文档介绍：第六讲第二节 大型底栖海藻生态
主要内容
What are seaweeds?
底栖藻类固着生长
对光的需求产生形态上的适应
Seaweed的种类:绿藻、褐藻、红藻
Grazers, competition and defence
Seaweed as part of an ecosystem
The rigours of seaweed life
Wherever seaweeds grow they have pete for space, anic nutrients and light. They are also in constant danger of being grazed on by gastropods(腹足动物), fish, sea slugs(海蛤蝓) and sea urchins(海胆) and have some sinister tactics for putting off predators.
An “army”of Littorina snails grazing green seaweeds form a rock surface (Fig. p59)
Fighting for space
1)种内竞争:
when there is mass settling and germination of spores of the same species in a confined area, competition naturally occurs between the thalli(叶状体).
In general this results in an inverse relationship between density and size. This is particularly applicable to stands of fast-growing, short-lived species such as Ulva(石莼),Bangia(红毛菜), Enteromorpha(浒苔) and Porphyra(紫菜).
Those much slower growing encrusting coralline pete for space: they end up growing into and over each other, sometimes ing quite indistinct(模糊的) as individuals.
2)种间竞争:
并不一定是大的藻类在空间竞争中就获得优势,例如大型褐藻Egregia laevigata(优秀藻)就竞争不过较为小型的红藻,因为这些小型的藻类能够快速地占领空间,使得大型褐藻的孢子难以附着并萌发。
3)与动物的空间竞争:
barnacles(藤壶)、 mussels(贻贝)等也是大型藻类空间的竞争对手。
There are mechanisms by which seaweed inadvertently(不经意地) helps to strip the creatures from the rocks, so creating a space in which to grow.
The robust Postelsia(囊沟藻) inhabits parts of the shore that are also occupied by barnacles and mussels. Small Postelsia have been seen growing firmly attached to barnacles. When they reach a certain size, the increased drag causes the seaweed, together with the attached barnacle, to be ripped from the rock surface. The bare area of rock is immediately colonised by Postelsia spores.
4) 附生植物 epiphytes
One of the most effective ways to gaining an advantage in the quest for space and light is to grow on the surface of a moving animal or on the surface of another seaweed.
Most seaweeds, from encrusting corallines (钙质