carbonate skeletons as they grow. The corals studied belong to the species Cladocora caespitosa, the only coral in the Mediterranean capable of building reefs.
The samples were taken in the Columbretes Islands marine reserve, one of the few areas in the Mediterranean where this species still builds large colonies. This coral has been studied here for more than two decades, with special attention to the impacts it suffers from the climate crisis. The area is a “sentinel” of global change at an international level due to these studies and the associated historical data series, a figure that is reinforced by the results of this study now published.
Previous knowledge of the growth rates of this coral made it possible to date the date of incorporation of the SCP particles detected in the skeleton during the analyzes carried out at University College London.
In addition, these particles were analyzed with electron microscopy and x-rays to look for the characteristic chemical signature of pollution originating from coal or oil combustion plants. The corals showed a “significant increase” in SCP contamination between 1969 and 1992, a time when Europe was rapidly industrializing and coal consumption in Spain increased dramatically.
“The results align with other SCP pollution measurements taken in mountain lakes in Spain, supporting the idea that corals can serve as natural archives to measure changes in pollution levels over the years,” Kersting said.
The finding comes as the scientific community seeks tools to mark the beginning of the Anthropocene, a unit of geological time used to describe the most recent era in Earth’s history in which human activity is exerting a dominant influence on the climate and the environment of the planet.
“There are scientists who advocate using the presence of SCPs as a marker of the beginning of the Anthropocene, and their discovery in coral skeletons supports this argument,” says the CSIC researcher. “In fact, corals were the only record regularly used in paleoconstructions in which SCPs had not yet been detected, having already been identified in marine and lake sediments, ice cores and peat beds,” he noted.
The authors of the study note that “as it becomes clearer that humans have altered the natural environment to an unprecedented level, these pollutants act as indelible markers, indicating the beginning of the Anthropocene epoch. This finding is very valuable to better understand the history of human impact on the natural environment, and serves as a powerful reminder of how extensive human influence is on the environment.”
