Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter.
Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page 114
5
Other Approaches to Setting a Ballast Water
Discharge Standard
The EPA and USCG seek a scientifically based process for determining a
ballast water discharge standard that will protect against the establishment of
new nonindigenous aquatic species in the nation’s waterbodies and protect and
preserve resident species and other beneficial uses in these systems. In the ab-
sence of data and models necessary to support a science-based quantitative ap-
proach (see Chapter 4), expert opinion has been a common alternative to model-
ing to advance discharge standards.
Expert opinion can be defined as a process by which a person, or team of
individuals, with a high degree of knowledge pertaining to a particular topic
draws upon that knowledge to propose an estimate. In the area of standards for
living organisms in ballast water discharge, expert opinion processes have taken
a number of forms and, as observed by Lee et al. (2010), produced a wide range
of outcomes. This chapter discusses strengths and weaknesses of the expert-
opinion approach and reviews three expert opinion-based standards for living
organisms in ballast discharge: the (1) IMO standard setting approach, (2) Cali-
fornia’s Zero Detectable Living Organism standard setting approach, and (3)
Natural Invasion Rates as a basis for a standard. The Natural Invasion Rate me-
thod put forward by Cohen (2005, 2010) starts with a desired invasion rate based
on expert opinion, and then combines it with a quantitative risk–release relation-
ship (much like those discussed in Chapter 4), to derive allowable discharge
levels. This chapter considers only the expert opinion-based portion of the me-
thod.
EXPERT OPINION AS AN APPROACH TO DECISION-MAKING
Expert opinion has been applied in the field of biological invasions in a
number of ways. First, expert opinion has been used to identify nonindigenous
species that may pose problems if introduced to a new country (see IUCN, 2000;
European Environment Agency, 2010; and Kolar and Lodge, 2002). The Cana-
dian government developed a risk assessment for silver and bighead carp species
114
OCR for page 115
Other Approaches to Setting a Ballast Water Discharge Standard 115
based upon expert opinion, which resulted in a regulation banning live sales by
fish retailers (Mandrak and Cudmore, 2004). Expert opinion also has been used
to screen for invasive, weedy plants and insect pests, among others (see Tucker
and Richardson, 1995; Daehler et al., 2004; Paini et al., 2010).
An inherent advantage of the expert opinion approach is that it can produce
estimates in the absence of robust data sets. Some models based on expert opi-
nion can be cross-checked using other methodologies, allowing researchers and
managers to consider the biological realism of their predictions (Phelong et al.,
1999; Paini et al., 2010). Nonetheless, there often remains considerable uncer-
tainty in the output from expert opinion, especially when there are critical gaps
in understanding underlying mechanisms.
Expert opinion can be greatly affected by problem framing, context depen-
dence, and motivational bias by participants (Burgman, 2005). Thus, a key
problem is that very different outcomes may result from different parties consi-
dering the same problem. It is also difficult to test the output for validity since
critical considerations are often implicit in the process. Consensus-based expert
opinion by cross-disciplinary teams may help eliminate blind spots in the analy-
sis in terms of types of expertise, but these exercises often must limit the number
of experts per discipline to one individual. As a result, inherent biases within an
expert become a greater concern.
Maguire (2004) concluded that risk assessment based upon expert opinion
is often conflated with risk management, and that assessments of risk based on
individual judgment often incorporate personal outcome preferences. A further
problem is the influence of incomplete information on decision making. For
example, highly invasive species including the emerald ash borer (Agrilus pla-
nipennis) and quagga mussel (Dreissena rostriformis bugensis) had little or no
invasion history prior to colonizing North America, and expert opinion based on
invasion history likely would have concluded that these species pose little risk.
While risk assessments based upon performance (effect) in native regions may
be informative and are commonly conducted, the colonization process can result
in evolutionary (genetic) changes, where native and introduced populations dif-
fer substantially. Moreover, invasions by definition place species in novel envi-
ronments, with a different assemblage of organisms. Thus, native populations
may be poor predictors of population dynamics, interactions, and effects in an
invaded area.
Data on the concentration of living organisms in ballast water and on the
probability of invasions occurring in U.S. waterbodies as a result of ballast water
are extremely limited. Thus, despite its drawbacks, expert opinion has unders-
tandably played a major role in ballast discharge standard-setting to date, and it
will likely be involved as part of the risk management decision-making process
into the future.
