2023-08-29 04:31:12
Scientists from the Institute of Diversity and Austral Evolution (IDEAus-Conicet) investigate the biology and conservation status of lampreys, a species about which almost nothing was known until now. These animals lack a jaw, have a cartilaginous skeleton like sharks, and have a large circular toothed suction cup that they use to extract blood and meat from other organisms. It is estimated that they have existed for 360 million years and are anadromous, that is, they live in both rivers and the sea.
“A company called us to carry out environmental impact studies for the imminent construction of two hydroelectric dams on the Santa Cruz River. The aim was to evaluate how migratory routes and access to lamprey breeding and breeding sites upstream of the dams would be affected,” says Carla Riva Rossi, IDEAus researcher.
In other countries, migratory barriers were responsible for the decline of lamprey populations, especially in high-altitude dams. Knowledge of these animals allows us to think about conservation measures. Lampreys in the southern hemisphere, like those in Argentina, play a significant role in aquatic ecosystems as they recycle and purify organic matter by digging and filtering in the river bed. In addition, they provide marine nutrients when the adults die after releasing their eggs.
“Together with my colleague Pamela Quiroga, a specialist in the habitat of anadromous fish in Patagonia, to protect the lampreys we mapped their movements, spatial distribution and the use of the sections of the river that would be affected by the dams. Furthermore, together with a scientist working in New Zealand, we are designing experiments aimed at exploring the ability of these fish to overcome obstacles,” says Riva Rossi.
vampire fish
The term lamprey is a mix of Greek and Latin words, and translates as stone lickers. They are born in fresh water as small brownish larvae and feed on particles and microorganisms. They then transform into young fish and as they grow they develop eyes and change to a shiny silver with two blue stripes and form the sucking mouth.
When they migrate to the sea they become parasites in search of blood. Through an anticoagulant method, lampreys can remain attached to their victims for months while they feed until they die. They then return to fresh water to reproduce and die.
“Lampreys have a very particular life cycle that lasts between seven and eight years. Their lifestyle draws attention as they feed on the blood and tissues of other creatures, including fish and whales. They use their round, jawless mouth, full of small sharp funnel-shaped teeth, to cling to their prey,” highlights the researcher.
In Argentina, it was long mistakenly believed that the national lampreys belonged to the same species as those present in other countries in the southern hemisphere: Geotria australis. However, scientists detected that this was not true and provided fundamental knowledge for the conservation of these animals.
Unique in its kind
The researchers investigated historical archives and found an old taxonomic study that described a species of lamprey captured alive on a street in the city of Buenos Aires, swept away by a strong storm. The animal was described by the naturalist Carlos Germán Conrado Burmeister in 1867.
In the scientific presentation of the specimen found, carried out at the Paleontological Society of Buenos Aires, the specialist named it Petromyzon macrostomus. Later, in 1893, Carlos Berg, a German zoologist living in Argentina, reviewed the material and reassigned it the name Geotría macrostoma.
Despite being correct, these first descriptions were rejected. The results obtained by the specialists from the analysis of mitochondrial DNA and comparisons between the morphology of current specimens and the original descriptions, demonstrated that the Argentine lamprey is Geotria macrostoma, a species with unique characteristics in its ecology, physiology and behavior.
“Ignoring or ignoring this uniqueness and implementing conservation actions designed for other lamprey species can lead to erroneous management decisions, inadequate to guarantee the population viability and evolutionary potential of the Argentine lamprey,” highlights Riva Rossi.
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