Prey-size plastics are invading larval fish nurseries


November 11, 2019

A new research study has revealed that larval fish species from various ocean habitats are now being threatened by plastic pollution that infects their nursery habitats — at levels on average eight times higher than those recently found in the Great Pacific Garbage Patch.

The study is also the first to show that larval coral reef fish and pelagic species consume plastic, as early as just a few days after they’re born. While scientists had known that adult fish consume plastic, until now it had not known whether larval fish also did so, nor the health implications. dead fish among plastic A scribbled filefish, about 50 days old and 2 inches long, surrounded by plastics. Sample taken from a surface slick off Hawai‘i Island. Photo courtesy of David Liittschwager Download Full Image

The study was published in the journal Proceedings of the National Academy of Sciences.

Researchers at Arizona State University’s Center for Global Discovery and Conservation Science (GDCS) worked alongside an international team of scientists from NOAA’s Pacific Islands Fisheries Science Center to conduct one of the most ambitious research studies to date. To perform their work, the research team used a combination of advanced remote sensing techniques, field-based plankton tow surveys and fish dissection to observe the impact of plastics on the larval fish. They conducted the research along a pristine area off the west coast of Hawai’i Island, the southeasternmost island in the Hawaiian Archipelago. 

They explored a prominent feature of these coastal waters called surface slicks, which are naturally occurring, ribbon-like, smooth water features at the ocean surface. 

The locations of the surface slicks were identified by an advanced remote sensing technique pioneered by researchers at GDCS. This technique involved using more than 100 shoebox-size satellites, built and operated by partner Planet to discern textural sea surface differences between surface slicks and regular seawater.

“Surface slicks had never been mapped before, but we knew it would be vital to scaling up the field-based study. Our new method developed for this study can be applied anywhere in the world,” noted co-author Greg Asner, director of GDCS and a professor in ASU's School of Geographical Sciences and Urban Planning.

Surface slicks act as nursery habitats for larval fish because they contain a rich and steady diet of planktonic organisms.

“Slick nurseries also concentrate lots of planktonic prey, and thereby provide an oasis of food that is critical for larval fish development and survival,” said Jonathan Whitney, a marine ecologist for the Joint Institute for Marine and Atmospheric Research and NOAA, and co-leader of the study. 

NOAA researchers used tow surveys to collect planktonic organisms, larval fish and plastic pieces by using a straight-conical ring net towed behind a small boat. After the organisms and plastics were identified, the researchers then dissected the larval fish to analyze what they ingested. 

“We found tiny plastic pieces in the stomachs of commercially targeted pelagic species, including swordfish and mahi-mahi, as well as in coral reef species like triggerfish,” said Whitney. Plastics were also found in the stomachs of flying fish, a vital food source for apex predators like tunas and Hawaiian seabirds. 

Larval Fish

Often at just weeks old, numerous larval fish already had plastics in their stomachs, including mahi-mahi (top left), flying fish (top right), spearfish (middle right), jacks (bottom right), triggerfish (two sizes, bottom left) and damsels (middle left). Photo by Jonathan Whitney/NOAA Fisheries

The team also found that larval fish found in surface slicks were larger, more well-developed and better swimmers compared with other fish. Larval fish that actively swim can better orient with their environment, and this suggests that tropical larval fish could be actively seeking surface slicks for their concentrated prey resources. 

Another important finding was that the same ocean processes that accumulate prey in surface slicks also concentrates buoyant plastics that threaten aquatic ecosystems. 

The researchers found that surface slicks make up less than 10% of ocean surface habitat but are estimated to contain 42.3% of all surface-dwelling larval fish and 91.8% of all floating plastics. 

In fact, the surface slicks contained seven times more plastics than larval fish with densities, on average, eight times higher than those recently found in the Great Pacific Garbage Patch. In comparison with neighboring surface water just a couple hundred yards away, plastics were 126 times more concentrated in the surface slicks. 

“The surface slicks we mapped have turned out to be like fish superhighways that connect different bays and reefs along the west coast of Hawaiʻi Island,” said Asner. “This is how reef fish get around over long distances, and that has enormous implications for reef management, since a change in fisheries activity in one bay can have an impact on more distant bays down the superhighway. Unfortunately, now we can also say these surface slicks are plastic superhighways.”

Researchers are still uncertain as to whether plastic ingestion is harmful to larval fish. In adult fish, plastics can cause gut blockage, malnutrition and toxicant accumulation. Likewise, larval fish are highly sensitive to changes in their environment and food, so prey-size plastics could impact their development and reduce their chances of survival. 

