Seaweed Cultivation Flashcards
Give some uses of seaweed?
Food, Hydrocolloid production (agar)
Costmetics, fish/animal feed, fertilisation
Biomass for fuel, waste water management
What types f seaweed are cultivated?
eucheumoid algae kappaphycus alvarezzi eucheuma spp. Elkhorn smeamass and Gigatinates Japanese sugar kelp Wake p.yezonesis, p, tenera, p.haitanesis
Explain the Lifecycle Kappaphycus, Eucheuma, Graciliaria
- Gametophyte
- Carposporophyte
- Tetrasporophyte (undergoes fragmentation)
- Tetraspores
- Produce Gametophyte
How are seeds cultivated in the species pyropia? Especially seed supply.
- Superior blades are selected from carbospores
- Carpospores form vegetative propogation to form vegetative fragments
- Carpospores + vegetative fragments form mass cultures of conchocelius
- Mass culture triggers growth, formation and maturation of sporangia, and induction of concehospore release
- Conchospores go through indoor and outdoor seeding
When are seeds cultivated (seed supply stage) in the species pyropia?
March - Oct
What happens in indoor seeding of pyropia spp?
Shells placed in tanks
nets are on reels rotating in tank
less than 1 hour
What happens in outdoor seeding of pyropia spp?
Shells places on seeding tarps with nets layered over shells
1 - 2 days
How are seeds cultivated in the species pyropia? Especially seabed culture.
- Seeded nets are placed on poles or fixed cultures
- Poles - nets hang from holes and height is adjusted for best drying regime
- Floating cultivation - Nets placed in nursery frames; drying regime to control disease and weeds
- Both cultures have nets with 2 - 3 cm long plants
- These plants are frozen then/or fixed on a pole/floating culture method is used to grow to harvest size
- Then harvested or frozen/held in a tank or processed
When are seeds cultivated (seabed cultivation stage) in the species pyropia?
Oct - April
What are the 2 indoor cultivation techniques used in kelp?
- Direct Seeding
2. Vegetative propagation of gemetophytes
Describe the method of direct seeding in the indoor cultivation of kelp
- Fertile algae –> preparation of sporogenic tissue
- Sporogenic tissue releases spores
- Released spores are innoculated
- Cultivation of juvenile sporophytes
Describe the method of ‘Vegetative propagation of gametophytes’ in the indoor cultivation of kelp
- Sporogenic tissue releases spores
- Gametophyte isolated clones
- Spraying of gametophytes and developing sporophytes
In kelp cultivation, when does seabed cultivation occur?
Saccharina are harvested May - June
Undaria are harvested March
In kelp cultivation, how does seabed cultivation occur?
Manual work - vertically grown seaweeds are called droppers
In Eucheumoid Cultivation, What 2 Techniques are used?
- Fixed-off-bottom moonlike method
2. Long-line floating method
In Eucheumoid Cultivation, Describe the long-line floating method
- Can be tropical or sub-tropical
- vegetative propagation
- Seed stack sourced from cropping (wild) and multiplied in nurserys
- Cutting tied to monotones at 30cm intervals
- Harvested at approximately 1-kilo manually
What are the 4 methods used I the cultivation of Gracilaria?
- Pond Farming
- Rope Farming
- Bottom Stocking
- Tank Cultivation
Describe ‘pond farming’ when regarding gracilaria?
- Seed Stock sourced from the wild from crops in other ponds or in nursery rearing cuttings
How long until you can harvest gracilaria from pond farming?
30-45 days anytime of year
Describe ‘rope farming’ when regarding gracilaria?
- Vegetative material is tied/inserted to ropes
OR - Spore settlement onto ropes
Describe ‘Bottom Stocking’ when regarding gracilaria?
- Transfer of rocks bearing Thali
- Tie Thali to Rocks
- Seaweed is forced into the sediment
Give 3 diseases/threats that eucheumoids encounter
- Grazing by herbivores
- Epiphytes produced by benthic algae
- Ice-Ice by micro-organism
What does Ice-Ice (from bacteria and fungi) do to eucheumoids?
- Causes slow growth, pale thali, loss of shiny branch surface, presence of epiphytes,
- occurs in summer ad calm weather
How can Ice-Ice be prevented?
Transfer eucheumoids to cold water and good current movement
How can grazing on eucheumoids be prevented?
Use floating method in deep water
How can the effects of epiphytes on eucheumoids be prevented?
- submerging 1m below the surface
- good current flow
How and what are epiphytes produced by?
Produces by benthic algae
produce in summer blooms
Give a few examples of diseases and threats to pyropia?
- Chytridosis, red rot disease, filamentous disease
- Atrophy, green rot disease, discolouration disease
Describe what Chytridosis does to pyropia and how it can be prevented.
Cytridosis is produced by a fungus and causes mould and reduced production of pyropia
It can be prevented by decreased density of cultures
Give a few examples of diseases and threats to saccharia?
- Twisted frond disease, Malformation disease
- Blister Disease, White/green Rot disease
What is the seaweed abalone cultivation?
An integrated cultivation with Ulva and Gracilaria
It is a large part of gracilaria biomass for china
What does IMTA stand for?
Integrated multitrophic Aquaculture (cultivation system)
What are the positive impacts of seaweed cultivation?
- Uptake of excess nutrients
- No catch area for fish
- New habitats and biodiversity
What are the negative impacts of seaweed cultivation?
- Nutrient depletion/changes in seascape
- Structure only temporal
- Increased O2 consumption at the bottom (no light for photosynthesis)
What are the expected impacts of seaweed cultivation?
- new habitats and changes to water column
- changes to local hydrodynamics
- changes in sedimentation patterns
- benthic impacts from increase organic matter supply and shading of seafloor
What qualities constitutes sustainable cultivation of seaweeds?
- no fertiliser/pesticides/consumption of FW
- Effective CO2 capture
- Nutrient Stripping of eutrophicate coastal waters
- High productivity compared to land plants
- Enourmour available surface for cultivation
