Cabomba Caroliniana: Viability And Regeneration Of Fragments

Write a concise summary of the research aims, expected outcomes, and overall significance of the research. 

Aims
Describe the aims of the project. Ensure that you show how the planned research addresses a current research question.

Background/Literature Review/Significance
Include in this section information about the current understanding of the field of the research based on published literature, and the relationship of this proposal to work in the field generally. Preferentially refer to refereed papers that are widely available. Make sure that you cite the literature appropriately. Detail the significance of the research and describe how the anticipated outcomes advance the knowledge of the discipline. 

Research plan, methods, and timetable
Outline how the research will be carried out and which existing or new methods are applied. Show how the research plan and methodology will address the aims of the project. Detail the conceptual framework, design, and methods, and demonstrate that these are adequately developed. Prove that your approach is feasible and achievable given the time and logistic constraints of the time line of your project. Include a timetable detailing when the research activities are performed. 

Cabomba caroliniana is an invasive aquatic plant that is native to America, as well as to China, Japan and Europe. The aquatic plant has a national significance and high potential to expand further. It has been found that there is an urgent need to develop effective control strategies in order to manage the existing populations and further spread of Cabomba (Bruckerhoff, Havel & Knight, 2015). The study is designed in order to examine the Cabomba fragment persistence in substrate and identify effective control strategies. In this regards the study will investigate the viability and survival of Cabomba caroliniana fragments buried in substrate for an extended periods of time. In addition the study will carry out an experiment in order to examine the effect of desiccation time and burial depth on regeneration of fragments. It will help to recognize the minimum desiccation periods in order to prevent the regrowth of the Cabomba after refilling the water bodies and will help to develop efficient control strategies.

Aim and Significance of the project:

Aims: The research aims to-

1. Measure the effects of desiccation time and the moisture content of the soil on the viability and regeneration of Cabomba
2. Measure the effect of burial depth on Cabomba

Significance: The study will measure the survival rate of the Cabomba fragments that are buried in the different moisture containing substrate, impact of burial depth and desiccation period. The artificial environment created in the laboratory will help to determine the minimum desiccation periods in order to prevent the regrowth of the Cabomba after refilling the water bodies and will help to develop effective control strategies as well.

Cabomba caroliniana has been identified as one of the world’s most invasive aquatic plants that is native to South and North America. In addition the invasive aquatic plant is native to other parts of world such as, USA, China, Japan, Canada and many parts of Europe. It is considered as s weed of national significance in Australia (Bickel, 2012). The aquatic plant has high potential for expansion. The aquatic plant is commonly known as Carolina fanwort, green Cabomba, Washington grass, Carolina water shields and fanwort fish grass. Cabomba is found to be grown in the mud of stagnant to  slow flowing water for example, ditches, sloughs, ponds, lakes, streams and small rivers. In some areas of United States it has been found that Cabomba is grown as weed (Vukov et al., 2013). The stems become brittle in later summer that causes the invasive aquatic plant to break part, thus, facilitates its invasion and distribution in the new water bodies. It has been found that vegetative reproduction is one of the most important vehicle that helps the aquatic plant in order to spread to new water bodies. Research has indicated that the aquatic plant has the potentiality of growing 50mm in a day. In some areas of United States the aquatic plant is used as food and it has been found that there are some commercial use of Cabomba in Asia and some other countries (Bickel, 2012).

Aims and Significance

However, there are some problematic outcomes of invasive aquatic plants such as Cabomba caroliniana. It has been found that Cabomba has the potentiality to reach high density has tendency to change the physical and chemical environment. It reduces the diversity of native plants, invertebrates and fish. In addition such invasive aquatic plant interfere with the boating and swimming as well. Thus, leads to high economic impact, for example, excessive decline in the value of the property and high costs for controlling the species (Matthews et al., 2013). Research has identified that invasive aquatic plant such as Cabomba is difficult to eradicate if established once as it has the high potentiality to reach nuisance density. Thus, there is an urgent need to control the growth of Cabomba and introduce effective control strategies (Bickel et al., 2015).

Many studies has identified that invasive aquatic plants introduce several life history traits as a response to the environmental restraints. One of the important structuring forces of invasive plants is disturbance and some models have been found which predicted that invasive plants contains plant strategies in disturbed habitats. Such models has indicated that the ability to regenerate or recover from the disturbance is the major factor that play an important role in population maintenance of invasive aquatic plant such as Cabomba caroliniana (Barnes et al., 2013). Some general views of research have indicated that regeneration of Cabomba is facilitated through sexual propaguels. Some other studies have shown that high regeneration rate and seed production is related to the vegetative reproduction, extensive bud and propagule formation. It is quite difficult to understand that which reproduction process lead to the high regeneration rate of Cabomba as both the vegetative and sexual reproduction is used by the particular invasive aquatic animal and there are poor development of research related to regenerative strategies (Julien, McFadyen & Cullen, 2012). However, some studies has considered clonal growth as one of the most common regenerative strategies along with some vegetative diaspores in invasive aquatic plants, whereas, the sexual reproduction plays minor roles in such process. On the other hand, it has been considered that vegetative reproduction favors the invasive aquatic plants in case of scouring floods due to the uncertainty of sexual reproduction (Bickel et al., 2017).

