Risk of extinction cascades from freshwater mussels to a bitterling fish

January 04, 2021

Bitterling fishes (Subfamily: Acheilognathinae) spawn in the gills of living freshwater mussels obligately depending on the mussels for reproduction. On the Matsuyama Plain, Japan, populations of unionid mussels--Pronodularia japanensis, Nodularia douglasiae, and Sinanodonta lauta--have decreased rapidly over the past 30 years. Simultaneously, the population of a native bitterling fish, Tanakia lanceolata, which depends on the three unionids as a breeding substrate, has decreased. Furthermore, a congeneric bitterling, Tanakia limbata, has been artificially introduced, and hybridisation and genetic introgression occur between them. Here, we surveyed the reproduction and occurrence of hybridisation between native and invasive species of bitterling fishes. We collected mussels in which these bitterlings lay their eggs, kept them separately in aquaria, collected eggs and larvae ejected from the mussels, and genotyped them using six microsatellite markers and mitochondrial cytochrome b sequences.

The introduced T. limbata was more abundant, had a longer breeding period, and produced more juveniles than the native T. lanceolata. Hybrids between the two species occurred frequently, and in total 101 of the 837 juveniles genotyped were hybrids. The density of P. japanensis was low, at most 0.42 individuals/m2. Nodularia douglasiae and S. lauta have nearly or totally disappeared from these sites. Hybrid clutches of the Tanakia species occurred more frequently where the local density of P. japanensis was low. The mussels were apparently overused and used simultaneously by three species of bitterlings.

The decline of freshwater unionid populations has heightened hybridisation of native and invasive bitterling fishes by increasing the competition for a breeding substrate. We showed that a rapid decline of host mussel species and an introduction of an invasive congener have interacted to cause a rapid decline of native bitterling fish. The degradation of habitat and the introduction of invasive species interact to cause a cascade of extinctions in the native species. In our study, obligate parasite species are threatened because the host species are disappearing, resulting in a serious threat of coextinction.

Ehime University

Related Invasive Species Articles from Brightsurf:

The invasive species that Europe needs to erradicate most urgently are identified
An international research team analyzed the risk impact and the effectiveness of possible erradication strategies for invasive species already in the region as well as those that have yet to arrive

Crayfish 'trapping' fails to control invasive species
Despite being championed by a host of celebrity chefs, crayfish 'trapping' is not helping to control invasive American signal crayfish, according to new research by UCL and King's College London.

Climate change is impacting the spread of invasive animal species
What factors influence the spread of invasive animal species in our oceans?

Invasive alien species may soon cause dramatic global biodiversity loss
An increase of 20 to 30 per cent of invasive non-native (alien) species would lead to dramatic future biodiversity loss worldwide.

Protected areas worldwide at risk of invasive species
Protected areas across the globe are effectively keeping invasive animals at bay, but the large majority of them are at risk of invasions, finds a involving UCL and led by the Chinese Academy of Science, in a study published in Nature Communications.

Charismatic invasive species have an easier time settling into new habitats
An international study, in which the University of Cordoba participated, assessed the influence of charisma in the handling of invasive species and concluded that the perception people have of them can hinder our control over these species and condition their spread

Invasive species with charisma have it easier
It's the outside that counts: Their charisma has an impact on the introduction and image of alien species and can even hinder their control.

Invasive species that threaten biodiversity on the Antarctic Peninsula are identified
Mediterranean mussels, seaweed and some species of land plants and invertebrates are among the 13 species that are most likely to damage the ecosystems on the Antarctic Peninsula.

Research networks can help BRICS countries combat invasive species
BRICS countries need more networks of researchers dedicated to invasion science if they wish to curb the spread of invasive species within and outside of their borders.

Look out, invasive species: The robots are coming
Researchers published the first experiments to gauge whether biomimetic robotic fish can induce fear-related changes in mosquitofish, aiming to discover whether the highly invasive species might be controlled without toxicants or trapping methods harmful to wildlife.

Read More: Invasive Species News and Invasive 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.