Transcript "A stench from its inky surface putrescent with the oxidizing... the shadows of the overreaching trees add stygian blackness and...

"A stench from its inky surface putrescent with the oxidizing processes to which
the shadows of the overreaching trees add stygian blackness and the suggestion of
some mythological river of death. With this burden of filth the purifying agencies
of the stream are prostrated; it lodges against obstruction in the stream and rots,
becoming hatcheries for mosquitoes and malaria. A thing of beauty is thus
transformed into one of hideous danger."
Texas Department of Health 1925
"There are three kinds of lies. Lies, damned lies, and statistics!"
Mark Twain
Under carefully controlled laboratory conditions an organism does what it damn
well pleases.
Harvard Law
"What's the use of their having names", the gnat said, "if they won't answer to
them?"
"No use to them," said Alice; "but it's useful the people who name them, I
suppose.“ Through the Looking Glass – Lewis Carroll
Cyclomorphosis
Cyclomorphosis as the name indicates is a cyclic change in body form. This occurs primarily in
female lemnetic species such as Daphnia pulex and Daphnia rosea. A population of
cyclomorphic species has a homogeneous “normal,” or rounded head, form during the late fall,
winter, and early spring. As the water becomes warmer and the populations develops, however,
there is a commonly progressive increase in the longitudinal axis produced by a general
elongation of the head and the appearance of a “helmet”. Characteristically, the helmets become
fully developed by midsummer, when they may be quite bizarre. Beginning in late summer or
early autumn, the morphology of the head progressively reverts so that the “normal” condition
prevails by late autumn. In the words of Coker (1939), “The changes in form are not simple
functions of external conditions or of any inherent cycle, but rather of a combination of internal
and external conditions in a way that becomes exceedingly baffling the more we know about it.”
Theories about helmet shapes
Under conditions of low dissolved oxygen Cladocera often produce hemoglobin to facilitate the
transfer of oxygen. Studies have been done which strongly suggest that given the choices
red/pink Cladocera and a normal colored Cladocera, fish choose the red/pink Cladocera.
There would therefore appear to be a selective disadvantage to becoming red/pink. One theory
suggests that the increased size of the helmet of Cladocera functions to increase the surface area
over which oxygen can be extracted from the water and therefore changing helmet dimensions is
a function of reduced dissolved oxygen..... temperature.
Another theory suggests that as the water temperature increases the density of water decreases
and therefore animals such as Cladocera have to expend more energy to keep from sinking.
Since the food of the cladocerans is mostly algae and since algae live near the surface, decreasing
the amount of energy necessary to stay higher in the water column would be a selective
advantage. One way to counter the tendency to sink would be to increase the helmet dimensions.
Poikilotherm – having a body temperature that varies with the environment,
cold blooded as are amphibians, reptiles, fishes, insects
Homiotherm – having a constant body temperature, warm-blooded as are mammals
and birds
Q10 law or VanHoft’s Law which states that a doubling of temperature between 10
and 20 ºC increases the metabolic rate by 2 fold.
Inverse metabolic rate law – the smaller the organism the greater the metabolic rate
on a per gram basis. Therefore, it takes more energy to support 10, 1 gram organisms
than it does 1, 10 gram organism. If a rhinoceros had the metabolic rate of a mouse it
would have to endure boiling temperature at its surface in order to dissipate heat
generated as a result of metabolic processes.
Physoclist, physostome, no gas bladder
Diurnal
Diel
Nocturnal
Very Early Stages of Development Embryo (0 hours old)
Embryo +3 Hours
Embryo +5 Hours Old
Embryo +8 Hours
Embryo +11.5 Hours
Embryo +13.5 Hours
Embryo +14 Hours
Embryo +14.5 Hours
Embryo +16.5 Hours
Embryo +17.5 Hours
Young C. dubia In Last Embryonic Membranes
First Antennae of Female Ceriodaphnia dubia
First Antennae of Male Ceriodaphnia dubia
First Antennae of Male Ceriodaphnia dubia
Female With Fertilized Egg In Brood Pouch
Female With Fertilized Egg In Brood Pouch
Ephippium With Resting Egg
Ephippia
Sampling Devices
Ekman Dredge
Ponar Dredge
Surber Sampler
Kick Net
½ meter net – macrozooplankton
Microzooplankton closing net
Artificial Substrates
Diatometer
Distributions
Mean, Variance, Standard Deviation and Confidence Limits
Data Set 1
Data Set 2
10
5
10
80
10
0
10
1
10
0
10
0
10
0
10
7
10
3
10
4
Total
100
100
n
10
10
Ave
10
10
Variance
0
St. Dev
0
C.I.
