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Volume and contents of residual water in recreational watercraft ballast systems

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Abstract

Transient boaters are a known vector of aquatic invasive species. This has led to the establishment of prevention guidance to reduce the risk of most boating activities. However, this guidance may not adequately reduce the risk of invasive species transport in wakeboard boats due to the presence of ballast systems, which may be difficult or impossible for a boater to drain. We documented that these watercraft transport relatively large volumes of residual water (mean water volume 31.7 L) even after drain pumps run dry and that live organisms can be found in residual water for at least a week after use. The amount of residual water found in ballast tanks was variable (range of 1.0 L to 86.8 L), indicating that there may be factors that would allow for more complete drainage of ballast tanks. Analyses of the invertebrate communities from the residual water found that native zooplankton were common in the samples, with two of the watercraft transporting small numbers of dreissinid veligers. Future efforts should identify factors that can reduce the amount of residual water and identify what other invasive species may potentially be transported through this new pathway. Additionally, more effort should be made to better understand the boating behaviors of wakeboard boat users.
Management of Biological Invasions (2016) Volume 7 article in press
© 2016 The Author(s). Journal compilation © 2016 REABIC
Open Access
Short Communication CORRECTED PROOF
Volume and contents of residual water in recreational watercraft ballast systems
Tim Campbell1,2*, Todd Verboomen3, Gary Montz4 and Titus Seilheimer5
1University of Wisconsin Sea Grant Institute, 1975 Willow Drive, Madison, WI 53706 USA
2University of Wisconsin Extension Environmental Resources Center, 445 Henry Mall, Madison, WI 53706 USA
3East Central Wisconsin Regional Planning Commission, 400 Ahnaip Street, Menasha, WI 54952 USA
4Minnesota Department of Natural resources – Division of Ecological and Water Resources, 500 Lafayette Road, St. Paul, MN 55155-4025 USA
5University of Wisconsin Sea Grant Institute, 705 Viebahn St., Manitowoc, WI 54220 USA
*Corresponding author
E-mail: tim.campbell@wisc.edu
Received: 1 December 2015 / Accepted: 22 March 2016 / Published online: 18 April 2016
Handling editor: Justin McDonald
Abstract
Transient boaters are a known vector of aquatic invasive species. This has led to the establishment of prevention guidance to reduce the risk
of most boating activities. However, this guidance may not adequately reduce the risk of invasive species transport in wakeboard boats due to
the presence of ballast systems, which may be difficult or impossible for a boater to drain. We documented that these watercraft transport
relatively large volumes of residual water (mean water volume 31.7 L) even after drain pumps run dry and that live organisms can be found
in residual water for at least a week after use. The amount of residual water found in ballast tanks was variable (range of 1.0 L to 86.8 L),
indicating that there may be factors that would allow for more complete drainage of ballast tanks. Analyses of the invertebrate communities
from the residual water found that native zooplankton were common in the samples, with two of the watercraft transporting small numbers of
dreissinid veligers. Future efforts should identify factors that can reduce the amount of residual water and identify what other invasive
species may potentially be transported through this new pathway. Additionally, more effort should be made to better understand the boating
behaviors of wakeboard boat users.
Key words: aquatic invasive species, prevention, invasion pathways, boating, risk assessment
Introduction
Transient boaters can inadvertently transport vegetation,
water and debris between waterbodies and are known
vectors of aquatic invasive species (AIS; Johnson et
al. 2001). Vegetation fragments can be invasive, and
residual water on the boat can contain live organisms
(e.g., viruses and invertebrates) and potential
invasive species (Kelly et al. 2013). In the water-rich
Great Lakes region, there are many waterbodies with
multiple established invasive species where these
pathways could introduce AIS into un-invaded areas.
Simple actions, such as removing attached aquatic
vegetation and draining water, can greatly reduce the
risk of watercraft transporting these species
(Rothlisberger et al. 2010). These simple actions
have become the standard preventative actions for
the general boating public (e.g. Stop Aquatic
Hitchhikers!). Many boaters across the country are
required to follow these steps to comply with
regulations designed to prevent the spread of invasive
species (e.g. Wisconsin, Minnesota, and Michigan).
