Ocean 220 Projects for Year 2002 Ocean 220 Projects for Year 2002Geological oceanographers use the grain-size characteristics of sedimentary deposits to interpret the physical processes (e.g., currents and waves) and mode of transport in the environment at the time of deposition. In this way, past as well as present marine environmental conditions can be interpreted from the characteristics of sedimentary strata. In order to illustrate this procedure, marine sediments will be sampled from a wide variety of environments within Puget Sound and subjected to grain size analysis. Once the sediment size distribution is known, several techniques can be used to evaluate the depositional environment.
To use the grain-size distribution of sea-bed sediments to interpret the mode of sediment transport and physical conditions in the marine environment at the time of deposition.
To sample and analyze the grain-size distribution of bed sediment collected in the study area. To apply threshold of grain motion curves and C-M diagrams to the observed grain-size distributions.
All plants contain chlorophyll a (Chl a), the green pigment which fuels the conversion of inorganic substances such as CO2 into some of the good things in life: honey, wood and fruits. Phytoplankton, the most important marine plants, also contain Chl a. Participating in this project you will learn to measure and interpret phytoplankton Chl a data. Chl a estimates are amongst the most fundamental measurements made in oceanography and are collected in all oceanographic field work. The data obtained are often used to estimate phytoplankton distribution and biomass.
On our cruise throughout Puget Sound we will stop at many different places, called stations. At each station a CTD will automatically measure salinity, temperature, in-situ fluorescence etc. In parallel to these data we will take water samples from discrete depths. We will filter the seawater, extract and measure Chl a from these filters.
You will probably learn a lot of unanticipated things in this class. However, I am certain you will have the opportunity to learn some or all of the following:
In this project, we will try to determine how fast the plankton in Puget Sound are growing. To access growth, we will look at how oxygen concentrations change over time. We will try to measure changes in oxygen concentrations in screened bottles. We will also measure changes in nutrient concentrations to see if utilization of nutrients and generation of oxygen are linked in a meaningful manner. This project also attempts to measure biological productivity and relate it to the chemical and physical features of the water that might control productivity. Where in Puget Sound do you think phytoplankton will be growing the fastest? Will the places with the most plankton also be the places where they are growing the fastest?
We will use the classic (and still standard) Winkler oxygen titration method in order to determine the quantity of oxygen in our samples. This technique, as modified by Carpenter, has a precision less than 1 micromolar (pretty good). We will need that precision in order to make our measurements, so excellent analytical skills will be developed for this project. Our experimental protocol will be to collect water from several depths at the stations and put it carefully into cleaned glass jars without contaminating with air. Then we will incubate the jars for periods of up to 24 hours, sacrificing some every few hours in order to determine how oxygen concentrations change over time. If oxygen goes up, we know the phytoplankton are growing. If oxygen goes down, then we know that respiration is exceeding phototrophic growth. Finally, we will measure nutrient (ammonium, nitrate, phosphate, and silicate) concentrations and see if they change during the incubations.
We should be able to ask and answer several questions, and learn a great deal about phytoplankton growth. Some are outlined here: Is it possible to simply measure the primary productivity of phytoplankton in Puget Sound, or do we need also to access the rate of respiration? Is the rate at which phytoplankton are growing related to the abundance of phytoplankton in the water? Should there be any relationship between oxygen concentrations and nutrient concentrations? What about heterotrophic organisms (e.g. zooplankton)- how fast are they breathing?