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Science practice 20

15 questions ~9 min recommended
⏱ 00:00
Score
—

Mouth

Stomach

Gastrodermis

Coenosarc

Tentacle

Nematocyst

Outer epidermis

- Mesoglea

Digestive filament

Septum

Theca

Basal plate

Atmospheric concentration of CO2

Carbonic acid, HzCO3 (mol/kg)

Bicarbonate ion, HCO3- (mol/kg)

Carbonate ion, CO3- (mol/kg)

Total dissolved inorganic carbon (mol/kg)

Average pH of surface oceans

Calcite saturation

Aragonite saturation

Preindustrial (1750)

280 ppm

1,768

225

2,003

8.18

5.3

3.4

Today (2013)

380 ppm

13

1,867

185

2,065

8.07

4.4

2.8

Projected (2100)

560 ppm

19

1,976

141

2,136

7.92

3.3

2.1

Overall

Calcareous algae

Corals

Bivalves

Mollusks

Gastropods

Coccolithophores

Echinoderms

Crustaceans

Seagrasses

*

Survival

*

Calcification

I

Growtht

*→

*

Photosynthesist Metabolism

I

*

I

I

Reproduction or Juvenile stages

Reproduction decrease

Slow development, decreased fertilization and larval survival

B: Slow development, decreased f fertilization and larval survival

M. Rep: Lara suriers

M: Larval survival

ILL

IIV

N/A

TI

N/A

N/A

Reproduction decrease

Larval growth/survival

Larval growth/calcification

Slow embryonic development

Scientist 1, 2009

N/A

→

Scientist 2, 2010

Scientist 3, 2011

Scientist 4, 2011

T = Increase = Decrease

* = Significant < = No change

I = Mixed response

but overall increase

• = Mixed respons

• but overall decreasi

= Mixed response but + = Interspecies

overall no change variability

Corals build the habitat that is the home for the fish and other marine species that live on the reef. The corals grow by creating aragonite forms of calcium carbonate cups in which the polyp sits. Figure 6.11 identifies the anatomy of a coral polyp.

Figure 6.11

Source: http://oceanservice.noaa.gov/education/kits/corals/media/supp_coral01a.html.

Millions of photosynthetic algae, called zooxanthellae, reside inside polyp tissues. They serve as an energy source for corals as well as providing the coloration for which corals are known.

Current research indicates that increasingly acidic waters may be to blame for the decline in coral populations. Oceans absorb atmospheric carbon dioxide. Table 6.2 depicts changes to ocean chemistry and pH estimated using scientific models calculated from surface ocean measurement data.

TABLE 6.2 Ocean Chemistry and pH

Some coral become less successful at reproducing sexually in acidic waters. Studies also show links between ocean acidification and coral bleaching. Figure 6.12 summarizes the physiological responses of marine organisms to biological ocean acidification experiments done by various scientists.

Figure 6.12

Source: Data adapted from "Recognising Ocean Acidification in Deep Time: An Evaluation of the Evidence for Acidification across the Triassic-Jurassic Boundary," Sarah E. Greene, Rowan C. Martindale, Kathleen A. Ritterbush, David J. Bottjer, Frank A. Corsetti, and William M. Berelson, Earth-Science Reviews, volume 113 (1-2), copyright © 2012 by Elsevier.

1. Zooxanthenellae would logically inhabit which part of a coral?

2. The data in Table 6.2 indicates that as the concentration of carbon dioxide in the water rises:

3. Based on the information in Table 6.2, what conclusions can be drawn about ocean chemistry?

4. Factors that might impact the data found in Table 6.2 include:

I. seasonal changes in temperature.

II. variations in photosynthesis.

III. runoff from rivers.

IV. fluctuations in respiration.

Which of these is likely to account for fluctuations in the geographic pH of ocean waters?

5. The saturation horizon is a natural boundary in seawater, above which calcium carbonate (CaCO3) can form and below which it dissolves. Which species from Figure 6.12 most likely lives below the saturation horizon?

6. Calcifying organisms that produce the calcite form of calcium carbonate, such as foraminifera, can be less vulnerable to acidification than those constructed with aragonite structures, such as corals. Which of these provides a logical explanation for these findings?

7. Based on the information in Figure 6.12, decreased fertilization affects corals as well as:

8. In Figure 6.12, the most significant data with regard to the health of marine ecosystems is:

9. According to Figure 6.12, which species appear to be most affected by ocean acidification?

10. Which of the following terms best describes the relationship between zooxanthellae and corals?

11. Corals have several features that help them survive in the shallow ocean. Which part of a coral's anatomy may protect against fluctuating environmental changes such as temperature?

12. Some corals can reproduce in a variety of ways. Which of these methods would produce the most diverse offspring?

13. Which of the following is most likely to result from declines in a coral polyp's zooxanthellae population?

14. Scientists design an experiment in an attempt to predict the effect increasingly acidic seawater will have on coral reproduction. They may use the following in the experiment:

- Aquarium tanks

- Seawater

- Tap water

- Corals

- Carbon dioxide bubbles

Which experimental design will allow the scientists to investigate their hypothesis fairly and produce high-quality data for analysis?

15. Changes in the biological processes in the surface ocean water affect deeper portions of the ocean because:

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