While these general recommendations are easy to
perform on the majority of watercraft, there are
some types of watercraft, such as wakeboard boats,
where these recommendations may be more difficult
to implement and may not acceptably reduce the risk
of AIS transport.
Wakeboard boats are a relatively recent addition
to recreational boating, with the sport becoming
popular in the late 1980s, and the industry growing to
sell around 10,000 new boats each year (NMMA
2011). Wakeboard boats often have a ballast system
that is used to increase displacement to create a large
wake that is used as a launching point for a towed
rider to perform tricks behind the watercraft. These
watercraft can take on hundreds of liters of ballast and
T. Campbell et al.
Figure 1. While wakeboard boat
ballast systems are often custom and
can differ from boat to boat, a
common configuration is to have two
ballast bags in the back storage and
one in the center storage locker.
Water is typically drawn into the
system on the bottom through the hull
and it exits the system out of a
through-hull fitting on the bow.
have the potential to transport large volumes of
residual ballast water. The ballast systems are often
located in storage compartments and can be difficult,
if not impossible, for a boater to drain completely
(Figure 1). Anecdotal reports have indicated that
these boats have transported large amounts of water,
but until now it has never been verified.
In order to gain a better understanding of these
watercraft and to ultimately prescribe better preven-
tion actions, we undertook a study to determine if
wakeboard boats were transporting water, and if so,
how much water. We also quantified the types of
invertebrates that were being transported. This study
will provide the AIS and boating community with
additional understanding of this issue, which can
then be used to develop best practices to reduce the
risk of AIS transport.
Methods
Twenty-three wakeboard boats were sampled in
September and October of 2013 at Ft. Fremont
Marine in Fremont, Wisconsin. Wakeboard boats
were first identified from the pool of watercraft on
site and checked for ballast systems. If ballast systems
were present, then system type was identified. Only
boats with ballast bags (as opposed to hard ballast
tanks) were chosen for sampling given the difficulty
of sampling hard tanks, which are not easily
removable (Figure 2). Before the ballast bags were
removed for sampling, they were drained using the
existing pumps to ensure only water that could not be
drained was being measured. The ballast bags were
then removed and any residual water emptied into
buckets which were then weighed (kg) and converted
to a volume (L, 1.0 kg = 1.0 L). The residual ballast
water was then filtered through a 90 micron plankton
net and the contents preserved in 70% ethanol.
For the invertebrate analysis, the preserved
samples were filtered through 80 micron mesh in the
lab and diluted with distilled water. The entire
volume of each sample was analyzed by using
subsamples of 20–25 mL that were then transferred
to a gridded plate where veligers were then counted
using cross polarized light microscopy and normal
light was used to determine relative abundances of
all other invertebrates (Montz and Hirsch unpubl.
data). Sample processing was completed by
Minnesota Department of Natural Resources staff.
Results
Out of the 23 wakeboard boats examined, five water-
craft had no ballast tanks while another five had hard
tanks that were inaccessible. The remaining thirteen
watercraft had bag ballast systems that could be
effectively removed and sampled. The mean residual
ballast water in the thirteen watercraft examined was
31.7 L (± 28.7 L) with a range of 1.0 L to 86.8 L
(Figure 3).
Nine of the thirteen watercraft with removable
ballast bags had viable organisms present in the residual
Volume and contents of residual wakeboard ballast
Figure 2. A ballast bag is pliable and
collapsible, and often has two connected
hoses in order to fill and drain the ballast
(left). It was observed that the hoses could
lift the drain connection above the lowest
part of the ballast bag, resulting in a
significant amount of residual water in the
ballast bag (right). A hard ballast tank
(bottom) fills an entire compartment, even
when not full, and is generally
inaccessible without tools. Photo credit:
Tim Campbell.
ballast water, with thirteen different families of zoo-
plankton and macroinvertebrate observed (Table 1).
