Sunday, July 21, 2024

Whale Shark Health Relies On Habitat, Diet – And The Right Mix Of Microbes


Loss of habitat and human activities such as fishing and shipping pose a grave threat to wildlife but diseases driven by the smallest organisms in the ocean are a less-understood side of marine conservation.

These diverse and abundant microbiome communities perform complex processes on skin and tissue of marine wildlife – and Flinders University scientists are breaking ground by understanding their role in an endangered shark species and to describe new marine microbes for the first time.

In a new article published in Scientific Reports, scientists from around the world have collaborated to sample microbes on the skin surface of the world’s largest fish – the whale shark – at five of the most famous diving sites around the world, including Ningaloo Reef in Western Australia, Oslob in the Philippines, Mafia Island in Tanzania and La Paz and Cancun in Mexico.

Whale Shark (Adobe Stock)
Whale Shark (Adobe Stock)

With these docile filter-feeding sharks, the scientists from 12 international institutions collected microbial samples and then used cutting-edge genomic sequencing technology to describe the types of microbes on the skin surface of the whale sharks.

The study is the most extensive microbiome study to date of a wild marine animal of this physical size, involving 74 whale sharks in the three major ocean basins, and will form a baseline for future analysis and highlight how microbial species differ around the world, according to Dr. Michael Doane, a researcher from the Flinders Accelerator for Microbiome Exploration (FAME) group in South Australia:

“While microbial species differ across the world, they work together to form a balanced network that contributes to the health of the sharks.

“It’s important to measure and analyze the distinct and diverse epidermal microbiome of the global whale shark populations to work towards understanding how the microbes affect the wellbeing and survival of this amazing animal.

“The characteristics of a balanced microbial community are not well described for any species, but especially for sharks, which form a vital link in ocean foodchains and ecosystems.

“The microbes form a complex network pattern on the skin surface, which is consistent across sharks from each location, revealing characteristics of what comprises a balanced or unbalanced microbiome.”

At the right time of the year you can see Whale Sharks when on a Maldives Liveaboard
Whale Shark (Adobe Stock)

The scientists used mathematical modeling to investigate how the microbes interacted with one another to form a community or network.

In addition to revealing the emergent structure of the shark skin microbiome, the study also described 34 new species of microbes.

The whale sharks from Ningaloo had the highest number of novel microbial species, “suggesting we have lots to learn about the microbial organisms inhabiting animals in Australian waters,” adds study co-author and Flinders University Professor Elizabeth Dinsdale.

Check out the paper in Scientific Reports.

(Featured image credit: Dr. Michael Doane/Flinders University)

John Liang
John Liang
John Liang is the News Editor at He first got the diving bug while in High School in Cairo, Egypt, where he earned his PADI Open Water Diver certification in the Red Sea off the Sinai Peninsula. Since then, John has dived in a volcanic lake in Guatemala, among white-tipped sharks off the Pacific Coast of Costa Rica, and other places including a pool in Las Vegas helping to break the world record for the largest underwater press conference.