AlgaeMichael Renfroe

Algae – diverse group of organisms

Ubiquitous distribution – algae can grow anywhere

Desmococcus grows on the fur of a sloth in warm jungle areas

This species of Chlamydomonas forms pink colonies on snow packs

Desmococcus grows the sloth’s fur and a sloth moth eats the algae which keeps it from getting too thick on the sloth fur. The moth lays eggs in the sloth feces, continuing the moth population that controls the algal growth on the sloth.

The green Desmococcus helps camouflage the sloth and make it harder for predators like eagles and harpies to spot the sloth. The alga is passed along to the offspring as they cling to the mother during the first months of their life.

Acetabularia - Mermaid’s wine glass is a macroscopic single-celled alga that has been important in early studies of molecular biology making clear the role of mRNA in protein synthesis.

Algae can grow in a desert by growing on underside of quartz. Sunlight penetrates the quartz while moisture collects on the underside and provides water for the algae.

Acetabularia has very large cells. Each of these is a single cell.

Chara corralina

This alga was important in studying cyclosis or cytoplasmic streaming and illuminating the role of microfilaments in the biology of the cell.

Prokaryotic algae – Kingdom Monera

Blue-green algae: Cyanophyta or Cyanobacteria

Eukaryotic algae – Kingdom Protista (Protoctista)

Green algae: Chlorophyta

Red algae: Rhodophyta

Brown algae: Phaeophyta

Golden-brown algae: Chrysophyta

Dinoflagellates: Pyrrhophyta

Algae are grouped into a variety of taxonomic groupings:

Algae changed course of evolution on earth.

When photosynthetic algae evolved, they began the oxygenation of water which led to the extinction of many obligate anaerobes. Their

presence is evidenced by the banded iron formations formed from the iron oxide precipitates that formed in the oceans.

Algae produced so much oxygen that it began to enter the atmosphere, leading to the formation of the ozone layer. The ozone layer shielded the land masses from lethal doses of UV

radiation and allowed the evolution of terrestrial species.

Algae components:

Non-digestible structural carbohydrates (non-nutritional)

Up to 25% soluble carbohydrates and proteins (nutritional)

Vitamins A, B1, B12, C, D, E, riboflavin, niacin, pantothenic acid, folic acid (nutritional)

Iodine (nutritional)

Edible Algae:

Many species of algae are edible and are part of the human diet.

Why eat algae?

Of 160 spp. of algae used for food, 3 genera are most important

Porphyra

Laminaria

Undaria

Porphyra

Nori - Japan

Laver – U.K, U.S.

Luche - Chile

Slack - Scotland

Sloke - Ireland

common names:

Conchospores are released and form new gametophyte fronds.

Sporophytes attach to calcareous shells

Edible fronds are haploid gametophytes

Porphyra life cycle

gametes fuse to form zygote that grows into new sporophyte

Nori

Nori is harvested, washed, chopped, dried into sheets, and used for making sushi rolls

sushi prepared in traditional bamboo roller

Laminaria

kelp kombu

kelp is used in soups and stews

Kombu harvest in Japan

Kombu harvest in Japan

Kombu harvest in Japan

Kombu harvest off Maine

Kombu harvest off Maine

Undaria

Wakame

Increases instestinal absorbtion of Ca, aids bone formation and maintenance

Undaria life cycle

Spirulina – a cyanobacterium

Contains up to 72% protein (dw)

High productivity: 10 tons/ac

Compare to: wheat – 0.16 tons/ac

beef – 0.016 tons/ac

Dunaliella bardawil

Source of: β-carotene, glycerol

This is a commercial source of carotene that is used to dye cheeses and margarines orange.

