A two-year field study was made of a population of the California
Sea Mussel, Mytilus californianus, located on a protected tidal bench
at Yaquina Head on the Central Oregon Coast. This animal was
chosen because it is attached to the rocks, filters particulate matter
from the water, produces large amounts of eggs, and is a prominent
member of the intertidal community.
An equation was developed on both an empirical and a theoretical
has is for determining mussel tissue temperature from continuously,
recorded physical data in order to determine the annual temperature
trends and the daily rate of heating. Heating during exposure is an
important contribution to mussel temperature during the spring and
possibly during the fall.
Particulate organic material 100 to 200 m in diameter was
measured throughout the year and was found to range from 1 to 3 mg
dry weight per liter of sea water. During the spring, increases in particulate oxidizable material are associated with diatom blooms.
The rest of the year, detritus associated with the mixing action of
waves contributes a significant portion to the suspended particulates.
A gonad index was developed which separated the germinal
tissue from the storage tissue in the gonad. The denominator of this
index equation was the weight of the somatic tissue rather than the
total weight of the animal. The largest amount of reproductive
tissue observed was 800 mg per gram dry weight of somatic tissue,
but the population generally maintained a germinal gonad index of
about 60% of its potential maximum. The storage stage was found to
be greatly reduced in this population unlike that found in M. edulis.
The seasonal reproductive progress was studied by quantitatively
following three categories of oocyte stages. The number of
oogonial clusters was used as an index of mitotic activity. Few clusters
of oogonia appeared when numerous mature oocytes were present.
The number of previtellogenic oocytes was taken as an index of early
meiotic activity. Previtellogenic processes were initiated during the
spring when the tissue temperature was rising. Mature oocyte numbers
increased as vitellogenesis occurred, and the rate of increase
of mature oocytes was best correlated with particulate organic concentration
in the water. Partial spawning and resorption of lysed eggs
were the predominant fate of mature eggs. The dynamic aspect of oogenesis was followed using a flow model
for the categories of occyte stages. From this model rates of change
of each cell type were estimated. Only 40% of the total oocytes produced throughout the year was lost by spawning.
Gonadal tissue was chemically divided into biochemical fractions
to determine the chemical characteristics of each reproductive stage
and the rates of accumulation of chemical components between bimonthly
samples. The rates of accumulation of protein and lipid
increased from 1.7 to 3.6 mg per day per gram animal and 0.6 to
1.8 mg per day per gram animal during previtellogenesis and vitellogenesis
respectively. RNA increased at the rate of 0. 6 mg per day
per gram animal, while the amount of glycogen decreased.
Isochrysis galba, a flagellate, labeled with carbon-14 was fed
to mussels under different exposure and thermal regimes to determine
the rate of incorporation and the percentage of food allocated to the
gonad. For mature gonads undergoing partial spawning, about 10% of
the food was found in the gonadal tissue within 3 days. The translocation
and synthetic pathways associated with protein and RNA appear
to be the most active. The amount of protein per egg determined
directly or indirectly was found to decrease as the reproductive year
progressed.
A hypothetical scheme for the environmental and physiological
control of oogenesis M. californianus is presented and evaluated in terms of the data. As a result o the observed timing of events and
the variation in the population, elucidation of the relationship between
reproductive phenomena and the environment by conventional techniques
would require analysis of 50 to 70 specimens every 2 weeks for
a period of at least 2 years. / Graduation date: 1975
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/28666 |
| Date | 29 May 1974 |
| Creators | Elvin, David Winter |
| Contributors | Gonor, J. J. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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