Biotic Factors of the Pacific Ocean: Life from Phytoplankton to Whales

Primary Producers

• Phytoplankton: Diatoms, dinoflagellates, cyanobacteria—base of food web, global O₂ source.
• Macroalgae: Kelp forests (temperate), coral reef algae (tropical).
• Seagrasses: Shallow coastal meadows.

Consumers

Zooplankton (Primary Consumers)

• Copepods, krill, salps, larval fish—invast numbers, daily vertical migration.

Fish (Secondary+ Consumers)

• Forage: anchovy, sardine, herring.
• Predators: tuna, billfish, sharks, salmon.
• Reef: >5,000 species in Coral Triangle alone.
• Deep: lanternfish, grenadiers, orange roughy.

Marine Mammals

• Cetaceans: blue whale, humpback, sperm whale, orca, dolphins.
• Pinnipeds: elephant seal, sea lions, fur seals.
• Sirenians: dugong (tropical).
• Otters: sea otter (kelp forest keystone).

Seabirds

• Albatrosses, petrels, shearwaters, boobies, frigatebirds, penguins (Galápagos/Humboldt).

Benthic Communities

• Invertebrates: corals, sponges, echinoderms (urchins, stars, cukes), crustaceans (crabs, shrimp), mollusks (clams, snails, cephalopods).
• Chemosynthetic: hydrothermal vent/ cold seep communities (tube worms, mussels, bacteria).

Microbial Loop

Bacteria, archaea, viruses recycle dissolved organic matter—critical for nutrient regeneration.

All interact in a complex, dynamic food web shaped by currents, upwelling, ENSO, and human pressures.