Oceanic regions of the world:
i. Tropical oceans
ii. Polar oceans
iii. Temperate oceans
Match the graphs (A to C) to the correct oceanic region (i to iii).
(1) A-i, B-ii, C-iii (2) A-ii, B-i, C-iii
(3) A-i, B-iii, C-ii (4) A-iii, B-ii, C-i

Key Patterns of Plankton Biomass by Oceanic Region

1. Tropical Oceans

• Characteristics: Receive abundant sunlight year-round, but are often nutrient-poor due to strong stratification of the water column.

• Plankton Biomass Pattern: Biomass remains relatively low and stable throughout the year, with minimal seasonal fluctuation.

2. Polar Oceans

• Characteristics: Experience extreme seasonal changes in sunlight, with long dark winters and continuous summer daylight.

• Plankton Biomass Pattern: Biomass is extremely low or nearly absent during the dark winter, followed by a sharp, brief peak (bloom) in the spring or early summer when light returns and ice melts, allowing nutrients to mix into surface waters278.

3. Temperate Oceans

• Characteristics: Have moderate, seasonal changes in temperature and light, and experience mixing of water layers in spring and autumn.

• Plankton Biomass Pattern: Two distinct peaks (blooms) occur: a major one in spring and a smaller one in autumn, separated by lower biomass in summer (due to nutrient depletion) and winter (due to low light)678.

Matching the Graphs

Given the above, here’s how each region’s graph typically appears:

• Tropical: Flat, steady line (low, constant biomass)

• Polar: Very low most of the year, sharp single peak in spring/summer

• Temperate: Two peaks (spring and autumn), with lower values in summer and winter

Applying the Patterns to the Options

Let’s match the graphs (A, B, C) to the regions:

• A: If the graph shows two peaks (spring and autumn), it represents the temperate ocean.

• B: If the graph shows a long period of low biomass with a single sharp peak, it represents the polar ocean.

• C: If the graph is flat and low throughout the year, it represents the tropical ocean.

Now, check the options:

1. A-i, B-ii, C-iii

   • A = Tropical, B = Polar, C = Temperate

2. A-ii, B-i, C-iii

   • A = Polar, B = Tropical, C = Temperate

3. A-i, B-iii, C-ii

   • A = Tropical, B = Temperate, C = Polar

4. A-iii, B-ii, C-i

   • A = Temperate, B = Polar, C = Tropical

Option 4 (A-iii, B-ii, C-i) matches the classic patterns:

• A (Temperate): Two peaks

• B (Polar): Single sharp peak

• C (Tropical): Flat, low line

Conclusion

The correct matching of the graphs to the oceanic regions is:

Option (4): A-iii, B-ii, C-i

• A: Temperate oceans

• B: Polar oceans

• C: Tropical oceans

This reflects the distinctive seasonal cycles of plankton biomass in each region, shaped by light, temperature, and nutrient dynamics.