10+/-0
611
24.7
10+/-17.7
Variance = (xi2) - (xi)2/n
Standard Deviation (St. Dev) = square root of the variance
n-1
Confidence Interval (CI) = Mean  tvalue (St. Dev.) The t value is chosen based on sample size and  or probability
n
level
t value for 95% Confidence Interval and n=10 is 2.262
1-/2 n-1 d.f.
If  = 0.05
Data Set 3
10
12
14
Calculate the mean, variance
standard deviation and 95%
Confidence limits for Data Set 3
17
28
Mean = 13.5
2
Variance (s2) = 55.17
6
Standard deviation = 7.43
21
Mean  5.3 (13.5  5.3)
10
15
If you have an n of more than one you can
calculate a mean and confidence intervals
about the mean
1000
Failing to reject the null hypothesis does not
mean that there is not a difference!!!!
Ho: There is no difference in the mean
number of benthic organisms above
and below the outall.
Ha: There is a difference in the mean
number of benthic organisms above
and below the outfall.
0
Correlation and Regression
The purpose of correlation analysis is to measure the intensity of association observed between any pair of variables
and to test whether the association is greater than can be expected due to chance alone. Once established, such an
association is likely to lead to reasoning about causal relationships between variables. Students of statistics are told
at an early stage not to confuse significant correlation with causation.
Regression deals primarily with the means of one variable and how their location is influenced by another variable.
Regression comes close to implying cause and effect relationships. Thus, where a correlation coefficient tells us
something about a joint relationship between variables, a regression coefficient tells us that if we alter the value of
the independent variable then we can expect the dependent variable to alter by a certain amount on the average.
The correlation coefficient r can range between -1 and +1 and the value of r tells us something about the degree of
relationship between two variables.
The coefficient of determination r 2 used in regression analysis (the square of the correlation coefficient) tells us how
much of the variation in the dependent variable can be explained by its association with the independent variable.
An r2 value of .90 indicates that 90% of the variation in the dependent variable can be explained by its relationship
with the independent variable.
In a sample size of 200, an r of 0.2 would be significant at the 1% level of significance, but would indicate that only
4% of the variation in the Y value could be explained by its relationship with the X variable. A verdict of statistical
significance shows merely that there is a linear relation with non-zero slope.
In fact, the condition factor was significantly correlated with DNA
damage (R= -0.413, P=0.045) and MT levels (R= -0.622, P=0.03).
At a probability level of 0.05, any value of P less than this would
be statistically significantly different.
Significance in these cases means that the slope is statistically
significantly different from 0.
-0.413 = 17%
-0.622 = 39%
dichotomous key
Starlings (Sturnus vulgaris)
It is the first of February, and everyone is talking about starlings. Starlings came to this country on a passenger liner
from Europe. One hundred of them were deliberately released in Central Park. According to Edwin Way Teale,
Their coming was the result of one man’s fancy. That man was Eugene Schiefflein, a wealthy New York drug
manufacturer. Schieffelin formed a group of people called Acclimatizers who had as their goal the introduction into
the US all of the birds mentioned by William Shakespeare. The birds were released in Central Park in New York
and first nested under the eaves of the Northwest wing of the Museum of Natural History. The birds acclimated
splendidly, in less than 60 years the 100 or so birds released into Central Park increased to more than a million and
by 1954 they had reached Alaska.
These birds are controlled in England and other parts of Europe by the normal array of competitors, predators, and
diseases with which the bird evolved. These controls were not present in the US so the bird spread rapidly, and out
competed many of our native birds. You’ll begin to hear pneumatic cannons on our campus a little later in the spring
as attempts are made to drive off the starlings and boat tail grackle that roost on our campus.
Anne Dillard in her book Pilgrim at Tinker Creek writes, “Starlings are notoriously difficult to “control”. The story
is told of a man who was bothered by starlings roosting in a large sycamore tree near his house. He said he tried
everything to get rid of them and finally took a shotgun to them killing three. When asked if that discouraged the
birds, he reflected a minute, leaned forward, and said confidently, ‘Those three it did.”
