Progress 10/01/02 to 09/30/08
Outputs
OUTPUTS: Our research has had an impact in the following ways: 1) I was invited to participate on an advisory board to Veolia Water Company, water providers for the city of Indianapolis, and the Indiana Blue-green Algal Task Force on the potential of a new, invasive blue-green alga (Cylindrospermopsis raciborskii) to produce toxic compounds in water supplies. I produced a new website to help water quality specialists identify this organism and a web-based publication on this and other toxic blue-green algae, both of which are available to the public. 2) Our research on the potential of a bacterium (originally isolated at Louisiana Tech University) to control Cylindrospermopsis was disseminated to lake managers and aquatic resource personnel via a publication in Lake and Reservoir Management. 3) Collaborations with the Army Corps of Engineers provided them with information on the potential of smokes and obscurants (used for signaling and obscuring troop movements) to contaminate aquatic environments, specifically algae and aquatic plants. This research resulted in a report to the Corps, which was the basis for a publication (submitted but not in press yet). 4) Collaboration with Dr. David Spencer at the University of California, Davis, resulted in recommendations to the rice growers of California on how to effectively manage algae that disrupt early rice growth. This information has been disseminated via talks at regional meetings and at meetings of the rice growers. 5) We tested a number of new synthetic chemicals to determine their potential to control problem-causing algae. This information was provided as confidential reports to industry. Some of this effort is disseminated to the public via my web publications and pond management meetings when new chemistry is introduced. 6) We completed a study of the potential of barley straw to control algae in ponds. The resulting web publication has broad distribution across the U.S. and is widely referred to by the public when deliberating the use of barley straw in their lakes and ponds. PARTICIPANTS: Individuals: Dr. David Spencer, USDA-ARS, University of California, Davis initiated the project to study the ecology and management of algae in California rice fields. Partner Organizations: USDA-ARS; Aquatic Ecosystem Restoration Foundation; BASF, Syngenta; Army Corps of Engineers Collaborators: Dr. H. L. Walker, Louisiana Tech University Training: Graduate students Lee Ann Glomski (M.S.), Kathryn Wilkinson (Ph.D.) and Clay Britton (Ph.D.); Undergraduate students Jennifer Dudash, Beth Vucolo, Ellen Knapke. TARGET AUDIENCES: Target audiences include the people of Indiana and the U.S. who deal with water quality issues, specifically those related to the management of nuisance algae. These people include managers of drinking water reservoirs and recreational impoundments, owners of lake properties and retention ponds, and commercial aquatic pesticide applicators. California rice farmers (through the California Rice Growers Board) benefited from our strategies for algae control. Much of our information has been disseminated through extension web publications (e.g. Aquatic Plant Management; Barley Straw for Algae Control; Fact Sheet on Toxic Blue-green Algae; Cylindrospermopsis and Pseudanabaena). I have given numerous talks and workshops on these topics. For example, in May 2008, I gave several talks to aquatic pesticide applicators at a symposium sponsored by the University of Florida in Coral Springs, FL. Since much of my time over the past 5 years was devoted to revising our textbook, Applied Weed Science (published July 2008), I believe this effort will impact substantial numbers of undergraduate and graduate students, particularly in the area of invasive plant ecology and management. PROJECT MODIFICATIONS: None.
Impacts
1) Our studies of the toxic blue-green alga Cylindrospermopsis raciborskii over a three-year period in a central Indiana lake confirm that both the growth of the organism and the production and germination of akinetes (the overwintering cells) are primarily regulated by water temperature. Rapid population growth occurs at 22-24 C (April to June in our study lake) and correlates with reported temperatures for akinete germination. Akinete formation, reported to occur at 15-25 C, starts in June and is completed by October. Peak populations of more than 100,000 cells/mL occurred only in those years when water temperatures were above 25 C. No toxin production was detected. 2) Our studies of a cyanolytic bacterium, which we tentatively identified as Lysobacter cf. brunescens, showed that it could effectively eliminate C. raciborskii populations at bacterial concentrations as low as 7.5 million pfu/mL in lake water. This finding, which has been published, offers the potential of substituting a biocontrol agent for the algicides (mostly copper-based) that are currently being used. 3) Our research also established background information needed to develop strategies for algae management in California rice fields. An example is that copper, the algicide of choice, binds significantly to straw residues in the fields, rendering it ineffective for algae control. One of our recommendations is that those fields with algae problems be permitted to burn their straw residues prior to copper application. 4) Our research with barley straw, which included a pond owner survey, suggests that the approach, both from our controlled studies and those obtained by users, is very inconsistent. Although we do not discourage the use of barley straw for those who wish to try it, we do not encourage its use or guarantee that it will work. We have not yet been able to pinpoint the reason for this inconsistency.
Publications
- Glomski, L. M., Wood, K.V., Nicholson, R. L. and Lembi, C. A. 2002. The search for exudates from Eurasian watermilfoil and hydrilla. J. Aquat. Plant Manage. 40:17-22.
- Spencer, D., Lembi, C. and Blank, R. 2006. Spatial and temporal variation in the composition and biomass of algae present in selected California rice fields. J. Freshwater Biol. 21:649-656.
- Spencer, D. and Lembi, C. 2007. Evaluation of barley straw as an alternative algal control method in northern California rice fields. J. Aquat. Plant Manage. 45:84-90.
- Flaherty, K. W., Walker, H. L., Britton, C. H. and Lembi, C. A. 2007. Response of Cylindrospermopsis raciborskii and Pseudanabaena limnetica to a potential biological control agent, bacterium SG-3 (Lysobacter cf. brunescens). J. Lake and Reservoir Management 23: 255-263.
- Ross, M. A. and Lembi, C. A. 2008. Applied Weed Science, including the Ecology and Management of Invasive Plants. 3rd ed., Pearson Education. 561 pp.
|
Progress 10/01/06 to 09/30/07
Outputs
OUTPUTS: We have three primary research projects: 1. We are trying to develop an inexpensive and rapid detection method for low cell populations of the toxin-producing cyanobacterium Cylindrospermopsis raciborskii using quantitative PCR (qPCR). Four strains (two from Florida and two from Indiana) of C. raciborskii and non-target cyanobacterial species have been compared using this method. In addition, monthly sampling of Lake Lemon, IN, a temperate lake infested with C. raciborskii, was completed. Controlled environment experiments were initiated to examine the differences (if any) between Florida and Indiana isolates, including a phylogenetic study. 2. We completed testing of new compounds for the control of noxious algae, with emphasis on the planktonic cyanobacteria, in water supplies. These included the ALS inhibitors bispyribac, imazamox, and penoxsulam, compounds that are close to EPA registration for water. 3. We have been working with Dr. David Spencer (USDA) at U. C. Davis
on the control of algae in seedling rice culture. We tested the ALS inhibitors plus two protox inhibitors on Nostoc, a cyanobacterium that we had isolated from rice fields previously. We also tested the potential of zinc sulfate to substitute for copper sulfate, the standard algicide treatment in California rice fields, which is not effective for the control of Nostoc. Since copper can be bound to organic materials, we also conducted tests to determine if copper is bound to the rice straw that is present in the fields at the time of flooding and planting.