OCR for page 116
116 Propagule Pressure and Invasion Risk in Ballast Water
IMO STANDARD SETTING APPROACH
The best-known example of an expert opinion-based standard setting
process for ballast water is the agreement reached at the 2004 Diplomatic Confe-
rence of the International Maritime Organization (IMO), which included 74
IMO member countries, the European Community, and 18 non-governmental
organizations (Gollasch, 2005). This agreement was formalized as the IMO
International Convention for the Control and Management of Ships’ Ballast
Water and Sediments and was signed by 67 IMO member countries. As of May
2011, the Convention has been ratified by 28 countries collectively accounting
for over 28 percent of global merchant shipping (IMO, 2011). The IMO Con-
vention will come into force one year after not less than 30 States representing
35 percent of the world’s merchant tonnage have ratified without reservation.
In this rendition, the expert-opinion process involved at least two sets of ex-
perts (there was some overlap) and two sets of rules. Specifically, the IMO Ma-
rine Environment Protection Committee (MEPC) requested the assistance of a
Study Group (on Ballast Water and Other Ship Vectors) of the International
Convention for the Exploration of the Sea (ICES), and also a group from the
shipping industry to propose a starting point for IMO negotiations to achieve
discharge standards. The ICES Study Group, predominantly aquatic invasion
biologists, reviewed available data sets to date related to concentrations of or-
ganisms in untreated ballast, characterizing the range and distribution across
many vessels for different types of organisms. This expert group recommended
that to “significantly reduce the risk of invasions associated with ballast water
beyond the present situation, permissible discharge concentrations identified by
any treatment/management standards should fall greatly below the median val-
ues observed presently for untreated/unmanaged ballast water.” This would
have the effect of reducing high concentration discharges, and the group consi-
dered empirical and theoretical evidence indicating that invasion likelihood in-
creases with increasing concentration (International Council for the Exploration
of the Sea, 2003).
Recognizing that biological invasions via ballast water occur across a broad
span of phyla and size classes, and that organisms comprising these groups dif-
fer tremendously in abundance in both nature and ballast water, the ICES study
group recommended that the IMO performance standard classify biota contained
in ballast water into categories based on size or taxonomic group. This group
made recommendations of discharge standards for two of these sizes classes:
greater than 50 m (zooplankton) and between ten and 50 m (phytoplankton)
to achieve concentrations three orders of magnitude below observed median
values in untreated ballast (the recommended standards correspond to 0.4 zoop-
lankton per m3 and 13.3 phytoplankton per liter). Because the recommended
approach considers total abundance of organisms in a particular size class (i.e., a
guild) in a ship’s discharge, the risk associated with release of any one species
would be expected to be lower since ballast water communities usually comprise
numerous species.
OCR for page 117
Other Approaches to Setting a Ballast Water Discharge Standard 117
The first stage of the process for crafting the IMO standard represented the
consensus expert opinion of the ICES Study Group experts involved. The out-
put of this analysis was then transmitted to the relevant IMO committees and
working groups to be considered along with operational concerns cited by indus-
try. The standard that emerged from this two stage process places numerical
limits on abundances in treated ballast effluent of less than ten viable organisms
per m3 greater than or equal to 50 μm in minimum dimension (zooplankton and
zoobenthos) and less than ten viable organisms per ml less than 50 μm but
greater than or equal to 10 μm in minimum dimension (including phytoplankton
and protists). The IMO also incorporated into the standard toxigenic Vibrio cho-
lerae (serotypes O1 and O139), the etiologic agents of pandemic cholera, and
two routinely used fecal-indicator bacteria, E. coli and intestinal Enterococci.
These latter two are frequently used to assess the safety of recreational surface
waters, e.g., swimming beaches. Some are concerned that the allowable levels
of live organisms in the standard generally are too high to be protective. In par-
ticular, the USCG during negotiations for the IMO agreement indicated that
standards needed to be considerably more stringent (i.e., 100 times) to be protec-
tive, approaching more closely recommendations from the ICES Study Group.
Regardless, it appears that the IMO D-2 standard represents a significant reduc-
tion in concentrations beyond ballast water exchange, especially for the largest
size range (International Council for the Exploration of the Sea 2003; Minton et
al., 2005).
