Fan mussel larval dispersal for the future of an endangered species

December 11, 2020

Fan mussel populations -the biggest bivalve mussel in the Mediterranean- are endangered due to the severe parasitosis caused by the protozoan Haplospridium pinnae since 2016. Now, a study published in the journal Frontiers in Marine Science reveals the fan mussel would express a certain natural ability to recover thanks to the dispersal in the marine environment of larvae from populations which are not affected by the pathogen. These populations would be crucial for the future of the species.

The study is led by the expert Diego Kersting, from the Faculty of Biology and the Biodiversity Research Institute (IRBio) of the University of Barcelona. More than twenty institutions take part in the study as well, such as the Mediterranean Institute for Advanced Studies IMEDEA-UIB-CSIC), the Oceanographic Centre of the Spanish Institute of Oceanography (COB-IEO), the Coastal Observation System of the Balearic Islands (SOCIB), the University of Alicante, the University of Murcia, the Environment and Water Agency of Andalusia, the Catholic University of Valencia, the Abdelhamid Ibn Badis Mostaganem University (Argelia), SUBMON entity in Barcelona, Zagreb University (Croatia), the Oceanographic Institute Paul Ricard (France), and University of Messina (Italy), among others.

A lifesaver for an endangered species

The future of the fan mussel (Pinna nobilis) -one of the largest and long-lived bivalves worldwide- is becoming more and more uncertain. The parasitosis has affected almost all populations of this species in the Mediterranean, "except for some which seem to be free from pathogens and are in environments -specially in coastal lagoons or deltas- which are under certain conditions of salinity, such as the Mar Menor (high salinity) and the Ebro Delta (low salinity). Apart from these particular habitats, most populations of the fan mussel would have disappeared or are endangered species since 2016", says Diego Kersting, member of the Department of Evolutionary Biology, Ecology and Environmental Sciences of the UB and first author of the article.

As part of the study, experts monitored for three years the effects of massive mortality in fan mussels during the recruitment process, that is, the introduction of young individuals to the adult population. in the study, experts used larval collectors placed in 38 localities of the western Mediterranean, northern Africa and the Adriatic Sea.

The study shows that massive mortality alters the recruitment process of the fan mussel, which involves a loss of adult population and an obstacle for the recovery of the species. "The recruitment is the main way to recover the species as long as there are recruiters that resist the disease, and unaffected populations that can work as larval exporters", notes Kerving.

However, exceptionally, recruitment episodes have also been recorded in areas where fan mussel populations had disappeared due to massive mortality. By using current models and the location of unaffected populations, experts have determined the areas of origin of these larvae -for instance, the Ebro Delta or the coast of Algeria and southern France- which would become a true lifesaver for this species in extreme situation

"Populations in areas not affected by the parasite are exporting larvae that can travel hundreds of kilometres thanks to ocean currents. Therefore, these populations can play a decisive role in the recovery of the species in the Mediterranean", says Kersting. "In addition, everything suggests that the parasitosis does not seem to affect dramatically larvae or juvenile specimens during the first months of life".

The recovery of the affected populations, if this takes place, could be a very limited process and many years in duration, experts warn. However, the protection of marine areas that can act today as larvae donors should be extreme. "In general, these are highly anthropized areas and are subject to many threats. For this reason, its conservation and protection should be a priority to avoid any type of impact or ecological stress on fan mussel populations, which build the only hope for the recovery of the species", says Kersting.

Science to protect an emblematic species in the Mediterranean

In only a short time, the fan mussel has gone from being considered a vulnerable species to joining the Red List of Threatened Species of the International Union for Conservation of Nature (IUCN) (Kersting et al., 2019). Apart from the study on recruitment as the main process of recovery of populations, the international research effort to save the species also focuses on studying the parasitosis and the causative pathogen, in order to better understand how it works and thus predict the evolution of the infection in the future.

"Today, it has to be yet confirmed whether the virulence of the disease is due solely to the protozoan H. pinnae or whether other microorganisms could also be involved. Despite the efforts of the international groups to collaborate on this issue, it would be necessary to provide more support to current research by the scientific community in order to provide an appropriate response to the critical situation of the fan mussel and prevent the disappearance of an emblematic Mediterranean species", concludes Diego Kersting.
-end-


University of Barcelona

Related Endangered Species Articles from Brightsurf:

After election: making the endangered species act more effective
Following the presidential election, a leading group of scientists are making the case that a 'rule reversal' will not be sufficient to allow the Endangered Species Act to do its job.

Improving the Endangered Species Act requires more than rule reversal
Although species are disappearing at an alarming rate worldwide, the Trump administration recently finalized a series of substantial changes to the regulations that underpin the U.S.

New shark research targets a nearly endangered species
They are some of the most iconic and unique-looking creatures in our oceans.

Preservation of testicular cells to save endangered feline species
A research team at the German Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW) developed a method to isolate and cryopreserve testicular cells.

Endangered species on supermarket shelves
Imagine purchasing products from your local grocer, only to find out that those products are comprised of critically endangered species!

What is an endangered species?
What makes for an endangered species classification isn't always obvious.

In developing nations, national parks could save endangered species
A new study of animal populations inside and outside a protected area in Senegal, Niokolo-Koba National Park, shows that protecting such an area from human interaction and development preserves not only chimps but many other mammal species.

New mathematical model can help save endangered species
One of the greatest challenges in saving endangered species is to predict if an animal population will die out.

Bioactive novel compounds from endangered tropical plant species
A Japan-based research team led by Kanazawa University has isolated 17 secondary metabolites, including three novel compounds from the valuable endangered tropical plant species Alangium longiflorum.

Newly discovered hummingbird species already critically endangered
In 2017, researchers working in the Ecuadorian Andes stumbled across a previously unknown species of hummingbird -- but as documented in a new study published in The Auk: Ornithological Advances, its small range, specialized habitat, and threats from human activity mean the newly described blue-throated hillstar is likely already critically endangered.

Read More: Endangered Species News and Endangered Species Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.