Passer domesticus
The English sparrow entered the US as a gesture of friendship. As the steamship
Europa steamed up the Hudson River the birds were a gesture of friendship to the
U.S. In reality the English sparrow was introduced numerous times before it
finally took hold.
Native to the Old World, the bird was first introduced into the United States
about 1850 to combat cankerworms, and it rapidly became widespread.
Aggressive as well as prolific, it has largely replaced many native birds in urban areas.
In 1912 The English Sparrow As a Pest? Farmers
Bulletin #493, by USDA noted they eat more than ½
their own weight in grain or other food a day. It
contained recipe for house sparrows.
•By 1887, some states had already initiated efforts to eradicate HOSPs. States such as
Illinois (1891-1895) and Michigan (1887-1895) established bounty programs. According to
Keith Kridler, since the bounty on "English" Sparrows was only a few cents per bird in
many states, young children killed these birds to earn money for "hard candy." The children
quickly learned to wait for the eggs to hatch and thus quadruple their bounty. County clerks
often felt sorry for these children, and paid out the bounty on any species of sparrow. A
3/16/1892 article in an Indiana PA paper stated "The different county treasurers of Illinois
have paid out in round figures $8,000 as bounty money under a law allowing 2 cents for the
head of each sparrow killed during December, January and February in that State. This
shows that about 450,000 sparrows were killed, but the frisky bird seems more numerous
than ever."
•On 09/06/1888, The Cartersville Courant-American newspaper noted "The English
Sparrow, with its grown and growing progeny, is a conspicuous nuisance. Can they be no
way devised to abate him, if not totally, at least partially?"
•An 1883 article in The Messenger (Indiana, PA, 06/27/83) said "The little sparrow has
been declared an outlaw by legislative enactment and they can be killed at any time. They
were imported into this country from Europe some years ago as a destroyer of insects,
but it has been found they are not insectivorous. Besides they drive away all our native
song birds and give no equivalent. Let them all be killed."
•In 1903, W.L. Dawson wrote "Without question the most deplorable event in the history of
American ornithology was the introduction of the English Sparrow." (The Birds of Ohio,
1903)
Professor Ettiene Leopold Trouvelot
Professor Trouvelot wanted a hardy caterpillar which would feed on oak leaves and
spin a cocoon of silk. He thought such a useful creature might be produced by crossing
the American Silk Moth, Bombyx mori, which feeds on mulberry and produces a large
cocoon, with the Gypsy Moth, Lymantria dispar, which feeds on oak leaves. He was
apparently culturing the gypsy moths on trees in his backyard when some of them
escaped. Trouvelot understood the potential magnitude of this accident and notified
local entomologists, but no action was taken. After the “accident”, outbreaks began to
occur in Trouvelot’s neighborhood and in 1890 the State and Federal Government
began their attempts to eradicate the gypsy moth. Trouvelot apparently lost interest in
entomology and became interested in astronomy. About 10 years after the accident He
became famous for his illustrations of astronomical details of Venus and was
eventually given a position at Harvard University in Astronomy. A crater on the moon
was named in honor of Trouvelot and he won the French Academy’s Valz prize for his
astronomical research.
The gypsy moth is now one of North America’s most devastating pests. In one of their
record breaking years they defoliated almost 13 million acres; in 1993, they devoured a
mere 1.8 million acres. This species originally evolved in Europe and Asia where it has
existed for thousands of years. Each year about 1 million acres of forest are sprayed
aerially with pesticides in order to suppress outbreaks of gypsy moth populations.
Though some areas are treated by private companies under contract with private land owners,
most areas are sprayed under joint programs of the state and USDA Forest Service. Millions
of dollars of tax money have been spent trying to eradicate and/or control the gypsy moth.
More recently, the Asian gypsy moth—traveled as stowaways on boats from Russia to the
West Coast in 1991 and from Germany to North Carolina in 1993. The Asian moths eat more
voraciously than the Europeans and, because the females can fly, may spread four to five
times faster. This gypsy moth is known to feed on the foliage of hundreds of species of plants
in North America but its common hosts are oak and aspen. Gypsy moth hosts are located
throughout most of the conterminous US but the highest concentrations are in southern
Appalachian Mountains, the Ozark Mountains, and the Northern Lake States. Every year
isolated populations of are discovered beyond the contiguous range of the gypsy moth. Most
die out but it is inevitable that the gypsy moth will continue to expand in the future.
