''Chondria tumulosa'' is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

red algae Red algae, or Rhodophyta (, ; ), make up one of the oldest groups of eukaryotic algae. The Rhodophyta comprises one of the largest Phylum, phyla of algae, containing over 7,000 recognized species within over 900 Genus, genera amidst ongoing taxon ...

in the family Rhodomelacae. It was first discovered in 2016, growing in small patches in the Pearl and Hermes Atoll in the

Northwestern Hawaiian Islands The Northwestern Hawaiian Islands also known as the Leeward Hawaiian Islands, are a series of islands and atolls located northwest of Kauai and Niihau, Niihau in the Hawaiian Islands, Hawaiian island chain. Politically, these islands are part of ...

. By 2019, the species had spread to cover several thousand square meters, smothering and killing vast swathes of the atoll's

coral reef A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. Most coral reefs are built from stony corals, whose polyps cluster in group ...

s. ''C. tumulosa'' is unlike any other species in its

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

, having a

tumbleweed A tumbleweed is a structural part of the above-ground anatomy of a number of species of plants. It is a diaspore that, once mature and dry, detaches from its root or stem and rolls due to the force of the wind. In most such species, the tumbl ...

-like growth form that allows fragments to break off and spread, allowing it to colonize new areas. The true origin of ''C. tumulosa'' in the region remains unknown; it displays many characteristics of an

invasive species An invasive species is an introduced species that harms its new environment. Invasive species adversely affect habitats and bioregions, causing ecological, environmental, and/or economic damage. The term can also be used for native spec ...

and is not closely related to any other Hawaiian '' Chondria'', but it would have been relatively difficult to colonize such a remote area. It has also been suggested that it is a native species that suddenly spread due to changes in the ecosystem. Control and mitigation strategies will have to be made to prevent the species' spread.

Management and Monitoring

A novel environmental DNA (eDNA) assay has been developed to detect ''Chondria tumulosa'' in the Papahānaumokuākea Marine National Monument (PMNM), a significant marine reserve. This red alga, which is known for its invasive traits, forms dense mats that overgrow coral reefs, threatening native species and ecosystems. The eDNA assay uses quantitative polymerase chain reaction (qPCR) and high-throughput sequencing to detect ''C. tumulosa'' from seawater samples, even at low abundance levels (below 1%). The high sensitivity and reliability of this method support its use for early detection and management of ''C. tumulosa'', providing valuable insights for conservation efforts and invasive species control. This tool helps mitigate the spread of ''C. tumulosa'' in PMNM and similar ecosystems, enhancing management strategies for invasive species containment and eradication.

References

Northwestern Hawaiian Islands Rhodomelaceae Pearl and Hermes Atoll {{rhodophyta-stub