Research after Hurricane Harvey shows more fish food, larger jellyfish

A groundbreaking study in a leading scientific journal is offering a broader picture of the effects of hurricanes on zooplankton life in the Gulf of Mexico.

Zachary M. Topor, a PhD Candidate, and Drs. Kelly L. Robinson and Mark A. Genung, Assistant Professors of Biology at the University of Louisiana at Lafayette, conducted the study. Scientific Reports published the results in May 2022.

In the Scientific Reports paper, the researchers identify, for the first time, hurricane-related, environmental drivers of zooplankton abundances and diversity. Researchers used archived samples to compare historic hurricane years with non-storm years, including samples collected after Hurricane Harvey, Hurricane Rita, and Hurricane Ike.

Zooplankton are small, drifting sea creatures that serve as food for fishes, marine mammals, and birds, Robinson explained.

“Understanding the amount, distribution, and identity of zooplankton is important for evaluating how much food is directly available for key fisheries species like gulf menhaden, which ultimately impacts top predators like dolphins and pelicans,” she said.

Researchers discovered that after Hurricane Harvey, more zooplankters were found in low salinity, coastal waters. Additionally, Post-Harvey zooplankton communities were less diverse compared to those collected after Hurricanes Rita and Ike or those from non-storm years. Researchers also noted that jellyfish were generally larger after Harvey.

“Because of the challenges associated with sampling immediately after a major storm or hurricane, we don’t fully understand the role storms play in modifying these [zooplankton] communities, or how these storms could alter coastal food webs,” says Topor.

To answer this challenge, researchers coupled samples they collected following Hurricane Harvey in 2017 with samples collected by the Southeast Area Monitoring and Assessment Program (SEAMAP), a long-running sampling partnership between the National Marine Fisheries Service and the Gulf States Marine Fisheries Commission. Zooplankton were collected off Galveston, Texas and samples were rapidly processed using novel benchtop imaging technology. 

More than 150,000 organisms were identified with advanced machine learning approaches and used to compare how different hurricanes might impact zooplankton communities uniquely. These organisms represented 11 animal phyla, ranging in size from 200 micrometers – about the width of two human hairs – to nearly four and a half inches.

Topor said that the hurricanes’ impact on zooplankton will “set the stage for scientists to ask key questions concerning how these predicted wetter hurricanes may influence the way energy travels through food webs or the fate of carbon in coastal oceans.”

In addition to Topor and Robinson, Dr. Mark Genung contributed to data analysis and drafting of the manuscript.

Scientific Reports is the Nature’s open access multidisciplinary journal. It publishes research papers and reviews in all areas of science.

Read the article here: https://www.nature.com/articles/s41598-022-12573-y