Seaweed and Marine Light Zones Study Guide

Vocabulary flashcards covering seaweed anatomy, ocean light zones, algae classifications, species identification, commercial uses, and seaweed farming.

Macroalgae

The scientific term used instead of 'seaweed'.

Holdfast

The root-like part of a seaweed that acts like an anchor to hold it in place.

Stipe

The stem-like structure of a seaweed that connects the holdfast to the blade.

Blade

The leaf-like part of a seaweed where photosynthesis happens.

Gas bladder (pneumatocyst)

A floating structure that helps the seaweed stay buoyant to remain close to the surface and the sun.

Thallus

The complete body structure of a seaweed, encompassing the blades, float, stipe, and holdfast.

Marine Producer Resource Acquisition

The method by which seaweeds obtain their essential needs directly from the surrounding water ($CO_2$, water, and nutrients) and from the sun (light), unlike land plants that use roots, transport systems, and air.

Desiccation prevention adaptations

Protective adaptations in seaweed to keep from drying out, specifically possessing a waxy coating and producing a covering mucus.

Photic zone

The lighted area of the ocean comprised of both the euphotic and disphotic zones together.

Distance sunlight travels in the ocean

The vertical zones of the ocean divided by light penetration: the euphotic (sunlight) zone ($0\text{--}200\text{ meters}$), the dysphotic (twilight) zone ($200\text{--}1000\text{ meters}$), and the aphotic zone ($1000\text{ meters}\text{ and deeper}$).

Euphotic zone

The sunlit zone extending to $200\text{ meters}$ deep that receives a lot of light, beyond which sunlight rarely penetrates.

Dysphotic zone

The twilight ocean zone extending from $200\text{ meters}$ to $1000\text{ meters}$ where dim (little) light rapidly decreases and photosynthesis is not possible.

Aphotic zone

The deep ocean zone at $1000\text{ meters}\text{ and deeper}$ that is bathed in darkness with no sunlight penetration; includes the bathypelagic ($1000\text{--}4000\text{ meters}$), abyssopelagic ($4000\text{--}6000\text{ meters}$), and hadopelagic ($6000\text{ meters}\text{ and deeper}$) zones.

Blue light (marine penetration)

The color of visible light that penetrates deepest into ocean waters.

Red light (marine penetration)

The color of visible light that disappears first in ocean waters.

Chlorophyta

Green seaweeds that use red and blue light for photosynthesis and grow at shallow ocean depths.

Sea lettuce

A sheet-like species of green seaweed (Chlorophyta).

Dead man's fingers

A branching, finger-like species of green seaweed (Chlorophyta).

Rhodophyta

Red seaweeds that use green and blue light for photosynthesis and can live at deep ocean depths.

Irish moss

A bushy species of red seaweed (Rhodophyta) used as the source for carrageenan.

Coralline algae

A calcified, branching species of red seaweed (Rhodophyta).

Phaeophyta

Brown seaweeds that absorb red, green, and blue light for photosynthesis and can be found everywhere across various ocean depths.

Kelp

A large brown seaweed (Phaeophyta) that serves as the natural source of algin.

Rockweed

A species of brown seaweed (Phaeophyta) with prominent bladders found clinging to rocks.

Carrageenan

A substance extracted from Irish moss (red seaweed) used as a thickener in shampoo, conditioner, and dairy products.

Algin

An extract obtained from kelp (brown seaweed) used as a thickener in ice cream, lotion, and paint.

Agar

A red algae derivative used in laboratories as a growth medium for bacteria and on deli meat and cheese as a preservative to keep them from drying out.

Seaweed farming

The practice of growing lines of seaweed in the ocean to harvest and sell, typically cultivated alongside shellfish such as clams, mussels, and oysters.

Carbon sequestration via seaweed farming

The mitigation of carbon levels in water and air through large-scale seaweed cultivation, which increases photosynthetic activity and draws down $CO_2$.