New studies suggest that Dimilin, one of the most effective pesticides against the gypsy moth,
does more damage to the environment than previously thought. Dimilin, also destroys insects
vital to the health of the forest ecosystem. Dimilin is the cheapest and most efficacious way to
kill gypsy moths but the chemical has also become the “bad boy” of pesticides because of its
non-target effects. Studies indicate that of all the arthropods in the tree canopy, the macroLepidoptera larvae which includes the butterflies and big moths suffer the greatest loss. These
arthropods, and others don’t seem to recover for longer than a year after spraying, play a
critical role in the forest ecosystem as food for bats and birds. Dimilin is also incredibly toxic
to aquatic invertebrates compared with alternatives.
Under the Toxic Substances Control Act (TSCA) the risk of
chemicals to human health and the environment are supposed to be
evaluated before a chemical is allowed into commerce. Many of the
100,000 chemicals in commerce have never been evaluated because
they were already in commerce when the TSCA was passed in 1976.
Approximately 2,000 new chemicals come into commerce in the US
each year.
The ecological risk assessment is done by calculating the ratio
between the Predicted Environmental Concentration (PEC) and the
Predicted No Effects Concentration (PNEC). For fish medicines*based on acute data the ratio of these two parameters is <1 the
environmental effects are considered low are non-existent. If the ratio
is greater than 1 or the log Kow is >3 or the DT50 in water is greater
than 4 days further studies including chronic toxicity are carried out.
*the various factors DT, Kow, organisms tested vary depending on the
environmental compartment into which the chemical might go (air,
water, soil, etc.)
The use of dimilin (diflubenzuron) is expected to cause adverse
acute and chronic effects to both freshwater and estuarine/marine
invertebrates, including endangered species.
To lessen the environmental risks posed by diflubenzuron, EPA is
requiring the following risk mitigation measures:
Row crops and orchard uses must include a 150 foot buffer zone for
aerial applications and a 25 foot vegetative buffer strip to decrease
runoff in all cases (buffer strip will also serve as a buffer zone for
spray drift from ground applications);
Aerial applications must include the most current spray drift
language; and
All products must CONTAIN a hazards statement warning about
possible adverse effects to aquatic organisms.
White Pine Blister Rust – Cronartium ribicola
2,3,7,8-Tetrachloro-dibenzoIntroduced into the
US from timber shipments from Europe. It is a
p-dioxin
heteroecious (requires two hosts) parasite. The two hosts are the white pine
Agent valuable
Orange and
has wild
beencurrant
linkedand
to gooseberries of
tree which is commercially
cancers and other diseases in
the Genus Ribes.
Dioxins:
Congeners
several
epidemiological
studies.
One spore is found Congener:
associated
with
white
pine tree and this spore must
a member
of the the
same class,
or group.
The
Agent
Orange
cancers
and
Each
individual
PCDD
or
PCDF
is
termed
a
congener.
be transmitted to the intermediate host, the wild currant or gooseberry
diseases
include
prostate
cancer,
There
are
75
PCDD
congeners
and
135
PCDF
congeners.
before the spores infectious to the white pine tree, are formed.
respiratory cancers, (lung,
The spores that infecttrachea/bronchus,
the white pine treeslarynx),
may travel
long distances;
softhowever, the spores that
carry
the infection
from the wild currants and
tissue
sarcoma,
non-Hodgkin
gooseberries to the white
pine trees
seldom travel
more than 1000 feet. The
lymphoma,
Hodgkin
disease,
control strategy for this disease was to eradicate the wild currant and
chronic lymphocytic leukemia
gooseberry bushes within 1000 feet of white pine trees.
(CLL), and multiple myeloma.
9
8
O
7
9
1
O
6
2
8
3
7
2
O
6
4
Dibenzodioxin
PCDD
3
4
Dibenzofuran
PCDF
Cl
O
Cl
Cl
Cl
O
Cl
Cl
2378-TCDD
1
Cl
O
Cl
We used 2,4,5-Trichlorophenoxy acetic acid and 2,4-Dichlorphenoxy acetic
acid.
2378-TCDF
Unlike PCBs dioxins have no uses they are contaminants of
manufacturing
Kudzu Vine Brought to the U.S. in 1859 from China or Japan....
