Volume 6, Spring 2008 - Saddleback College

Fall 2007 Biology 3A Abstracts
Wong, C. and Jelacic, S. (2000). The Risk of the
Hemolytic–Uremic Syndrome after Antibiotic
Treatment of Escherichia coli O157:H7 The New
England Journal of Medicine. Volume 342:1930-
1936
Effect of Tide Level on Nitrate and Phosphate Concentration in Marine Water
Nathaly Leal- Arteaga and Saori Shimamoto
Department of Biological Science
Saddleback College
Mission Viejo, CA 92692
It is known that several factors such as tide level, temperature, water nutrient level,
seasons and salinity affect phytoplankton activity. The objective of this study was to see
the relationship between the tide level and the concentration of nitrogen gas and
phosphorous ions, both of which affect the phytoplankton level in marine environments.
The sea water was collected at Dana Point Harbor off the California coast on April 17,
2008. A DR/850 Colorimeter was used to measure the concentration of two ions. Three
10mL water sample were observed and the average value was analyzed. The nitrate ion
concentration was 1.07 ± 0.3 ppm (± se) at low tide and 1.5 ± 0.1 ppm (± se) at high tide.
The mean phosphate acid concentration resulted 0.28 ± 0.02 ppm (± se) (N=3) at low tide
and 0.77 ± 0.09 ppm (± se) (N=3) at high tide. Both nitrate ions and phosphate acid levels
increased as the sea level increased; however, there was no significant difference between
low tide and high tide in the nitrate ion concentration (p>0.05).
Introduction
Combined inorganic nitrogen gas and
phosphorus acid is the major limiting nutrient in
many aquatic ecosystems (Small et al, 1989).
Nitrogen fixation is the major way for blue-green
algae and phytoplankton to precede the nitrogen
metabolism by reducing the atmospheric nitrogen to
ammonia. Nitrogen fixation is related to blue-green
algal blooms, nitrogen compounds in lakes, and the
role of the heterocyst (Horne et al, 1972). Heterocyst
is the section where the cells in a filament carried out
only by nitrogen fixation. Horne et al (1972)
represented the role of the transparent heterocyst cell
giving good measurement rates of nitrogen fixation
by Anabaena; a freshwater algae that contaminate the
water with a fishy odor and taste.
Nitrogen gas ends up in the environment
mainly through agricultural processes, and thereby
also ends up in the ocean. The most widely applied
nitrogen fertilizers is sodium nitrate; these fertilizers
mainly contain nitrate, ammonia, urea, ammonium
ions and amines are adding to the abundance of
nitrogen compounds found in water masses, such as
lakes, oceans and rivers. After fertilization, crops use
a relatively small amount of added nitrogen
compounds (Horne et al, 1972), therefore leaving the
rest to run off into the water.
Not only do the nutrients such as nitrogen gas
and phosphorus gas control the phytoplankton
population but other marine systems affect the water.
May et al (2003) sustained observations and
experimentations in South San Francisco Bay with
numerical modeling analyses to search for general
principles that define phytoplankton population
responding to physical dynamics. Characteristics of
shallow nutrient-rich coastal waters, tides, wind and
the flow of water influence the phytoplankton
concentrations. May et al (2003) indicated in their
study that the sensitivity of estuarine phytoplankton
dynamics to spatial and temporal variations in
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Saddleback Journal of Biology
Spring 2008