Diagram

Diagram displaying the different accumulation of planktonic prey, plastic pieces and larval fish in surface slicks compared with nearby ambient waters. Image courtesy of Gove et al.

“Larval fish are foundational for ecosystem function and represent the future cohorts of adult fish populations,” noted Jamison Gove, an adjunct faculty at GDCS, research oceanographer for NOAA and co-lead of the study. “The fact that larval fish are surrounded by and ingesting non-nutritious toxin-laden plastics, at their most vulnerable life-history stage, is cause for alarm.”

Victoria Vandekop

Digital communications intern, Center for Global Discovery and Conservation Science

214-558-9916

2nd annual Social Cohesion Dialogue takes deep dive into America’s complex histories


November 12, 2019

What is the nature of social justice? How can each of us take action in a way that is responsible to the whole community? What does it mean to be on lands that have been defined by profound and divergent histories?

These are a few of the questions that have risen to the top in the 10 facilitated ASU and community discussion groups in the weeks leading up to this year’s ASU Social Cohesion Dialogue, to be held Thursday, Nov. 14 at the Arizona State University Tempe campus. Authors and activists Dina Gilio-Whitaker and Robert W. Lee Acclaimed authors and activists Dina Gilio-Whitaker and Robert W. Lee are featured guests for the 2019 ASU Social Cohesion Dialogue, on Nov. 14 at 6 p.m. in the Carson Ballroom at Old Main on the ASU Tempe campus. Download Full Image

The event features acclaimed activists Dina Gilio-Whitaker (Colville Confederated Tribes), indigenous educator and author of the groundbreaking work on the ecocide against Native peoples, "As Long As Grass Grows: The Indigenous Fight for Environmental Justice, from Colonization to Standing Rock”; and Rev. Robert W. Lee, collateral descendant of the Confederate general whose name he shares, and author of the memoir, "A Sin By Any Other Name: Reckoning with Racism and the Heritage of the South."

Selected for their ability to dialogue with diverse participants on critical contemporary and historical issues and challenging topics of racism, privilege, resistance and justice, the authors will first engage in a conversation with Lois Brown, ASU Foundation Professor of English and director of the Center for the Study of Race and Democracy, and then in an open Q&A with audience members.

For the 200-some people who participated in the pre-event book discussion groups led by ASU faculty and community leaders, that conversation is already well underway.

"Our authors are keen to talk with each other and with members of our ASU and Arizona communities," Brown noted. "These books have already prompted powerful changes in our ASU and Arizona readers. Some have found the details about American environmental history devastating and so many in our book groups have revealed the powerful ways in which both books are calling them to consider more bravely than ever the difficult truths about entrenched and pervasive histories of racism and division."

With many participants expected to attend Thursday’s event, the inquiry and reflection should be richer than what can usually be accomplished in a two-hour public dialogue, she added, though one need not have read the books in advance to attend.  

Book groups have been a defining feature of the Social Cohesion Dialogue program since its inception in February 2019. Created by Stanlie James, vice provost for Community Engagement and Inclusion, as part of ASU's Campaign 2020, the Social Cohesion Dialogue is committed to engaging audiences in meaningful and inspiring conversation with each other. This year, the Center for the Study of Race and Democracy added three book group discussion sessions in the Phoenix community. Held in South Phoenix at Azukar Coffee, in downtown Phoenix at the Phoenix Youth Hostel and Cultural Center and in Tempe at the public library, these sessions were well-attended and enthusiastically received.

“The books have motivated a lot of good conversation in the greater ASU community,” said Duane Roen, dean of the College of Integrative Sciences and Arts and ASU Polytechnic campus vice provost, who co-facilitated a book discussion at that campus with Chandra Crudup, faculty fellow in the Center for the Study of Race and Democracy and associate director and lecturer in the School of Social Work.

“People are finding all sorts of touch points that resonate with them in the perspectives of two people who have quite different lived experiences," observed Roen. "Both are courageous and committed individuals, using their unique experiences to explore the concepts and responsibilities called for in true environmental and social justice.”

The Social Cohesion Dialogue is free and open to the public and a book signing with the authors will follow the conversation and Q&A. The event begins at 6 p.m. in the Carson Ballroom of Old Main, on the ASU Tempe campus. Register at Eventbrite.

The 2019 Social Cohesion Dialogue is coordinated by the College of Integrative Sciences and Art’s Center for the Study of Race and Democracy, in collaboration with the ASU Office of the University Provost, Office of Inclusion and Community Engagement, and American Indian Studies. 

Maureen Roen

Manager, Creative Services, College of Integrative Sciences and Arts

602-496-1454