Hairy, wide leaves with fragrant purple flowers
Grows to 60 feet
Edible roots
Originally planted in eroding soils
Deciduous, nitrogen fixing bacteria associated with roots
Protein concentration about like alfalfa, leaves have been made into breakfast cereal
Now blankets everything including tall trees in the deep south
Hydrilla
Most native aquatic vegetation enhances aquatic ecosystems. Some of the benefits that are derived include fish and
water fowl habitat, sediment stabilization, and improved water quality with respect to nutrient removal and water
clarity. However, many introduced species can have negative impacts. Aquatic ecosystems are often destroyed as a
result of the increased biomass, dense canopy production, and the loss of diversity due to aggressive, weedy growth
patterns that overwhelm native vegetation.
One such non-native aquatic plant that causes excessive negative impacts is hydrilla (Hydrilla verticillata (L.f.)
Royle). Hydrilla is native to Southeast Asia and Australia. It was first discovered in the U.S. in the 1960s. Two
distinct biotypes; one monoecious (both sexes on one plant) and dioecious (one sex per plant) exist in the U.S.
Monoecious Hydrilla was discovered in 1982 in the Potomac River, just outside Alexandria, VA. It has since been
found in other parts of Virginia, in addition to North Carolina, Delaware, Maryland, California and Washington.
Hydrilla is also found in Texas and in fact is in Lake Ray Roberts, North Lake, Lake Conroe, among others.
Once Hydrilla invades an aquatic ecosystem, the plant spreads rapidly either by root crown and stolon growth or by
drifting fragments or turions. Hydrilla also produces an underground tuber, another reproductive strategy for
survival. Monoecious Hydrilla produces viable seed, whereas dioecious hydrilla in the U.S. produces only female
flowers. Hydrilla can rapidly produce a dense canopy, shading out desirable native vegetation and reducing plant
diversity.
To improve hydrilla management, the U.S. Army Corps of Engineers' Aquatic Plant Control Research Program
supports studies in four main technology areas. Biological control, chemical control, ecological, and simulation
technologies. The biological control technology areas is investigating fungal pathogens, and insects as potential
control agents. The chemical control technology area examines concentration and exposure times required for
aquatic herbicides and evaluates their use on an operational level. The ecological technology area examines the
environmental parameters that determine the distribution of Hydrilla. The simulation technology area has been
developing growth models for Hydrilla as well as predictive models for specific control techniques used on the
species, such as herbicides, harvesting, or triploid grass carp.
Water Hyacinth (Eichhornai crassipes)
Hyacinth allegedly was first brought from Brazil or Argentina to North America in 1884. The plant was imported as
a table decoration for an exposition in New Orleans. A woman brought one from the exposition to Florida and put it
in her backyard fish pond. Within 10 years the colorful plant had become a public menace. Unchecked by natural
enemies and nourished by Florida's nutrient rich waters, the water hyacinth (which can double its population in just
over two weeks) rapidly displaced native aquatic plants and took over.
Transported by boat propellers, river currents, birds, and wind, the floating aquatic weed soon spread over six
southeastern states including, North Carolina, South Carolina, Georgia, Alabama, Mississippi, and Florida.
A 1947 survey showed that an estimated $4,013,000 in fish and wildlife was destroyed annually.
Characteristics:
The hyacinth is very plastic in its habitat. It has the tenacious ability to multiply. It floats on the surface and extends
its roots 6 to 24 inches into the water. It can survive under extreme conditions. If water dries up it extends its roots
into the bottom mud. It forms dense mats on the surface making navigation by boat almost impossible. The dense
mats also block the surface exchange of oxygen from the atmosphere and the water which can lead to anaerobic
conditions. The mass of vegetation can become so dense that it actually causes flooding during spring rains.
Control
Efforts to control the water hyacinth began in 1898 with the "help" of the Army Corps of Engineers which was
authorized by Congress to remove the hyacinth from navigable waters of Florida, Mississippi, Alabama, Louisiana,
and Texas. The methods they used were:
1. mechanical chopper
2. within two years the COE found a chemical sodium arsenite, which did the job much more efficiently. Even
though sodium arsenite was recognized as a deadly chemical, the COE used the chemical for hyacinth control for
about 35 years between 1902 and 1937.
