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| NAS - Nonindigenous Aquatic Species |
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Common Name: red alga
Synonyms and Other Names: C. ornatum, Asterocytis ramosa, A. smargadina/smargdina, A. ornata, Goniotrichum ramosum, G. caerulescens, Hormospora ramosa, and Conferva ornata
Taxonomy: available through 
Identification: This is an epiphytic red alga with thalli consisting of monosiphonous pseudofilaments. These are unbranched or exhibit false branching, which increases with pseudofilament length. The thalli are blue-green to emerald green and the globose to ellipsoid bulbous and gelatinous cells are arranged in an irregular uniseriate pattern. Within each cell there is one stellate, axial plastid with an obvious pyrenoid. In the Great Lakes, this red alga occurs on Cladophora (Fries and Pettersson 1968; Santos 1973; Sheath and Morison 1982). Cells range in size from 4–16 by 6.4–20 µm in freshwater and marine environments (Santos 1973; Sheath and Morison 1982).
Size: to 20 microns
Native Range:
Unclear. This species is known by many different names and it has been recorded around the world in both marine and freshwater habitats (Guiry and Guiry 2007). It is typically considered native to the Atlantic coast of North America by authors concerned with its distribution in the Great Lakes. See Remarks.
Nonindigenous Occurrences: C. ramosum was first reported from western Lake Erie in 1964 and now also occurs in Lake Ontario, Lake Huron, Lake St. Clair, and drainages around these lakes (Taft 1964; Sheath and Morison 1982; Mills et al. 1993).
Ecology: C. ramosum can grow in marine intertidal zones. It is common on the Atlantic coast of North America. Marine isolates can tolerate a wide range of salinities (Lewin and Robertson 1971).
C. ramosum is an epiphyte on around 1–7% of Cladophora examined in Lake Ontario, Lake Erie, and Lake Huron. It is often found on older or dead cells of Cladophora in conjunction with epiphytic diatoms. It is most abundant in Lake Ontario and Lake Erie. It does not occur at all in the St. Lawrence River and Lake Superior, possibly because low wave action in these regions may prevent survival due to lack of gas and nutrient exchange. C. ramosum can occur epiphytically on other species in marine and freshwater environments around the world. The marine form is relatively heterotrophic. It requires vitamin B12 but can also use organic nitrogen, carbohydrates, and acetate (Fries and Pettersson 1968; Sheath and Hymes 1980; Sheath and Morison 1982).
C. ramosum reproduces asexually via monospores that emerge from the parent filament as the sheath surrounding the spores is digested (Sheath and Morison 1982).
Means of Introduction: It is unlikely that C. ramosum could have dispersed up the St. Lawrence River from the Atlantic coast into the Great Lakes, given that the St. Lawrence lacks the wave action this species requires. It was very likely introduced in ballast water (Mills et al. 1993).
Status: Established where recorded.
Impact of Introduction: Unknown.
Remarks: C. ramosum is synonymous with C. ornatum, Asterocytis ramosa, A. smargadina/smargdina, A. ornata, Goniotrichum ramosum, G. caerulescens, Hormospora ramosa, and Conferva ornata (Guiry and Guiry 2007), which are all names that have been employed in other regions. Formerly, the genus name Chroothece also often referred to freshwater forms of this species.
C. ornatum has been recorded under various names from freshwater and marine environments in Europe, North America, the Caribbean Islands, the Pacific Islands, the Atlantic Islands, southern Asia, South America, Africa, the Indian Ocean Islands, and Australia and New Zealand (Fries and Pettersson 1968; Zinova and Konaklieva 1974; Sheath and Morison 1982; Suarez and Cortes 1983; Mills et al. 1993; Guiry and Guiry 2007).
References
Fries, L. and H. Pettersson. 1968. On the physiology of the red alga Asterocytis ramosa in axenic culture. British Phycological Bulletin 3(3):417-422.
Guiry, M. D. and G. M. Guiry. 2007. AlgaeBase version 4.2. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org; searched on 09 November 2007.
Lewin, R. and J. A. Robertson. 1971. Influence of salinity on the form of Asterocytis in pure culture. Journal of Phycology 7:236-238.
Mills, E. L., J. H. Leach, J. T. Carlton, and C. L. Secor. 1993. Exotic species in the Great Lakes: a history of biotic crises and anthropogenic introductions. Journal of Great Lakes Research 19(1):1-54.
Santos, M. F. 1973. Contributions to the knowledge of fresh water algae of Portugal. Part 3. Boletim da Sociedade Broteriana 47:105-138.
Sheath, R. G. and B. J. Hymes. 1980. A preliminary investigation of the freshwater red algae in streams of southern Ontario, Canada. Canadian Journal of Botany 58(11):1295-1318.
Sheath, R. G. and M. O. Morison. 1982. Epiphytes on Cladophora glomerata in the Great Lakes and St. Lawrence seaway with particular reference to the red alga Chroodactylon ramosum (=Asterocytis smargdina). Journal of Phycology 18:385-391.
Suarez, A. M. and I. Cortes. 1983. Wealth of phyto benthos in a zone of the North Coast of Havana, Cuba. Revista de Investigaciones Marinas 4(1):3-22.
Taft, C. E. 1964. New records of algae from the west end of Lake Erie. Ohio Journal of Science 64:43-50.
Zinova, A. D. and S. D. Konaklieva. 1974. Algae from the Ahtopol Bay, southeastern Bulgaria. Novosti Sistematiki Nizshikh Rastenii 11:125-129.
Author: Rebekah M. Kipp
Contributing Agencies: 
NOAA - GLERL
Revision Date: 6/22/2007 Citation for this information:
Rebekah M. Kipp. 2009. Chroodactylon ramosum. USGS Nonindigenous Aquatic Species Database, Gainesville, FL.
<http://nas.er.usgs.gov/queries/factsheet.asp?SpeciesID=1711> Revision Date: 6/22/2007
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