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UTA biology researchers publish study on how land use affects biodiversity of stream organisms

From left, William Budnick, Sophia Passy, and Katrina Pound
From left, William Budnick, Sophia Passy, and Katrina Pound

An international team of biology researchers, led by Sophia Passy's lab at The University of Texas at Arlington, has published research with far-reaching implications for biodiversity conservation.

William Budnick, a fifth-year doctoral student in Passy’s lab, is lead author of the study, titled “Local and regional drivers of taxonomic homogenization in stream communities along a land use gradient”. It was published in the November issue of the journal Global Ecology and Biogeography.

Making his participation on the project considerably more challenging was the fact that Budnick also had to deal with a cancer diagnosis. He underwent surgery and, later, chemotherapy which left him cancer-free.

Co-authors include Katrina Pound, a former postdoctoral researcher in Passy’s lab, and an international team of scientists from France, Finland, and Canada. Passy is the corresponding author.

“We show that on two continents, agriculture compared to forest land cover leads to loss of regional biodiversity (beta diversity) in major stream organisms, including algae, insects and fish, due to increased inputs of nitrogen and phosphorus,” said Passy, UTA associate professor of biology. “The loss of beta diversity is of conservation concern because it may impair ecosystem ability to recover from disturbances.”

The study examined how agriculture affects the local and regional drivers of taxonomic homogenization, which is an ecological process that results in increased similarity of aquatic communities, Budnick explained.

“In our study, we found that streams overly enriched with nitrogen and phosphorus by agriculture tended to be more homogenized in their constituent biota than predominantly forested streams,” Budnick said. “We also found that larger scale regional processes had a stronger impact on beta diversity of small-bodied and passively dispersing organisms (e.g., algae and aquatic insects), whereas both local and regional scale processes drove beta diversity of larger-bodied, actively dispersing organisms (e.g., fish)."

“This discovery will facilitate potential conservation efforts because they are scale-dependent,” Passy added. "Our investigation not only showed an inter-continental loss of regional biodiversity in human-modified vs. natural streams, but further attributed this process to changing patterns of species commonness and rarity in the region. Under agriculture, some species tended to become particularly abundant and widespread, making communities at different locations more similar to one another."

Pound commented, “Our findings suggest that the species abundance distribution (SAD) is the dominant contributor to beta diversity across land use patterns. However, the importance of SAD increased and aggregation decreased in agricultural streams. This result sheds light on the mechanism of decreased beta diversity with eutrophication (the over-enrichment of water by nutrients), indicating higher dominance of common species in disturbed sites.”

In August 2018, during final preparatory work on the paper, Budnick was diagnosed with cancer. He underwent surgery and continued working on the paper, which was completed and submitted in January 2019. In July, the cancer became metastatic when it was discovered that residual cancer spread to a lymph node and started to grow in it. Budnick had to endure chemotherapy treatments from August through mid-October.

“During the pre-chemo period, from August 2018 to July 2019, life just moved on and I was able to still be on top of much of my work,” Budnick said. “I was particularly motivated to keep a level head and keep myself busy. I felt that even though I had been diagnosed with this illness, I still had research that needed to be done, and a dissertation to be written. I also felt I had way too many people counting on me to finish my dissertation, and I don't like leaving jobs unfinished.

“Thus, we were able to get the paper out without too much distraction, other than my blood work, MRIs, and doctor appointments sometimes interrupting the flow. After I completed treatment, I am happy to report that I am currently clean of any cancer. But, we are on a very regular surveillance protocol for now to make sure it doesn't come back.”

Budnick said that initially, he didn't let too many people know about his condition. But, when he did make his diagnosis known, he said, the “outpouring of support and accommodation I got from the Biology department was amazing.”

“This paper makes important contributions to science, but it is also a story of personal adversity and exceptional courage,” Passy said. “After his diagnosis, William underwent surgery, treatment, and extensive chemotherapy. His struggle, however, did not diminish his resolve. He gave everything—his time, his thought, and his heart—to bring this international project to a successful end. My students, collaborators and I are truly inspired by him.”

Budnick’s interest in ecology stems from a lifelong love for fish and crustaceans. His interest in aquatic biology began when he went to a state-of-the-art aquaculture high school in New Haven, Connecticut, called Sound School. He went to Auburn University and earned a bachelor’s degree in aquaculture and went on to earn a master’s degree from LSU.

He published his first paper as lead author in the October 2018 edition of the journal Hydrobiologia, an article which was featured as the cover story. It was a study based on his master’s thesis of crayfish sampling in Gulf of Mexico coastal streams.

“I learned I had a real talent for understanding and translating in layman’s terms the complex mathematical and statistical machinery that ecology relies on,” he said. “I felt that was a niche that I could easily fill in my professional work, and that was the major source of inspiration for me to pursue a Ph.D. I blame the crayfish, the model organismal group that I studied during my undergraduate and master's research, for getting me this far!”

He chose to come to UTA and join Passy’s lab for his doctoral work because he felt he was missing a crucial component to his professional experience – theory testing and application.

“I never had much exposure to the development and testing of integrative and complex hypotheses, which is exactly what Sophia has a world-renowned reputation for doing,” he said. “Hence, I felt that coming to UTA and learning under Sophia’s mentorship was probably the best decision for my career prospects.”