Table 1.

Comparison between the bloom-forming type and the attached type in Ulva prolifera.

	Bloom-Forming Type	Attached Type
Subspecies name	Ulva prolifera subsp. qingdaoensis	Ulva prolifera subsp. prolifera
Habitat/Distribution	Offshore and coastal waters in the Yellow Sea	Brackish and estuarine waters in cold–temperate regions
Season for maximum population abundance	Early summer	Winter to early spring
Temperature at which thallus growth turns to zero or negative	Around 25 °C	Around 20 °C
Branch density of cultured thalli	>100 per 1 cm of main stem	0.4–14 per 1 cm of main stem 1
Life cycle	Sexual	Sexual or obligate asexual by special spore (zoosporoid)
Crossing affinity to Ulva linza	Complete incompatibility	Partial gamete incompatibility
5S sequence	5S-A type or 5S-B type 2	A large number of various types 3 different from 5S-A and 5S-B types

¹ Data from the type locality population [40]; ² The two types reported by [18]; ³ Thirty-one types reported by [42] and several more [19,43,47].