ALGAE Multicellular Protist or Primitive Aquatic Plant? Cyanobacteria Plant-like Protists Multicellular Protist or Primitive Aquatic Plant?

Algae

Algal Characteristics Vary in size from nanoplankton (< 2 µm cyanobacteria ) to Giant kelps (> 70 m long). Possess a cell wall. Contain pigments chlorophylls a, and many often have another chlorophyll, like b, c, or d and accessory red, blue and brown photosynthetic pigments

Algae - What are they? Primitive plants No true roots, only attachment structures (Holdfasts) Produce spores (not seeds)– motile or non-motile Most have sexual and asexual reproduction Non-vascular, do not possess an internal transport system.

Algae vs. ‘REAL’ plants Similarities and differences: Both are photoautotrophic Similar metabolic functions to higher plants eg. photosynthesis different anatomical structures, reproductive structures. different reproduction. No true roots, stems leaves. Non-vascular, therefore nutrient uptake over surface. And wastes washed away from surface by aquatic environment

Classification - a few Algal Phyla Cyanophyta: Blue-green or Cyanobacteria.          Prokaryotic. Marine, FW and terrestrial. Pyrrophyta, Chrysophyta, Euglenophyta: Marine and FW phytoplankton – Photosynthetic Protists. KINGDOM PLANTAE: Rhodophyta: Red algae. Mostly marine. Phaeophyta: Brown algae. Mostly marine. Chlorophyta: Green algae. Marine, FW and terrestrial.

The role of these pigments is to absorb light - In water the problem is that red and violet wavelengths do not penetrate the vertical column very well. So Chlorophylls do not work well at greater depths. Algae that inhabit greater depths do so with the help of accessory pigments, these algae take on a variety of colours.

-Chlorophyta – Contain Chlorophyll a + b. So green wavelengths reflect -Chlorophyta – Contain Chlorophyll a + b. So green wavelengths reflect. They store their products of photosynthesis as starch. - Phaeophyta – Contain Chlorophylls a + c as well as an accessory pigment Fucoxanthin. So yellow and brown wavelengths reflect. Store food as starch and as oil. Rhodophyta - Contain Chlorophyll a + (d) as well as accessory pigment Phycobillins. These phycobillins are specialized for absorbing blue light, which allows them to inhabit the deepest depths.

Where do Algae live? Marine habitats: Freshwater habitats: seaweeds, phytoplankton Freshwater habitats: streams, rivers, lakes and ponds Terrestrial habitats: stone walls, tree bark, leaves, in lichens, on snow

Marine Biomes

Freshwater habitats

Terrestrial habitats

How do algae function? Photoautotrophs: 6C02 + 6H20  C6H1206 + O2 use carbon, light, and water produce chemical energy (carbohydrates) and produce O2 as a by-product. Basic storage products: carbohydrates as starch or converted to fats as oil Require nutrients: N, P and minerals.

Why are ALGAE important? Ecological importance of algae a) Production of Oxygen as ‘by-product’ of photosynthesis: All aerobic heterotrophic organisms require O2, e.g. fungi and animals need O2, to run cellular respiration to stay alive b) Production of biomass: autotrophic organisms - represent the base of the food chain/web, particularly in aquatic environments.

Algal diversity Algae ARE NOT a single phylogenetic grouping, but give rise to several independent evolutionary lines. Our focus is on “CHLOROPHYTA” as it is believed to give rise to the terrestrial plants. Very diverse, very well adapted to certain environments, Range from unicellular,  colonial  multicellular e.g. marine, freshwater, terrestrial; often extreme habitats CHLOROPHYTES share Similarities to true plants – Same two chlorophylls a and b, Store products of photosynthesis as starch, cell wall primarily made of cellulose.

Algal construction types : Morphology 1. Unicellular algae 2. Colonies 3. Filaments 4. Multicellular

Unicellular algae ‘Microalgae’ - some may form colonies

Algal colonies e.g. Chlorophyta: Volvox (Order Volvocales) - 500-5000 cells per colony. - Colonies spherical up to 1.5 mm diameter. - Individual cells surrounded by a mucilaginous sphere - marine and freshwater http://www.youtube.com/watch?v=w8O4OolGcPg

Volvox colony – with Daughter colonies

Filamentous algae Unbranched filaments Branched filaments Different branches can have different morphologies:

MULTICELLULAR - Macroscopic

Why are algae important? Primary producers, basis of food webs, “FORESTS/GRASSES OF THE SEA” Pioneer Species: on rocky shores, mudflats, hot springs, lichen communities, 'snow algae' O2 production and carbon fixation in aquatic habitats. Rare autotrophic organisms in extreme habitats.

Examples of ecological importance Red tides, other algal blooms Hot springs Kelp forests Rocky shore ecology Aquaculture

Cyanobacterial bloom

Extreme halophytes

Uses of Seaweeds Present Potential Food Hydrocolloids and some chemical substances Fertilizers Potential Source of energy/compost by digestion Waste-water treatment