Marine Ecology
Research Highlights
National Marine Water Quality Laboratory
P. O. Box 277 West Kingston, R. 1.02892
Vol. 1, No. 2 - January 1974
A HOLE IN NOAH'S ARK.
Francis C. Lowell invented the first American power loom,
established a factory on the Merrimack River in 1822, and named
it Lowell (Mass.). Henry David Thoreau, writing in 1839, was
disturbed by the silent disappearance of shoals of magnificent
Atlantic salmon which had inhabited the Merrimack and other New
England rivers prior to the establishment of the textile industry.
Thoreau, commenting about the Merrimack River, which had been
bereft of most of its fish life after the factories were built,
said in part "perchance after a thousand years, if the fishes will
be patient, and pass their summers elsewhere, meanwhile, nature
will have leveled the Bellerica Dam, and the Lowell factories, and
the Grass-ground river run clear again, to be explored by new
migrating shoals."
Until very recently, man's concern for the survival of Atlantic
salmon had changed little over the 134 years which have followed
the comments of Thoreau. Today the Atleitic salmon, once a dominant
species of the North Atlantic Ocean, is among the species endangered
and now facing extinction.
WATER QUALITY CRITERIA (WQO FOP THE SEA.
The concept of water quality criteria is a basic first step for
man if he is to respect the aquatic environment. Public law mandates
that criteria be developed that truly can assure environmental protec-
tion. Necessarily, the development of WQC must depend upon interplay
An Associate Laboratory of the National Environmental Research Center • Corvallis
200 S.W. 35th Street, Corvallis, Or. 97330
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among scientific and other disciplines such as aquatic biology,
pathology, physiology, chemistry, bacteriology, toxicology,
engineering, law, economics and politics. The National Marine
Water Quality Laboratory (NMWQL) is attempting to gain biological
information needed to establish WQC for aquatic life in the marine
environment. Although highly technical and advanced in mammalian
medicine, several sciences had not applied their skills to biota
of the aquatic environment until efforts to establish WQC for our
coastal waters began. What follows is an account of the research
effort of one scientific discipline integrated into the NMWQL
approach; the science of histopathology.
DID THEY SA “HISTOPATJJÔLOGY? ”
Histology is the study of normal tissues, and histopathology is
the study of abnormalities in tissues. Traditionally these studies
are approached by cutting microscopically thin sections of the
tissues studie&, staining them to bring out cellular structure of
the tissues, and examining them under a microscope. Once tissues
are taken from an autopsied plant or animal, they must be fixed
(chemically treated to prevent decay), stained (according to the
structural feature8 of the cells to be examined), sectioned (cut
into slices only microns thick), mounted on a microscope slide,
and sealed under a cover glass to await examination. This process
involves highly specialized technical skills and equipment. Still
more specialized scientific personnel——histopathologists——are needed
to analyze these tissues for lesions, structural abnormalities which
differ in appearance from normal tissues. Lesions can be tumors,
breakdown of normal tissue layers, concentrations of blood cells in
abnormal places, abnormally enlarged cells or tissue layers, altered
cellular structure or intracellular parts, or any of a number of
such structural differences from healthy tissues.
Techniques routinely applied in mammilan histology first had to
be modified and applied to invertebrate and vertebrate organisms of
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great diversity, ranging from the microscopic copepod to the macro-
scopic shark. Sound histological evaluation begins with good
fixation. Formalin, routine in mmmiu lian and vetrinary tissue
fixation, was not adequate for general use with marine biota. The
NMWQL histological unit evaluates up to 5000 organisms per year.
These evaluations represent as many as 133 species, and an average
25,000 microscope slide preparations and analyses. Obviously, a
routine method of fixation had to be established. Dietrich’s and
Zenker—Formal Fixatives, for use with fishes and invertebrates
respectively, met the needs admirably. Minor technical barriers
have been encountered among the variety of organisms evaluated,
such as sand in the tissues of many filter—feeding invertebrates
which interferes with thin sectioning of tissues. However, the
laboratory has overcome these barriers and advanced to the utili-
zation of more advanced histochemistry, electron microscopy,
autoradiography, time—lapse, and video—tape recording for study
of marine biota exposed to pollutants.
KNOWLEDGE OF CYCLIC CHAHGES A MUST IN NATURE AND THE LAB .
