Cabomba Caroliniana: Ecological Impact and Management Strategies

This report analyzes Cabomba caroliniana, a popular submerged aquatic weed that invades freshwater bodies. The study investigates its survival mechanisms, including desiccation resistance and the impact of burial depth and water drawdown. It explores the plant's reproduction through stem fragments and its preference for nutrient-rich substrates, while also noting its ability to survive in less nutrient-rich environments. The report references several studies to examine the viability of the plant under various conditions, particularly during lake drawdowns, and highlights the role of humans in its dispersal. Furthermore, it discusses how the drawdown of water can be an unsatisfactory control mechanism as the plant can regenerate itself. The findings suggest that prolonged burial time can promote the survival of Cabomba caroliniana fragments, and the implications of these findings are used to suggest control strategies, such as water drawdown, to manage the weed's growth in aquatic bodies in Australia. The report emphasizes the importance of understanding the plant's traits to develop effective management strategies.

Running head: CABOMBA CAROLINIANA
Cabomba Caroliniana
Name of the Student
Name of the University
Author Note

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Discussion
Cabomba caroliniana is one of the most popular submerged aquatic weed which can
invade the fresh water bodies such as dams, lakes and slow flowing rivers. In Australia, the
growth of this plant is quite significant as well. The roots of this plants are growing in the
bottom of the water bodies and on the other hand stems of this weed can reach up to the
surfaces of the water. Cabomba caroliniana is very sensitive to the drying out and that is the
reason the weed requires a permanent shallow water bodies to survive in the environment.
The species Cabomba caroliniana spreads and reproduces through the movements of small
plant pieces or fragments and it is reported that, it does not produce any seeds to reproduce its
species. It is reported that Cabomba caroliniana, this plant prefers a high level of nutrients in
the substrate (U.S Fish & Wildlife Service, 2018). However, in various studies, it is also
reported that, the in laboratory experiments, the importance of nutrients are not established
for the growth of the Cabomba caroliniana. This situation indicates that, Cabomba caroliniana
can also grow in the poor nutrient system if the substrate is comprised of adequate nutrients.
In studies, it is reported that, the issue of desiccation resistance of Cabomba caroliniana can
affect the potential dispersal radius. The study showed that, like other aquatic plants
Cabomba caroliniana also can reproduce through the stem fragments of the plants and it is
reported that, humans are the primary vectors for the dispersal (Bruckerhoff, Havel, &
Knight, 2015). According to the study of Dugdale et al. (2013), it is reported that, the
Cabomba caroliniana can also survive in the adverse condition like drawdown of lakes within
the mounds of stranded vegetation. It is reported that, the control process of submerged
aquatic undergrowth during lake Drawdown is considered to be slowed down by the mounds
of stranded growth which protect the stems of Cabomba caroliniana from desiccation. In this
study, the viability of stranded Cabomba caroliniana was investigated during the winter
season at Lake Benalla, Victoria, Australia. Generally, the viability of Cabomba caroliniana

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is defined by the ability of the plant to regenerate new shoots and it was related to the
substrate exposure status, mound height, soil moisture and location of the lake ( Bickel et al.,
2018). The viability was compared in terms of the DAE exposure and it was reported that,
the stem of viability of Cabomba caroliniana at 34 and 69 DAE was most closely related with
the substrate exposure status of this plant;. It was found that, in case of ∼20% stems under
mounds were viable even in relatively dry substrate condition and in case of saturated
substrate the viability was observed among the e ∼95% stems which were mounds under
saturated substrate (Dugdale et al., 2013). In multiple studies, it was reported that, the in the
control mechanism of Cabomba caroliniana by drawdown of water from the water bodies
can be unsatisfactory as this plant is capable of regenerating themselves from the stems. The
mechanism, which is associated with this poor control mechanism, is the regeneration of
Cabomba caroliniana from stem fragments that is development of mounds of vegetation
consisting of stems of the Cabomba caroliniana which are exposed over the lakebed as water
retrocedes. Stems which are at the upper sides of these mounds dies due to the desiccation
and on the other hand the stems which are located at the base of the mounds are protected by
the overlying vegetation and they are also capable of showing viability (Fleming & Dibble,
2015). After that, when the lake is refilled again this small number of stems produces a huge
number of viable stems in the lake. The crowns of this viable stems results in vegetative
colonization in the lake water. In the study also support the present study as the present
study also aims to examine the persistence of Cabomba caroliniana fragments in the moist
surface. On the other hand the study of Lu et al. (2018), investigated the effect of water level
fluctuation on the regeneration of macrophytes such as Cabomba caroliniana. This study is
also correlated with the present study as in the present study, the effect of burial depth on the
regeneration of Cabomba caroliniana fragments was examined. In the study of Lu et al.
(2018), the authors investigated the effect of water level drawdown followed by the rewetting