PARTICIPANTS: Clay H. Britton, graduate student; Dr. Robert E. Pruitt, Purdue University; Dr. David F. Spencer, USDA, University of California, Davis; Dr. Michael D. Netherland, U. S. Army Corps of Engineers and the University of Florida, Gainesville.
TARGET AUDIENCES: U.S. and state agencies involved in water quality monitoring; municipal drinking water providers; California Rice Research Board and rice farmers; Indiana pond and lake users and managers.
Impacts
1. Results of our qPCR work indicate that we are able to accurately amplify and detect our four isolated strains of Cylindrospermopsis raciborskii. Furthermore, non-target cyanobacteria (e.g., Anabaena, Nostoc, and Microcystis) are not detected during the course of the reaction, showing that this assay is selective for the target organism. Based on dilutions of DNA, concentrations as low as 1000 cells/ml are detectable. However, work is continuing to verify and gain more sensitivity from the extraction method. The monthly sampling of the organism shows that its populations, as high as 1 million cells/ml, correlate best with highest water temperatures in late July and August. 2. Of the ALS inihibitor compounds tested, penoxsulam was the most effective for the control of cyanobacteria. The compound appeared to be relatively selective, affecting only one out of five tested green algae. However, the effect appeared to be algistatic rather than algicidal, and we concluded
that this product should not be labelled specifically for algal control. Temporary cessation of algal growth could be a beneficial outcome as a result of its use for the control of invasive underwater flowering plants. This information was helpful to the companies that are developing these products for the aquatics market. 3. Although the ALS and protox iinhibitors were somewhat effective in controlling Nostoc, the concentrations were generally higher than can be tolerated by rice seedlings. Therefore, we do not think they should be commercialized for this purpose. Zinc does seem to be a better algicide than copper, and field testing will be conducted to verify these results. Clearly, rice straw does bind to copper, thus lowering the amount that is available for algal control. Unfortunately, culture practices in California no longer permit rice straw burning, so this will be a problem as long as copper continues to be used.
Publications
- Spencer, D., Lembi, C., and Blank, R. 2006. Spatial and temporal variation in the composition and biomass of algae present in selected California rice fields. J. Freshwater Biol. 21:649-656.
- Flaherty, K. W., Walker, H. L., Britton, C. H., and Lembi, C. A. 2007. Response of Cylindrospermopsis raciborskii and Pseudanabaena limnetica to a potential biological control agent, bacterium SG-3 (Lysobacter cf. brunescens). J. Lake and Reservoir Management 23:255-263.
- Britton, C.H., Lembi, C. A., and Pruitt, R. E. 2007. A temperate lake study of the cyanobacterium Cylindrospermopsis raciborskii. Abstract (page 30) in Program for the 47th meeting of the Aquatic Plant Management Society, Nashville, TN, July 15-18, 2007.
- Lembi, C. A., Netherland, M. D., and Lubelski, D. D. 2007. Effects of the ALS inhibitors on algae. Abstract (page 41) in Program for the 47th meeting of the Aquatic Plant Management Society, Nashville, TN, July 15-18, 2007
|
Progress 10/01/05 to 09/30/06
Outputs
Research has continued developing an inexpensive and rapid detection method for low cell populations of the toxin-producing cyanobacterium C. raciborskii using quantitative PCR (qPCR). To date, primers and a probe have been created to specifically target one of C. raciborskiis nitrogen fixation genes (nifH). PCR conditions and primer/probe concentrations have been optimized to ensure qPCR efficiency and accuracy. Also, a DNA extraction protocol to obtain DNA from lake samples has been found. In addition to developing this assay, sampling of Lake Lemon, IN continued throughout the year. After C. raciborskii concentrations reached 1 million cells/ml in summer of 2005, cells were still present over the course of the winter and early spring months of 2006. During the summer of 2006 cells again showed bloom concentrations around 400,000 cells/ml. Filaments of C. raciborskii from Lake Lemon were isolated into unialgal culture and submitted to the University of Texas (UTEX)
Culture Collection of Algae. Additional research has been conducted on testing potential algicides as a substitute for copper. ALS-inhibitor and Protox inhibitor herbicides are being screened against a variety of cyanobacterial target species, with special emphasis on Nostoc spongiformae, a species that we have identified as being the major weedy alga in rice fields in California. Of the compounds tested, the Protox inhibitors, at concentrations greater than 500 ppb appear to provide significant control. Further testing in the field is now required.
Impacts
Our research has helped focus attention on a serious water quality problem, that of the toxic blue-green algae, particularly invasive species such as Cylindrospermopsis raciborskii. We seek to develop a rapid, inexpensive, and sensitive detection method using DNA primers and PCR that could be adopted by water utility and management companies. If cell populations can be detected before they reach bloom proportions, the insertion of a management method could be effective without causing perturbations to the environment (such as toxin release or oxygen depletion). We are also testing non-copper based herbicides to determine their ability to control problem blue-greens such as Cylindrospermopsis and Nostoc spongiformae. The latter is a problem alga in California rice fields.
Publications
- No publications reported this period
|
Progress 10/01/04 to 09/30/05
Outputs
We concluded a project to determine the efficacy of bacterium SG-3 (patent held by Dr. H. L. Walker of Louisiana Tech University) to control blue-green (cyanobacterial) algae. SG-3 was an effective algicide at low cell concentrations on important toxin (Cylindrospermopsis raciborskii) and taste-and-odor producing (Pseudanabaena) phytoplanktonic blue-greens. SG-3 acted as an algistat on mat-forming species such as Oscillatoria. The bacterium appears to have to make contact with the cyanobacterial cells in order to cause lysis; the slime produced by the mat-formers prevents cell access to the interior of the mat. Research has been initiated to develop an inexpensive and rapid detection method for low cell populations of C. raciborskii using real time PCR. Primers targeting a region coding for one of the nif genes were found to be specific to C. raciborskii. At this time extraction protocols to prepare DNA from lake water are being tested and optimized. In conjunction
with this study, water samples collected from Lake Lemon, IN in summer 2005 show bloom concentrations of C. raciborskii as high as 1 million cells/ml. It is clear that a method sensitive to only a few cells/ml is needed in order to initiate control measurements prior to bloom establishment.
Impacts
Our research has helped focus attention on a serious water quality problem, that of the toxic blue-green algae, particularly invasive species such as Cylindrospermopsis raciborskii. We seek to develop a rapid, inexpensive, and sensitive detection method using DNA primers and PCR that could be adopted by water utility and management companies. If cell populations can be detected before they reach bloom proportions, the insertion of a management method could be effective without causing perturbations to the environment (such as toxin release or oxygen depletion). We also now have a body of information on a potential biocontrol agent for Cylindrospermopsis, which, if future testing continues to show promise, could substitute for the current copper applications that are currently being made to infested bodies of water.
Publications
- No publications reported this period
|
Progress 10/01/03 to 09/29/04
Outputs
We focused on two projects this year. The first involves the testing of new non-copper based strategies for the control of noxious algae in water supplies. Using an algal bioassay screening procedure, we tested two organically-based herbicides and a bacterial product. The first herbicide, a triazinone, provided some control of certain types of algae but was weak on a major target group, the blue-green algae. The second, based on hydrogen peroxide, is a very effective contact material on most algae with the exception of certain mat-forming species in which penetration by any chemical is difficult to achieve. A bacterial product in which the bacteria presumably out-compete the algae for nutrients was not effective under the constraints of our screening procedure. We are currently testing additional compounds. The second area of interest is the continued study of the bacterium, SG-3 (patent held by H. Lynn Walker of Louisiana Tech University) to control blue-green algae.
