Single-celled marine organisms called Foraminifera (Latin for “hole bearers” but nicknamed by marine scientists as “forams”) are tiny, single-celled organisms that usually have ab external shell (called “tests”) made of calcium carbonate and live on or within the sediment of the deepest parts of the oceans.
The earliest known reference to forams comes from Herodotus, who in the 5th century BCE noticed that they comprised the rock that forms the Great Pyramid of Giza. They are consumed by a variety of larger organisms, including invertebrates, fish, shorebirds and other forams.
Their shells record the chemical and physical properties of their seawater, providing the basis for most climate research. This is the reason why foraminifera are considered one of the most important archives of ancient and modern oceans
Marine scientists believe that because certain types of forams are found only in certain environments, their fossils can be used to figure out the kind of environment under which ancient marine sediments were deposited; conditions such as salinity, depth, oxygen levels and light conditions can be determined from the different habitat preferences of various species of forams. This makes it possible to track changing climates and environmental conditions over time by aggregating information about the forams that are present.
The organisms have fascinated Prof. Sigal Abramovich of the department of earth and environmental sciences at Ben-Gurion University (BGU) of the Negev in Beersheba. She wants to persuade regulators in Israel and around the world to include regular monitoring of the geochemistry forams as an indicator of pollution in the ocean.
In a series of studies over the past three years, Abramovich and her BGU team (Dr. Danna Titelboim, Nir Ben Eliahu, Chen Kenigsberg, Sneha Manda, and Doron Pinko and colleague Prof. Barak Herut from the Israel Oceanographic and Limnological Research Institute and Dr. Ahuva Almogi-Labin from the Geological Survey of Israel) have found that foraminifera found on the ocean floor store evidence of the pollution around them within their shell formation. Coastal infrastructure makes the marine ecosystem susceptible to pollution by industrial metals that, even if relatively short-term, could cause damage to local ecosystems or affect the quality of the water. Traditional monitoring methods are insensitive to these events, said Abramovich, so better and more comprehensive monitoring methods are needed.
Foraminifera build their shells by sequential addition of chambers, and each shell thus represents a natural monitoring sequence recording heavy metals in the ambient seawater over months. This chronological documentation of heavy metals in the seawater makes it possible to recognize and assess the amount of short-term pollution events. Since forams are abundant, small and their shells are preserved after death, the monitoring can be carried out retroactively and with a very clear image. “We have been able to quantify the amounts of heavy metals pollution injected by the brine discharge from desalination plants across the Mediterranean coast of Israel,” stated Abramovich.
In one of the BGU studies, Abramovich wrote that “the continuous growth of industry and agriculture introduce hazardous chemicals including heavy metals into marine environments. With increasing intensive utilization of coastal areas, for example as a major source of seawater for desalination, it becomes a
priority to develop better and more comprehensive methods for continuous long-term monitoring of seawater quality.” The harmful effects of polluting industry, especially involving heavy metals, require the environment authorities to measure concentrations of pollutants and to monitor them. Monitoring foram shells can detect the “industrial footprint” of coastal facilitiesm including areas that were considered clean nature reserves.
In addition to detecting pollutants, she wrote in another study that since the Mediterranean Sea and particularly its eastern basin is expected to be one of the most affected areas by global warming and the rise on ocean temperatures, studying the effects on forams can serve as a model system for understanding global patterns in other marine ecosystems.
She is working with an international network of oceanographers to encourage countries around the world to adopt regular foram monitoring based on the methods she developed in her lab. Her research has been supported by the Israel’s Ministry of Science and Technology, by a GIF (German-Israeli Foundation for Scientific Research and Development) grant and the Israel Science Foundation.