Sphacelaria lacustris
Schloesser and Blum, 1980
Common Name:
A brown alga
Synonyms and Other Names:
Identification:
This alga comprises brown filamentous half-discs exhibiting heterotrichous growth. Many of the filaments are frequently tangled and some are modified as rhizoids. The erect filaments are greatly reduced in comparison to those of S. fluviatilis. Filaments may exhibit some branching and are uni- or biseriate. In both the erect and prostrate regions of this alga there are relatively long hairs that grow basally out of an enclosed meristem (Schloesser and Blum 1980). This species is ≤ 2 mm in diameter and erect filaments are greatly reduced in comparison to S. fluviatilis, which has also been introduced to the Lake Michigan drainage. See Schloesser and Blum (1980) for more detailed cell dimensions.
Size:
< 2mm diameter
Native Range:
Unknown. S. lacustris was first described from the Great Lakes drainage, where it is considered an exotic species (Mills et al. 1993).
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This map only depicts Great Lakes introductions.
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Great Lakes Nonindigenous Occurrences:
S. lacustris first occurred in Lake Michigan in 1975 (Schloesser and Blum 1980; Mills et al. 1993).
Ecology:
It is quite rare for a brown alga to grow in a freshwater system. In the Great Lakes drainage no sexual reproduction occurs in S. lacustris, which indicates that this species could have evolved in a marine environment instead of a freshwater habitat. In Lake Michigan, S. lacustris was recorded from the sublittoral zone on the western shore at 9–10 m depth and was observed growing epilithically on igneous rocks and gravel (Schloesser and Blum 1980; Mills et al. 1993).
Cells of this species contain physodes, which are vesicles filled with compounds that may be unpalatable to grazers. S. lacustris in the Great Lakes reproduces asexually, probably via propagules that break off as tri-branched nodules, as well as unilocular zoidocysts that form at the ends of branched basal filaments (Schloesser and Blum 1980).
Means of Introduction:
S. lacustris was very likely introduced in ship ballast water or via aquarium release to the Great Lakes basin (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 Sphacelaria lacustris has significant environmental impacts in the Great Lakes.
Sphacelaria lacustris was originally reported in Lake Michigan at depths ranging from 5-15 m (Schloesser and Blum 1980). At the time of that study it was not interfering with the growth of the native Cladophora glomerata, which created a dense cover on rocks at depths of 1-5 m. Since the Dreissena invasion and increased penetration of sunlight, Cladophora now can be found at depths greater than 20 m (C. Brooks pers. comm., Malkin et al. 2008). There has been no more recent research to assess S. lacustris impacts on Cladophora given this expanded range of suitable habitat.
Sphacelaria lacustris does not reproduce sexually in the Lake Michigan population and is therefore unlikely to affect native populations genetically.
There is little or no evidence to support that Sphacelaria lacustris has significant socio-economic impacts in the Great Lakes.
There is little or no evidence to support that Sphacelaria lacustris 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:
There is a limited amount of research that has been conducted on the population of S. lacustris in Lake Michigan. While there is still a population present, it does not seem to be expanding through vegetative reproduction.
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, Sphacelaria lacustris Schloesser and Blum, 1980: 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=1676&Potential=N&Type=0&HUCNumber=DGreatLakes, Revision Date: 9/12/2019, Access Date: 4/19/2024
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.