We extended the number of susceptible species by showing that it controls Cylindrospermopsis, a toxin-producing blue-green that is spreading into the northern part of the United States. Our research suggests that SG-3 produces a toxin, and we are currently attempting to isolate and identify it.
Impacts
The biological control aspect of our program is intended to find an environmentally friendly method of controlling noxious cyanobacteria. The cyanobacteria are major water quality problems, and currently, they are controlled using copper compounds such as copper sulfate. Since copper is a heavy metal it is important to find a nonpersistent alternative.
Publications
- No publications reported this period
|
Progress 10/01/02 to 09/30/03
Outputs
We focused on two projects this year. In the first, we studied the potential of the bacterium, SG3 (patent held by H. Lynn Walker of Louisiana Tech University) to control mat-forming species of cyanobacteria. Our results show activity, as much as 90 to 100% control, on species of Oscillatoria, Lyngbya, and Phormidium. SG3 also shows excellent activity in controlling Pseudanabaena, a planktonic cyanobacterium that causes taste and odor problems in drinking water supplies. The second project is a study conducted in cooperation with the Construction Engineering Research Laboratory (U.S. Army Corps of Engineers) in Champaign, IL. We tested the effects of military smokes (red, green, and yellow grenades) and obscurants (fog oil and fog oil plus graphite) on the submersed aquatic plant, sago pondweed, and on the green planktonic alga, Selenastrum. The study was conducted at Edgewood proving ground in Maryland in May and August. Our results indicate that at the
concentrations and times used (up to 120 minute exposure) there were minimal negative effects on either the pondweed or the alga.
Impacts
The biological control aspect of our program is intended to find an environmentally friendly method of controlling noxious cyanobacteria. The cyanobacteria are major water quality problems, and currently, they are controlled using copper compounds such as copper sulfate. Since copper is a heavy metal it is important to find a nonpersistent alternative. Our research on the military smokes and obscurants is to help the Army fulfill its objectives of minimizing negative environmental impacts of its operations on endangered and/or native species. Although further testing may be necessary to determine long term impacts, our study suggests that in the short term, these compounds do not negatively affect aquatic plants or algae, which are the base of the aquatic food chain.
Publications
- No publications reported this period
|
Progress 10/01/01 to 09/30/02
Outputs
This year we have focused on the study of noxious cyanobacteria in Indiana waters. During a study of a major drinking water reservoir in Indiana, we discovered the presence of Cylindrospermopsis, a toxic planktonic cyanobacterium that has apparently invaded Indiana waters from the southern states. This is the first report of the organism forming blooms in drinking water supplies in a northern state. We have obtained cultures of the Florida strain of Cylindrospermopsis and have added it to our study of determining potential management approaches for this group of organisms. This year we tested the efficacy of several organic (non-copper based) compounds developed by industry to control target cyanobacteria and algae. Also, we are working with Dr. H. Lynn Walker at Louisiana Tech University to study a potential biological control agent for cyanobacteria. Our results with this organism on mat-forming cyanobacteria have been mixed, and we are in the process of determining
why results have varied. We are also developing growth curves for mat-forming cyanobacteria based on responses to light and temperature so that we can better predict the circumstances under which these organisms will occur and cause problems. We will continue to study these approaches on more cyanobacteria, including Cylindrospermopsis.
Impacts
Based on these and future studies, we hope to develop effective control methods for cyanobacteria that are toxic (e.g. Cylindrospermopsis), cause taste and odor problems (e.g. Pseudanabaena) and have negative visual and use impacts (e.g. mat-forming genera such as Oscillatoria) on bodies of water.
Publications
- Glomski, L. M., K. V. Wood, R. L. Nicholson, and C. A. Lembi. 2002. The search for exudates from Eurasian watermilfoil and hydrilla. J. Aquat. Plant Manage. 40:17-22.
|
Progress 10/01/00 to 09/30/01
Outputs
Research was conducted on the potential of the weedy invasive aquatic species Hydrilla and Eurasian watermilfoil to produce secondary metabolites. There have been reports of some aquatic plants releasing secondary metabolites into the water that might have ecological consequences, but the information on these two species has not been clear cut. Plant tissues and water samples were collected from laboratory cultures and pond populations. These samples were analyzed using solid phase extraction, HPLC, and various methods of mass spectrometry including electrospray ionization, GC/MS, electron impact, and chemical ionization. Previously reported compounds such as tellimagrandin II (Eurasian watermilfoil) and a caffeic acid ester (hydrilla), along with a newly discovered flavonoid, cyanidin 3-dimalonyl glucoside (hydrilla), were readily detected in plant tissues but were not detected in any of the water samples. Our experiments indicate that if compounds are being
released, as suggested by researchers using axenic cultures, they may be rapidly degraded by bacteria under natural growing conditions.
Impacts
Invasive plant species are thought to out compete native species because of growth forms that are more competitive, physiological characteristics that allow the invasives to take advantages of limiting growth factors, or reproductive characteristics. Aquatic invasive plants have similar characteristics; e.g. their growth form allows them to shade out native species. Evidence suggests that some invasives produce secondary compounds that are allelopathic; i.e. they release toxins into the soil or surrounding water that prevent the growth of potential competitors. It has long been thought that the success of hydrilla and Eurasian watermilfoil in aquatic systems is also due to allelochemical production. In addition, it was feared that released compounds could be carcinogenic to people using infested waters. Our research indicates that neither plant is releasing detectable secondary compounds into water. Therefore, these two invasive species appear to be extremely
successful without the production of allelochemicals. The potential for releasing carcinogenic or mutagenic compounds also appears to be minimal.
Publications
- Lembi, C. A. 2000. Relative tolerance of mat-forming algae to copper. J. Aquat. Plant Manage. 38:68-70.
|
Progress 10/01/99 to 09/30/00
Outputs
One possible alternative to the use of copper products for algae control is the use of forages, in which organic toxic compounds leach from the forage into the water and reduce the growth of the algae. Laboratory research showed (in 1998) that exudates from alfalfa hay could effectively kill target algal species. However, small scale research (in 1999) in the field was not able to duplicate these results. One problem may have been that we conducted the tests for only 30 day periods. In 2000, we conducted more small scale field tests that were allowed to run the whole summer. We compared treatments using barley, reed canarygrass, alfalfa hay, and alfalfa pellets that were applied on March 24. A second treatment was applied on July 10. No significant differences were observed in algae (as measured by chlorophyll) between barley and the untreated controls. In general, the alfalfa products caused an increase in algae populations. We initiated a second set of small scale
tests in large cylindrical aquaria in the greenhouse. These treatments consisted only of barley and untreated controls and were initiated on July 18. By mid-September, clearing of the planktonic algae was noted in the barley-treated aquaria. However, the barley had no effect on mat-forming algae. Our conclusions so far are that treatment with forages can provide algae control but that the effects may be inconsistent. The inconsistency may be caused by differential responses among algal species, but this remains to be verified. Other projects that were initiated this year include 1) a study of bacterial products which supposedly compete with algae for nutrients, thus reducing their growth, 2) a field and laboratory study of the environmental requirements and distribution of the cyanobacterium Oscillatoria spp., a mat-forming species that we previously showed has extremely high tolerance to copper, and 3) development of a bioassay for hydrilla tolerance to the herbicide fluridone.
