Marine Algae

smc bio 15

Algae is…

mostly photosynthetic, less structurally complex than plants, polyphyletic (not one evolutionary group)

Diatoms

have glass (silica) cell walls, make up 90 percent of eukaryotic phytoplankton

summarize dinoflagellates

have two flagella (for movement), can cause red tides (harmful algal blooms), some are bioluminescent

brown algae

division phaeophyta, includes kelp, dominates cold and nutrient-rich waters

Red Algae

division rhodophyta, just red algae

green algae

division chlorophyta, closest relatives of land plants

Parts of Kelp?

Holdfast, Stipe, Blades, and Pneumatocysts

What does the holdfast do?

Anchors the kelp to a rocky substrate so waves don’t tear it away, not the true root

What does the stipe do?

A stem-like support that connects the holdfast to the blades

What do kelp blades do?

basically the leaves, where photosynthesis occurs

What are pneumatocysts?

gas-filled floats, they lift the blades towards the surface where there is more light so they can do more photosynthesis

Kelp Bed vs Kelp forest

kelp beds don’t reach the surface, they grow on the bottom and stay underwater while kelp forests grow all the way up to the surface

Macrocystis

giant kelp that dominates the west coast, forms the California kelp forests

Laminaria

kelp that dominates the East Coast

What is a red tide?

harmful algal bloom (HAB), caused by a massive increase in dinoflagellates that can make the water appear red, brown, or orange

What are mangroves?

Trees that grow along tropical coastlines, important because they can be fish nursery habitats, improve coastal water quality, protect coastlines from storms and erosion, as well as supporting many different organisms

Why do people cut down mangroves?

Humans cut them down to build houses, hotels, and create beaches

Why is it harmful to cut down mangroves?

• Less storm protection.

• More coastal erosion.

• Worse water quality.

• Damage to coral reefs.

• Loss of nursery habitat.

Economic Uses of Algae?

• Food

• Agar (research media, food industry)

• Algin/Carrageenan (thickeners & stabilizers)

• Fertilizer

• Animal feed

Why are kelp, algae, and corals so important?

They are the bases of the ecosystems, in tropical systems its corals.

KNOW HOW TO DO THE PHOTOSYNTHESIS GRAPH!!!

know how to label this

Chemical formula for photosynthesis?

6CO₂ + 6H₂O —(light)→C₆H₁₂O₆(sugar) + 6O₂

Chemical formula for respiration?

C₆H₁₂O₆ + 6O₂ —(light)→ 6CO₂ + 6H₂O + chemical energy

What is the maximum level of photosynthesis referred to as?

P_max

What is I_k in a photosynthesis vs irradiance graph?

Saturating irradiance, the amount of light it takes to achieve maximum photosynthesis

What is it called when plants make as much as they consume?

the compensation point

Do we ever know the full amount of oxygen produced in photosynthesis?

No, we can only measure how much comes out after the plant is also respirating. know P_gross = P_net + Respiration

What is the most important part of photosynthesis?

Chloroplasts

Do all organisms that use photosynthesis have the same pigments?

No, deeper ocean organisms require different types of pigments that are able to capture light all the way down there

How do red algae adapt to harsher habitats?

they deposit calcium carbonate into their bodies which makes parts of them hard

What are some benefits and tradeoffs to corals hardening?

beneifts: “armor” against sea urchins), support to resist waves, and protection from intense sunlight

tradeoffs: costs energy and resources, makes algae heavier and less flexible, and reduces growth rate compared to non-calcified species

sea grasses

are not algae, true vascular plants that have xylem(transports water and minerals) and phloem (transports sugar/food). felxible and bend with the waves