Volume 6, Spring 2008 - Saddleback College

Fall 2007 Biology 3A Abstracts
turbidity depends on available light, rather than
nutrients limiting phytoplankton growth.
Large amounts of nitrate ions and phosphate
gases may cause eutrophication, an excess of
nutrients resulting in the abundance of photosynthetic
algae and plankton causing a serious effect on the
marine organisms’ life. Domoic acid (C 15 H 21 NO 6 ) is
a naturally occurring amino acid phycotoxin
produced by algae and plankton in all marine coasts
(Pan et al, 2008). This extreme chemical
proliferation is triggered by temperature in seasonal
algae blooms during the months of March and June
contaminating phytoplankton, shellfish and sardines
which later poison lipid rich sea mammals. California
sea lions are primarily affected by domoic acid; this
neurotoxin attacks the hippocampus part of their
brain causing memory loss, blindness and seizures
that will lead to death. Borchelt (1997) has a handful
of possible explanations for the increase of toxic
tides: increase in the amount of nitrogen gas,
phosphorus gas and other nutrients are disposed from
land fertilizers and animal waste; sewage and effluent
pollution in oceans.
Temperature, salinity, wave conditions, sea
levels caused by high tide and low tide influence
phytoplankton activity- Nitrogen gas and Phosphate
ion levels are well known to increase phytoplankton
concentrations in ocean waters (Lehman, 2006).
Therefore, in this study, nitrogen gas and phosphate
ion levels are being tested to determine the
relationship between tides and the abundance of
phytoplankton which lead to severe toxin
concentrations.
Materials and Methods
This experiment was conducted over a period
of three days in April of 2008. Water samples were
collected behind the Ocean Institute at the Dana Point
Harbor in Southern California and the analysis were
performed in the laboratory at Saddleback College,
Mission Viejo, CA. On Sunday April 6, 2008, three
sterilized bottles were used to collect sea water
during high tide. According to 2008 Dana Point
Harbors Tide Calendar, high tide was at 9:30 am with
a 4.7 MSL (mean sea level) which are recorded by
stationed tide clocks and gauges. The bottles were
then placed in a refrigerator to prevent bacterial
growth. Later that day at 3:50 pm three other
sterilized bottles were used to collect water samples
during low tide, 0.6 MSL. The samples were also
placed refrigerator to obtain accurate results. Samples
were taken to laboratory to examine on April 7,
2008.
A DR/850 Colorimeter (Hach Company, CO.
U.S.A) was used to measure the concentration of
dissolved nitrate ions and phosphate ions in the water
samples. This devise had several settings and packets
that contain compounds that create a reaction; a blank
test tube with sample water was always needed to
calibrate the calorimeter between readings. Nitrogen
was first tested, with a Nitra Ver 5 Nitrate packet
mainly containing: Cadmium, Gentisic Acid,
Magnesium Sulfate, Potassium Phosphate,
Monobasic and Sulfanilic Acid. Using the low tide
samples ten mL of sea water was placed into three
special glass bottles with the Ver 5 Nitrate packets,
they were shaken vigorously for one minute and were
set aside for five minutes while the Colorimeter read
the blank sample which was then zeroed out (0.0
mg/L No3-N). The water samples were also tested for
Phosphorus; a 3 Phosphate Reagent packet was used
that contains: Ascorbic Acid, Potassium Pyrosulfate
and Sodium Molybdate. Using low tide samples, 10
mL of each bottle was placed in three special bottles
that the colorimeter could read. Phos Ver 3 powder
was added to each test tube, shaken for 15 seconds,
were then left to stand for two minutes to allow the
reaction occur. The blank tube was placed in the
colorimeter to zero out (0.0 mg/L P04). Each water
sample was placed in the device to be read.
For both nitrogen gas and phosphorus gas, the
average concentrations of the three measurements
were recorded by summing all the three values and
dividing by three. Those average values were
demonstrated on bar graphs using Microsoft Excel
2007 to compare the concentration differences at low
tide and high tide.
Results
The nitrate ion concentration measurements were
taken from the three water samples from low tide and
were placed into the digital colorimeter that measures
in gram per liter (mg/L) which is also known as parts
per million (ppm). The samples displayed 1.6 mg/L,
0.8mg/L and 0.8mg/L with an average concentration
of 1.07 ± 0.3 ppm (± se) (N=3). For high tide, the
nitrate concentration was measured to be 1.6mg/L,
1.3 mg/L and 1.6mg/L with a mean of 1.5 ± 0.1 ppm
(± se) (N=3). T-test was performed to see whether
the difference is significant or not; resulting with a p-
value of 0.1, the concentration of nitrate ions at low
tide and high tide was not significantly different
(Figure 1).
Phosphate ion concentration was measured in
the same manner for both low and high tide. The
samples displayed 0.29 mg/L, 0.32 mg/L and 0.24
mg/L and that average concentration was 0.28 ± 0.02
ppm (± se). For high tide, the phosphate ion
concentration sample was 0.57 mg/L, 0.69 mg/L, and
0.94 mg/L. Due to the high concentration of
phosphate ions between low and high tide, the water
18
Saddleback Journal of Biology
Spring 2008