Histological evaluations and conclusions must be based on a
knowledge of basic structural and physiological make—ups of the
organism. For instance, the physiological and structural condition
of most marine organisms changes seasonally according to seasonal
environmental conditions—including laboratory captivity. There-
fore, histophysiological studies must be continuous. Investigations
of the bay scallop have determined thrit these organisms undergo a
continuing change which can be followed.using the content of acid—
staining granules in its nervous system. The change, which cycles
on an annual basis, is considered normal and can be correlated with
ambient water temperature. It is essential, therefore, that these
oddities be understood when evaluating effects of man’s impact on
the aquatic system.
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Copepods, common zooplankton animals routinely cultured at NMWQL
for laboratory experimentation, represent another example of the
importance of examination of experimental animals’ tissues. In-
terestingly, histophysiological evaluations with these organisms
have determined that captivity will affect a unique unicellular
gland. These glands, which are usually numerous, disappear after
nine days of laboratory culture. Further, the offspring of these
and following generations do not possess the glands. Laboratory
study has revealed that the offspring of cultured copepods demon-
strate a sensitivity to toxicants that is five times greater than
that of the non—cultured copepod.
FIELD AND LAB STUDIES ESTABLISH WATER QUALITY STANDARDS .
Exposure of organisms to toxicants is usually conducted in the
laboratory first by utilizing a preliminary rough (acute) bioassay
to be followed by a more precise, long—term, sub—acute, or chronic
bioassay. From the histological standpoint, organisms are evaluated
for presence and similarity of lesions in both instances. Whenever
possible, these studies are followed by studies of field situations
to determine whether the reaction(s) of non—captive organisms ex-
posed under natutal conditions compare with laboratory findings.
These results, combined with those from other scientific interplay,
can provide the basis for WQC. Research results described below
demonstrate the value of the histological technique as it has been
applied at NMWQL to determine WQC.
DO MAN AND FISHES GET THE SAME DISEASES ?
Both heavy metals and petroleum products represent a major con-
cern in terms of universal environmental contamination. Minimata,
or Itai—Itai disease is a disturbing, but real—life example of what
too much mercury in water can do to the human body. Too much
cadmium affects fishes in a way that is similar to what has been
documented for higher vertebrates, including man. When cadmium is
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accumulated in the kidney, irreversible damage occurs. Very low
levels of the metal will depress normal development of eggs in the
oyster ovary, while higher more acute concentrations will also
affect the oyster’s kidney.
Copper, too, may induce lesions in the kidneys of some fish
and of some invertebrates. However, of more vital ecological con-
cern are the neurotoxic properties of the metal. Physiological
and behavioral observations have in the past indicated that copper
may be neurotoxic to aquatic biota. Histological evaluations only
recently confirmed the presence of morphological alterations.
These lesions are significant, because they involve the lateral
line (by which organ a fish detects changing water pressures) and
the olfactory organs (essential to sensing odors). Obviously,
these organs ate vital to normal behavior patterns of feeding,
schooling, reproduction, and migration, but very directly to the
detection of their enemy, prey, and of social partners. Mercury
and silver will also damage these organs of the sensory system,
although the lesions do differ in appearance. Damage to sensory
organs have also been demonstrated in fishes recovered from the
sites of fish kills in the real environment. Biological damage
of this nature can lead to the progressive disappearance of a
species because it can prevent the species from relating to a
viable environment. Headlines about a massive “fish kill” creates
public dismay. However, in reality, subtle biological damage which
goes unnoticed may have a much further reaching implication. Subtle
pressure due to chemical or physical adulteration of the environment
can transform an entire biological community without any external
catastrophic warning signals by altering established predator prey
relationships.
MULTIPLE METAL WASTES ARE BAD NEWS .
The prospect of combined metal waste impact can be disturbing
if metals act in a synergistic manner. The combination of cadmium
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and copper represent a classic example of how two metals can act
synergistically. Toxicity of a combination of these two metals,
which would ordinarily be very low for copper alone and nearly non—
existant for cadmium by itself, becomes markedly greater in laboratory
bioassaya. Normally, for the metal concentrations used, copper would
induce a neurosensory lesion, while cadmium fails to elicit a kidney
lesion. However, in combination at the same concentration, the
metals induced both neurosensory and kidney lesions and increased
the toxicity by several orders of magnitude.
Physical factors in the aquatic environment are found to influence
toxicity of some compounds, such as cadmium. Nevertheless, alteration
of salinity, temperature, pH, or dissolved oxygen does not alter the
outcome in terms of lesion development. Only time is a variable.
