Lab 9A
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University of Houston Downtown *
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Course
1304
Subject
Geography
Date
Dec 6, 2023
Type
docx
Pages
3
Uploaded by ChiefHerringPerson172
1.Within the ocean, ______ occurs at all depths where life exists.
a.cellular respiration
2.Net primary production takes into account______.
d.carbon lost by cellular respiration
3.Variations in net primary production are chiefly due to changes in ______.
b.nutrient supply
4.Based on Figure 9A-1, the primary production in near-surface waters (1 m and 40 m) at
Bermuda reaches a maximum in ______.
a.March
5.As the phytoplankton that produced the first increase die, they become nutrients for other
phytoplankton. This produces a secondary minor increase in ______.
b.July-August
6.Bermuda is located in the Sargasso Sea within the North Atlantic subtropical gyre, where
waters have relatively low total production. The warm and saline surface waters typically are
stratified all year so that upwelling and vertical mixing are not factors in net primary production.
The reason for the early spring maxima in net primary production at 1 m and 40 m is likely due
to ______ at that time of year.
b.increasing solar radiation
7.The subsequent decline until June in net primary production at 1 m and 40 m is likely due to
declining ______.
a.nutrient supply
8.Sunlight is a limiting factor in photosynthesis. Solar radiation is attenuated by ocean water.
Even in clear, clean ocean water, red light is completely absorbed within the first 15 m (49 ft.)
and typically only about 1% of absorbed sunlight reaches 150 m (492 ft.). The section of water
that light penetrates is called ______.
c.the photic zone
9.In Figure 9A-1, net primary productivity at a depth of 100 m reaches a maximum in ______.
c.August
10.From Figure 9A-1, the net primary production generally occurs above a water depth of
______ m.
a.40
11.Refer to Figure 9A-2. During the late fall and winter months, the nutrient concentration is
______ for the year. This is the time of the year when cooling surface ocean water sinks, causing
more or less continuous convection and mixing within the upper water column.
a.lowest
12.The concentration of phytoplankton increases in ______.
a.March-April
13.The sunlight curve extends upward through winter and into spring as the Sun rises higher and
the daily period of daylight lengthens in the mid-latitude sky. This increased sunlight and
existing high nutrient concentrations cause the productivity, evidenced by the phytoplankton
concentration, to ______ in late winter or early spring. This dramatic change in productivity is
referred to as a spring bloom.
b.rapidly rise
14.After the spring bloom, the phytoplankton concentration ______. Even though the amount of
sunlight continues to increase, the phytoplankton change occurs because of the abrupt reduction
in the nutrient concentration. This reduction comes about as phytoplankton, through
photosynthesis, combine nutrients with carbon dioxide and water to form organic compounds.
The dramatic phytoplankton population growth depletes the nutrient concentration and leads to
the inevitable reduction of phytoplankton.
c.rapidly decreases
15.Because of low nutrient concentrations during the rest of spring and into late summer, the
productivity remains low until the ocean surface layer begins the cooling associated reduction in
incoming sunlight. This cooling and the strengthening of surface winds cause mixing of ocean
water to depths where ocean waters are nutrient rich. Why do nutrient levels increase following
the fall bloom in October?
c.Both a and b are correct.
16.Compare the Hydrostation “S” single-year productivity data in Figure 9A-1, at the 1 m and 40
m levels, with the Figure 9A-2 phytoplankton curve. The two datasets are most consistent during
what time of year?
a.During the spring bloom in March.
17.Figure 9A-3 shows curves of dissolved oxygen concentration (mg/L) with depth in the
Atlantic (red) and Pacific (blue) to a depth of 5000 m. Respiration leads to lower oxygen values
because ______.
d.both a and b are correct
18.Oxygen values are higher in the Atlantic Ocean than the Pacific Ocean because it has been a
______ time since the deeper water in the Atlantic contacted the atmosphere.
b.shorter
19.Referencing Figure 9A-3, the OMZ occurs at about ______ m depth in the Atlantic Ocean and
______ m in the Pacific Ocean.
c.500 … 800
20.According to Figure 9A-4, water oxygen level is the least ______.
c.along equatorial regions
21.Dead zones are fueled by ______.
c.excess nutrients from land
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