3. in 1937 a crusher boat was designed for mechanical removal and it proved successful opening hundreds of miles
of waterways of Louisiana. Using conveyors large mats of hyacinth were dumped along river banks and left to dry
out and die, sodium arsenite was finally abandoned. Mechanical removal was not entirely successful, the boats could
not operate in shallow water along river banks, nor could they penetrate the tangled foliage of swamps. The
hyacinths in these areas quickly spread back into the cleared areas.
4. in the mid-1940's the herbicide 2,4-D became commercially available and became the most effective deterrent
available for this purpose; however, hyacinth continues to creep across southeastern American lakes and rivers.
Recently scientists have sought to join forces with nature. There are several predators (herbivores) which in large
enough numbers could eliminate the constant attention and manpower necessary in mechanical and chemical control.
A species of weevil from Argentina already is being used in Florida waters. This species of weevil feeds on
hyacinths exclusively so there is "no" danger it will attack beneficial plants. There is a small snail from Puerto Rico
that has been examined but it feeds on plants other than hyacinth. Other mites, fish, and turtles have been tested as
possible control mechanisms.
In 1976 we were spending $15x106 per year for hyacinth control. Attempts have also been made to use the
beneficial aspects of hyacinth. It has been tested for nitrogen and phosphorus removal in sewage treatment - NASA
has tried to use harvested hyacinth for fertilizer, food supplements for cattle... not only removes N and P but also
metals, pesticides, etc....... food supplements????
Studies at the University of Florida in Gainsville analyzed the chemical content and nutritional value as cattle feed.
Found that it cannot comprise more than 25% water hyacinth or the cattle's body weight will go down. Another
problem with hyacinth is that cattle apparently don't like its taste. Cost remains a problem as well as harvesting and
drying.... i.e., the cost effectiveness of using Hyacinth in this manner is questioned.
A century of control efforts with minimal success.
Fire Ants
Seven species of fire ants (Solenopsis) are distributed throughout the warm
temperate regions of the Americas. Shortly after World War I a dark form S.
saevissima from Argentina became established in Mobile, Alabama and slowly
spread to surrounding regions. In the 1930’s a smaller reddish form of Solenopsis
appeared in the same region, apparently representing a second major introduction.
The latter form aggressively made its way beyond the State’s borders swamping out
by interbreeding and internecine warfare (violent death marked by slaughter) the
established black phase. At present the North American populations are chiefly the
red phase, tending to replace native forms as well as the dark phase.
In 1957 the U.S. Department of Agriculture requested congressional approval for
control of the fire ant. The request was granted and a 2.4 million dollar allocation was
approved with the stipulation that matching funds be made available. Most states and
many individuals did respond with matching funds, but very often control programs
went ahead without them. A massive operation was set up with great speed. The first
spraying using 2 pounds of dieldrin (chlorinated hydrocarbon, on the POPs list) or
heptachlor (chlorinated hydrocarbon on the POPs list) per acre began in November
1957. Over two and one-half million acres were aerially treated. Not until the
operation was well underway were wildlife and health authorities notified. Immediate
opposition to the program resulted-opposition was to grow to a national controversy.
Fish, wildlife, livestock, and poultry suffered losses, the destruction of wildlife
bordered on the catastrophic. The insect was not considered more than a nuisance in
any of the southern states; it did not destroy crops, wildlife, and livestock.
However, chemicals did eliminate vertebrates from some areas, it did cause residue
problems, it did contribute to insect outbreaks themselves requiring control. It did not
eradicate the fire ant; the ants re-infested most of the treated areas. The Plant Pest
Control Division of the Dept. of Agriculture had clearly made a massive mistake; the
operation was a failure from its inception.
Between 1962-1978 Mirex was used as a bait to kill fire ant colonies. Mirex was
banned for use (it is on the POPs list) by EPA because it was shown to pose serious
human health hazards. Mirex is converted to Kepone by photolysis.
The imported fire ant now infests more than 230 million acres in Alabama, Florida,
Georgia, Louisiana, Mississippi, North and South Carolina, and Texas. Somewhere in
the neighborhood of 175 to 200 million federal dollars have been spent trying to first
to eradicate and now control this pest.
