Epipelagic/Photic zone Surface to 200 m Surface to 200 m Warmest and best light for photosynthesis Warmest and best light for photosynthesis Divided into coastal and oceanic zones Divided into coastal and oceanic zones

Epipelagic Nearly all primary production takes place within the epipelagic system. Nearly all primary production takes place within the epipelagic system. Primary Production: the conversion of CO 2 into organic matter by autotrophs (phytoplankton). Primary Production: the conversion of CO 2 into organic matter by autotrophs (phytoplankton). Supplies food (fish and zooplankton) to marine organisms and humans. Supplies food (fish and zooplankton) to marine organisms and humans.

Feeding Lacks deposit feeders but suspension feeders are plentiful. Lacks deposit feeders but suspension feeders are plentiful. There are also many large predators such as fish, squid, and marine mammals. There are also many large predators such as fish, squid, and marine mammals.

Plankton Plants or animals that float and drift with the current. Plants or animals that float and drift with the current. Phytoplankton = plant plankton. Phytoplankton = plant plankton. Main primary producers in epipelagic Main primary producers in epipelagic – Cyanobacteria, Diatoms, Dinoflagellates & Coccolithophores. – Eaten by herbivores. Zooplankton = animal plankton. Zooplankton = animal plankton. – A fundamental part of the epipelagic food web is the flow of energy from phytoplankton to herbivorous zooplankton. – May be herbivores or carnivores – May be herbivores or carnivores.

Zooplankton Copepods Copepods – Most abundant members of the net zooplankton; practically everywhere in the ocean – Most are omnivores Krill Krill – Dominant zooplankton in polar seas – Omnivores that will eat detritus (dead organic matter) including fecal pellets.

Meroplankton Holoplankton Holoplankton – Spend their whole lives as plankton – Diatoms & Dinoflagellates Meroplankton Meroplankton – Temporary plankton – Invertebrate & Fish larvae

Nekton Large strong swimmers including fishes, marine mammals and squid. Large strong swimmers including fishes, marine mammals and squid. Planktivorous nekton include: Planktivorous nekton include: Small fishes like herring, sardines and anchovies Small fishes like herring, sardines and anchovies The worlds largest fishes: the whale and basking sharks. The worlds largest fishes: the whale and basking sharks. Baleen Whales, seals, penguins. Baleen Whales, seals, penguins.

Plankton Adaptations for the Epipelagic Must have an adaptation to keep from sinking -- must stay in epipelagic! Must have an adaptation to keep from sinking -- must stay in epipelagic! Shells and skeletons are denser than water. Shells and skeletons are denser than water. Organisms must increase their water resistance so they sink slower OR make themselves more buoyant so they dont sink in the first place. Organisms must increase their water resistance so they sink slower OR make themselves more buoyant so they dont sink in the first place.

Plankton Adaptations for the Epipelagic The higher the surface area, the higher the resistance and the slower the organism sinks. The higher the surface area, the higher the resistance and the slower the organism sinks. – Small organisms sink slower than large ones – Flat body shape – Long projections or spines increase surface area Increased buoyancy = doesnt sink Increased buoyancy = doesnt sink – Storing lipids such as oils or fats in the body (diatoms, sharks & whales) – Pockets of gas (bubbles or vacuoles), or floats

Epipelagic Food Webs Tend to be long and complex because they contain many species and many epipelagic animals feed at different tropic levels. Tend to be long and complex because they contain many species and many epipelagic animals feed at different tropic levels. Basic flow of Energy: phytoplankton to zooplankton to small nekton to large nekton to top predators. Basic flow of Energy: phytoplankton to zooplankton to small nekton to large nekton to top predators. Energy from one tropic level to the next: Energy from one tropic level to the next: – Epipelagic herbivores convert more than 20% – Epipelagic carnivores convert more than 10%

Primary Productivity The base of all epipelagic food webs. The base of all epipelagic food webs. Some epipelagic ecosystems are among the most productive on earth, while others are the deserts of the ocean. Some epipelagic ecosystems are among the most productive on earth, while others are the deserts of the ocean. Phytoplankton need light and essential nutrients to perform photosynthesis. Phytoplankton need light and essential nutrients to perform photosynthesis.

So how do the nutrients get circulated? Overturn and mixing caused by the cooling of surface waters. Overturn and mixing caused by the cooling of surface waters. Upwelling: the upward movement of nutrient-rich deep water towards the surface. Upwelling: the upward movement of nutrient-rich deep water towards the surface. The Coriolis Effect: the deflection of a water particle to the right in the N. Hemisphere and the left in the S. Hemisphere. Each layer of water moves slightly below the next creating an Ekman Spiral. The Coriolis Effect: the deflection of a water particle to the right in the N. Hemisphere and the left in the S. Hemisphere. Each layer of water moves slightly below the next creating an Ekman Spiral.

Ekman Spiral

Coastal Upwelling Carries huge amounts of nutrients into the photic zone. Carries huge amounts of nutrients into the photic zone. Major coastal upwelling areas are among the most productive waters of the epipelagic. Major coastal upwelling areas are among the most productive waters of the epipelagic. Upwelling tends to be seasonal. Upwelling tends to be seasonal.

El Niño C hange in the surface currents along the coasts of Chile and Peru. C hange in the surface currents along the coasts of Chile and Peru. Every year, usually in December, the trade winds slack off, upwelling decreases and the water gets warmer. Every year, usually in December, the trade winds slack off, upwelling decreases and the water gets warmer. BUT, every few years, the surface water gets much warmer, and upwelling stops. BUT, every few years, the surface water gets much warmer, and upwelling stops.

El Niño Trade winds stop Trade winds stop Warm currents push cold coastal currents back Warm currents push cold coastal currents back California & Humboldt (Peru) currents are most affected California & Humboldt (Peru) currents are most affected

Local Effects No upwelling = no nutrients No upwelling = no nutrients Fish must move, adapt or die to find food Fish must move, adapt or die to find food Fisherman have no fish to catch = no money Fisherman have no fish to catch = no money

Global Effects Weather extremes including flooding, drought, hurricanes & blizzards Weather extremes including flooding, drought, hurricanes & blizzards