seaweeds

• marine multicellular primary producers: seaweed, seagrass, salt marsh plants, and mangroves
• Seaweeds that arisen from a single event of primary plastid endosymbiosis: chlorphyta, rhodophyta, and terrestrials plants (blue-green algae)
• Chloroplast contains chlorophyll = allows organisms to produce their own nutrients through photosynthesis
• Seaweeds that arisen from a secondary event of primary plastid endosymbiosis: phaeophytha and stramenopiles
• Advantage of endosymbiosis event: they became autotrophs (can produce their own nutrients)
• Seaweeds are paraphyletic -- they share common ancestors but not all of them
• • 3 main phyla of seaweeds (macro algae)
  • Green (chlorophyta)
  • Red (rhodophyta)
  • Brown (phaeophyta)
• Seaweeds are an example of a fouling community
• Fouling communities are an assembly of populations of different organisms growing on an intertidal or submerged artificial structure
• Ballast water is an example of a fouling community
• Environmental factors that influence seaweed zonation:

  • Temperature
  • Light
  • Wave action
  • Availability of nutrients
  • Salinity
• Warmer temperatures are more conducive to seaweed growth (it's harder for seaweeds to acclimate in colder environments)
• Algae life cycles can be “perennials” and “annuals”
• Perennials – can live several years
• Annuals – yearly lifespan; only one year
• Seaweeds life cycles coincide with different temperature fluctuation (EX. Perennials release gametes during summer because the water is warmer)
• The main factor in seaweed zonation is light
• Chromatic adaptation involves different chlorophyll types; Certain types of chlorophyll can absorb different wavelengths of light
• Tidal exposure and dessication refers to seaweed's tolerance to exposure to outside air
• Free-floating seaweed can tolerate more waves, while seaweed attached to substrates can only tolerate a certain amount of force
• • Coastal areas receive balanced freshwater influx and salinity from oceans that allows the variety of seaweeds
• • Seaweeds mostly get their nutrients from the freshwater influx, organisms that live near seaweed that release their wastes
• Since they are submerged in water, seaweeds don’t need vascular tissue
• Seaweed structures:

  • Holdfast — attach to the substrate
  • Stipe – support
  • Blade – surface of organisms
  • *Air bladder – filled with gas that it accumulates that allows for buoyancy
  • *Reproductive structures
• • Entire body of the seaweed is called “thallus”
• • Some seaweeds can be filamentous → form long, thread-like structures
• Coraline seaweeds hold calcium carbonate in their structures → important in binding coral fragments
• Seaweeds have 2 patterns of reproduction:

  • Asexual reproduction via fragmentation
  • Asexual and sexual reproduction in the alternation of generations
• Types of algae (differ based on the type of chlorophyll they have):

  • Chlorophyta — Chlorophyll a and b
  • Rodophyta — Chlorophyll a and d
  • Phaeophyta — Chlorophyll a and c
• All types of algae maximize the amount of light they can absorb by using different pigments
• Which algae do you think would survive best in shallow and deep waters?

  • Shallow = Chlorophyta (green) or Phaeophyta (brown)
  • Deepest = Rodophyta (red)
• Accessory pigments of green algae:

  • Carotenes
  • Xanthophylls
  • Phychobillins
• There are 2 main types of green algae:

  • Prasinophyceans (marine phytoplanktons)
  • Ulvophyceae (true seaweeds)
• Ulvophoeceans are coenocytic with cellulose in their cell walls
• Coenocytic means they undergo nuclear division, but not cellular division (which is why they have multiple nuclei)
• Calcium carbonate in green algae is used as a defense mechanism against herbivory through:

  • presence of toxins
  • hard to chew
  • less nutritious
• Some herbivores develop adaptations to eat algae with calcium carbonate by:

  • piercing thallus of coenocetic tissue
  • sucking out the toxin and the chlorophyll
  • making them bright and toxic
• Red algae is the most common and biodiverse seaweed type; 98% of its species is marine
• Red algae accessory pigments include:

  • phycoerythrin
  • phycocyanin
• Red algae can be epiphytic (growing on plants) or epizoic (growing on animals)