Industrial uses of algae - Phycocolloids

Alginates

Carrageenans

Agars

Algae are the source of chemicals that have many industrial and commercial uses. These chemicals are water soluble or stay suspended in aqueous solutions. The three main classes of phycocolloids are:

Alginates

Algae Sources:

Macrocystis

Laminaria

Ascophyllum

Ecklonia

Durvillea

Composed of alginic acid and salts

Absorbs 200-300X own wt in water

Mainly mannuronic and guluronic acids

Macrocystis – harvested by ship

Reciprocating cutter (like underwater hedge clippers)

Cuts off tops of algae, which re-grow over time

Other species are harvested by smaller boat:

Ecklonia

Laminaria

Ascophyllum

Durvillea

Alginate uses:

Paper industry – sizings

Paint – suspend pigments, forms pseudoplastic soln., smoothes paint on surface

Charcoal briquettes – binder

Food industry – emulsifier

Cosmetics – emulsifier

Medicines – emulsifier

Ice cream – colligative binder, prevents ice formation

Beer – foam stabilizer

Alginate uses:

Fruit congealer

Artificial cherries

Fake caviar

Dental retainers – with heavy metals, forms settable plastic

High quality audio speakers – special treatment to form fibers

Synseeds – synthetic seeds for somatic embryos

Carrageenans

Chondrus crispus Irish moss

Thickening and gelling agent

Thermally reversible (solidifies as cools, can re-heat and re-melts)

Harvested in N. Atlantic

Uses:

Source:

Carrageenans

Harvested in PhillipinesEuchemaSource:

Carrageenan uses – suspension and thickening

Milk pudding – blanc manges

Chocolate milk – keeps cocoa

particles suspended

Yogurt

Egg nog

Ice cream (ice milk)

Toothpaste

Binds well with proteins (e.g. casein – milk protein)

Clarifying wort in brew kettle

Agar

Sources:

Gelidium

Gracilaria

Pterocladia

Acanthopeltis

Ahnfeltia

Properties:

Very hygroscopic

Soluble in hot water

Used in tissue culture and microbiological research to form semi-solid nutrient media

Agar uses:

Moisturizing agent in baked goods, e.g. cakes

Clarifying agent (complexes with proteins) for wines, vinegars, juices

Binder – sushi rice (glues long-grain rice grains together, so sushi does not crumble apart)

Food-grade agar

Algal Fertilizers

1665 – King Charles II of England – allowed subjects to harvest seaweed to use as fertilizer in fields to increase yields

Chlamydomonas mexicana – has mucilaginous secretions that lead to soil flocculation – improves porosity of compacted soils improving aeration and water penetration

To improve compacted soils, can apply algae such as

Algal Fertilizers

Green manure for soil fertility

Hi in K, N; Low in P

Land reclamation - Ireland

Calcareous algae (corraline red algae) used to neutralize soil acidity

Farmers mix sand and algae on rocky land to form new soil in which potatoes are planted

These algae have calcium carbonate as part of their structure

Cyanobacteria

Carry out nitrogen fixation in specialized cells called heterocysts, thus acting as natural fertilizers

Anabaena azollae is a cyantobacterium that lives symbiotically with Azolla, an angiosperm called water fern

When grown together – increase yield in rice paddies by 18%

0.2 kg Azolla / ha is equivalent to 30 kg / ha N-fertilizer

Anabaena heterocyst

Azolla

Fossil algae - Diatoms

Diatomaceous earth (Fuller’s earth, Keiselguhr)

Siliceous frustules act as filtering agent

e.g., sugar and oil refining, pool filters, beer and wine filters

Abrasive polishing agent in toothpaste and silver polishes

Diatom shells made of silica

Make good filters and abrasives once diatom is dead leaving shell behind

Wastewater Treatment

Algae are very important in wastewater treatment for water purification and reducing biological oxygen demand (BOD) of wastewaters so they can be discharged into rivers without adverse consequences.

When bacteria and fungi grow, they have to have oxygen to support their respiration, so they create a biological oxygen demand. Algae photosynthesize and add oxygen back to the water, lowering the BOD value, keeping the water oxygenated so that it can support fish and other aquatic organisms.

Wastewater Treatment

Primary treatment – solids settle out

Secondary treatment – fungi and bacteria digest soluble organic fraction, flocculate to form sludge and fall out as solid residue. By reducing the nutrients in the water that would cause microbes to grow in the river, treatment has reduced BOD in the discharge water.

