Seaweed and Plants: Multicellular Primary Producers

Types of Algae Classes Chlorophyta = Green Phaeophyta = Brown Rhodophyta = Red

Seaweeds Seaweeds are another class of primary producers. Technically they are not weeds, but algae, and still eukaryotic. Most biologists agree that macrophyte is a much better name. Some also call them macroalgae.

Seaweeds: Green algae Have the same pigments as land plants (chlorophyll) More than 7,000 species Seaweeds are “macro” algae Alteration of generations

Filamentus algae such as Ulva forms paper thin sheets. “Dead man’s fingers,” Codium fragile and several spp. of Culerpa are known for their tube-like structures. Padina (brown algae) with flat, calcified blades... advantage?

Phaeophyta Largest (size) and most complex of the algae Nearly all are marine (~1500 spp.) Brown color comes from accessory pigments (fucoxanthin)

Fucus sprialis a common brown algae can be found on rocky shores. Unlike other algae in this category, its thallus lacks gas bladders. Knotted rockweed, Ascophyllum nodosum, is common to N. America and Europe.

Kelps! Kelps are the largest seaweed we encounter in the ocean. They are also the most complex. Due to this large size, many of the kelps are harvested for food! Who knows where we will find seaweed next?

A giant kelp typically grows very slowly because much of its huge thallus is in deep dark waters. True False

It’s also eaten on a regular basis as “sea noodles.” Sea palm (Postelsia palmaeformis) contains internal support structures that help them withstand wave action! It’s also eaten on a regular basis as “sea noodles.”

Macrocystis pyrifera, the largest of the kelps anchors itself to the sea floor by use of a massive holdfast. Here we can see not only the large blades, but the extensive pneumatocysts, which are used for buoyancy. Remember: Pneumatocysts developed as a means to maximize energy production through photosynthesis by keeping the seaweed close to the surface.

Thalus

The holdfasts of seaweeds are analogous to roots because both provide an anchor and absorb nutrients to supply the entire algal body or thallus. True False

In some seaweeds, leaf-like portions called blades are kept near the sea surface with gas-filled bladders called pneumatocysts. True False

The Chlorophyta includes the largest algae, the giant kelps. True False

These kelp obtain huge proportions growing as much as 0.5m/day! These are when large kelp group together  a kelp forest is develops. Kelp forests are great for sheltering all sorts of marine life, including Garibaldi, scallops, seals and sharks. They also provide an opportunity for selective harvesting of the upper sections of the blades for food.

Members of the species Rhodophyta red algae, are more numerous than the green and brown algae combined (if we include aquatics). Although many red algae are in fact red; due to the presence of red pigments known as phycobilins, which mask chlorophyll, these algae may display an even greater intensity when exposed to sunlight! Nearly 4,000 marine species exist and many are used for food or other specialty products. Porphya, a “red” algae

Corallina, a coralline algae, deposits CaCO3 within its cell walls which provides structural support and often encrusting many surrounding surfaces.

Sexual Reproduction, or not… Sexual reproduction is expensive both energetically and physiologically. Sometimes it’s better to reproduce by asexual means from fragments, spores, or buds. Sometimes algae use both sexual and asexual reproduction depending on environmental conditions.

A seaweed with a large sporophyte and a tiny, barely visible gametophyte could be which of these? sea lettuce common red alga giant kelp any brown alga

In many seaweeds, the thallus seen most often is a sporophyte gametophyte zoospore carposporophyte

In flowering plants, the sperm consists of motile zoospores. a well-developed free-living gametophyte forms. marine and nearshore species do not have roots. leaves are present.

Products from Seaweed: Phycocolloids—form gels and increase viscosity of liquids Algin—stabilizer in ice cream (Macrocystis) Carageenan—emulsifier (Irish Moss, Chondrus) Agar—jellies (and of course all your plates in microbiology, Gelidium, Pterocladiella)

Seagrasses (lillies) reproduce through rhizomes, or horizontal stems which grow beneath the sediment.

Sea grasses grow in clusters interconnected with horizontal root-like stems. True False

Seagrasses are considered to belong to the Kingdom Plantae because they carry on photosynthesis. can attach to sand. have chlorophyll. have specialized tissues that transport nutrients and food.

These vascular tissues include Xylem and rhizoids Pnematocyst and xylem Xylem and phloem Xylem and phycoclloid

Sea grasses, being angiosperms, reproduce with flowers that attract insects. True False

In salt marsh, cordgrasses grow well below the water level. pickle weed and other halophytes live at higher levels. mangroves are the dominant plants. seeds germinate while on the parent.

Mangroves

Mangroves Mangroves thrive in salty environments and are able to obtain freshwater from saltwater. Some spp. secrete excess salt through their leaves while other block absorption of salt at their roots.

Salt marsh plants such as cordgrass are fully marine species. True False

In some mangrove plants, seeds germinate before detaching from the parent tree. True False

Mangrove Forest http://www.youtube.com/watch?v=4mSDrAQp4dQ

Mangrove Impacts At one time, nearly 0.5 million acres of mangroves surrounded Florida’s coastal zone contributing to the ecosystem’s health in a variety of ways: Trap and cycle organics, chemical elements, sediment and minerals. Provide shelter for marine organisms.

Plate 9. Black Mangrove, Avecennia germinans.

Red Mangrove

Plate 10. White Mangrove, Laguncularia racemosa.

The northern limit of mangroves is set by which feature of the environment? salinity of the water frost light levels oxygen levels in the sediment

Rhizomes of seagrasses carry on photosynthesis. stick upright out of soft, muddy sediments. cannot transport water or nutrients. generally grow beneath the sediment.

Like calcareous green algae, coralline red algae can be involved in the development of coral reefs. live only in the tropics. always have thalli with segments. turn pink when dead.

Algin is used by people in which way? to wrap Japanese food as a medium to grow bacteria as a stabilizer and emulsifier in the dairy industry directly as food

Going from the surface to the point of attachment to a rock, which is the correct order in which the parts of a giant kelp occur? holdfast, stipe, pneumatocyst, blade stipe, holdfast, blade, pneumatocyst blade, pneumatocyst, stipe, holdfast pneumatocyst, stipe, blade, holdfast

Among red algae, dense clumps are characteristic of species living where? in deep water in areas rarely exposed to air on upper levels of rocky coasts as parasites on other algae

Green algae generally can be found in all of these habitats except fresh water. polluted areas. estuaries. rocks exposed to heavy wave action.

Which thallus shape is not found among kelp? thin filaments formed by a single cell a long stipe with one pneumatocyst several stipes and a massive holdfast a single large blade