University of Alabama at Birmingham Causes of Fish Kill in Alabama Lake Paper

University of Alabama at Birmingham

Question Description

Can you help me understand this Environmental Science question?

all the information needed is in the folder attached, the assignment must be at least 17 pages

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Final Answer

Hi! I appreciate your patience! I uploaded the essay, with a total length of 20 pages. Please read through it and let me know if you need any corrections and I can get those to you before the deadline. I ran a plagiarism report, which came back 3% (I attached a screenshot), I checked all the matches and none were greater than 33.3%, it was just information that sounded similar from the methods section. Nothing was a direct quote or copy. Citations were completed following ASCE style with proper in-test citations. There are 21 of them so the requirement was met. Again, let me know if you need anything additional!

RUNNING HEAD: Causes of Fish-Kill in Alabama Lake

Causes of Fish-Kill in Alabama Lake
Student Name
29 March 2020
Professor Name

Causes of Fish-Kill in Alabama Lake


A small residential lake in Alabama, following a major rain event, experienced a fish kill
accompanied by a strong odor. The residents of the lake requested help to determine what could
have possibly caused this to happen. In the watershed of the lake lies a cornfield and paved road.
Research into similar scenarios such as this one has been conducted before. This research found
a link between pesticides, fertilizers and increased nutrient levels to fish kills. We selected
appropriate analytical methods to test water and soil samples from the lake and the surrounding
environment. Agricultural fields often contain fertilizer derived from treated sewage, with
increased nutrient and pathogen levels. Similar to initial beliefs, following the rainstorm, soil
from the cornfield containing high levels of pathogens and nutrients was carried into the lake.
This initiated a series of events that decreased dissolved oxygen levels to a point that fish were
unable to survive.
Keywords: fill kill, pesticides, fertilizer, dissolved oxygen

Causes of Fish-Kill in Alabama Lake


The result of altered conditions in a water source can cause the loss of life of the species
inhabiting the water. Most often, this is caused by changes in dissolved oxygen concentrations
(Hooper, n.d.). Fish, similar to all other species, require oxygen to breathe. The form of oxygen
in water is different than that on land. The oxygen fish require is dissolved into the water giving
it the name, dissolved oxygen. When these levels become too low the fish are unable to breathe
and die as a result of suffocation. The largest factor altering the dissolved oxygen levels in water
is temperature. When the temperature of water increases, the dissolved oxygen concentration
decreases. In water, other organisms are consuming this oxygen besides fish. One of these is
algae, which grows mainly during the warmer summer months. A worst-case scenario for fish is
warm weather and an algal bloom. The warm weather already reduces the oxygen concentration
and now the limited supply is being partially consumed by the algae. This case can result in a
fish kill, as the dissolved oxygen is not high enough to support both species. A fish-kill from that
scenario would be linked to natural conditions.
This is not always the case; sometimes the cause of a fish-kill is the result of human
activities adding nutrients into the water (Hooper, n.d.). Some possible sources of these
pollutants are agricultural lands, manufacturing plants and sewage systems. To determine the
cause of a kill-off, appropriate tests must be conducted on the water supply and surrounding soils
to determine which factors have changed. Examination of the recently killed fish can also
provide insight into possible causes. No data was collected before the rain event so baseline
measurements cannot be conducted. Results will be based on water quality standards created by
the Environmental Protection Agency (EPA).

Causes of Fish-Kill in Alabama Lake


The month is February and a major rainstorm just hit the state of Alabama. A small
residential lake in the state recently experienced a fish kill and the residents noticed a foul smell
of rotten eggs. A depiction of the lake and its surrounding terrain is seen in Figure 1 of Appendix
A. Running along one side of the lake is a paved residential road; on the other side is a cornfield.
Both the road and cornfield lie in the watershed of the lake. In addition, four houses are
surrounding the perimeter of the lake. There are no watercrafts permitted on the lake. The fish
stocked in the lake are Bluegill Bream, which are used for fishing. The residents have asked for
help determining what may have caused this tragic event and what steps can be taken to manage
the situation.
To begin the investigation several analytical methods must be chosen. The chosen
methods presented below, are based on likely causes of pollutants and require knowledge of
factors affecting water quality. Some of these factors are nutrients such as phosphate or nitrate,
and certain man-made contributors such as fertilizer or domestic waste. Since the cornfield and
road are in the watershed of the lake, anything washed away during a rainstorm would be carried
to the water. Before performing any tests, it is hypothesized that after the heavy rainfall event
pollutants from the cornfield were washed into the lake. These pollutants created conditions that
are unable to support Bluegill Bream life and the result was a kill off. To determine an accurate
cause the analytical method must be employed.
Case Studies
Similar scenarios to the one seen in the residential lake have occurred before. The following
case studies provide real-world insight into past fish kills and present known causes.

Causes of Fish-Kill in Alabama Lake


Study #1
In 1973, at Lake Weiss in Alabama, a large number of fish were found lying on the banks
(Clark, 2009). The Environmental Protection Agency (EPA) was called in to conduct analysis on
the water and determine possible causes. The water quality was tested and the results came back
with high levels of Endrin, which is a chemical in many pesticides. Upon examination of the
environment, it was determined that a cotton field was planted too close to the water. At that
time, the method used by farmers to fertilize their crops was to fly over in an airplane and spray
the pesticides down onto the fields. With the farm being planted too close, each time the airplane
would fly over the pesticides were sprayed inadvertently into the water. There was no buffer
zone between crops and Lake Weiss. When heavy rain came, the water would wash additional
Endrin into the Lake. Finally, the concentration became too high and the fish were unable to
survive. This situation is similar to what is seen in the small residential lake. There is a cornfield
planted close to the lake, which lies in the watershed of the lake. With heavy rainfall, any
chemicals applied to these crops would be washed into the lake and could have led to the kill off
Study #2
In 2003, at the Pamlico Estuary in North Carolina, a foul odor led to the discovery of a
large number of fish washed up on shore (Kosal, 2003). It was a blistering hot summer day and a
group of friends had decided to make a trip to the water. While driving they began to notice a
foul smell and as they got closer the odor began to grow stronger. The friends being curious
decided to investigate the smell. As they approached the shore it was obvious what the cause of
the odor was. Hundreds of dead fish were seen lying on the bank. A group of biologists was
called out to examine the scene and determine a cause. With high temperatures, it was believed

