Chapter 4 (Limiting Factors and Trophic Levels/Food Webs)

Limiting factor

Something in the ocean (like light, nutrients, or oxygen) that limits how much plants and animals can grow.

Photosynthesis

When plants, algae, and phytoplankton use sunlight, water, and carbon dioxide to make food and oxygen.

Upwelling

When deep, cold water full of nutrients rises to the surface, helping plants and animals grow.

Eutrophication

Too many nutrients (from things like fertilizer runoff) cause lots of algae to grow, which can use up oxygen and harm sea life.

Nitrogen Fixation

Special bacteria change nitrogen from the air into a form plants and algae can use.

Stratification

When ocean water forms layers that don’t mix well, keeping nutrients trapped below.

Thermocline

A layer in the ocean where the temperature changes quickly with depth.

Trophic Level

A step in the food chain, showing who eats whom.

Producers

Plants, algae, and phytoplankton that make their own food and start the food chain.

Primary consumers

Animals that eat producers (like zooplankton or small fish).

Secondary consumers

Animals that eat primary consumers (like bigger fish or jellyfish).

Tertiary consumers

Animals that eat secondary consumers (like tuna or seals).

Quaternary consumers

Top predators at the very end of the food chain (like sharks or orcas).

Herbivores

Animals that only eat plants or algae (like manatees or sea urchins).

Carnivores

Animals that eat other animals (like squid, sharks, or dolphins).

Keystone Species

A very important species that keeps the whole ecosystem balanced (like sea otters in kelp forests).