It has been indicated by studies that, there is no available biological control option for controlling the growth of Cabomba. However, only one registered herbicide is available but the use of this herbicide is limited (Huang et al., 2017). Lake drawdown has been used as the effective control process of the growth of Cabomba (McCracken et al., 2013). In this regards experiment has been done in the Lake Benalla. Lake Benalla is an ornamental artificial lake that was formed by the impoundment of the Broken River behind the Benella weir. In the lake. Water level was maintained at a level so that it could cover the height of approx. 17ha. The bed of the river was relatively swallow and flat. The average depth of the lake was 1.5m and the maximum depth was 3.3m. The lake was incised by the two other former river channels. It has been found that Camboba has occupied the lake by reaching the beds of the lake in every area with the closed canopy surface between the depths of 0.5m to 2m. The average biomass of the Camboba in this lake was found to be 200g dry weight/m² approximately. Then, the lake was subjected to the winter drawdown in order to expose the Cabomba to the freezing conditions for overnight frost with the aim of killing the species in an effective manner. Almost all areas of the lake was drained of surface water except the remnant river channels. It has been found that major part of the bed of the artificial lake remained muddy. However, it was very unfortunate that the frosts of the lake were not that much severe or frequent during the time of drawdown. The local observation has indicated that minimum two heavy frosts has occurred in the lake during the period of drawdown and two light frosts were found. The final result of the drawdown in order to control the growth of the Cabomba has indicated that the idea of drawing down the lake for an entire winter was unable to achieve the long term control (Dugdale et al., 2013).  This is because the weed of Cabomba has grown again when the lake was refilled with water. Research has indicated that Cabomba stems that were underlying standard vegetation did not dry out sufficiently. It has increased the potentiality of the Cabomba to regenerate in an effective manner (Schooler, Cabrera-Walsh & Julien, 2012). Many aquatic weeds predominantly reproduce through regeneration of stem fragments, but there is little knowledge on the survival rate of stem fragments which are buried in the substrate. Thus, managers can’t estimate minimum draw down periods to manage aquatic weeds (Hussner, 2012). Thus, it can be said that strategy for controlling the growth of Cabomba through drawing down lake is not effective at all and further effective strategies need to be developed in order to reduce the negative impact of the invasive aquatic plant such as Cabomba (Day et al., 2014).

Challenges and Current Strategies

It has been found that the most common reason of global decline of biodiversity is invasions. It leads to the homogenization of ecosystem. Aquatic plants have been identified as the most alien invasive species worldwide and it has significant economic, social and ecological impacts (Hussner, 2012). Thus, in order to control the growth of the invasive aquatic plant such as Cabomba it is important to consider the dispersal of invasive organisms which is the initial stage of multi-layered invasion process in the invasive plants and effort needs to be provided focusing to the dispersal of invasive organisms (Bickel, 2015). It has been found that research has ignored the importance of dispersal in the invasion process. The pathways related to dispersal helps to shape the invasive potential and play an important role in influencing the propagule pressure in the invasive aquatic plant such as Cabomba, thus helps to increase the success rate of establishment. It has been recognized that managing the dispersal pathways especially the unintentional transport through boating can be proved effective in case of invasive aquatic plants in order to understand the process of dispersal of such plants in the landscape. Such effort related to understanding the dispersal process would help to introduce effective control strategies. Thus, it can be said that in order to control the invasive aquatic plants such as Cabomba, understanding the factors that influence the dispersal rate is most important (Julien, McFadyen & Cullen, 2012). One of the major factor that has been identified during research is recreational boating. It has been considered as the one of the most important vector of spreading invasive aquatic plants. The reason is, most of the macrophytes easily attach to the trailers or boats and the boaters visit different lakes over a short time period. The invasive aquatic plants produce seeds faster through the vegetative reproduction and plant fragmentation. These fragments resulted in the new population. Furthermore, vegetative propagules also spread in the lakes. In this way the invasive aquatic plants successfully establish their population through boating (Bickel, 2015). However, the rate of viability and regeneration depends on the climatic conditions such as exposure to drying conditions and the time period for which the boaters leave their boats out of the water. The moisture content of soil is also an effective factor that contributes to the growth of invasive aquatic plants. In addition, it has been found that in the regions where the density of lakes is high, fragments of the plants spread more effectively. Thus, it is important to focus in the dispersal pathway of invasive aquatic plants in order to introduce effective interventions to control the growth of Cabomba (Barnes et al., 2013).