The Chironomidae, Cladocera, and Copepoda were
the most commonly detected zooplankton families.
Dreissenid veligers were detected in two samples,
with 9 and 47 veligers (2.4 and 0.6 veligers/liter,
respectively) present in those samples.
Discussion
These results document the existence of residual
water and invertebrates, including dreissenid veligers,
in wakeboard boat ballast systems even after onboard
pumps indicate that the ballast water systems are
empty. This transport of water in ballast systems
creates risk of these watercraft transporting AIS and
makes watercraft with these types of ballast water
systems in violation of regulations prohibiting the
transport of lake and river water designed to prevent
the spread of AIS (e.g. Wisconsin Administrative
Code chapter NR 40, Minnesota state statute
Conservation Chapter 84D.09). The variability in the
volume of ballast water in a given watercraft suggests
that there may be certain situations or equipment
that are more effective at draining water than others.
Given the small number of watercraft we were able
to sample, no patterns emerged indicating what
systems or watercraft drained the most amount of
water. However, ballast systems are often aftermarket
additions to watercraft and can be added to many
places on a boat by any marine service center which
increases the variability in ballast system design.
This provides the opportunity to develop best
practices that minimize residual ballast water for both
ballast system design and installation, and for boater
behaviors. The less residual ballast water remaining
will make manual draining or other treatment options
easier and more efficient.
Given the results of this study, the simple actions
that drain water on other types of watercraft (e.g.
fishing boats, cruisers), such as pulling the drain
plug and emptying the bilge, will not achieve the same
risk reduction in wakeboard boats with ballast water
systems. Owners of wakeboard boats can manually
T. Campbell et al.
Figure 3. Liters of residual ballast water
documented in each watercraft that was
sampled. The striped bar is the mean (±1σ)
of all 13 watercraft.
Table 1. Invertebrate abundances for residual wakeboard ballast water. Native zooplankton were relatively common across the
samples. Dreissenid veligers were found in only two samples (2 and 12). Samples 1 and 7 were not analyzed due to sample collection
errors. Relative abundances per subsample are as follows: Rare (1–4), Present (5–9), Common (10–14), Abundant (15+).
Sample
Total ballast
volume (L)
Veligers
Veliger/liter
Bythotrephes
Amnicola
Amphipoda
Ceratopogonidae
Chironomidae
Cladocera
Collembola
Copepoda
Diptera
Hydrachnida
Odanata
Oligochaera
Ostracoda
2 3.8 9 2.4 R
3 4.6 0 P P
4 10.3 0 R R R
5 14.4 0 P P
6 18.6 0 R R A R A P
8 38.8 0
9 39 0 R P
10 45.9 0 R R A C R A P
11 47.2 0 R C A P R A
12 84.3 47 0.6 C P
13 86.8 0
remove and drain some of the onboard ballast
systems, but this process took around five minutes
per ballast bag the course of this study, with most
watercraft having three ballast bags. The time and
effort required to take prevention actions are two
reasons anglers cite for not taking prevention actions
on their watercraft (Moy et al. 2014), so it is ques-
tionable as to whether boaters with more complex
watercraft would be willing to manually remove and
drain ballast bags, even with regulations that may
require it. More education and enforcement efforts
may be needed to get boaters to take these prevention
actions. Additionally, watercraft design is becoming
more complex and some ballast systems are placed
where they are inaccessible, making them difficult to
drain. One possible solution would be to attempt to
use the pumps to drain the ballast systems while on
an incline or a boat ramp so that more water reaches
the drain pump which often isn’t placed at the lowest
point of the watercraft. Alternatively, design features
Volume and contents of residual wakeboard ballast
that reduce AIS transportation risk without added
effort from the owner could be used something that
could be marketed to customers.
