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Ruth PATRICK, diatoms as indicators of river health

“Leave the world a better place for having passed through it.” - Frank Patrick

Portrait of Dr Ruth Patrick

Credit: The Independent, article posted on 7 october

The natural environment is an intriguing and captivating place of amazing creatures invisible to the naked eye. Environmental microorganisms are microscopic creatures living in the environment, including water, soil and air. Despite common beliefs, microorganisms could be more helpful than harmful to both humans and the earth. Diatoms are dominant microscopic algae found in marine or freshwater environments around the world. They are a source of food for aquatic organisms and contribute to  oxygen production. In the forties, Dr Ruth Patrick was a trailblazer scientist who revealed that several environmental factors can affect diatom colonization and development; therefore, diatoms can be used as indicators to monitor environmental conditions.

Diatoms at the microscope (photograph)

Credit: NNehring sur Getty images

Growing and early interest in the biology of diatoms

Ruth Myrtle Patrick was born on November 26, 1907, in Topeka, Kansas, USA Born into a family that valued education, her father, a lawyer, instilled in her a love for natural science through childhood explorations in the forests. Her father’s passion for diatoms had a big influence on Ruth’s future scientific career and her interest in nature. Ruth received her first microscope at the age of 7 years old from her father. Ever since she observed diatoms under a microscope, she became fascinated by these species and sparked her interest in science and scientific research.

By 1929, Ruth earned a bachelor’s degree in botany at Coker College. Following the advice of her father, she gained her first exposure to biological sciences through summer laboratory internships, at Cold Spring Harbor and Woods Hole Oceanographic Institutions. Ruth was passionate about science and desired to continue to higher education. She therefore leveraged her professional network and refined her interest in algae and specifically diatoms. She joined the Professor Ivy Lewis research group, an eminent algae researcher, and earned a master’s degree in 1931 and a Ph.D. in Botany in 1934 at the University of Virginia. Her works on the Dismal Swamp and the Great Salt Lake highlighted that diatoms could be valuable indicators of natural processes (soil erosion…) and environmental changes.

Diatoms biological indicators to assess the health of freshwater

In 1945, Dr. Ruth Patrick shared her latest research on the use of diatoms to monitor environmental changes at the American Association for the Advancement of Science. Her presentation resonated with industrial companies and government agencies.  She was approached by Mr. WB Hart, responsible for waste disposal for the old Atlantic Metal Refining Company and Head of the State of Commerce of Pennsylvania. In the early 1900s, scientific understanding began to identify the detrimental effect of pollution on human health. However, many of the United States’ waterways remained polluted with waste and toxic chemicals. Mr Hart raised funds for Ruth’s research to investigate how industrial contaminants could pose a threat to aquatic species.

Dr Ruth Patrick studying diatoms in rivers

In the 1900s, Ruth was a woman pursuing a career in a predominantly male-dominated field and it was unusual for a woman to receive research funds to lead her research. In this leadership position, Ruth knew that she might encounter challenges and her ability to lead effectively might be questioned. Therefore, in 1947, Ruth mobilized a multidisciplinary team of scientists for field-intensive research and investigated the effects of industrial pollution on river water quality, conducted at the Conestoga River Watershed in Lancaster County.

Ruth Patrick and her team at the river Conestoga in Lancaster County.

She developed the diatometer to monitor diatoms and distinguish between different sources of contamination in freshwater. This device allowed her to collect diatoms from the river and examine their composition and diversity in the laboratory.

Diatomètre développé par Ruth Patrick 

Ruth and her team's research, published in 1949, highlighted the crucial link between these microorganisms and the health of our aquatic ecosystems. Taking a holistic approach, they show us how chemical analysis and the diversity of aquatic organisms can help us detect signs of pollution and protect our precious water sources. Their work paves the way for global collaboration between scientists, industries and governments to preserve our waterways for future generations.

Legacy of Dr Ruth Patrick

From 1937 to 1945, Ruth Patrick contributed significantly to the Academy of Natural Sciences of Philadelphia (later called The Academy of Natural Sciences and Drexel University) as an unpaid assistant curator to work on the diatom herbarium. In 1945, she was appointed salaried chair of the Limnology Department (renamed Patrick center for Environmental Research). During 26 years, Ruth contributed to increasing the diatom collection accumulated from numerous rivers, lakes and streams surveys. She facilitated the access of the collection by improving the records and the accessibility for researchers. The diatom herbarium collection started in the twentieth century and since then has accumulated over 220,000 slides.

Ruth was a renowned expert of diatoms and contributed to over 200 articles and books. She was the first woman to lead a major research on environmental science gathering bacteriologists, chemists, and animal and plant experts. Ruth advised several American presidents (President Johnson, President Reagan) and governors to improve water policies and address emerging pollution challenges. She received many awards and prizes including the National Academy of Sciences in 1970, the American Philosophical Society in 1974 and the National Medal of Science from President Clinton in 1996.

President Clinton honored Dr Ruth Patrick with National Medal of Science in 1996

Since 1998, the Ruth Patrick Award, granted annually by the Association for the Sciences of Limnology and Oceanography (ASLO), acknowledges outstanding scientists involved in the conservation and protection of ecosystems and species.

Brilliant, dedicated and determined with an insatiable curiosity, Dr. Ruth Patrick passed away in September 2013 at the age of 105. She raised awareness of the importance of biodiversity and water quality. Biodiversity and water are interconnected, therefore utmost care should be taken to preserve biological indicators for water quality.

Dr Ruth Patrick at the Patrick Center surrounded by scientists

Written by Akila R. and edited by Tiffanie C.



Dr. Ruth Patrick Ruth Patrick Science Education Center


Pioneering Ecologist Dr. Ruth Patrick Dies

Ryan James Hearty; The Patrick Principle: Ruth M. Patrick, River Ecology and the Transformation of the Academy of Natural Sciences of Philadelphia, 1935-1975; Thesis submitted to Johns Hopkins University

Thomas L. Bott and Bernard W. Sweeney, Ruth Patrick 1907-2013 Biographical Memoirs

Potapova, M., Veselá, J., Smith, C., Minerovic, A., Aycock, L. (Editors) 2024. Diatom New Taxon File at the Academy of Natural Sciences (DNTF-ANS), Philadelphia. Retrieved on March 8, 2024, from


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