Impacts
There is a tremendous interest among pond owners, lake managers, and regulatory agencies in the potential use of forages for algae control. Many sites have been treated. In some cases, the treatment has been effective; in others, it has been a complete failure. This has also been the case among researchers in other states. In Minnesota, barley seems to have controlled algae whereas in Nebraska it completely failed. Our studies have confirmed that control can be inconsistent. We have tried to document the algae that are not controlled using this method, but since so many algal species are involved in water quality work, it is as yet impossible to get a good handle on this. In November 2000, researchers (including myself) from across the U.S. who are working on this approach will meet and compare notes. If the results are mostly positive, then I will consider some pond tests in the summer of 2001. This summer we obtained pre-treatment data on algae and water quality
parameters at three pond sites, which will be the test sites for barley application next summer
Publications
- Liu, X. and C.A. Lembi. 1999. Laboratory evaluation of mefluidide effects on elongation of hydrilla and Eurasian watermilfoil. J. Acquat. Plant Manage. 37:55-60.
- Berry, H.A. and C.A. Lembi. 2000. The effect of temperature and irradiance on the seasonal variation of a Spirogyra (Chlorophyta) population in a midwestern lake. J. Phycol. 36:841-851.
|
Progress 10/01/98 to 09/30/99
Outputs
Our major research goals are to 1) document life cycle and environmental conditions that regulate the growth of weedy filamentous algae and cyanobacteria, and 2) to study the potential of non-copper based products to act as effective algicides. Although copper is a heavy metal and does not break down in the environment, it is widely used to treat municipal water supplies. A biologically derived compound that breaks down to harmless compounds is desirable as an alternative treatment. This year we quantified the relative tolerances of filamentous algae and cyanobacteria to copper. From least to most tolerant (with EC50s in ug-L Cu) are Spirogyra (1.0), Oedogonium (3.0), Pithophora (46), Hydrodictyon (48), Rhizoclonium (53), and the cyanobacterium Oscillatoria (290). The extreme tolerance of Oscillatoria, which is rapidly spreading in lakes and ponds across the midwest, is another reason for the need to develop an alternative algicide to copper. We conducted small-scale
field trials with barley, reed canary grass, and alfalfa to determine their algicidal properties. None were effective at the dosages tested (up to 0.4 g dry wt-L) on filamentous algae. Barley appeared to be effective in clearing the water of phytoplanktonic algae. These tests were only conducted for 30 day periods and will be repeated for longer time intervals next summer.
Impacts
There is no impact from this particular study yet. We do not want to make recommendations until we have completed our field tests, which will continue in the summer of 2000.
Publications
- No publications reported this period
|
Progress 10/01/97 to 09/30/98
Outputs
Our major research goals are to 1) document life cycle and environmental conditions that regulate the growth of weedy filamentous algae and cyanobacteria, and 2) to study the potential of non-copper based products to act as effective algicides. Although copper is a heavy metal and does not break down in the environment, it is widely used to treat municipal water supplies. A biologically derived compound that breaks down to harmless compounds is desirable as an alternative treatment. 1) What we thought was one species of the mat-forming cyanobacterium Oscillatoria causing problems in Indiana, Michigan, and Illinois has turned out to be a suite of at least 5 to 6 species. We continue to isolate these species into culture and collect data on their distribution. We found that this organism is extremely tolerant to copper treatments, more so than any other target alga. 2) We developed an algal bioassay that consists of 10 microscopic (4 cyanobacteria, 3 greens, 2 diatoms,
and 1 euglenoid) and 2 mat-forming (Pithophora and Spirogyra) algae. The bioassay was used to study the algicidal potential of 9 forages (bales of straw placed in bodies of water). In addition to barley (which is used as a control measure in England but has not provided consistent control here) alfalfa and reed canary grass had algicidal properties. Wheat and oats were ineffective in controlling algae. Euglenoid algae were tolerant to straw treatments, diatoms were extremely sensitive, and green algae and cyanobacteria were variably affected, depending on the species. We plan to conduct field trials next summer.
Impacts
(N/A)
Publications
- No publications reported this period
|
Progress 10/01/96 to 09/30/97
Outputs
Our major research goals are to document life cycle and environmental conditions that regulate the growth of weedy filamentous algae, and to study the potential of non-copper based products to act as effective algicides. Although copper is a heavy metal and does not break down in the environment, it is widely used to treat municipal water supplies. A biologically derived compound that breaks down to harmless compounds is desirable as an alternative treatment. This is a new project, and work was initiated this summer. We isolated the filamentous cyanobacterium Oscillatoria limosa into culture and have begun to collect data on its distribution in the state. We developed an algal bioassay that consists of 10 microscopic (4 cyanobacteria, 3 greens, 2 diatoms, and 1 euglenoid) and 3 filamentous (Pithophora, Oscillatoria limosa, and Spirogyra) algae. The bioassay was used to study the algicidal potential of pelargonic acid (a natural product derived from tallow and sold
commercially as a herbicide), but this product was not effective. We also are using the bioassay to study the algicidal/algistatic properties of forages. Bales of barley straw placed in bodies of water in England have been shown to be algistatic. Since barley is not grown in Indiana, we are testing 8 other forages common to this state to determine if they provide as effective an allelopathic effect on algae as barley. We soon will be initiating a study with researchers at the University of Hawaii to determine if extracts from cyanobacterial algae collected from around the world have algicidal properties.
Impacts
(N/A)
Publications
- No publications reported this period
|
Progress 10/01/95 to 09/30/96
Outputs
Our major research thrust is to determine the efficacy of plant growth regulators, specifically the gibberellin synthesis inhibitors (GSIs), in reducing (but not killing) aquatic weed growth so that it is available for habitat and oxygen production in aquatic systems. A major objective is to reduce the height of exotic weedy species such that they become more susceptible to competition from native species. In 1995, we determined that, in conjunction with GSI treatments, it may be possible to reestablish southern vallisneria (a native species) in a hydrilla (weed)-infested stand in deeper water where light is low but that this is less likely in shallow, well-lit areas. This year we conducted similar studies with a pairing of northern vallisneria (native) and Eurasian watermilfoil (weed) under conditions of low light. GSI-treated stands of vallisneria did not effectively out-compete and reduce stands of Eurasian watermilfoil under these conditions. The reason for the
difference may be the narrower leaf width on northern versus southern vallisneria, which provides less shading and canopy formation. Our studies also indicate that GSIs effectively reduce tuber formation in hydrilla, which is beneficial. Unfortunately, they also reduce tuber formation in sago pondweed, a species which has important wildfowl value. This is the first report of GSI effects on tuber formation in aquatic plants.(Lembi).