Allowing a watercraft to dry for five or more days
is also an often recommended prevention action
(ANSTF 2013). This is effective for many vessels
and potential AIS when all of the recommended
practices are completed. However the large amounts
of residual ballast water in wakeboard ballast systems
documented in this study undermine the potential
effectiveness of this guidance. The design of these
ballast systems prevents them from completely
draining, and the closed system would not allow any
amount of water to evaporate in even the thirty days
that some AIS prevention programs in the western
United States use as a standard quarantine time. Live
invertebrates were found in the residual ballast water
of watercraft examined in this study at least seven
days after the watercraft arrived at our sampling
location. It is possible that the organisms may have
survived longer than seven days since we only know
the day the watercraft arrive at the our sampling
location. The actual time organisms survived in
these ballast tanks was seven days plus the number of
unknown days it was unused before being delivered
for winterization. Future work could determine how
long organisms would be able to survive in
recreational ballast tanks. Recent work shows that
quagga mussel veligers can survive at least seven
days in small amounts of water (Snider et al. 2014),
and up to 27 days in less extreme conditions (Choi et
al. 2013). Another AIS of concern, the spiny water
flea (Bythotrephes longimanus), has a dormant resting
egg that has been noted to be viable after years of
dormancy, making it well suited to survive long
periods of time in residual ballast water provided the
ballast tanks do not desiccate or reach temperatures
above 50°C (Branstrator et al. 2013).
The presence of viable veligers confirms that this
is a potential invasion pathway for these highly
invasive mussels. The abundances counted in these
samples were low relative to a similar study of other
recreational watercraft (Montz and Hirsch unpubl.
data), but the watercraft in our study were sampled
out of convenience and might not accurately reflect
the risk of these watercraft transporting AIS. Since it
is unknown where the boats in this study originated
from, additional work should pair sampling of lake
water and residual ballast water at sites with known
populations of invasive species at times where their
abundances are high. This will help quantify the
highest densities of AIS that these systems can be
expected to retain and transport. An increased sample
size of wakeboard watercraft and craft details will
also help managers obtain a clearer picture of what
watercraft pose more of a risk than others and what
they might be transporting.
Little is known about the boating habits of
wakeboard boat owners. While each watercraft with
a ballast water system is likely transporting water, it
is important to note that wakeboard and ski boats
make up a small amount of the new boats sold each
year in the US, with around 10,000 new units sold
each year (NMMA 2011). Conversations with local
industry representatives suggest that many wakeboard
boats may pose a reduced risk of transporting potential
AIS to new waters given that they stay on the same
body of water and when they do travel, they often
visit many of the same locations repeatedly. However,
wakeboard boat owners may transport their
watercraft long distances for a vacation or competition.
Understanding these movement patterns and the
current prevention behaviors exhibited by wakeboard
boat owners will be important in assessing risk and
developing specific AIS prevention recommendations
for this portion of the boating market.
The wakeboard boat industry is aware of AIS
issues. The American Boat and Yacht Council hosted
an AIS Summit in Consideration of Watercraft
Design for Invasive Species Prevention in January of
2015. Both AIS professionals and members of the
boating industry attended and partnerships were
formed to begin to address AIS issues, including
design issues that would help all types of watercraft
drain more fully (ABYC 2015). Filtration devices
(e.g. the Wake Worx Mussel Mast’R) are a possible
solution that could prevent the transport of
organisms in wakeboard ballast. While they have
proven to be effective at preventing organisms from
entering ballast, they do not necessarily ensure that
these watercraft comply with all existing local
regulations. Collaboration between regulators and
industry will be needed to make sure that any techno-
logical solutions (i.e. filtration, chemical treatment)
are complementary in preserving access to water
bodies whilst protecting against AIS translocation
through compliance with local regulations.
Collaboration will also be needed so that industry
can continue to be aware of AIS issues and design
solutions into future model years.
Acknowledgements
Thank you to Denny Fox and Fort Freemont Marine—their
willingness to partner with the authors to provide access to
watercraft made this project possible. The authors appreciate the
effort and comments of the reviewers. Their insights improved the
quality of this manuscript. This work was supported by the
University of Wisconsin Sea Grant Institute and the University of
Wisconsin Extension Environmental Resources Center.
