Oceanography midterm 2

Q1: What does it mean that water has a high heat capacity?

It can absorb or release large amounts of heat with only small temperature changes.

Q2: How does water’s high heat capacity help moderate Earth’s climate?

Oceans store heat in the day/summer and release it slowly at night/winter, reducing temperature extremes.

Q3: What is latent heat of fusion?

The heat absorbed or released when water freezes or melts without a temperature change.

Q4: How does latent heat of fusion help stabilize Earth’s temperature?

Freezing and melting of water absorb or release heat, buffering temperature swings in polar and temperate zones.

Q5: What is latent heat of vaporization?

 The energy absorbed or released during evaporation or condensation without temperature change.

Q6: How does latent heat of vaporization moderate climate?

 Evaporation cools the ocean surface, and condensation releases that heat in the atmosphere, redistributing energy globally.

Q7: What type of bond holds hydrogen and oxygen together within one water molecule?

Covalent bond (intramolecular force).

Q8: What type of bond forms between different water molecules?

: Hydrogen bond (intermolecular force).

Q9: What is the freezing point of pure water?

0°C (32°F).

What is the freezing point of seawater with salinity of 35‰?

About -1.9°C (28.6°F).

Q11: What are the 3 major depth layers of the ocean?

 Surface (mixed) layer, Pycnocline/Thermocline (middle), Deep layer.

Q12: Which layer is warmest?

 The surface (mixed) layer.

Q13: Which layer is coldest?

The deep layer.

Q14: Where is the strongest pycnocline found globally?

In tropical regions, where warm surface water sits above cold deep water.

Q: What are the two main sources of salts in the ocean?

A: 1) Weathering and erosion of rocks on land (ions carried to the ocean by rivers)
2) Hydrothermal vents and volcanic outgassing adding ions from Earth’s crust

Q: What process on land contributes salts to the ocean?

A: Chemical weathering and erosion of continental rocks

Q: What process under the sea adds salts to the ocean?

A: Hydrothermal vent activity and submarine volcanism

Q: What are the seven most abundant ions dissolved in seawater?

A: Chloride (Cl⁻), Sodium (Na⁺), Sulfate (SO₄²⁻), Magnesium (Mg²⁺), Calcium (Ca²⁺), Potassium (K⁺), Bicarbonate (HCO₃⁻)

Q: Which two ions make up about 85% of seawater’s salinity?

A: Sodium (Na⁺) and Chloride (Cl⁻)

Q: What is the definition of “residence time” in ocean chemistry?

A: The average time an element or ion stays dissolved in seawater before being removed

Q: How is residence time calculated?

A: Residence time = (Amount of substance in ocean) ÷ (Rate of input or removal)

Q: What does a long residence time mean for an ion’s distribution?

A: It’s well-mixed and has a relatively constant concentration throughout the ocean

Q: What are conservative elements/ions?

A: Elements that have long residence times and constant ratios throughout the ocean

Q: Give two examples of conservative ions in seawater.

A: Sodium (Na⁺) and Chloride (Cl⁻)

Q: What are non-conservative elements/ions?

A: Elements whose concentrations vary with location and biological activity, due to short residence times

Q: Give two examples of non-conservative ions in seawater.

A: Nitrate (NO₃⁻) and Phosphate (PO₄³⁻)

Q: What is the average pH of modern seawater?

A: About 8.1 (slightly basic or alkaline)

Q: Is seawater acidic or basic?

A: Slightly basic

Q: How much is seawater pH expected to change in the next few decades?

A: A drop of about 0.3 to 0.4 pH units

Q: How does the expected future pH change compare to the change from the 1700s to 1900s?

A: The ocean’s pH dropped about 0.1 units between the 1700s and 1900s, so the current rate is 3–4× faster

Q: What causes the ocean’s pH to drop (acidification)?

A: Increased CO₂ absorption from the atmosphere forming carbonic acid (H₂CO₃) in seawater

Q: Why is ocean acidification especially harmful to calcifying organisms?

A: It decreases carbonate ion (CO₃²⁻) concentration, making it harder to form calcium carbonate shells and skeletons

Q: Give examples of calcifying marine organisms affected by ocean acidification.

