World's Largest Known Clone: Vast Population Originates from a Single Alga

In an intriguing discovery, researchers have identified what could be the largest clone in the world, originating from a single female alga in the Baltic Sea. This finding contrasts with previous assumptions that these organisms belonged to a distinct species of seaweed.

According to a study published in the journal Molecular Ecology, millions of identical clones of Fucus vesiculosus, commonly known as bladderwrack, stretch across the seabed of the Baltic Sea. While certain areas are populated solely by these clones, others contain both cloned and sexually reproduced specimens.

The significance of this discovery lies in the genetic implications of such a large clone. Unlike typical populations that maintain genetic diversity through sexual reproduction, a clone lacks this variation, which is crucial for adaptation and survival. The research team, led by scientists from the University of Gothenburg, estimates that this particular clone could be around 8,000 years old, a relatively young age compared to known clonal organisms like the ancient Pando aspen grove in the U.S., which spans over 40 hectares and is believed to be up to 80,000 years old.

This extensive clone stretches over 500 kilometers, from Öregrund to just south of Umeå, making it the most significant clonal population identified in the Baltic region. The researchers clarified that the organism is indeed bladderwrack and not a separate species as previously thought, noting specific characteristics like narrower fronds that contributed to this misconception.

However, the absence of genetic diversity poses serious risks, particularly in light of climate change. The researchers indicated that the environmental conditions predicted for the coming decades could threaten the survival of Fucus vesiculosus in the northern and eastern Baltic Sea if the population cannot adapt to these new challenges.

Bladderwrack is primarily found along the coasts of the North and Baltic Seas, thriving in shallow waters and providing essential habitats for various marine species, including fish, snails, and crustaceans. It is the dominant large macroalga in many Baltic regions, capable of tolerating low salinity levels, which allows it to flourish in brackish waters.

The team conducted genetic analyses across 55 locations in the Baltic Sea, revealing this widespread clonal organism that formed through the dispersal of fragments by water currents, leading to the establishment of new individuals.

Despite its extensive coverage, the future of this giant clone appears precarious. Historically, bladderwrack was abundant along the German Baltic coast, but recent decades have seen a significant decline attributed to factors such as nutrient over-enrichment and climate change. The loss of such a vital marine organism poses a substantial threat to the marine ecosystem.

Many marine species, including macroalgae, rely on clonal reproduction, which can limit their adaptability to changing environmental conditions. As climate change accelerates, particularly in confined bodies of water like the Baltic Sea, the impacts are expected to be felt more rapidly than in larger oceans.