On March 2, 1978, several empty shells of the fresh water clam, Corbicula manilensis Phillipi, were collected in the Minnesota River near the Blackdog electric generating plant in Burnsville, Minnesota. Since this Asiatic species was first observed in America in 1935, it has spread into all major river systems of North America. Its northernly extension in the Mississippi River system was, however, thought to end in northeast Iowa and to exclude Minnesota. Occurrence of this species is a potential liability because it often exerts a disruptive influence in the community that it invades

Cummings, Steven E.

Jones, James A.

English

University of Minnesota, Morris (UMM): Digital Well

Journal of the Minnesota Academy of Science Volume 44 Number 3 Article 5 1978 Occurrence of Corbicula manilensis Phillipi in the Lower Minnesota River Steven E. Cummings Macalester College James A. Jones Macalester College Follow this and additional works at: https://digitalcommons.morris.umn.edu/jmas  Part of the Biology Commons Recommended Citation Cummings, S. E., & Jones, J. A. (1978). Occurrence of Corbicula manilensis Phillipi in the Lower Minnesota River. Journal of the Minnesota Academy of Science, Vol. 44 No.3, 13-14. Retrieved from https://digitalcommons.morris.umn.edu/jmas/vol44/iss3/5 This Article is brought to you for free and open access by the Journals at University of Minnesota Morris Digital Well. It has been accepted for inclusion in Journal of the Minnesota Academy of Science by an authorized editor of University of Minnesota Morris Digital Well. For more information, please contact skulann@morris.umn.edu. Occurence of Corbicula Manilensis Phillipi in the Lower Minnesota River STEVEN E. CUMMINGS* and JAMES A . JONES** ABSTRACT - On March 2, 1978, several empty shells of the fresh water clam, Corbicu/a manilensis Phillipi, were collected in the Minnesota River near the Blackdog electric generating plant in Burns-ville, Minnesota. Since this Asiatic species was first observed in America in 1935, it has spread into all major river systems of North America. Its northernly extension in the Mississippi River system was, however, thought to end in northeast Iowa and to exclude Minnesota. Occurence of this species is a potential liability because it often exerts a disruptive influence in the community that it invades. First observed in the state of Washington in 1938, Corbi-cula manilensis, introduced from Asia, has relentlessly in-vaded every major river basin in North America. Such rapid and widespread dispersal of a fresh water mollusk in North America is unparalleled (Clench). In the Mississippi River basin. this species first appeared in Lousiana and Mississippi. Having permeated the waters of southern United States, its range began to extend northward and soon included the upper Ohio River (Stein, Burch, as cited by Eckblad). In 1974 the clam was discovered in the effluent channel of a power plant at Lansing, in northeast Iowa (Eckblad). This northerly progression by C. manilensis was not surprising in light of its high reproductive capacity and tolerance of ex-treme environmental conditions. The clams' existence in Minnesota was not documented, however, until the summer of I 977, when several small shells were collected in the St. Croix River near Hudson, Wisconsin. They were found by researchers from the Philadelphia Academy of Science (Krosch). Most recently, C. manilensis was discovered in the Minne-sota River on March 2, 1978, at the Northern States Power Company's Blackdog electric generating plant near Burns-ville , Minnesota. The discovery was made by the Field Zoo-logy class of Macalester College. Eight empty half shells were collected by hand from silt substrate, within three meters of shore. One week later 42 additional empty half shells and one live specimen were retrieved at that site. Most of the shells were located along the margin of a small lake which receives the thermal effluent from the Blackdog generating plant and which discharges directly into the river by means of a small channel. Some specimens were also found in the channel, and a few were located slightly down-stream in the main body of the river. The shells varied in height from six to 44 millimeters; in age from one to five years. From the estimated ages of the collected shells, this clam apparently has lived undetected in Minnesota waters for at least four years. A plausible explanation for the lack of detection is that small specimens of C. manilensis are similar in appearance to native Sphariidae, and sometimes mistaken for them. Also, a significant mortality of C. mani-lensis may have ·occured recently, resulting in a greater a-bundance of empty shells deposited near shorelines. Other reports (Eckblad, Rodgers et al., Gardner et al., Krosch) indicate that C. manilensis has been found near electric generating plants elsewhere. Explanations include the possibility that the clam "hitch-hikes" on coal barges as *STEVEN E. CUMMINGS was a student at Macalester College in St. Paul at the time of the research project reported here. • *JAMES A. JONES is a professor in the Biology depart-ment at Macalester College. Journal of, Volume Forty-Four, No. 3, 1978 a means of dispersal. Thus, it is transported directly to these sites. Also, research indicates that water temperature , now rate, turbidity, and plankton density contribute significantly to the population dynamics of this species (Rinne). These factors may be more favorable in the vicinity of generating plant~. Bottom composition does not appear to be a limit-ing factor since C. manilensis has been found on highly varying substrate types. C. manilensis has often created a substantial economic and ecologic problem where it occurs. In fact, it is described as "currently the most costly liability of all exotic mollusks in North America" (Sinclair). Vast beds of this prolific organism are reported to have clogged steam condensers and conduits carrying untreated water (McMahon), and to have ruined sand or gravel substrate used in the production of cement (Sinclair). Furthermore, they are responsible for the decimation of endemic