T. Campbell et al.
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... Transferring water between river basins can introduce aquatic organisms, that may become problematic or invasive in their new environment, or may contribute to the spread of diseases. For example, organisms can survive for extended periods in ballast tanks on boats and be dispersed to distant locations when the water is discharged (Campbell et al. 2016). Implementing restrictions on water transfers could help mitigate this risk. ...
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... A survey of 2 lakes in Minnesota found that boats operated in the last 24 h contain a median of 4945 mL of residual water in their sterndrive engine and an average of 13 zebra mussel veligers per boat (Doll 2018). Some boats with ballast tanks harbor large volumes of residual water (1.0 to 86.8 L), even after their tanks are drained with a pump (Campbell et al. 2016, Doll 2018. Another study found that boaters who believed that their boat's bilges were empty actually had >13 L of water, and boats with more standing water were found to carry more pelagic zooplankton (Kelly et al. 2013). ...
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... Air temperature or relative humidity were not included in the analyses for our study, since all replicates for the air-drying experiments were conducted within the same week, with the start of trials for each air-drying duration staggered such that the end of each exposure period coincided on the last day. However, based on the evidence from the literature, recreational boaters should be mindful of equipment and compartments such as live wells, ballast tanks, the bilge and engine, that may retain humidity or pooled water, and which would enable any organisms present to survive for longer periods 5,8,24,46 . Overall, despite air-drying seemingly being the easiest means of decontamination to implement, its efficacy cannot be generalised to include all invasive gastropods or plants, and recreational boaters should be aware of the type of AIS potentially present in the lakes they visit to ensure that the appropriate decontamination measures are applied. ...
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The Mediterranean Sea is a marine biodiversity hotspot under threat. One of the major impacts on its biological resources and services comes from the invasiveness of non-indigenous species (NIS). Nevertheless, NIS monitoring programs in the south basin of the Mediterranean Sea are in an early implementation stage. This study aims to describe NIS and cryptogenic species distribution in Monastir Bay (Tunisia) and to identify risk areas for the introduction and spread of invasive species, providing a baseline for future monitoring programs. To this end, a series of Rapid Assessment Surveys were carried out to identify NIS and cryptogenic species in one marina, five fishing ports, two aquaculture farms and the Special Conservation Area of the Kuriat islands. 24 species were found, of which 11 constitute new records for Monastir Bay, which represent a 33.3% of the total NIS reported in this Bay. Assemblages differed between substrata types, being NIS more abundant in artificial than in natural substrata. Regarding locations, Cap Monastir Marina was the most invaded site, the most transited by vessels and the only one visited by international sailing. Hence, this marina constitutes the main risk area to be monitored, although the fishing ports and fishing farms in the semi-enclosed coastal lagoon of Monastir Bay can also be considered as risk areas. Nevertheless, more research effort is needed in Monastir Bay in order to update the records of NIS and cryptogenic species and increase insight on the ecological evolution of these species and their related impacts on natural communities and marine resources.
Technical Report
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The purpose of Uniform Minimum Protocols and Standards for Inspection and Decontamination Programs for Dreissenid Mussels in the Western United States (UMPS IV) is to 1) provide the best possible recommendations for watercraft inspection and decontamination (WID) programs and 2) to provide the best standards, practical science, and technology currently available for WID program consistency.
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On 6 January 2007, invasive quagga mussels [Dreissena rostriformis bugensis (Andrusov, 1897)] were discovered in the Boulder Basin ofLake Mead, Nevada, a popular site for recreational boating in the southwestern United States. Recreational watercraft are considered aprimary vector for overland dispersal of quagga mussel veliger larvae between water bodies. Thus, effective decontamination of veligers inresidual water carried by trailered recreation boats is critical to controlling this species’ spread. The survival rate of quagga mussel veligerswas measured during exposure to environmental temperature conditions mimicking those experienced in the residual water of traileredvessels during warm summer and cooler autumn months in the semi-arid southwestern United States. Under warm summer conditions,quagga mussel veligers survived approximately five days while under cooler autumn conditions they survived 27 days. When tested underautumn temperature conditions veliger survival times increased with increased level of larval development. The results suggested a greaterlikelihood of veliger transport in the residual water of trailered watercraft during autumn months. The results indicated that presentlyrecommended vessel quarantine times to kill all externally attached juvenile and adult dreissenid mussels prior to launching in an uninfested water body should be increased to generate 100% veliger mortality in residual water unable to be fully drained from the internal areas of watercraft.
