A healthy microbiome is key to fitness in sharks and rays, but increasing amounts of heavy metals in the ocean could disrupt these microbes and impact shark and ray immune systems. Miguel wants to understand shark microbiomes because impaired immunity will make already threatened sharks and rays more susceptible to environmental stress. His project will sample gut microbes from smooth hammerheads and giant electric rays in the Gulf of California, Mexico. By describing the microbiome in these sharks and rays from both polluted and unpolluted sites, Miguel hopes to understand if heavy metals lower microbial diversity.
I was born in La Paz in southern Baja California, Mexico, where we are privileged to be surrounded by pristine beaches and incredibly rich marine fauna. As my father was a marine biologist, when my brother and I were young we spent a lot of time at sea, where he taught us to appreciate and protect all marine animals. Naturally, this led me to study marine biology too. But while I really loved field trips and ecological studies, at some point I realised that I was more interested in understanding marine life at a deeper level. So I shifted from...
To describe the gastro-intestinal microbiome of sharks and rays from a site with high levels of heavy metals and from two other unpolluted sites. With this information we will attempt to determine whether heavy metals induce lower diversity in the microbial composition and to identify potential biomarker communities.
The gastro-intestinal microbiome in animals is a crucial factor in their health and their response to the environment. Heavy metals can disrupt microbial communities with deleterious effects on the host’s metabolic capacity or immune system, resulting in the host being more susceptible to disease or environmental fluctuations. This project will provide baseline information about the microbiome diversity in a pelagic shark and a demersal ray and will identify changes in the composition of their microbiomes due to heavy metal pollution.
The microbial community present in the gastro-intestinal tract of animals plays a pivotal role in food digestion and nutrient uptake. The composition of the gastro-intestinal microbiome of terrestrial and marine animals can be affected by the presence of heavy metals; either the diversity of bacteria may be reduced or the abundance of metal-resistance bacteria may be increased. Such structural shifts in the microbial composition can be used as bio-indicators when monitoring the health status of elasmobranchs. However, there are still no comprehensive studies that describe the core microbial composition of sharks and rays. It is therefore important to first characterise the microbiome composition of the gut in species with different lifestyles and diets and then determine whether heavy metal pollution induces a shift from the ‘normal’ composition to a low-diversity microbiome community.
The Gulf of California in Mexico has a rich diversity of elasmobranch species, resulting in an important small-scale fishery that targets sharks and rays. Moreover, the coastal region around Santa Rosalia, inside the Gulf of California, is known to have high levels of heavy metals due to historical copper-mining activities. In particular, high levels of copper, zinc, cobalt, manganese, lead and uranium have been identified in sediments and have led to an important accumulation of these metals in several invertebrates. As top predators, sharks and rays are particularly vulnerable to the bio-accumulation of heavy metals, since the most important route of heavy metal uptake is through food. Previous studies have already detected the presence of heavy metals in the tissue of sharks and rays from the Santa Rosalia basin. In this project we aim to find out whether microbial diversity is lower in sharks and rays from a site with high levels of heavy metals in relation to sharks and rays from unpolluted sites.
Anna is collecting genetic information from white shark fin clips to assess this species’ population size in South Africa. Using close-kin mark-recapture analysis instead of traditional methods, she hopes to provide an accurate account of South Africa’s white shark population size. She also aims to develop a monitoring protocol that can use genetic samples collected during shark net and drumline patrols by the KwaZulu-Natal Sharks Board. This information is needed in South Africa, where the conservation of a protected species is balanced against concerns about bather safety, and where sharks are caught in bather protection gear.
Faqih is filling the gaps in the scant knowledge of giant guitarfish in Java’s Karimunjawa National Park marine protected area (MPA). Karimunjawa is located near Northern Java’s main fishing grounds, but evidence of giant guitarfish caught in some of the use-zones of the MPA hints that the park may be a sanctuary for the species. Managing giant guitarfish in Karimunjawa requires species-specific information.
Faqih’s project is a socio-ecological one to help inform management and draws on new information about relative abundance and distribution, historical occurrence and fishing pressures to paint a contemporary picture of the species in the park.
Cindy wants to know if bonnethead sharks in the Eastern Pacific constitute a third, cryptic species. The Bonnethead complex need clarification in all its distribution range, and Panama is a key country to solve this question since we have the Caribbean sea and the Pacific Ocean. By collecting fin clip samples to compare species at the genetic level and collecting specimens to compare how they look (morphology), Cindy hopes to resolve the taxonomy of Sphyrna tiburo vespertina – that is, whether it’s a cryptic third species for bonnetheads in the region. Her information can help update the IUCN Red List for bonnetheads and improve fisheries policies in Latin America where bonnethead sharks are commonly caught.