Causes of Fish-Kill in Alabama Lake


the deaths were caused by low dissolved oxygen levels. Upon further testing, it was determined
that oxygen levels were low, but not critical and fish would be able to survive in them. The
biologists stated that estuaries generally have plenty of nutrients, which are carried in the water
flowing in from surrounding streams (Kosal, 2003). The group observed the nutrient levels and
determined levels were not low they were actually too high. The effect of this is the production
of toxins by some of the plankton within the water. In this example, the plankton was Pfiesteria,
which produces a deadly toxin that causes fish to become lethargic and breaks down skin (Kosal,
2003). The plankton then feeds on these open cuts in the fish, which leads to their death. This
case study could provide insight into our problem. There was a foul odor, but the stench was
different than that at the residential lake. There could though have been increased levels of
nutrients washed into the lake from surrounding runoff after the long rain. In addition to testing
dissolved oxygen concentration, we should test nutrient levels and determine if there are any
toxin-producing plankton in the water.
Study #3
In 2015, at Longfellow Creek in West Seattle, the populations of Coho salmon were on
the decline (Doughton, 2016). With urban development came the construction of new roadways
and new challenges for migrating salmon. Each year as the salmon migrate upstream, teams of
scientists show up to provide help but also track population numbers. What was noticed was the
populations each year were less than the previous. It was initially believed that the roads
prevented salmon from crossing so they were unable to reproduce. To test this hypothesis,
scientists traveled downstream to check population levels. It was determined population levels
were similar and there was another factor causing the decrease. After testing water samples, high
levels of oil and chemicals were found. It was found that stormwater runoff was carrying a

Causes of Fish-Kill in Alabama Lake


combination of oil and grime from the roadways into the streams that were extremely toxic to the
salmon (Doughton, 2016). The results showed that roads constructed near streams were
detrimental to the populations within the stream. This case study provides a further possible
insight into the problem seen at the lake. There is a road running alongside the like, that also lies
in the watershed of the lake. There could have been oil and chemicals from the road that washed
into the lake and poisoned the fish
Analytical Methods

Temperature #2550 (Standard Methods)
The temperature measurement is calculated using standard methods under method
#2550. The recommended equipment to obtain the temperature in a body of water is a
thermistor (Clesceri et al. 2017). The independent variable is the thermometer depth and
the dependent variable is the temperature. The water temperature will vary by depth, as
the water closer to the surface receives more heat from the sun. The deeper the thermistor
is placed, the lower the water temperature should be.
No actual samples should be collected for this method, instead, the thermistor can
be dropped directly into the lake. It is important to analyze enough data points of
different depths to get an average temperature. This method was chosen for its relation to
dissolved oxygen. Temperature and dissolved oxygen are inversely proportional to each
other. Meaning that as temperature increases the available dissolved oxygen decreases.
Dissolved oxygen is the type of oxygen fish use to breathe. Without sufficient levels the
fish are unable to survive, in the same way, humans would be unable to survive without
oxygen in the air.

Causes of Fish-Kill in Alabama Lake


The baseline value for dissolved oxygen is 8 mg/L. The dissolved oxygen
concentration is considered low or hypoxic at 2 mg/L (“Dissolved Oxygen and Water”,
2020). If a body of water is considered hypoxic, the fish will have a difficult time

Chemical Oxygen Demand by Semi-Automated Colorimetry #410.4 (EPA)
The determination of chemical oxygen demand (COD) in the lake is conducted
using EPA standards under method 410.4. This value can be used to determine water
quality (EPA 1993). The applicable range is 3-900 mg/L. The specific instrument used
for measurements is a colorimeter. The water being sampled all come from the same
body of water. The independent variable is the location of water collected, such as in the
middle of the lake or near the shore. The dependent variable is the COD value. Different
areas of the lake will have different COD as the concentration of bacteria will be higher
around spillways or entry points for runoff water.
This test is chosen for its ability to determine water quality. It provides us with the
amount of oxygen required to convert organic material into carbon dioxide in the lake
(EPA 1993). The use of a strong oxidizing agent such as potassium dichromate is
required. The water samples should be collected into plastic bottles that have been
adequately cleaned with a reagent. There are not specific volumes of water required, but
samples should be collected from various locations around the lake. For this test in the
residential lake, water would be collected around areas where runoff enters the lake and
additional areas away from any runoff. This would allow analysis to attempt to find a
reason for altered COD levels. All collected samples should be tested quickly or stored in

Causes of Fish-Kill in Alabama Lake


cool temperatures until the tests can be conducted. Another reason this method was
chosen is related to a short time required and a high level of accuracy.
The healthy range of COD for treated water is 29-37 mg/L, In a freshwater
source, the healthy range is 394-644 mg/L (Grisolia et al. 2005). When evaluating the
results of the samples, a COD value above 644 mg/L would be considered polluted. A
high number means larger amounts of oxygen are required to break down organic
compounds and produce carbon dioxide in the water. If oxygen levels are low, the
organic compounds are not broken down and the water remains polluted.

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