ZERO-DETECTABLE DISCHARGE STANDARD
The State of California’s existing and anticipated standard for larger plank-
tonic organisms in discharged ballast water is “zero detectable” living or cultur-
able organisms. Like the IMO standard setting process, the process associated
with the genesis of this standard also involved the opinions of technical experts
(biologists) as well as industry and other groups (California State Lands Com-
mission, 2010). The expert group recognized that (a) the probability of invasion
declined with concentration and (b) there was great uncertainty surrounding the
risk–release relationship. This group took a precautionary approach, while ac-
knowledging that enforcement against a standard of zero living organisms has
practical constraints. Unlike the IMO D-2 standard, the zero detectable dis-
charge standard applies to all size classes and taxa (if the word “living” may be
considered applicable to viruses) and is to be put in force by January 2020
(Faulkner, 2010). [The interim standard is zero detectable living organisms for
taxa >50m, 0.01 organisms per ml for sizes between 10 and 50 m, and no
more than 103 bacteria and no more than 104 viruses per 100 ml of ballast water
discharge. Interim standards are to be in place between 2009 and 2016 (Faulk-
ner, 2010).]
This approach to a standard is appealing in its straightforwardness, but as
Lee et al. (2010) argue, its rationale is predicated on an actual zero discharge,
OCR for page 118
118 Propagule Pressure and Invasion Risk in Ballast Water
while its practical application can differ substantially from zero detectable dis-
charge. The zero-detectable concept is constrained heavily by the sampling re-
gime employed and associated sensitivity, which will depend on the analysts’
technical capabilities and financial resources. Recent advances in molecular
ecology, such as use of species’ environmental DNA (e.g., Mahon et al., 2011;
Jerde et al., 2011), are expanding our capability to detect rare organisms in wa-
ter, although none can yet unequivocally decipher whether all organisms de-
tected are living or dead.
Because of the practical constraints in detecting living organisms when they
are rare, the zero-detectable standard may be operationally no more stringent
than other standards. The lower the density of living organisms achieved in the
effluent, the more difficult the task of detecting organisms and determining
whether the water is compliant with the zero-detectable standard. Lee et al.
(2010) nicely summarized this by estimating the uncertainty inherent in sam-
pling different volumes of water (their Table 18). For example, even should a
10 m3 sample (a huge sample) of ballast water contain no organisms, the actual
concentration of organisms in the tank could be as high as 0.3 per m3. Arguably,
there could be fine tuning of the Lee et al. (2010) analysis should the distribu-
tion of organisms be found to be other than Poisson, but any such change would
only alter the levels of uncertainly associated with a particular sampling regime.
More recently, Miller et al. (2011) also considered organisms with a Poisson
distribution in ballast water effluent. They demonstrated that the density of or-
ganisms and volume sampled had strong effects on decisions to reject whether
ballast water is compliant with a selected standard, while the permissible type I
error rate (i.e., false positives or rejection of compliant ballast) had slightly less
influence as modeled.
Thus, while a laudable ideal, the zero-detectable standard is functionally de-
fined by the ability to characterize concentrations of organisms at low densities.
If organisms are detected, it is clear a ship’s ballast effluent is in violation.
However, critically, the absence of live organisms in a sample or set of samples
does not provide sufficient information to accurately assess densities, and there
is always a non-zero probability that organisms are present below some thre-
shold (defined by the specific sampling effort imposed). Thus, while Califor-
nia’s standards clearly represent a reduction in concentrations below those ob-
served in ballast water exchange, the exact discharge standard is largely unde-
fined and contingent on sampling protocols, representing an operational defini-
tion that is driven by sampling statistics.
NATURAL INVASION RATES
The Natural Invasion Rate (NIR) approach to standard setting incorporates
both a risk assessment and a risk management component. The risk assessment
component assumes that an empirical, linear relationship can be determined be-
tween the rate of organism release in ballast water and the resulting rate of new
OCR for page 119
Other Approaches to Setting a Ballast Water Discharge Standard 119
species invasions (see Chapter 4). The risk management component proposes an
acceptable target invasion rate based on expert opinion from which the corres-
ponding target discharge rate is determined. In this case, expert opinion has
concluded that the natural (i.e., non-anthropogenic, background) invasion rate
should be the target ballast-mediated invasion rate. This discussion focuses on
this latter component of the approach (i.e., the risk management step).