Economic-When soybean combines cut through fire ant mounds their blades and
rollers must be replaced two or three times a season compared to once every four
years under good conditions. Farmers have been known to leave valuable crops in
the field to protect their machinery. Citrus growers in Florida are spending about
$110/acre/year to replant some varieties of young trees that die because they are
girdled by fire ants. Studies by two U of Florida researchers found that infestations of
fire ants actually increased on insecticide treated plots that originally had low
infestation levels. The amount of increase on treated plots was somewhere between
200 and 3000 percent. Because the imported fire ants colonize better than other ants
you inadvertently select for imported ants when you eradicate all other ants.
Home control can be achieved by using boiling water on the mounds. Tends to kill
the grass around the mounds. Farmland and Rangeland controls using synthetic
growth hormones like Pro-Drone that prevents the larvae from developing into
normal workers. Large areas of Texas have been treated. Some researchers believe
that the Pro-Drone will act like the broad spectrum pesticides and actually increase
the infestation.
Researchers are looking for predators, fungi, or bacteria in native Brazil for control
mechanisms. In Brazil the fire ant is not a significant problem. Clearly something in
Brazil is controlling the density of fire ants. Our native fire ant species is a minor
nuisance at home, but a major pest in India where it was inadvertently introduced.
Former Texas Agriculture Commissioner Regan Brown told a national fire ant
symposium that, “This is not an infestation it is an invasion.” This is the same guy
who, on national TV, stuck his fist into a fire ant mound and then spent the rest of the
interview trying to get the dam things off of him.
Zebra Mussel (Dreissena polymorpha)
The Zebra mussel is a fingernail sized mussel native to the Caspian Sea. First discovered in 1986 in the St. Clair
River near Detroit where larvae were probably discharged along with freshwater ballast, these incredibly prolific
bivalves have spread explosively throughout the Great Lakes. Female Zebra mussels can produce up to a million
eggs per year, which develop into microscopic, free swimming larvae that form shells and attach to any surface.
Unchecked by natural predators--in Europe they are eaten by fish and diving ducks--the mussel can reach
populations densities of >90,000 animals per square meter. They clog pipes and shut down water intake systems.
They pile up on boats, buoys, and piers, crowding out native species. One utility estimated it will cost $50 to 100
million dollars to scrape the mussels from cooling pipes at their power plants. One "beneficial" effect is that the
mussels have made Lake Erie noticeably clearer by filtering its water through its feeding apparatus. Native drum, a
bottom dwelling fish, eat these mussels and may help control their spread.
The exotic Zebra mussel probably invaded the Mississippi Basin via canals linking Lake Michigan to the Illinois
River, a major tributary of the Mississippi River. First reports in the basin were from these canals in 1989 and 1990,
so it is not surprising the densest and most extensive populations in the basin are from Illinois (up to 94,504/m2) at
river mile [RM] 5.5. The percentage of native mussels infested with zebras increase from 3% upriver to 995 down
river. The most likely explanation for the upriver down river gradient is that larvae from populations in southern
Lake Michigan or the upper Illinois River were released during the Great Flood of 1993 and carried far down river
before settling. This hypothesis is supported by the size distribution of the zebras: most (99%) of them down river
were less than 15 mm long, indicating they settled in the spring or early summer of 1993, whereas fewer (62%) small
zebras occur at upriver sites. The upriver-down river gradient of native mussel densities, from 0.3/m2 at River mile
181 to a maximum of 12.2/m2 at river mile 5.5 is attributable to a long-existing gradient in sediment and water
quality (due to pollution from the Chicago area), rather than to effects of the newly arrived Zebra mussels on the
native mussels. However, judging from observations made by researchers in the area, the zebras threaten the 23
species of native mussels extant in the Illinois River. Freshly dead native mussels (with meats inside) were found so
heavily infested with zebras that their shells could not be forced closed. Others were held shut by tufts of byssal
threads attached to both shells.
The researchers recommend that action should be taken now to cryogenically preserve gametes or fertilized eggs of
native riverine mussels or to move adults into hatcheries where they can be maintained and perhaps propagated.
Native mussels might be stocked in the future if the zebra mussel populations ever crash.
Sometimes we introduce new species in an attempt to solve problems created by previous introductions but end up
making the situation worse. In Hawaii and several Caribbean Islands for instance, mongooses were imported to help
control rats that had escaped from ships and were destroying indigenous birds. Since the mongooses were diurnal,
however, while the rats were nocturnal, they tended to ignore one another. Instead the mongooses also killed native
birds and further threatened endangered species.