A: Corals, mollusks (clams, oysters), foraminifera, and coccolithophores

Q: What is an autotroph?

A: An organism that produces its own food using energy from sunlight or chemical reactions.

Q: What is a heterotroph?

A: An organism that obtains its food by consuming other organisms.

Q: What are the four DNA base letters?

A: Adenine (A), Thymine (T), Cytosine (C), and Guanine (G).

Q: What are proteins used for in cells?

A: Building cell structures and performing chemical reactions (enzymes).

Q: What is found at trophic level 1 in a trophic pyramid?

A: Primary producers (autotrophs) such as phytoplankton.

Q: What is found at trophic level 2 in a trophic pyramid?

A: Primary consumers (herbivores or zooplankton) that eat the primary producers.

Q: What are the three domains of life?

A: Bacteria, Archaea, and Eukarya.

Q: What are the two main categories of plankton?

A: Phytoplankton and zooplankton

Q: What are two examples of algal primary producers?

A: Diatoms and dinoflagellates

Q: Which domain of life do algae belong to?

A: Eukarya

Q: What three nutrients most often limit ocean productivity?

A: Nitrogen, phosphorus, and iron

Q: What is the typical maximum depth of the euphotic zone?

A: About 200 meters

Q: What mainly limits photosynthesis in high-latitude regions?

A: Lack of sunlight

Q: Where are high-nutrient, high-productivity regions found?

A: Coastal upwelling zones and continental shelf areas

Q: What does the term “Cambrian Explosion” refer to?

A: A rapid diversification of animal life about 540 million years ago, when most major animal phyla first appeared in the fossil record.

Q: List the nine animal phyla (in order of increasing complexity) with examples.

A:
1⃣ Porifera – Sponges
2⃣ Cnidaria – Jellyfish, corals, anemones
3⃣ Platyhelminthes – Flatworms
4⃣ Nematoda – Roundworms
5⃣ Annelida – Segmented worms
6⃣ Mollusca – Snails, clams, octopuses
7⃣ Arthropoda – Crabs, shrimp, lobsters
8⃣ Echinodermata – Sea stars, sea urchins
9⃣ Chordata – Fish, mammals, birds

Q: What is the difference between ectothermic and endothermic marine organisms?

A:

• Ectothermic: Body temperature depends on environment (e.g., most fish, invertebrates).

• Endothermic: Maintain constant internal temperature (e.g., whales, seals, seabirds).

Q: What does “isotonic” mean in the context of marine organisms?

A: Their internal fluids have the same salinity (osmotic pressure) as seawater, preventing net gain or loss of water.

Q: Why can rocky intertidal environments host diverse and abundant life?

A: They provide stable surfaces for attachment, nutrient availability, and shelter from predators, allowing many species to coexist.

Q: Why are sand and muddy beaches inhospitable for abundant life?

A: They are unstable, constantly shifting, and provide few surfaces for attachment, making survival difficult.

Q: What factors have contributed to the decline of the Great Barrier Reef?

A: Climate change (warming oceans), coral bleaching, ocean acidification, pollution, and overfishing.

Q: What is the deep scattering layer (DSL)?

A: A layer in the ocean where zooplankton and fish migrate daily, reflecting sonar signals.

Q: At what depths do deep scattering layer communities live?

A: Roughly 200–1000 meters, migrating upward at night to feed.

Q: What communities are found at mid-ocean ridges?

A: Hydrothermal vent communities.

Q: What are the primary producers that fuel mid-ocean ridge ecosystems?

A: Chemosynthetic bacteria that use chemicals from vent fluids.

Q: What are some characteristic animals at hydrothermal vents?

A: Tube worms, giant clams, vent crabs, and shrimp.

Q: What is symbiosis?

A: A close ecological relationship between two different species.

Q: What is mutualism? Give an example.

A: Both species benefit; e.g., coral and zooxanthellae.

Q: What is commensalism? Give an example.

A: One species benefits, the other is unaffected; e.g., barnacles on whales.

Q: What is parasitism? Give an example.

A: One species benefits, the other is harmed; e.g., parasitic copepods on fish.