populations of other bivalves , thus threatening the ecological balance of the aquatic com-munity they invade (Gardner et al. ). The alarmingly rapid and widespread distribution of C. manilensis in North America is attributed to several factors . The larvae are incubated and released as free living pelagic veligers , whose dispersal is not restricted by dependence on a parasitic host (Sinclair). Also, the larvae may survive di-gestion by aquatic birds which carry them to new areas (Clench, Britton and Murphy). Man plays the most significant role in their distribution , however, by providing the clams with nationwide transpor-tation for use as food, fish bait, and aquarium novelties. Irrigation canals have been a source of overland transporta-tion in the southwest. Once established, this species has proven to be highly resistant to many environmental stresses. Furthermore, growth is rapid and sexual maturity is reached within a year. Factors such as these have aided C. manilensis in achieving a very expansive range. However, the limits of its expansion have yet to be realized. The extent to which Corbicula manilensis will become a liability in Minnesota waters remains to be seen. Therefore, further study of this clam in our fresh water communities is important, for it exists as an example of the potential con-sequences that may result from introducing a foreign species to a new environment. REFERENCES ANONYMOUS. 1973. Brief Communications. Malaco-logical Review. 6(1) . BRITTON, J.C. and MURPHY , C.E. 1977. New records and ecological notes for Corbicula manilensis in Texas. The Nautilus 91( 1). 13 REFERENCES (continued) BURCH, J.B. 1972. Freshwater Sphariacean clams (Mol-lusks: Pelecypoda) of North America. Biota of freshwater ecosystems identification manuel no. 3, Environmental Protection Agency, Washington, D.C. CLENCH, W .J. 1969. Corbicula manilensis (Phillipi) in lower Florida . The Nautilus. 84(1). ECKBLAD, J.W. 1975. The Asian clam Corbicula in the upper Mississippi River. The Nautilus. 89(1) . EMERSON, W.K. and JACOBSON, M.K. 1976. The Ameri-can Museum of Natural History Guide to Shells . New York . Knopf. GARDNER, J .A. Jr. , WOODALL, W.R. Jr., STAATS, A.A. Jr., and NAPOLI, J .F . 1976. The invasion of the Asiatic (Corbicula manilemis Phillipi) in the Al-tamaha River, Georgia. The Nautilus. 90(3). KROSCH , HOWARD. 1978. Personal Communication. McMAHON , R.F. 1977. Shell-size-frequency distributions of Corbicula manilensis Phillipi from a clam fouled steam condenser. The Nautilus . 91(2) RINNE, J.N. 1974. The introduced Asiatic Clam, Corbicula, in central Arizona reservoirs. The Nautilus. 88(2). RODGERS, J.H. Jr. , CHERRY, D.S., CLARK, J.R., DICK-SON, K.L., and CAIRNS, J. Jr. 1977. The invasion of Asiatic clam, Corbicula manilensis in the New River, Virginia. The Nautilus. 91(2). SINCLAIR, R.M. 1971. Annotated bibliography on the exotic bivalve Corbicula in North America , I 900-1971. Sterkiana. 43 . Space-Time in the Creative Process KATHLEEN COOPER• ABSTRACT - An inquiry about the nature of the universe and man's ability to perceive it : Do the concepts of time and space veil the realization of man's full potential and responsibility as a creative entity in a creative universe? A given star is said to be "a thousand light-years away." Is time equal to space or the opposite side of the same coin? Space is the distance between physical beings. Is time the distance between energy manifestations or spiritual occurr-ences? Speed shortens the time distance between physical objects, i.e., it shortens space. Speed also shortens the time between energy manifestations. Space trave1 causes the re-tardation of aging, and, if light traveled faster, the star would be less than "a thousand light years away." A star traveling fast enough would be immediately known. It would be no time and no space away. A physical object will fill up a given space if it is large enough. Can an energy occurrence fill up time if it is large enough? Are the acts of man, time being the distance be-tween these acts, minute manifestations of the all-encom-passing creative energy of the universe which in its "all" and unified in tensity knows no time, just as physical objects are part of the total physical world? In the equation E = M C2 the physical is an observable juncture between energy and energy. Physical objects are manifestations of temporally arrested energy. If matter travels fast enough (C2), the time between energy and energy is nothing, and the physical becomes nonexistent. Speed shortens time . Speed shortens space . And speed shortens the difference between energy and matter. •KATHLEEN COOPER, a teacher of German and English at Burnsville (Minnesota) Senior high school, received B.A. and S.S . degrees from the University of Minnesota and the M.A. degree from the University of Arizona. She has been employed at a Gymnasium in Essen, Germany, and has taught at the University of Arizona. 14 What is the creative process of the universe? -- A constant exchange of energy and matter, a giving of energy to form matter, a giving of matter to form energy. The exchange can take J?lace through speed or through the creative life process. The point where the exchange occurs knows no space or time. The physical and the energetic or spiritual are one. There are no physical characteristics or energy characteristics per se. There is only the "all," which undivided is the essence of both the spiritual and the physical. E(Matter spatially arrested in energy.) The moment of creation knows no time and no space. M(Energy temporally arrested in matter.) It is the essence of "all." Is the task of man to help direct the creative process? To help determine the balance between the material and the spiritual? Are space and time misleading and knowledge-limiting illusions? Is the "all" now? 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Occurrence of Corbicula manilensis Phillipi in the Lower Minnesota River

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Occurrence of Corbicula manilensis Phillipi in the Lower Minnesota River

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