Impacts
(N/A)
Publications
|
Progress 10/01/94 to 09/30/95
Outputs
Our major research thrust is to determine the efficacy of plant growth regulators, specifically the gibberellin synthesis inhibitors, in reducing (but not killing) aquatic weed growth so that it is available for habitat and oxygen production in aquatic systems. We attempted to determine the route of uptake of one of these inhibitors, flurprimidol, into the weedy species, Hydrilla verticillata, but we had trouble getting consistent results due to poor growth of the plant in our experimental apparatus. We continue to try to improve our procedures. We completed a study using outdoor stock tanks to determine the competitive interactions among flurprimidol-treated plants. Under low light conditions, the treated native species Vallisneria americana, the height of which is not significantly reduced by flurprimidol, successfully dominated when grown with hydrilla, a species in which stem length is greatly reduced by flurprimidol. Under high light conditions, however, the
hydrilla growth was not significantly reduced by the presence of vallisneria. Therefore, it appears that in conjunction with flurprimidol treatments, it may be possible to reestablish vallisneria in a hydrilla-infested stand in deeper water where light is low but less likely in shallow, well-lit areas.
Impacts
(N/A)
Publications
|
Progress 10/01/93 to 09/30/94
Outputs
Our major research thrust is to determine the efficacy of plant growth regulators, specifically the gibberellin synthesis inhibitors, in reducing (but not killing) aquatic weed growth so that it is available for habitat and oxygen production in aquatic systems. We are currently attempting to determine the route of uptake of one of these inhibitors, flurprimidol, into the plant. Our first experiment indicates that flurprimidol is taken up by both the roots from the soil and the shoots from the water. We have also initiated outdoor stock tank systems to begin studying competition among flurprimidol-treated plants. Preliminary results suggest that Hydrilla verticillata, a very weedy, competitive plant but one that is greatly reduced in plant height when treated with flurprimidol, actually loses biomass when grown in combination with the treated native plant Vallisneria americans. Vallisneria is not as susceptible as hydrilla to flurprimidol and therefore can exert a
shading influence on hydrilla. These results may have important implications for the reestablishment of native species in hydrilla-dominated systems.
Impacts
(N/A)
Publications
|
Progress 10/01/92 to 09/30/93
Outputs
We completed a 3-year study sponsored by the Army Corps of Engineers to determine the potential of plant growth regulators as management tools for submersed aquatic weeds. We screened flurprimidol, uniconazole, paclobutrazol, amidochlor, bensulfuronmethyl, triclopyr, and imazapyr for growth regulating properties and found the first four to have the greatest potential for reducing plant stand heights. Flurprimidol, uniconazole, and paclobutrazol (gibberellin synthesis inhibitors) are particularly efficacious on hydrilla, whereas amidochlor is effective only on Eurasian watermilfoil. Exposure time/dose response tests with amidochlor suggest that at least a 7-14 day exposure at 500 ppb is required for effective height reduction, which may make it impractical to use this compound in flowing systems. We are now beginning a 3-year continuation which will focus on 14C-uptake of flurprimidol in plant-water-soil systems and competition studies of height-reduced hydrilla with
non-target species. We have initiated stock tank systems to begin these competition studies and preliminary results suggest that flurprimidol-treated hydrilla produce as much biomass as non-treated hydrilla and that the treated plants produce a more extensive stolon network on the sediment surface. These results will be useful in interpreting future competitive interactions.
Impacts
(N/A)
Publications
|
Progress 10/01/91 to 09/30/92
Outputs
We continued work on the use of gibberellin synthesis inhibitors (GSIs) as management tools for submersed aquatic weeds. The goal is to reduce plant height so that the plants are no longer weedy but retain useful properties such as oxygen evolution and fish habitat. We completed dissipation studies on three GSIs and found that time of persistence in the environment was (from greatest to least) paclobutrazol, flurprimidol, and uniconazole. Flurprimidol was screened against target and non-target (native) submersed species and had minimal effect on some important non-target species such as Vallisneria but maximal effect on hydrilla, an important weedy species. The effect of low light intensities (e.g. those at greater depths in a body of water) on GSI activity was investigated and found to have minimal impact on height reduction. We also have been studying strategies to reduce algicide contamination of algae-infested waters. In the laboratory we found that winter (cold
water, short daylengths) treatments of copper sulfate were as effective as summer treatments in controlling the growth of Pithophora, a weedy, difficult-to-control alga. Although this strategy needs to be verified in the field, it holds out the promise of reducing Pithophora biomass early in the season before it builds up to levels in the summer which are almost impossible to control except with extremely high dosages of copper.
Impacts
(N/A)
Publications
|
Progress 10/01/90 to 09/30/91
Outputs
Studies were continued on the potential uses of the gibberellin-synthesis inhibitors as management tools for submersed aquatic weeds. The idea is to reduce plant height so that the plants are no longer weedy but retain useful properties such as oxygen evolution and fish habitat. In small scale, outdoor tests, flurprimidol concentrations of 75 /M/g/L and 200 /M/g/L were effective in significantly reducing the plant heights of hydrilla and Eurasian watermilfoil, respectively, after only 2 hour exposure times. Height reduction after a 2 hour exposure was maintained for at least 28 days. Water, plant and sediment samples were collected for flurprimidol residue analysis. The compound has a short half-life in the water and plant at 9.1 and 9.9 days, respectively. Persistence is greater in the sediment with a half-life of approximately 264 days. Flurprimidol concentrations in Eurasian watermilfoil tissue of greater than 3-4 ng/g fr. wt. provided effective control. These
concentrations are approximately fifty fold less than those monitored in terrestrial plants. Our results suggest that flurprimidol may dissipate relatively rapidly from the water, and that it is either being retained by the plant at extremely low tissue concentrations or is being taken up from the sediments by the plant to provide relatively long term height reduction. These characteristics are desirable if we are to eventually use this group of compounds as alternatives to herbicide treatments in water.
Impacts
(N/A)
Publications
|
Progress 10/01/89 to 09/30/90
Outputs
Studies were continued on the potential use of gibberellin-synthesis inhibitors and other possible growth regulating compounds as management tools for aquatic weeds. Recovery experiments in field container studies with the gibberellin-synthesis inhibitor flurprimidol showed that only a 1 hour exposure was required for effective height reduction in hydrilla; however, 24 hour exposure was required for height reduction in Eurasian watermilfoil. Water, plant, and soil samples over a 4-week period were collected from flurprimidol-treated containers this summer and are currently being analyzed for flurprimidol residues with gas chromatography-mass spec. Other compounds tested for growth regulating properties in a laboratory bioassay were the herbicides bensulfuron-methyl, triclopyr, imazaquin, imazethapyr, and imazapyr. Only bensulfuron and imazethapyr appeared to have growth regulating properties. These properties were expressed only on Eurasian watermilfoil, not
hydrilla. Additional studies were initiated with R. Nicholson to determine the phenolic acid composition of hydrilla. Phenolic compounds are inhibitory to fungi; these studies are intended to develop base line data so that eventual inhibitors of phenolic acids can be developed to render hydrilla more susceptible to fungal attack. The major compound present in hydrilla is a caffeic acid ester that represents as much as 1/2 of the leaf dry weight.