Dispersal and Boating

Furthermore, research has indicated that Cabomba could be controlled through lowering water levels and subsequent desiccation of stranded Cabomba (Bruckerhoff, Havel & Knight, 2015). This project will focus on the survival of the stem fragments that are buried in substrate for various time frames and substrate depths. It is expected that findings from this project will allow more efficient control of Cabomba in the future.

In order to examine the persistence time frames, the fragments of Columba will be maintained in a predetermined moisture containing soil under controlled climatic conditions before planted in the aquaria for a range of time frame. In order to experiment the burial death, plants will be buried in various depth in pots and cultured in aquaria in order to measure the subsequent regeneration and growth. The experiment will be done in the following method-

1. Fragments will be placed in pots with a known moisture containing substrate (to be determined from the field data) and then stored in a stable climatic condition for a range of tome frame (from 0 to 100 hours).
2. After that the pots will be placed in an aquarium. The temperature of the water will be maintained at 25⁰c and the pH will be regulated at 6.5 through CO₂injection in order to create ideal condition for the growth of Cabomba. Light will be supplied for 12 hours a day through the aquarium LED lights.
3. The pots will be placed randomly in the aquarium following the Completely Randomized Design and the pots will be monitored weekly in order to shoot emergence in an effective manner.
4. At the end of the experiment, dry mass, shoot density and the length of the shoot will be measured in order to establish the result.

References:

Barnes, M. A., Jerde, C. L., Keller, D., Chadderton, W. L., Howeth, J. G., & Lodge, D. M. (2013). Viability of aquatic plant fragments following desiccation. Invasive Plant Science and Management, 6(2), 320-325.

Bickel, T. O. (2012, October). Ecology of the submersed aquatic weed Cabomba caroliniana in Australia. In Eighteenth Australasian Weeds Conference, Melbourne (pp. 8-11).

Bickel, T. O. (2015). A boat hitchhiker’s guide to survival: Cabomba caroliniana desiccation resistance and survival ability. Hydrobiologia, 746(1), 123-134.

Bickel, T. O. (2017). Processes and factors that affect regeneration and establishment of the invasive aquatic plant Cabomba caroliniana. Hydrobiologia, 788(1), 157-168.

Bickel, T. O., & Schooler, S. S. (2015). Effect of water quality and season on the population dynamics of Cabomba caroliniana in subtropical Queensland, Australia. Aquatic Botany, 123, 64-71.

Bruckerhoff, L., Havel, J., & Knight, S. (2015). Survival of invasive aquatic plants after air exposure and implications for dispersal by recreational boats. Hydrobiologia, 746(1), 113-121.

Day, C., Petroeschevsky, A., Pellow, B., Bevan, J., O’Dwyer, T., St Lawrence, A., & Smith, G. (2014). Managing a priority outlier infestation of Cabomba caroliniana in a natural wetland in the Blue Mountains, NSW, Australia–could this be eradication. In Draft paper to 19th Australasian Weeds Conference, Hobart, Australia.

Dugdale, T. M., Butler, K. L., Clements, D., & Hunt, T. D. (2013). Survival of cabomba (Cabomba caroliniana) during lake drawdown within mounds of stranded vegetation. Lake and reservoir management, 29(1), 61-67.

Huang, W., Shao, H., Li, W., Jiang, H., & Chen, Y. (2017). Effects of urea on growth and photosynthetic metabolism of two aquatic plants (Cabomba caroliniana A. Gray and Elodea nuttallii (Planch.) H. St. John). Aquatic Botany, 140, 69-77.

Hussner, A. (2012). Alien aquatic plant species in European countries. Weed Research, 52(4), 297-306.

Julien, M. H., McFadyen, R. E., & Cullen, J. (Eds.). (2012). Biological control of weeds in Australia. CSIRO PUBLISHING.

Matthews, J., Beringen, R., Lamers, L. P. M., Odé, B., Pot, R., Velde, G., ... & Leuven, R. S. (2013). Risk analysis of the non-native Fanwort (Cabomba caroliniana) in the Netherlands.

McCracken, A., Bainard, J. D., Miller, M. C., & Husband, B. C. (2013). Pathways of introduction of the invasive aquatic plant C abomba caroliniana. Ecology and evolution, 3(6), 1427-1439.

Schooler, S., Cabrera-Walsh, W., & Julien, M. (2012). Cabomba caroliniana Gray–cabomba. Biological control of weeds in Australia. CSIRO Publishing, Collingwood, Victoria, Australia, 108-117.

Thomaz, S. M., Kovalenko, K. E., Havel, J. E., & Kats, L. B. (2015). Aquatic invasive species: general trends in the literature and introduction to the special issue. Hydrobiologia, 746(1), 1-12.

Vukov, D., Jurca, T., Ru?ando, M., Igi?, R., & Miljanovi?, B. (2013). Cabomba caroliniana A. Gray 1837: A new, alien and potentially invasive species in Serbia. Archives of Biological Sciences, 65(4), 1515-1520.