Environmental Engineering Reference
In-Depth Information
for conducting such toxicity tests, toxicity testing can
be conducted using other amphipod species, consid-
ering additional endpoints (i.e., survival, growth,
emergence, reburial, and reproduction) and exposure
durations (i.e., up to 28-day tests for
Leptocheirus
plumulosus
). It should be recognized that
Ampelisca
is a tube-dwelling species and, hence, may receive
less exposure to COPCs than other amphipod species
(potentially making it less sensitive to sediment-
associated COPCs). Toxicity testing with amphipods
is recommended because they tend to be sensitive
species and their responses are often correlated with
responses of the benthic community in the fi eld. At
least one study documented effects on the benthic
community at mean SQG quotients substantially
lower than those associated with toxicity to marine
amphipods in 10-day exposures, however (Hyland
et al
. 1999).
Toxicity testing with other species, evaluating
non-lethal endpoints over longer durations of expo-
sure, can provide relevant information of assessing
contaminated sediments. For example, 20- to 28-day
whole-sediment toxicity tests with polychaetes (e.g.,
Neanthes arenoceodentata
; endpoints survival and
growth) can provide useful information for assessing
risks to benthic invertebrates associated with expo-
sure to contaminated sediments. In addition, 48- to
96-hour sediment-water interface toxicity tests with
echinoderm (e.g.,
Arbacia punctulata
) or bivalve
mollusk larvae (e.g.,
Mytilus edulis
; endpoint devel-
opment) represent emerging toxicity tests that could
provide broader taxonomic coverage and reduce
uncertainties associated with the traditional use of
these species and life stages (i.e., in pore-water expo-
sures). The need for standardization of the sediment-
water interface toxicity testing protocols has been
identifi ed as one of the current limitations associated
with applying these tests on a routine basis. Therefore,
the relevance of such toxicity tests should be evalu-
ated on a case-by-case basis to determine if one or
more of these ancillary tests should be used to assess
contaminated sediments at a site.
Certain other toxicity tests may be relevant for
assessing marine and estuarine sediments. However,
it is now generally agreed that elutriate toxicity tests
should not be included in the core suite of tests that
are applied at marine and estuarine sites (except in
dredged material disposal analysis applications). In
addition, some challenges associated with the use of
than shorter-term tests, with an acute to chronic ratio
on the order of six indicated for
H. azteca
. Based on
these analyses, if only one of these tests were per-
formed, it would be desirable to conduct chronic (i.e.,
28- to 42-day) sediment toxicity tests with
H. azteca
measuring survival and growth (as length) instead of
10- to 14-day tests with
H. azteca
,
C. dilutus
, or
C.
riparius
.
Relative species sensitivity frequently varies among
chemicals; consequently, both ASTM (2008a) and
USEPA (2000a) recommend the use of a battery of
tests to assess sediment quality, including organisms
representing different trophic levels. However,
testing multiple species with every sediment sample
can be very costly. An alternative approach could be
to perform a preliminary evaluation on a few samples
from a site using a battery of tests (i.e., see proce-
dures for various species outlined in ASTM 2008a).
This preliminary evaluation could be used to identify
sensitive species or endpoints to include in a more
comprehensive assessment at the site. The prelimi-
nary evaluation should include samples representing
a gradient of contamination at the site of interest.
This approach was taken by Kemble
et al.
(1994) in
an assessment of the toxicity of metal-contaminated
sediments in the Clark Fork River in Montana. A
battery of acute and chronic whole-sediment and
pore-water tests were conducted with samples col-
lected from this site. The results of this investigation
indicated that a 28-day whole-sediment toxicity test
with
H. azteca
measuring survival and growth (as
length) was the most sensitive metric across a gradi-
ent of metal-contaminated stations at the site. The
results of chronic toxicity tests with
H. azteca
were
also predictive of effects observed on benthic com-
munity structure at the site (Canfi eld
et al.
1994).
Therefore, Kemble
et al.
(1994) recommended that
future evaluations of sediment toxicity at the site
should use chronic tests with
H. azteca
rather than
testing a suite of toxicity tests.
A diverse array of whole-sediment and pore-water
toxicity tests are available to evaluate contaminated
sediments at marine and estuarine sites. It is generally
recognized that 10-day whole-sediment toxicity tests
with marine and estuarine amphipods represent an
essential element of the suite of toxicity tests that
should be used to assess marine and estuarine sites.
Although
Eohaustorius estuarius
and
Rhepoxynius
abronius
are the most highly recommended species