PETROLEUM AND CANCER .
The effects of petroleum products on marine bJ ota demands a great
deal of WQL’s histological research effort, but with good cause.
Hydrocarbons are known to be carcinogenic and circumstantial evidence
indicates that they are a likely cause of cancer in marine animal
species. Cancer in invertebrates had not been thought to exist.
However, when NMWQL found an incidence of 22% cancerous animals in
one soft—shelled clam population exposed to an oil spill (jet fuel),
it was an amazingly rude awakening. Cancer has also been found In
hard—shelled clams collected from nearby Narragansett Bay, Rhode
Island. The ovarian cancer was similar to a type found in the human.
Occurrence of a precancerous lesion has been demonstrated In the
olfactory organs of a marine fish exposed to crude oil in laboratory
experimentation. The olfactory organ lesion was induced by the salt
water soluble fraction of crude oil, which is not readily visible to
the naked eye. In addition to its demonstrated carcinogenic proper-
ties in marine blota, petroleum exposure can also cause blood system
deterioration in scallops, oysters, and in fish. Petroleum also
discolors the soft tissues of the invertebrate, such as the clam.
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Histological evaluations have revealed that large amoeba—like cells
engulf particles of hydrocarbons, retaining them, and thereby iinpa t
a dark pigmentation to the whole animal.
NTA EFFECTS ON TISSUES .
NTA (Nitrilotriacetic Acid) was at one time proposed as a re-
placement for phosphorus in detergents prior to extensive research
into its effects on public health and on aquatic life. While pro-
posed as a substitute, the product was studied at NMWQL to determine
its effect on marine life, if any. Essentially, research indicated
that NTA was relatively non—toxic to a variety of marine organisms
as determined by bioassays. However, lesions occurred in some fishes
and sand shrimp at concentrations that easily could be realized in
the environment. NTA containing products were eventually removed
from the market, mainly because of suspected carcinogenic properties.
SENSES AND SURVIVAL IN THE SEA .
Neurosensory lesions can be induced by some metals and by petro—
leuin products. However, pesticides and kraft pulp mill effluents
can also inflict damage to these vital organs in saltwater fish.
These sensory organs are essential to the survival of the aquatic
organism. It is by use of its senses that the organism remains in
harmony with its environment. Further, it must be recognized that
impairment of only a portion of the total sensory system such as
olfaction will have the effect of reducing the overall accuracy of
correlating sensory perceptions, and thereby threaten survival.
With the above in mind, consider the loss of one sensory system,
the olfactory system, in a fish such as the Atlantic salmon. To the
salmon it would mean that its ability to migrate and orient to its
homestreain is impaired or lacking. Migration and homestream orien-
tation are accomplished through the detection of physio—chemical
factors in the homestream by their olfactory sensations. Visualize
now, a beautiful salmon stream such’ as the St. Croix River, which
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is the international boundry between Maine (USA) and New Brunswick
(Canada), and which is capable of supporting annual runs of 9,000
to 18,000 salmon. The St. Croix supported salmon runs of that
magnitude’ once, but now is sterile. It has been said, “if pollution
from a pulp mill can be reduced in the river (St. Croix) below
Woodlands (Maine) and the planting of young salmon results in suc-
cessful and successive migrations up the St. Croix, it may mean
that a magnificent river, sterile for almost a century has been
reclaimed.” The neurosensory lesion due to kraft pulpaill waste
previously mentioned originated from the pulp plant located below
Woodlands on the St. Croix, the test fish were Atlantic salmon, and
the lesion appears in the olfactory organ both experimentally and
in nature.
These facts serve to indicate the source of the river’s sterility
but they also serve to indicate that man can and must be adaptable
to change, for the pulp company has since settled with legal repre-
sentatives of the U.S. Environmental Protection Agency. The pulp
company is complying with recommended changes at this writing, so
perhaps the Atlantic salmon may flourish in the St. Croix and other
rivers once again. Hopefully Thoreau was wrong; perhaps the Atlantic
salmon will not have to wait the passing of 1000 years for Mother
Nature to lower man—made barriers.
By: George Gardner, Paul Yevich, Margaret James, and
J.C. Prager.
Permission to reprint this article and photographs to accompany it
may be had by addressing the Director, National Marine Water Quality
Laboratory.
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