Cohen (2005) identified some difficulties inherent in estimating natural in-
vasion rates and provided coarse estimates based on expert opinion that span
three orders of magnitude. Providing any validation or better assessment is
problematic because there is insufficient information to determine a natural in-
vasion rate. The scale of available paleontological data is inconsistent with that
needed for application of a NIR standard. For example, natural port-to-port in-
vasion rate data are required, whereas available data refer to large-scale disper-
sal events (e.g., trans-Pacific regional migrations; see Vermeij, 1991) and, thus,
are not an appropriate comparator. It is expected that natural estuary-to-estuary
trans-Pacific migrations would be much lower than the measured regional mi-
grations. While some natural invasion rate data are available, in terms of Pleis-
tocene migrations and faunal shifts along the California coast, including ancient
embayments (Roy et al., 1995), they do not include trans-Pacific species move-
ments. In addition, even if data were available for one estuary, differences like-
ly exist among different recipient ecosystems and would need to be taken into
account.
These problems with estimating the natural invasion rate interfere with the
potential to obtain a meaningful organism discharge standard that would be
equivalent in its effect for all locations, or that would indeed be a desirable tar-
get. There is an assumption within the NIR approach that an acceptable inva-
sion rate is less than the natural invasion rate. Such assumptions make it clear
that NIR is based on expert opinion as much as the IMO standards and the zero-
detectable standard of CA.
CONCLUSIONS
The data available from which to derive scientifically based standards for
living organisms in ballast discharge have been incomplete and insufficient.
This situation results partly from the degree of variability possible across ballast
discharges, the difficulty in garnering representative samples of live organisms
in ballast discharge and the lack of a systematic approach for doing so, and the
lack of baseline measures to detect the presence of newly established popula-
tions of nonindigenous organisms in U.S. waters. A discharge standard based
on expert opinion has provided a starting point for the regulatory process and
can facilitate progression to a scientific model. For example, as ships attempt to
meet the IMO D-2 standard, much of the variation in potential densities of live
organisms in ballast discharge will be modulated. Advancing scientific under-
standing of the probability of invasion associated with such discharges, and the
OCR for page 120
120 Propagule Pressure and Invasion Risk in Ballast Water
performance of existing standards to reduce invasion outcomes, requires quan-
titative measures of both the discharge and also associated invasions. While
compliance testing provides a potential framework to achieve part of this goal,
the broader integrative approach required has yet to develop (see Chapter 6).
In the area of discharge limits for live organisms in ballast water, expert
opinion has been tapped as an alternative to scientifically derived standard set-
ting processes in light of scientific uncertainties. While each expert opinion
process discussed above has conceptual merit, each is compromised by assump-
tions, data limitations, or operational difficulties. Despite these drawbacks, ex-
pert opinion has resulted in various standards (e.g., IMO D-2) that could provide
a manageable baseline for developing scientific models that can be used to quan-
titatively determine ballast water discharge standards.
REFERENCES
Blaschko, M. B., G. Holness, M. A. Mattar, D. Lisin, P. E. Utgoff, A. R. Hanson, H.
Schultz, E. M. Riseman, M. E. Sieracki, W. M. Balch, and B. Tupper. 2005. Auto-
matic in situ identification of plankton. Proceedings of the Seventh IEEE Workshop
on Applications of Computer Vision 79–86. doi 10.1109/ACVMOT.2005.29.
Burgman, M. 2005. Risks and decisions for conservation and environmental manage-
ment. Cambridge, UK: Cambridge University Press.
California State Lands Commission. 2010. 2010 Assessment of the efficacy, availabili-
ty, and environmental impacts of ballast water treatment systems for use in Califor-
nia waters. Sacramento, CA: California State Lands Commission.
Cohen, A. N. 2005. Memo on a natural invasion rate standard. Appendix 5 In: Califor-
nia State Lands Commission Report on Performance Standards for Ballast Water
Discharges in California Waters. Report produced for California State Legislature.
M. Falkner, L. Takata, and S. Gilmore, editors.
Cohen, A. N. 2010. The natural invasion rate model and California’s ballast water dis-
charge standards. Presentation to the National Academy of Science/National Rese-
arch Council Committee on Assessing Numeric Limits for Living Organisms in Ba-
llast Water Washington, DC. June 2, 2010.