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Recreational boats in tow between lakes are a known vector of the spread of aquatic invading species (AIS), but we have no test of the hypothesis that recreational boats are also a vector of secondary spread of AIS among freshwater ecosystems via in-water transport i.e., while boating between interconnected waterways. In this study, we surveyed recreational boaters travelling into Lake Simcoe (44�250N, 79�200W), Ontario, Canada, on their recreational activities, boat maintenance, and travel destinations, measured the degree of vessel fouling, and sampled all standing water and attached macrophytes associated with their vessels. A total of 321 zooplankton individuals comprising 15 different species were collected from the standing water in vessels, including veligers of the invasive zebra mussel Dreissena. The volume of water collected within the vessels significantly increased the number of zooplankton transported. Zooplankton species from pelagic habitats or with planktonic life stages were collected more frequently than species that occupy littoral or benthic habitats, likely reflecting the recreational activities of boaters. Patterns of boater activities, movements and hygiene habits, suggest recreational boating in the Lake Simcoe region is contributing to the spread of native and invasive species into nearby waterways. Our study validates the widespread assumption that recreational boats are an important in-water vector for the secondary spread of both native and invasive zooplankton species. Future management strategies to reduce the spread of AIS should be aimed at increasing awareness of boater hygiene practices, particularly the frequent draining of standing water.
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Trailered boats have been implicated in the spread of aquatic invasive species. There has been, however, little empirical research on the type and quantity of aquatic invasive species being transported, nor on the efficacy of management interventions (e.g., inspection crews, boat washing). In a study of small-craft boats and trailers, we collected numerous aquatic and terrestrial organisms, including some species that are morphologically similar to known aquatic invasive species. Additionally, a mail survey of registered boaters (n = 944, 11% response rate) and an in-person survey of boaters in the field (n = 459, 90% response rate) both indicated that more than twothirds of boaters do not always take steps to clean their boats. Furthermore, we used a controlled experiment to learn that visual inspection and hand removal can reduce the amount of macrophytes on boats by 88% ± 5% (mean ± SE), with high-pressure washing equally as effective (83% ± 4%) and low-pressure washing less so (62% ± 3% removal rate). For removing small-bodied organisms, high-pressure washing was most effective with a 91% ± 2% removal rate; low-pressure washing and hand removal were less effective (74% ± 6% and 65% ± 4% removal rates, respectively). This research supports the widespread belief that trailered boats are an important vector in the spread of aquatic invasive species, and suggests that many boaters have not yet adopted consistent and effective boat cleaning habits. Therefore, additional management efforts may be appropriate.
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Predictions of the geographic spread of introduced species are often limited by a lack of data on their mechanisms of dispersal. We interviewed boaters and inspected boating equipment at public boat launches on Lake St. Clair (Michigan, USA) to assess the potential for the zebra mussel, an invasive bivalve, to be dispersed overland to inland waters by transient recreational boating activities. Several mechanisms associated with recreational boating were found to be capable of transporting either larval or adult life stages. Larvae were found in all forms of water carried by boats (i.e., in live wells, bilges, bait buckets, and engines) but were estimated to be 40–100 more abundant in live wells than other locations. Dilution in receiving waters should, however, greatly reduce the risk of establishing new populations by the introduction of larvae. Contrary to common belief, mussel dispersal from these boat launches did not occur by direct attachment to transient boats. Rather, adult and juvenile mussels were transported primarily on macrophytes en-tangled on boat trailers and, less frequently, on anchors (5.3% and 0.9% of departing boats, respectively). Combining these data with estimates of survival in air and reported boater destinations, we predict that a maximum of 0.12% of the trailered boats departing these access sites delivered live adult mussels to inland waters solely by transport on entangled macrophytes. While this is a small probability, high levels of vector activity resulted in a prediction of a total of 170 dispersal events to inland waters within the summer season from the primary boat launch studied. Many other potential vectors remain to be assessed, but the dispersal of zebra mussels by trailered boats, particularly by ''piggybacking'' on macrophytes entangled on the trailers, must be controlled in order to limit further range expansion of the zebra mussel within North America.
