Chroodactylon ornatum
(C. Agardh) Basson, 1979
Common Name:
A red alga
Synonyms and Other Names:
Asterocytis ornata, A. ramosa, A. smargadina/smargdina, Chroodactylon ornata, Chroodactylon ramosum, Conferva ornata, Goniotrichum caerulescens, G. ramosum, Hormospora ramosa
Identification:
This is an epiphytic red alga with thalli consisting of monosiphonous pseudofilaments. These are unbranched or exhibit false branching (more prevalent with longer pseudofilaments). 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:
Up 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). Authors concerned with its distribution in the Great Lakes typically consider it native to the Atlantic coast of North America (see Remarks).
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This map only depicts Great Lakes introductions.
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Great Lakes Nonindigenous Occurrences:
Chroodactylon ornatum was first reported from western Lake Erie in 1964 and now also occurs in Lake Huron, Lake Ontario, Lake St. Clair, and drainages around those lakes (Mills et al. 1993, Sheath and Morison 1982, Taft 1964).
Table 1. Great Lakes region nonindigenous occurrences, the earliest and latest observations in each state/province, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Chroodactylon ornatum are found here.
Table last updated 5/2/2024
† Populations may not be currently present.
Ecology:
Chroodactylon ornatum 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). Chroodactylon ornatum 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 or in Lake Superior, possibly because low wave action in these regions may prevent survival due to lack of gas and nutrient exchange. Chroodactylon ornatum 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).
Chroodactylon ornatum 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 Chroodactylon ornatum 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.
Great Lakes Impacts:
Summary of species impacts derived from literature review. Click on an icon to find out more...
There is little or no evidence to support that Chroodactylon ornatum has significant environmental impacts in the Great Lakes.
Realized:
As a part of the Cladophora epiphyton community, Chroodactylon ornatum has a widespread distribution throughout Lakes Huron, Erie and Ontario. It is, however, a minor part of that community and has no recorded ecological impacts (Sheath and Morison 1982).
There is little or no evidence to support that Chroodactylon ornatum has significant socio-economic impacts in the Great Lakes.
There is little or no evidence to support that Chroodactylon ornatum has significant beneficial effects in the Great Lakes.
Management:
Regulations (pertaining to the Great Lakes region)
There are no known regulations for this species.
Note: Check federal, state/provincial, and local regulations for the most up-to-date information.
Control
Biological
There are no known biological control methods for this species.
Physical
There are no known physical control methods for this species.
Chemical
There are no known chemical control methods for this species.
Note: Check state/provincial and local regulations for the most up-to-date information regarding permits for control methods. Follow all label instructions.
Remarks:
Chroodactylon 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, Australia, and New Zealand (Fries and Pettersson 1968, Guiry and Guiry 2007, Mills et al. 1993, Sheath and Morison 1982, Suarez and Cortes 1983, Zinova and Konaklieva 1974). Formerly, the genus name Chroothece also often referred to freshwater forms of this species.
References
(click for full reference list)
Author:
Kipp, R.M., M. McCarthy, and A. Fusaro
Contributing Agencies:
Revision Date:
9/12/2019
Citation for this information:
Kipp, R.M., M. McCarthy, and A. Fusaro, 2024, Chroodactylon ornatum (C. Agardh) Basson, 1979: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, and NOAA Great Lakes Aquatic Nonindigenous Species Information System, Ann Arbor, MI, https://nas.er.usgs.gov/queries/greatLakes/FactSheet.aspx?Species_ID=1711&Potential=N&Type=0&HUCNumber=DGreatLakes, Revision Date: 9/12/2019, Access Date: 5/2/2024
This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.