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of the stems of Cabomba caroliniana. The study investigated that, the fate of the released
oxygen by the isotopically labelled macrophytes. It is reported that, the submerged stems of
the macrophytes plays a critical role in storing nutrition and as well as in the assimilating
process. The depth of the water that is the water level can cause lowering of water quality.
The rewetting incidents after the drawdown of the water level can cause release of carbon di
oxide and nitrogen from the previously desiccated sediments of Cabomba caroliniana and this
is known as Birch effect ( Bohren, 2017). In addition to this, the rewetting changes the
macrophytes beds to a source of nutrition from a nutrient sink area. The released nutrients
from the sediments may responsible for supplying the nutrients to the phytoplankton to grow
in the water. Moreover, it is also reported that the invasive aquatic plants have higher
amount of nutrient storage than that of the native species and in addition to this, those
invasive plants are also capable of releasing more nutrients during the adverse conditions
such as desiccation. Therefore, in multiple studies, it is reported that, the desiccated
macrophytes such as Cabomba caroliniana are competent to recover after the rewetting
process by using the germination from the fragments of or by the process of shoot fragment
growths in the water column (Bickel, 2017). These newly regrown macrophytes are able to
use those nutrients from the water bodies and from the sediments. As a result, it may
possible that, this released nutrients can be used by the regrown Cabomba caroliniana in the
water and that is the reason for regeneration of Cabomba caroliniana fragments during the
burial condition. However, it is not clear that if there is no relation among the two factors or
not (Fleming & Dibble, 2015). In addition to this, it is still not understood whether the
nutrients are stored in the fragments of the Cabomba caroliniana or not. There is also area of
confusion regarding the availability of the nutrients to the phytoplankton. The study result
showed that, the fate of the released nitrogen from the desiccated macrophytes such as
Cabomba caroliniana after the rewetting process can be greatly impacted by the sediment

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desiccation process (Lu et al., 2018). One the other hand, the study of Pickman and Burnes
(2017), showed that, the sediment burial reduce the mass loss and simultaneously enhances
the survival of aquatic invasive plants following desiccation for a short duration of time. In
this study, the aquatic plant Hydrilla verticillata was used and this study can be correlated
with the present study as Cabomba caroliniana is also an aquatic invasive plants. In the study
by Pickman and Burnes (2017), the desiccation tolerance level of the aquatic invasive plants
were examined. This study examined the desiccation tolerance levels of the aquatic invasive
plants and it will help to understand the survival habitat of the invasive aquatic plants in
different water depth levels. The researchers used Hydrilla verticillata as their sample plant
which is also an invasive aquatic plant like Cabomba caroliniana. In this study, the
researchers desiccated the plant fragments for the 3 hours on by keeping it on top of the
sediment, absence of the sediments and buried beneath the sediments. After the effect of
burial in substrate or sediments were examined and growth was measured upon
reintroduction of common aquatic environment. In order to understand the desiccation
resistances of aquatic invasive plants such as Cabomba caroliniana it is required to
understand the trait of this plant. It is reported that the resistance to desiccation and tolerance
to burial in the water level is associated with the presence of a particular trait in those
invasive aquatic plants such as Cabomba caroliniana and this trait determine the presence of
plant community in the areas like ephemeral streams, wetlands, tidally influenced waters, and
other aquatic habitats where the presence of regular water fluctuations is common (Stark,
Greenwood, & Brinda, 2017). In the those areas, it is very crucial to survive for the invasive
plants and they only can survive in those areas due to the presence of this trait (Kuntz,
Heidbüchel & Hussner, 2014)

