PADI Marine Biology & Conservation 4 — Questions and Answers
Question 1: Which chemical process is causing ocean pH to decrease over time, threatening shell-forming marine organisms?
- Eutrophication
- Ocean acidification from CO₂ absorption (Correct answer)
- Thermal stratification
- Salinity increase from glacier melt
Correct answer: Ocean acidification from CO₂ absorption
Oceans absorb about 30% of atmospheric CO₂, which reacts with seawater to form carbonic acid, lowering pH and reducing carbonate ions needed for shells and skeletons.
Question 2: What role do mangrove forests play in marine ecosystems?
- They primarily function as feeding grounds for large pelagic predators
- They serve as nursery habitats, storm buffers, and carbon sinks (Correct answer)
- They compete with coral reefs for sunlight and nutrients
- They are the primary oxygen producers for coastal waters
Correct answer: They serve as nursery habitats, storm buffers, and carbon sinks
Mangroves provide critical nursery habitat for juvenile fish and invertebrates, protect coastlines from storm surge erosion, and sequester large amounts of carbon.
Question 3: What is bioluminescence in marine organisms, and which group is well known for this ability?
- Color change using chromatophores; octopuses
- Light production through chemical reactions; dinoflagellates and deep-sea fish (Correct answer)
- Reflection of moonlight off scales; silversides
- Fluorescence under UV light; corals only
Correct answer: Light production through chemical reactions; dinoflagellates and deep-sea fish
Bioluminescence is the biological production of light via chemical reactions (luciferin-luciferase); dinoflagellates, anglerfish, and many deep-sea creatures use it for attraction, defense, or communication.
Question 4: Which diving practice causes the most physical damage to coral reefs during recreational diving?
- Using underwater cameras with strobes
- Poor buoyancy control leading to contact with corals (Correct answer)
- Wearing wetsuits in tropical water
- Using an alternate air source
Correct answer: Poor buoyancy control leading to contact with corals
Divers with poor buoyancy control accidentally contact and break coral polyps, which take decades to grow; even brief touches can introduce bacteria and disease.
Question 5: What is the significance of 'upwelling' in marine ecosystems?
- It warms surface waters, promoting coral growth
- It brings cold, nutrient-rich water to the surface, supporting high productivity (Correct answer)
- It disperses coral larvae across ocean basins
- It causes deep-water anoxic conditions
Correct answer: It brings cold, nutrient-rich water to the surface, supporting high productivity
Upwelling brings deep, cold, nutrient-rich water to sunlit surface layers, fueling phytoplankton blooms and supporting highly productive fisheries and marine food webs.
Question 6: A PADI diver notices starfish missing arms but still alive on a reef. What natural process does this likely indicate?
- Predation by triggerfish attacking at the arms first
- Regeneration — sea stars can regrow lost limbs (Correct answer)
- Disease from bacterial infection causing arm drop
- Collection by researchers for tagging studies
Correct answer: Regeneration — sea stars can regrow lost limbs
Sea stars (starfish) have remarkable regenerative abilities and can regrow lost arms; some species can even regenerate an entire body from a severed arm.
Question 7: Why is it important for divers to avoid touching or feeding wild marine life?
- It reduces underwater visibility for other divers
- It disrupts natural behaviors, can cause disease transmission, and makes animals dependent on humans (Correct answer)
- It violates PADI certification rules in all countries
- It primarily harms the diver through risk of injury
Correct answer: It disrupts natural behaviors, can cause disease transmission, and makes animals dependent on humans
Feeding and touching marine life alters natural feeding behaviors, can spread disease, causes stress responses, and conditions wild animals to associate humans with food, often leading to aggression.
PADI Marine Biology & Conservation 4
Which chemical process is causing ocean pH to decrease over time, threatening shell-forming marine organisms?