Daehler, C. C., J. S. Denslow, S. Aansari, and H.-C. Kuoa. 2004. Risk-assessment sys-
tem for screening out invasive pest plants from Hawaii and other Pacific Islands.
Conservation Biology 18:360–368.
European Environment Agency. 2010. Invasive alien species in Europe – Assessment
published May 2010. Available online at: http://www.eea.europa.eu/data-and-
maps/indicators/invasive-alien-species-in-europe/invasive-alien-species-in-europe.
Last accessed June 2, 2011.
Faulkner, M. 2010. Presentation to the National Academy of Science/National Research
Council Committee on Assessing Numeric Limits for Living Organisms in Ballast
Water. June 4, 2010. Washington, DC.
Gollasch, S. 2005. IMO BWMC: History, present status and challenges to the research
society. Presentation to the Ballast water introductions of alien species into the Bal-
tic Sea, Palanga.
OCR for page 121
Other Approaches to Setting a Ballast Water Discharge Standard 121
International Council for the Exploration of the Sea. 2003. Comments on draft Regula-
tion E-2. Submitted to the Marine Environment Protection Committee, MEPC
49/2/21.
IMO (International Maritime Organization). 2011. Available online at http://www.imo.
org/OurWork/Environment/BallastWaterManagement/Pages/Default.aspx#5. Last
accessed June 2, 2011.
IUCN (International Union for the Conservation of Nature). 2000. 100 of the World’s
Worst Invasive Alien Species A selection from the Global Invasive Species Databa-
se. Available online at: http://www.issg.org/booklet.pdf. Last accessed June 2,
2011.
Jerde, C., A. R. Mahon, W. L. Chadderton, and D. M. Lodge. 2011. 'Sight-unseen' de-
tection of rare aquatic species using environmental DNA. Conservation Letters doi:
10.1111/j.1755-263X.2010.00158.
Kolar, C. S., and D. M. Lodge. 2002. Ecological predictions and risk assessment for
alien fishes in North America. Science 298:1233–1236.
Lee II, H., D. A. Reusser, M. Frazier, and G. Ruiz. 2010. Density Matters: Review of
Approaches to Setting Organism-Based Ballast Water Discharge Standards.
EPA/600/R-10/031. EPA Office of Research and Development, National Health
and Environmental Effects Research Laboratory, Western Ecology Division.
Maguire, L. A. 2004. What can decision analysis do for invasive species management?
Risk 24:859–868.
Mahon, A. R., M. Barnes, S. Senapati, J. Darling, H.-C. Chang, J. L. Feder, and D. M.
Lodge. 2011. Molecular detection of invasive species in heterogeneous mixtures
using a microfluidic carbon platform. PLoS One 6(2):e17280.
Miller, A. W., M. Frazier, G. E. Smith, E. S. Perry, G. M. Ruiz, and M. N. Tamburri.
2011. Enumerating sparse organisms in ships' ballast water: why counting to 10 is
not so easy. Environmental Science and Technology (in press). dx.doi.org/
10.1021/es102790d.
Minton, M., E. Verling, A. W. Miller, and G. M. Ruiz. 2005. Reducing propagule sup-
ply by ships to limit coastal invasions: effects of emerging strategies. Frontiers in
Ecology and the Environment 6:304–308.
Paini, D. R., S. P. Worner, D. C. Cook, P. J. DeBarro, and M. B. Thomas. 2010. Using a
self-organizing map to predict invasive species: sensitivity to data errors and a com-
parison with expert opinion. Journal of Applied Ecology 47:290–298.
Phelong, P. C., P. A. William, and S. R. Halloy. 1999. A weed risk assessment model
for use as a biosecurity tool evaluating plant introductions. Journal of Environmen-
tal Management 57:239–251.
Roy, K., D. Jablonski, and J. W. Valentine. 1995. Thermally anomalous assemblages
revisited: patterns in the extraprovincial range shifts of Pleistocene marine mollusks.
Geology 23:1071–1074.
Tucker, K. C., and D. M. Richardson. 1995. An expert system for screening potentially
invasive alien plants in South African Fynbos. Journal of Environmental Manage-
ment 44:309–338.
Vermeij, G. J. 1991. When biotas meet: understanding biotic interchange. Science 253:
1099–1104.