Impacts
(N/A)
Publications
|
Progress 10/01/88 to 09/30/89
Outputs
Studies were continued on the potential use of gibberellin-synthesis inhibitors as a management tool for aquatic plants. Small scale field tests showed that these compounds were effective in reducing plant height in Hydrilla verticillata, Myriophyllum spicatum, Elodea canadensis, and Ceratophyllum demersum without adversely affecting physiological competence. Only a two hour exposure at 75 ppb was required to give a 6 week reduction in plant height in Hydrilla. Water samples were collected over the season and tested for gibberellin-synthesis inhibitor (specifically flurprimidol) residues using gas chromatography. Over the period between 5 June and 3 July 1989 the half life of flurprimidol at both 7.5 and 75 ppb in a static system was 6.8 days. Over the period 1 August and 9 October 1989 the half life of flurprimidol at 1 ppm in a static system was 15.9 days. This suggests that flurprimidol, which is highly susceptible to photodegradation, shows faster breakdown
under conditions of high light intensity and long days. Additional residue studies are being conducted on soil and plant tissue. In general, our study supports the idea that gibberellin inhibitors can be used to maintain aquatic plants at shortened (nonweedy) lengths but as functional components in the aquatic system for habitat and oxygen production. The residue studies suggest that these compounds will have minimal environmental persistence.
Impacts
(N/A)
Publications
|
Progress 10/01/87 to 09/30/88
Outputs
Effects of three plant growth regulators, paclobutrazol, flurprimidol, and uniconazol, on growth and physiological competence of Eurasian watermilfoil (Myriophyllum spicatum) and hydrilla (H. verticillata) in algal-free culture were investigated. All three compounds (inhibitors of gibberellin synthesis) reduced main and lateral stem elongation of both plants. Watermilfoil (7.5-7.5 (mu)g/L) was at least tenfold more sensitive than hydrilla (75-750 (mu)g/L). The compounds did not cause significant decreases in photosynthetic rates within these ranges. When treated plants were placed in fresh medium and allowed to recover over a period of 4 weeks, hydrilla resumed normal growth indicating gibberellin synthesis upon removal of the plant from the inhibitor, Milfoil, however, remained stunted for the period even when treated initially for only 24 hours. This suggests that these compounds will only be effective on hydrilla if biologically active concentrations can be
maintained through the growing season. In general, this study supports the idea of using gibberellin inhibitors as tools for aquatic plant management; i.e. maintenance of submersed aquatic plants at shortened (nonweedy) lengths but as functional components in the aquatic system for habitat and oxygen production.
Impacts
(N/A)
Publications
|
Progress 01/01/87 to 12/30/87
Outputs
Effects of plant growth regulators, specifically inhibitors of gibberellin synthesis, on growth of Eurasian watermilfoil (Myriophyllum spicatum) and hydrilla (H. verticillata) shoot segments in algal-free culture were investigated. Paclobutrazol was found to reduce main and lateral stem lengths at concentrations 7.5 ug/L and higher. Photosynthesis and respiration of hydrilla were minimally affected at concentrations as high as 750 ug/L. Small scale field tests on hydrilla verified laboratory results. Plant shoots after four weeks in paclobutrazol averaged 19 cm in length and growth was stoloniferous forming a thick "turf" over the sediment rather than vertical as in untreated controls (approx. length = 33 cm). This study supports the idea of using gibberellin inhibitors as tools for aquatic plant management: i.e. maintenance of submersed aquatic plants at shortened (nonweedy) lengths but as functional components in the aquatic system for habitat and oxygen
production. Research is continuing on required exposure times and duration of effect.
Impacts
(N/A)
Publications
|
Progress 01/01/86 to 12/30/86
Outputs
Seasonal variability in susceptibility to the algicide copper sulfate was studied using Pithophora oedoquonia, a copper-tolerant weedy mat-forming alga. Life cycle studies show high numbers of akinetes (spores) in the winter and early spring, akinete germination in May, and a build up of vegetative biomass in late summer. A field simulation study to determine the effects of copper was conducted using aquaria in a living stream and set at the temperature and light conditions at the time of mat collection. Copper-treated and untreated mats were compared for chlorophyll content after treatment periods of 1, 3, 7 and 14 days and a recovery period of 14 days. Pithophora was least affected by copper at the period of akinete germination. It was considerably more susceptible in June and July with tolerance increasing in late summer. Temperature and alkalinity effects were eliminated as possible causes of seasonal variability. Mat penetration studies indicated that copper
was not able to penetrate more than 2 cm into mats which often measure 10-12 cm in diameter. Results suggest that the best time to copper treat Pithophora is after akinete germination period and before biomass build up, i.e., July in Indiana. A second year's set of data is currently being evaluated.
Impacts
(N/A)
Publications
|
Progress 01/01/85 to 12/30/85
Outputs
A second year of runoff to determine nitrogen movement from erodible soils was conducted in 1985. Tillage treatments were no till and conventional plow system. Within each tillage treatment, 3 N-applcation methods plus an unfertilized control were used: 1) surface applied ammonium nitrate, 2) injected anhydrous ammonia, and 3) injected anhydrous ammonia with nitrapyrin. Water and sediment runoff was greater from conventional than no till plots under high rainfall conditions. Two year results suggest water runoff from no till areas are as high or higher than from conventional areas when the soil is dry. In both years the major contribution of no till was soil loss reduction. Movement of surface applied inorganic nitrogen was related to amount of water movement. Movement of NO(3) and NH(3) from injected and injected stabilized plots was minimal and not significantly different from that moving off untreated areas. Conversion from a conventional till surface applied
nitrogen system to a no till injected nitrogen system could lead to significant reduction in the growth of certain nusiance algae in receiving waters.
Impacts
(N/A)
Publications
|
Progress 01/01/84 to 12/30/84
Outputs
Runoff studies to determine inorganic nitrogen movement from erodible soils under different tillage and nitrogen application techniques were conducted in 1984. Tillage treatments were no-till and conventional plow system. Within each tillage treatment, three N-application methods were used: 1) surface applied ammonium nitrate, 2) injected anhydrous ammonia, and 3) injected anhydrous ammonia with nitrapyrin. A fourth set of plots was unfertilized. Runoff of water, NH(3), and NO(3) was greater from no-till than conventional till plots during the first rainfall of 1.5 inch. A greater nitrogen loss (coniciding with greater movement of filterable solids) was monitored from the conventional than no-till plots during a later rainfall of 2.5 inch. The only significant effect of N-application onN runoff was a greater NH(3) loss from surface applications. Use of the runoff data in conjunction with an algal growth model for our study watershed suggests that conversion from
a conventional till, anhydrous ammonia injected system to a no-till system with anhydrous injected alone or with nitrapyrin would lead to significant reduction in nuisance algal growth in receiving waters.
Impacts
(N/A)
Publications
|
Progress 01/01/83 to 12/30/83
Outputs
Results of simazine treatment for filamentous algae control are often variable. Culture studies were conducted to compare susceptibility to simazine for Pithophora oedogonita, Cladophora glomerata and Spirogyra jurgensii. Determinations of immediate photosynthetic response to simazine resulted in these I(50) (muM) values: Spriogyra, 1.1; Pithophora, 3.0; Cladophora, 3.8. This indicates that 3 to 4 times as much simazine is required to control Pthophora and Cladophora compared with Spirogyra. Algae exposed to 5 muM simazine for 18 days were transferred to medium without herbicide and photosynthetic rates measured. Photosynthetic rates of Spirogyra and Cladophora were reduced by 54 percent. In contrast, Pithophora exhibited a 75 percent increase in rates relative to controls. Biomass measurements indicated that at low to moderate light intensities (15 to 100 mueinsteins mEysEPG) 5 muM simazine was algistatic to all species but produced no phytotoxic effects even after 45
days. Biomass of Spirogyra was educed 100 percent at 400 muinsteins mEysEPG after 14 days. Pithophora biomass was reduced by only 35 percent at this light intensity. High light intensity requirements for algicidal action may explain why effective, long-term control is sometimes not achieved for filamentous green algae that grow in turbid water and/or form dense mats. In addition, certain species (Pithophora and Cladophora) are more tolerant of simazine.