Our lessons from this and similar introductions have a new technological twist. Some of the ethical questions
currently surrounding the release of genetically engineered organisms are based on concerns that they are novel
organisms, and we might not be able to predict how they will interact with other species in natural ecosystems--let
alone how they might respond to natural selective forces. We can't predict either their behavior or their evolution, it
is argued.
Polyploid – an individual or species whose chromosome number is a multiple other
than two of the haploid number of chromosomes.
Polyploidy – a condition in which an individual posses one or more sets of
homologous chrmosomes in excess of the normal diploid sets as, triploidy,
tetraploidy, hexaploidy, octaploidy, and 16, 32, 64 etc. ploidy. Colchicine
Heterosis – hybrid vigor, increased size, faster growth rates, resistance to disease,
etc.
Homologous chromosomes – a pair of chromosomes which have identical genes or
their alleles
DATA: 26,000 acre lake (surface acres)
"Weed" in the lake is Hydrilla verticillata, an import native to the Old World tropics (Africa).
Weed is spreading at a rate of 15% per year
Home owners around the lake have collected money and tried:
mowing machines
Eli Lily Co. applied chemicals, has not halted spread
Lake also used as a drinking water source for a major metropolitan area (provides 40% of the drinking water.
Homeowners and marina owners claim they are losing 10s of millions of dollars in lost revenue and property value
weed has choked off recreational use of shore lines and covers, the weed often traps swimmers and two have drown.
Homeowners have the opportunity to buy 240,000 grass carp (White Amur for $250,000 they have raised from
private sources ($1.04 per fish.
The grass carp, or white amur (Ctenopharyngodon idellas) brought from the Soviet Union, is being tried as a control
for water hyacinth and other undesirable species as well.
What Lake is it?
You work for the Texas Fish and Game Commission and you have to decide whether or not to let them bring in these
fish, i.e. there is a state law which prohibits the importation of piranha and walking cat fish in addition to the grass
carp. Therefore, the legislature would have to be convinced to do this.
Bass fisherman say that importing the fish will make the best largemouth bass lake in the State the worst.
Characteristics of the grass carp:
(1) known to eat vegetation other than Hydrilla
(2) requires running water to breed successfully
(3) resembles a big silver-colored goldfish and can weigh 45 kg (100 pounds)
Texas Legislature was convinced to approve a 5 year study beginning in 1981:
(1) by 1984 all significant vegetation in Lake is gone
(2) grass carp are eating leaves off of willow trees, and 2-3 inches of grass up the shoreline
(3) black bass are harder to catch (lack of cover and declining population? Black bass catch is down 25%, crappie
catch is down 60%; Grass carp catch is way up - corn and dog food used as bait- fish is a vegetarian (20-25 lbs
each), claims are made that they are good to eat.
The lake which had the reputation as being something of a duck lake, has been holding few if any waterfowl because
of the dearth of vegetation.
(4) Grass carp now found in the Trinity and San Jacinto rivers. Where they came from no body knows for sure.
(5) Some Parks and Wildlife biologists believe:
A. the carp will die out in 5 to 10 years (running water to spawn?
B. Hydrilla, which still has roots in the lake will return and the cycle will repeat itself.
C. Pressure is now on to use Grass Carp in:
Houston Lake
Lake Jacksonville
Lake Livingstone
Lake Worth
Lake Palestine
Triploid carp are available at $5.00 per fish.
A triploid grass carp permit is in effect on this lake. If a grass carp is
caught, it must be immediately returned to the water unharmed.
There have been repeated instances over time where organisms,
organisms, for a variety of reasons, have been imported into the U.S.
In some cases the organisms were brought in on a whim (starlings),
in the name of science (gypsy moth), to attack a specific problem
(English sparrow) or as an accident.
The current epidemic of the spread of bird flu is an example of how
quickly things can spread do to both natural conditions as well as our
ability to travel almost anywhere in the world.
The zebra mussel entered the US in the ballast of a ship as have
many other hitchhikers, the reverse movement from the US to other
countries is also possible.
One underlying problem associated with almost all of these
introductions is that at “home” they are generally well behaved (their
populations are controlled by many forces they have evolved with)
when introduced into a foreign area without the control mechanisms
the populations almost always explode.