Tertiary treatment – use algal/bacterial mixture to treat sewage. Algae add oxygen, keeps bacteria growing longer, mixture reduces BOD by 90%, reduces N & P by 80%, so discharged water is even cleaner and carrying less nutrients that would cause problems in the rivers.

Algae in Medicine

Algae are a source of a chelating agent for heavy metal poisoning or radionucleotide poisoning

Iodine to treat goiter (swollen thyroid)

Vermifuge (expels parasitic worms)

Digenia simplex – kainic acid

Potential anticarcinogenics

Algae have several medicinal uses and the potential for more:

Toxins from Algae

Effects:Direct- can act directly on human physiologyIndirect – can cause fish killsIndirect – can accumulate in filter feeders and poison humans

Algal blooms – proliferations in algal populations caused by (1) upwellings of nutrient rich waters or (2) heavy rains washing phosphates into ocean

Unfortunately, there are some species of algae that are harmful to human health.

Dermatitis – caused by exposure to high numbers of:

Oscillatoria

Anabaena Lyngbya

Schizothrix

Silicosis – chronic lung infection – silica dust from diatoms

Algal fish kills:

Prymnesium parvum – releases toxin that affects gill permeability in fish

Pfisteria – causes external ulcerations and death of fish

Red tides – caused by overabundance of dinoflagellates

Paralytic Shellfish Poisoning (PSP)Nausea, vomiting, diarrhea, tingling in extremities, disorientation, paralysis and death

Neurotoxic Shellfish Poisoning (NSP)Numbness and food poisoning symptoms (usu. non-fatal)

Ciguatera PoisoningToxins accumulate in organs of coral reef fish, consumption leads to nausea, abdominal cramps, muscle weakness

Dinoflagellates can release toxins into the waters causing:

Red tide organisms - dinoflagellates

Red tide outbreak as seen from airplane

Red tide and other coastal algal blooms

Nuisance Algae

Biofouling: attachment and colonization of underwater structures by algae.

Algal slime layer 1 mm thick results in 15% loss in ship spped, 80% increase in drag, costing marine industry over $1 billion/yr.

Nuisance Algae

Eutrophication

eutrophied

Non-eutrophied

University of Manitoba

Experimental Lakes Area

Algal “blooms” with rapid increase in population, followed by die-off and decomposition resulting in depletion of oxygen by aerobic decomposers and shading of photosynthetic autotrophs

Algal Blooms and Fish Kills

It is not the algae that kill fish. In an algal bloom, the algae populations grows rapidly because of nutrients in the waters. This population explosions by algae near the surface shades and kills the submerged aquatic vegetation from lack of sunlight. As the algae grow, they are adding oxygen to the water. When the nutrients run out, the algae die off and aerobic decomposers proliferate because of all the dead material on which to feed. These aerobic decomposers deplete the oxygen in the water, lowering the oxygen level to the point that fish cannot live. It is this oxygen depletion by the decomposers that leads to fish kills.

Important ecology concept to understand!

Salton Sea fish kill

Nutrient pollution, and warm shallow water is a deadly combination for fish – inadequate oxygen

Salton Sea

Raw sewage from Mexico drains into Salton sea

Eutrophication

High BOD

Inadequate oxygen for fish

Eutrophication of Black Sea

Eutrophication is a problem world-wide

Eutrophication of Australian lake

Future Uses

Aquaculture – food for fish, shrimp, crayfish, shellfish

Cellulose production from algae with cellulosic cell walls

Oils for biofuels – grow our oil instead of mining from fossil deposits

Water detoxification – use algae to absorb toxins from water

Shrimp farm - Belize

Algae for biofuelsbiological oil production

Biofuel reactors for growing oil-producing algae

Biofuel algae farms

The end

Algae not only made human life possible by altering the early earth’s atmosphere and making terrestrial life possible, algae continue to provide us with food, medicine, and many commercial products that enrich our lives, support the economy, and keep ecosystems healthy. It is when the ecology gets out of balance, that algae can be harmful to humans and other organisms and cause bad things to happen. Humans must learn to maintain healthy ecosystems if we wish to have a place in the environment and continue our species.