Impacts
(N/A)
Publications
|
Progress 01/01/82 to 12/30/82
Outputs
A model to describe the seasonal abundance of the weedy filamentous alga Pithophora oedogonia has been constructed. The model uses a Monod function to describe algal growth rates as a function of external nutrient concentration. Temperature effects on growth are included by incorporating regression equations that relate the Monod parameters, K(s) and u(max) to temperature (10-30 C.) Data on the intracellular concentrations of N (X = 14.5%) and P (X = 1.4%) were measured on Pithophora samples collected from Surrey Lake, IN during 1978-80 and are used in a second equation that describes nutrient dynamics resulting from algal growth. In general, model predictions agree well with levels of Pithophora observed in the lake in 1979 and 1981. The model can be used to determine the level of nutrient reduction required before a marked decrease in Pithophora growth can be expected.
Impacts
(N/A)
Publications
|
Progress 01/01/81 to 12/30/81
Outputs
Studies are being conducted on the susceptiblity patterns of weedy filamentous green algae to algicides in order to develop timely and appropriate management techniques. The resistance of the difficult-to-control alga Pithophora is greatest at the time of akinete (spore) germination (I(100) = 8uM Cu + +). Ungerminated akinetes are more susceptible (I(100) = 4uM Cu + +) and filaments are the most susceptible (I(100) = 1uM Cu + +). These findings have forced a reevaluation of standard herbicide recommendations which usually call for treatment with algicides such as copper sulfate in the late spring and early summer as waters warm to 20 C, a period which coincides with maximum akinete germination. The effects of diquat on the organism are not related to stage of growth but rather to water temperature and amounts of suspended sediments in the water. A 15 day exposure to 5 uM simazine resulted in a 50% reduction in photosynthetic capacity of Spirogyra and Cladophora
but had no detrimental effect on Pithophora. Results of long term (47 day) exposure indicate that simazine is an effective algistatic compound but has no apparent algicidal effect on Pithophora.
Impacts
(N/A)
Publications
|
Progress 01/01/80 to 12/30/80
Outputs
Studies were continued on the difficult-to-control, mat-forming green alga, Pithophora, with emphasis on the factors regulating its seasonal and spatial distribution in lakes in order to 1) develop timely and appropriate management techniques and 2) serve as a basis for studying other weedy filamentous algae of which little is known. Peak abundance of Pithophora biomass in an Indiana lake occurs in late summer and is associated with photosynthetic rates which increase from early spring to a maximum of 31.5 mg O(2)/g dry wt/hr in September. A portion of the vegetative filaments with akinetes (spores) makes up the overwintering population and is still photosynthetically competent with O(2) evolution rates of 2.33 mg/g dry wt/hr when measured in December. Tests with a commonly used algicide, simazine, show reduced initial rates of photosynthesis; however upon removal of the alga from simazine treatment, even after 14 day exposures, photosynthetic rates rapidly recover
to control rates. Simazine does not appear to be an effective algicidal material for Pithophora control. Spatial distribution of the alga in the study lake indicates a high nutrient requirement. Half-saturation constants (K(s)) at 20 degrees C relating filament growth to external concentrations of Nitrate-N is 1.23 mg 1 - 1 and for phosphate-phosphorus, 0.1 mg 1 - 1. This type of information is currently being expanded to develop water quality standards for local and state agencies to use in the control of this alga.
Impacts
(N/A)
Publications
|
Progress 01/01/79 to 12/30/79
Outputs
Growth studies of the difficult-to-control filamentous alga Pithophora show thatat 20C, growth rates exhibit saturation kinetics when compared to external NO(3)-N or PO(4)-P concentrations. The half saturation constant (K(s)) for NO(3)-N was 88 uM and 3.22 uM for PO(4)-P. The maximum growth rates were 0.15 doublings/day. Ammonium uptake and alkaline phosphatase activity in field collected algae showed that Pithophora growth is more often limited by nitrogen availability than by phosphorus availability. Other conclusions from this study are that akinete (spore) formation is stimulated by nutrient depletion and by gradual desiccation and that summer drawdowns are not effective for the control of the alga partly because of the increased production of akinetes. A 2-year field study on fluridone (0.5 ppm) as a potential aquatic herbicide was completed. Submersed plant control was most rapid (30 days) when treatment was made in early May on young plants rather than
later in the season. Although dissolved oxygen decreased initially, the lowest mean value (means of the depth readings) obtained in the 5 study ponds was 2.5 ppm. No changes in water hardness, pH, phosphorous or nitrogen were noted. An increase in alkalinity was the only consistent water chemistry change other than DO. No adverse effects on zooplankton or benthic invertebrates were found.
Impacts
(N/A)
Publications
|
Progress 01/01/78 to 12/30/78
Outputs
Research focused on the physiology, life cycle, and ecology of the herbicide-resistant green, filamentous alga, Pithophora. Resistance to the algicide copper sulfate is due to the presence of akinetes (spores). At the highest allowable use rate of copper sulfate in water (4 mg/1), 80% of the akinetes survive whereas only 20% of the filamentous cells survive. Copper is sorbed by the outer layers of the cell wall and exchanged with calcium, magnesium, and zinc ions. Using a silver reduction cytochemical technique, copper was shown to remain in the cell walls and not move into the cytoplasm of akinetes. Cell wall analysis showed that the major polysaccharides are cellulose and chitin; this is the first report of chitin in a green alga. A procedure (involving KOH hydrolysis and OsO(4) postfixation) was developed to selectively stain chitin for light and electron microscopy. Field research centered on periodicity of akinete formation. Akinete numbers plunged from
24,000 akinetes/g alga in mid-May to a low of 300/g by mid-June. Of the parameters measured, akinete germination correlated best with an increase in water temperature. Akinetes tolerate freezing, freeze-thaw cycles, long term storage, high temperatures, and anaerobic conditions. We anticipate that summer drawdowns of ponds would not significantly reduce Pithophora infestations; winter drawdowns would be effective only where prolonged periods of freezing and thawing could be insured.
Impacts
(N/A)
Publications
|
Progress 01/01/77 to 12/30/77
Outputs
This report summarizes the completion of a 2 year study on the effects of grass carp (Ctenopharyngodon idella) Val.) on small pond environments. Grass carp rapidly consumed all aquatic vascular plants. Dissolved oxygen in grass carp ponds remained high as long as bottom growths of the filamentous green alga, Spirogyra sp. were present, but consumption of this alga in addition to vascular vegetation led to significantly lower oxygen concentrations in the water directly above the sediments. The most affected parameters were turbidity and potassium, both of which were significantly higher in grass carp ponds. However, turbidity levels decreased to control levels at the end of both study years. Increased turbidity was not caused by plankton blooms but by particulate organic material and suspended sediment. Phytoplankton consisting primarily of dinoflagellates was not significantly affected by grass carp introduction although numbers were higher in grass carp ponds
than in control ponds in 1975 and lower in 1976. The decrease in 1976 may have been due to nitrogen limitation since both ammonia and nitrate levels were extremely low. Zooplankton showed a significant increase in grass carp ponds over control ponds in 1975. Benthic invertebrates increased in grass carp ponds in both study years and is reflected by the fact that they represented a larger proportion of sport fish diets toward the end of each season.