Article
Invasive quagga mussels (Dreissena bugensis) were first detected on the lower Colorado River at Lake Mead in January 2007 and have spread to a number of southern California reservoirs. Though it is highly likely that larval transportation along connected waters was the primary cause of these infestations, little is known about the potential for larval conveyance in association with trailered watercraft. We conducted laboratory experiments at the Lake Mead fish hatchery to determine the potential for larvae (veliger) survival under immersion and emersion conditions that simulate those potentially encountered on recreational watercraft when trailered from infested to uninfested waterbodies. Our results demonstrate that at or above an air temperature of 35°C there is no practical risk of conveyance under any condition of emersion or low volume immersion. For emersed veligers in high relative humidity microenvironments there is risk of conveyance over a 'next day' time frame at temperatures up to 25°C. For immersed veligers in volumes as small as 31 μl there is risk of conveyance for at least 20 hours at 30°C and for at least seven days at 25°C or lower. Larval densities in infested waters are low enough that a volume on the order of one droplet is unlikely to contain veligers, but low volume itself does not appear to be a significant impediment to survival. These studies support the development and implementation of robust decontamination methods for watercraft moving from infested or potentially infested waters to those assumed to be uninfested.
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Dormant eggs of zooplankton are considered to be tolerant of harsh environmental conditions, yet lethal thresholds of exposure have rarely been determined. We describe 3 yr of dose-response experiments that evaluate hatching success of the resting egg of Bythotrephes longimanus (Cladocera: Cercopagidae) in response to salinity, chlorination, heat, desiccation, and freezing. There was no decline in hatching success in response to salinity (up to 4 weeks at 35 g L-1 salt) or chlorination (including up to 5 min at 3400 mg L-1 chlorine). In response to heat there was an interaction between time and temperature; hatching occurred after exposure to 40 degrees C for 1 min, 5 min, or 10 min but declined with the two longer exposures. Hatching also occurred after exposure to 50 degrees C for 1 min, but no hatching followed exposure to 50 degrees C for 5 min or to higher temperatures for 1 min. In response to desiccation at 17 degrees C, exposure for <= 4 h had no effect on hatching but >= 6 h resulted in no hatching. When frozen, hatching success depended on whether eggs were frozen in water or without water. Collectively, the results are congruent with an evolutionary origin of B. longimanus in permanent, euryhaline basins. The results advance our understanding of dispersal limits of B. longimanus, including vector potential, and may inform management practices for reducing range expansion of B. longimanus by humans.
Aquatic Invasive Species Summit: Boat Design and Construction in Consideration of Aquatic Invasive Species Meeting Minutes
  • American Boat
  • Yacht Council
American Boat and Yacht Council (ABYC) (2015) Aquatic Invasive Species Summit: Boat Design and Construction in Consideration of Aquatic Invasive Species Meeting Minutes. Las Vegas, NV.
University of Wisconsin Sea Grant Institute. Madison, WI. National Marine Manufacturers Association (NMMA) (2011) Recreational Boating Statistical Abstract
  • P Moy
  • J Jones
  • T Campbell
Moy P, Jones J, Campbell T (2014) Train local groups to inspect and wash fishing tourney boats. Technical report. University of Wisconsin Sea Grant Institute. Madison, WI. National Marine Manufacturers Association (NMMA) (2011) Recreational Boating Statistical Abstract. Chicago, IL.