Multi Cellular Primary Producers - Marine Biology - Lecture Slides, Slides for Biology. Amity Business School


Description: These are the lecture slides of Marine Biology. Key important points are: Multi Cellular Primary Producers, Seaweeds and Plants, Marine Algae, Macroalgae, Phytoplankton, Body of Macroalgae, Pneumatocysts, Alteration of Generations, Types of Marine Algae
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Chapter 6

Chapter 6

Multi-cellular Primary Producers: Seaweeds and Plants

Marine Algae

• Marine algae are important primary _____ (photosynthetic)

• These algae are called by a generic term “seaweeds” or more formal term macroalgae or phytoplankton

• While some are thought to be the pre-cursors of plants, algae do not have the same advanced structures seen in plants such as roots, stems and leaves

Marine Algae

• The body of a macroalgae is known as a ____. • This thallus can be simple or more advanced in its

structure. • In some algae, there are:

– Blades – leaf-like structures – Stipes – stem-like structures – Holdfast – root-like structures (these structures lack the advanced conducting tissues seen

in true plants)

Marine Algae

• Some algae have pneumatocysts, (gas-filled bladders) to keep blades near the water’s surface for light/photosynthesis

• The blades, stipes and pneumatocysts of the giant kelp ( a brown algae) are shown in Fig. 6.8

Marine Algae • Like plants, algae exhibit a life history marked by an

alteration of generations. • To summarize, in the alternation of generations:

– A gametophyte stage produces gametes (eggs and sperm) that will fuse to become a zygote.

– This zygote then develops into a second stage, the sporophyte, that produces spores.

– These spores develop into the gametophyte stage and the cycle begins again (incidentally, plants are exhibit the same alternation of generations)

– The entire process is illustrated in Fig. 6.11, pg. 108.

Marine Algae

• Many algae also reproduce asexually by a means called vegetative growth.

• In this process, an algae reproduces new

individuals that are genetically identical to the parent algae.

Marine Algae

• Some algae are commercially important as food (ex: think of the algae used in the sushi industry)

• Other algae are commercially important because of extracts that are harvested from them

• For example, algin is an extract of brown algae that is used as a emulsifier in dairy products such as ice cream and cheese.

Marine Algae • Another example is the ____ harvested from red algae. • Carrageenan is also used as a thickening agent in dairy

products such as yogurt, milkshakes, etc. • Agar is a second extract from red algae. Agar is used to culture

microbes in the health care industry. It is also used as a thickener in foods, used as a filler in pharmaceuticals and cosmetics and to protect canned meats (ever opened a canned ham and noticed the “gel” around it? That’s agar.)


Types of Marine Algae

• ____ algae – ancestor of land plants – ~ 7000 species; less than 1000 are marine – Found worldwide in wet environments – Microscopic to macroscopic – Some coralline (produce calcium carbonate, Ex: Halimeda) – Chlorophylls A and B as well as carotenoids (same as in

true plants) – Store excess energy as starch (same as in true plants) – Cellulose in cell walls (same as in true plants)

Ulva or sea lettuce

Types of Marine Algae

• Brown algae – ~ 1500 species, almost all marine – Some microscopic, most larger - to 300+ feet – Prefer shallow, cold waters – Contain chlorophyll A and C and fucoxanthin – Typical body of holdfast, stipe and blades – Source of algin – Examples: kelp, Fucus, Sargassum

Types of Marine Algae

• Notable brown algae: – The kelps found in temperate and polar locations are the

largest of the algaes – In some species, like the giant kelp, each individual can be

hundreds of feet in length – This growth provides habitat for countless species of fish,

marine mammals, birds and invertebrates – this community is known as the kelp forest.

– Kelp forests are among the most productive (and important) marine habitats.

Types of Marine Algae

• Notable brown algae: – Sargassum is a species of brown algae found in the Atlantic

between North America and Europe as well as the Gulf of Mexico

– Massive floating mats of Sargassum provide habitat for countless species of fish, marine mammals, birds and invertebrates.

– This community is known as the Sargasso Sea. – Like the kelp forests, the importance of this community

cannot be overstated. •

Types of Marine Algae

• Red Algae – ~ 4000 species, almost all marine – Prefer deep cold waters or warm, shallow waters

depending on species – Some are corraline (produce calcium carbonate, Ex:

Corallina, shown in Fig. 6.10, pg. 108) – Mostly marine – Contains photosynetic pigments, chlorophyll A and


Advanced Primary Producers- Plants

• ____ are flowering plants. • Over 250,000 species exist worldwide,

however, only a few of these exist in the marine community.

• Those plants that do exist there must have mechanisms for dealing with salinity.

• These plants have true leaves, stems, roots and conducting tissues.

Advanced Primary Producers- Plants

• Seagrasses – About 60 species exist in temperate and mainly

tropical locations. – _____ are small and inconspicuous in most

species. – Pollen which forms sperm is carried by water

currents. – Tiny seeds produce by fertilization are also carried

by water currents or in the feces of animals that consume the seagrasses.

Advanced Primary Producers- Plants

• Seagrasses – Seagrasses are known to exhibit rapid growth and provide

food to many organisms – They also provide habitat for countless organisms that hide

among the blades in seagrass beds – Eelgrass is the most widely distributed of the seagrasses

where it is widely distributed in shallow water bays and estuaries.


Advanced Primary Producers- Plants

• Salt marsh Plants- plants bordering shallow bays and tidal creeks. – Cordgrass, Spartina, the predominant salt marsh plant is in the grass

family. – – Spartina is only exposed to saltwater at high tide. – Spartina is extremely important as habitat to young marine animals

such as juvenile invertebrates and fish. – Very little Spartina is directly consumed by herbivores. Instead, its

importance as a primary producer comes when plants die back in winter and bacteria and fungus break the leaves down to detritus, a nutrient source for countless organisms.

Spartina plants possess salt glands to help deal with excess salt. – Other _____ (salt-tolerant plants) exist in areas of higher elevation

than Spartina. Ex. Salicornia or pickle weed –

Advanced Primary Producers- Plants

• Mangrove trees – About 80 species of mangroves exist only in tropical and

subtropical areas. – They cannot withstand freezing temperatures. – Like Spartina, they only tolerate partial salt water

submergence. – Mangroves have a thick network of prop roots that are

heavily exposed at low tide (Fig. 6.14, pg. 112 displays the roots of the red mangrove tree)

Advanced Primary Producers- Plants

• Seeds of mangroves germinate while still attached to the parent plant and develop into elongated seedlings up to 1 foot in length before falling from the parent tree.

• These seedlings drop into nearby soils or are carried by water currents to new locations. One species occurs in Texas at _____.

Advanced Primary Producers- Plants

• Mangrove forests, or mangals, provide habitat for marine organisms such as invertebrates, fish, turtles, birds and marine mammals.

• They can be though of as the tropical equivalent of salt marshes.

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