Impacts
(N/A)
Publications
|
Progress 01/01/76 to 12/30/76
Outputs
Persistence studies on a water-soluble blue dye used in aquatic weed control show that the dye is removed from solution primarily through photodegradation with a dissipation rate following first-order kinetics. The clay fraction of soil also removes the dye from solution, but it is not readily susceptible to microbial degradation or absorption by aquatic plants. Field studies indicate that the dye can be efficacious on filamentous algae as well as submersed weeds provided the algae are lying on the pond bottom at the time of application. Efficacy studies on experimental aquatic herbicides show Velpar, Vel 5026, and Stauffer 24191 to be broad-spectrum and slow-acting (2-3 weeks) and are similar to simazine in their activity. Data is presently being analyzed at the conclusion of a 2 yr. field study on the weed-eating fish, the white amur, and will be available for circulation mid-summer, 1977. Laboratory studies on the difficult-to-control filamentous green alga,
Pithophora, show that the akinetes (spores) are more resistant to copper herbicides than vegetative cells with 25% survival at 16 ppm CuSo(4). Akinetes also survive freeze-thaw cycles (7% survival after 5 cycles), can germinate in the dark, and show long-term survival(50% survival after 5 mths. dark storage at 4mC). Field observations indicate that akinetes are present year long but increase in the fall from a low count of30,000 akinetes/g wet wt. to 67,000/g by December. These studies, along with productivity and limiting nutrient determinations, will be continued in 1977.
Impacts
(N/A)
Publications
|
Progress 01/01/75 to 12/30/75
Outputs
Studies on herbicidal and non-herbicidal methods of aquatic weed control included 1) efficacy of the herbicide simazine and effects of simazine-treated irrigation water on mixed plantings, 2) use of a water-soluble blue dye (Asquashade) and 3) studies of the herbivorous fish, the white amur. Simazine was an effective control agent for a wide range of aquatic plants including algae, elodea, and the difficult-to-control watermeal and duckweed. The herbicide is slow-acting and did not cause oxygen depletion problems. Simazine-treated pond water (0.5 ppm) did not cause injury to bluegrass, bentgrass, 7 ornamental and 7 vegetable species including tomatoes. Aquashade was found to be efficacious only in ponds without outlets. Half-life of the material was 2 months. One factor causing loss was absorption to suspended soil,primarily the clay fraction. The dye caused growth reduction in 5 plant species including elodea and sago pondweed. However, watermilfoil was not
affected by the dye and at low dye concentrations, milfoil growth was stimulated over that of the control. Aquashade was found to have minimal effects on plankton. Preferred foods of the amur included several Potamogeton species and Chara while filamentous algae were least preferred but were eaten. Fish stocked at the15-20 cm size did not survive field tests (in mixed species culture) whereas larger fish did. Studies with the fish toxicant, rotenone, showed the amur to have the same susceptibility as largemouth bass
Impacts
(N/A)
Publications
|
Progress 01/01/74 to 12/30/74
Outputs
Field results based on plotwork in Indiana farm ponds include: glyphosate is the most effective chemical to date for the control of spatterdock; 1 treatment is more efficacious than 2 treatments of silvex, from tests on cattails, spatterdock and reed canary grass, glyphosate is most effective on the latter 2 plants, pelleted slow-release formulations of copper sulfate are effective for early season control of filamentous algae, simazine has a slow action on the difficult-to-control alga Pithophora, but is more efficacious than any other aquatic herbicide. Studies conducted on the difficult-to-control species watermeal, show that the plant is induced to form resistant spore-like bodies byherbicides and that the spores will not germinate until placed in fresh media without herbicides. Herbicide sensitivity differs among species of watermeal; ultrastructural studies show that the most effective chemical for its control destroys both meristematic and vegetative portions
of the plant whereas less effective herbicides affect only the vegetative portion. Other studies were conducted on the flagellar ultrastructure of unicellular algae and support current theories on evolution and relationships among the green algae.
Impacts
(N/A)
Publications
|
Progress 01/01/73 to 12/30/73
Outputs
The correlation between herbicide effectiveness and timing of application for aquatic weed control was determined. Herbicides for higher plants can be applied in Southern Indiana ponds throughout the month of May whereas Northern Indiana ponds should not be treated until late May. Algae can be effectively controlled using spot treatments as early as April. New herbicides showing potential for aquatic weed control include simazine for submersed weeds and Chara, Pennwalt's TD1929 for submersed weeds, and glyphosate for perennial weedssuch as cattails and spatterdock. Correlative studies on the life cycle and control of the difficult-to-control aquatic weed, watermeal (Wolffia), indicate that herbicides are best applied when the plants are in the single or unbudded stage. Indoor studies on the white amur (Ctenopharyngogon idella), a potential biological control for aquatic weeds, show that the fish eats all common Indianaweeds and is extremely sensitive to the fish
toxicant, rotenone. On the negative side, it readily eats animal material and releases plant nutrients intothe water through defecation. Other projects were also carried out on the ultrastructure of the flagellar apparatus of a unicellular green alga and on theeffects of 2,4-D on unicellular algae.
Impacts
(N/A)
Publications
|
Progress 01/01/72 to 12/30/72
Outputs
I initiated a number of field and greenhouse plots to test the efficacy of various aquatic herbicides, both those now cleared for use and those still in the experimental stage. The most promising herbicides for our major nuisance alga, Pithophora, appear to be repeated applications of CuSO(4) and diquat-copper combinations. Studies on the life cycle of water meal (Wolfia sp.), a major vascular aquatic weed, show that the budding process peaks around the noontime hour while the unbudded plants are prevalent during the early morning hours. Unbudded plants were found to be more sensitive to diquat than budding plants; thus effective treatment may be best achieved during the early morning period. An algal culture collection was established, and research is now underway to isolate the plasma membranes from algae resistant or susceptibleto certain herbicides. A permit has also been obtained from the Indiana Fish and Game people to import and study the white amur fish, a
possible biological control for aquatic weeds.
Impacts
(N/A)
Publications
|
Progress 01/01/71 to 12/30/71
Outputs
During this 6 month period I initiated a field testing program for evaluating herbicides on aquatic weeds. There appear to be several problem species in Indiana (Naiads, water meal, Pithophora) which are relatively tolerant to commonly used aquatic herbicides while other species (curly-leaf pondweed, duckweed) are only temporarily controlled. These species will be the subject offuture field and laboratory investigations. Greenhouse facilities for growing aquatic weeds and an algal culture collection are presently being developed. Collaborative studies demonstrated the production of a genome-altering factor byisolated plant membranes exposed to the growth regulator herbicide, 2,4-D. Thiseffect may explain the pronounced nuclear responses by certain plant species to auxin herbicides.
Impacts
(N/A)
Publications
|
|