Uses of Phaeophyceae Flashcards
What is the scientific name of Kombu and where is it commonly found?
- Saccharina japonica syn. Laminaria japonica;
- it is commonly found in the intertidal-subtidal belt of temperate-cold waters, primarily in Korea and Japan areas.
What are the characteristics of Saccharina japonica (Kombu)?
- Large brown blades (fronds up to 2-5 m in length)
- Found in the intertidal-subtidal belt, up to 10-15 m of depth
- Intolerant of temperatures above 23°C
- Native to areas around Korea and Japan
How did L. japonica end up in China?
In 1927 L. japonica was accidentally introduced into China from Japan (by navigation) and naturalized on the shores of the Yellow Sea
What happened in 1951?
A cultivation program of L. japonica started in China:
- Cultivation techniques were experimented to reduce its life cycle from 2 years to 1 year
- Lines with more expanded surfaces and higher iodine content were selected
What are the current uses of L. japonica in China, and what challenges does its cultivation face?
Current uses in China:
- 50% as food
- 50% as a source of Alginates, Mannitol, Iodine
Challenges in cultivation:
Grazers (gastropod snails, amphipods) and diseases (some fungi) can cause significant harm to cultivated kelps, with biomass lowering by up to 85%.
What do the highlighted countries have in common in relation to S. japonica?
Main producer countries of Saccharina japonica
What do we see in the graph?
Global aquaculture production of S. japonica from 1959 to 2016
How long is the life cycle of S. japonica?
24 months
What is the first phase in the life cycle and when does it occur?
It starts in late autumn and lasts for 24 hours.
Events in this phase:
- Production and release of meiospores by sporophyte
- Meiospores settle down on the substrate
- Male and female gametophyte development
What is the second phase of the life cycle?
Takes place from December - February and lasts 2 months.
Events in this phase:
- Release of gametes - Fusion of gametes and growth of small sporophytes (~6mm)
What is the third phase of the life cycle?
This phase lasts for 20 months
Events in this phase:
- Development and maturation of sporophyte
What happens in the first and second year of the life cycle?
- 1st year: growth of the vegetative thallus
- 2nd year: growth of the thallus and production of sporangial sori
After the release of meiospores the old blade dies
How does the plant know when to switch from the 1st year to the 2nd year in the life cycle?
In the autumn – winter between 1st and 2nd year the seaweed perceives the “cold signal” ( = signal of transfer from 1st to 2nd year) and moves on to reproductive phase
How did researchers in China reduce the cultivation period of S. japonica to 11 months?
Through a technique called: forced cultivation
What are the 4 phases of this forced cultivation?
- Collection and settlement of zoospores on seed substrates
- Production of seedlings
- Growing of seedlings and transplantation
- Harvesting
What is the key to the rearing system (kweek systeem) of kelps?
Seedling production
How are seedlings produced in China during the summer?
Seedlings are produced in greenhouses during summer in China by controlling the water temperature and light.
How many seedlings can seedling production facilities in China produce yearly?
800 million seedlings
Where do the collected zoospores settle, and what occurs there?
The collected zoospores settle on substrates arranged in greenhouses (hatcheries), where the production of gametophytes occurs.
What steps are involved in breeding kelp gametophytes in greenhouses?
Breeding involves:
- Control of light intensity and photoperiod adjustment using black and white roof-curtains
- Control of seawater temperature adjusted by coolers
- Fertilization with chemicals, typically nitrate and phosphate
During which months are all steps of kelp breeding typically carried out in greenhouses?
All steps of kelp breeding are typically carried out in greenhouses from July to the end of October.
What happens when the seawater temperature in the greenhouse declines to 20°C?
When the seawater temperature in the greenhouse declines to 20°C, the young seedlings, attached to substrates, are moved to nursing sites for further rearing into large seedlings before transplantation into the sea.
Overview of cultivation phases
3 methods of growing Japanese kelp in different countries
- Vertical culture method
- Horizontal culture method
- Mixed culture method
Vertical culture method
Horizontal culture method
Mixed culture method
Cultivation process