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Interpretati on of findings
From the present study result, it was reported that, the Cabomba caroliniana buried
under the 1cm depth were not capable of emerging and in addition to this the fragments of
Cabomba caroliniana can survive in the buried substance for extended period of time. In the
study of Dudgale et al. (2013), it is reported that the substrate core for Cabomba caroliniana
was buried by 50 mm deep with a diameter of 50mm. In the lake water, 19 sites were marked
in an even manner for collecting the sample and the sediment cores were taken from the
same three corners of the lake water and moisture quantity of the substrate was same for the
three areas. No stem fragments were collected from the top level of water bodies as due to
desiccation they were about to die. The mounds of the cabomba survived throughout the 69
days of drawdown on the saturated substrates and the burial depth was almost < 0.5 cm with a
substrate thickness of 1.5 cm (Bruckerhoff, Havel & Knight, 2015). So, it can be said that,
the as in the present study, the burial depth was almost 1cm, that is the reason for not
regenerating of Cabomba caroliniana stems. On the other hand , by using the study result of
Pickman and Barnes ( 2017), it can be said that, there is no regeneration of Cabomba
caroliniana fragmemnts under the 1cm burial depths may be due to the air exposure. In this
study, it was reported that, such invasive aquatic plants is managed by the drawdown of water
bodies in which the level of water is lowered so that the plant fragments can be exposed to
air followed by the death of the plants. As in this experiments, the plant is buried under only
1cm depth, it may possible that the Cabomba caroliniana fragments are more exposed to air.
So, this may restrict the process of regeneration in this study result. On the other hand, the
present study result showed that, the prolonged burial time can promote the survival of
Cabomba caroliniana fragments. This finding of the present study can be described by using
the findings of Pickman and Barnes (2017). The study finding showed that, the desiccation
rate of the fragments buried under the substrates, is lowered due to the insulating effects

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provided by the substrates and simultaneously the evaporation rate is also lowered. As a
result, the mass loss during the dry period is masked. In addition to this, the presence of
sedimentation can affect the desiccation response in the aquatic invasive plants. The
reduction of mass loss also promote the prolonged survival of Cabomba caroliniana during
burial vcondition in the substrate.
Implication
So, it can be suggested that, the result of the desiccation experiments can be used in
the control strategy of Cabomba caroliniana. As a part of this, such measures can be taken so
that, the plants are exposed more to air and this will ultimately cause less growth of Cabomba
caroliniana in the aquatic bodies of Australia. The drawdown process should be performed in
the water bodies of the country so that the progression can be controlled. On the other hand, it
is reported that, the Cabomba caroliniana survive in the burial condition for a long period of
time and for its growth an optimum Ph of 4-6 is required. In the burial condition of this plant
the pH should be created above 8 as in this pH the plant cannot survive (Gettys, Haller &
Petty, 2014). So, in the burial substrate the pH should be maintained at that level so that their
progression can be restricted.

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References
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., Perrett, C., Vitelli, J., Xu, J., & Atkins, S. (2018). Control of Cabomba caroliniana
with flumioxazin: control efficacy and the effect of environmental factors. In 15th
International Symposium of Aquatic Plants.
Bohren, C. (2017). Invasive Plants. Weed Research: Expanding Horizons, 271-312.
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.
Dudgale, T., Butler, K., Clements, D., & Hunt, T. (2013). Survival of cabomba (Cabomba
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Fleming, J. P., & Dibble, E. D. (2015). Ecological mechanisms of invasion success in aquatic
macrophytes. Hydrobiologia, 746(1), 23-37.
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