|Ecology of the green macroalga Codium fragile (Suringar) Hariot 1889: invasive and non-invasive subspecies|
Trowbridge, C.D. (1998). Ecology of the green macroalga Codium fragile (Suringar) Hariot 1889: invasive and non-invasive subspecies. Oceanogr. Mar. Biol. Ann. Rev. 36: 1-64
In: Oceanography and Marine Biology: An Annual Review. Aberdeen University Press/Allen & Unwin: London. ISSN 0078-3218, more
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The large, green, branching macroalga Codium fragile (Suringar) Hariot 1889(Chlorophyta: Codiaceae) is one of the most abundant and widespread species inthe morphologically and taxonomically diverse genus of Codium. Six distinctsubspecies of C. fragile have been recognized, in addition to morphologicallyheterogeneous populations (with no subspecific name) on temperate and borealshores throughout the world. Three of the subspecies appear to occur primarily asrevealed that the spores released from 4 and 6 cm above the substrate show anormal disc development, whereas those released from 2 cm produced rhizoidsand smaller disc than the former. The spores released from 6 cm show the greatestgrowth. The spores with a greater density of fixation show distortions in the development of normal pattern and a smaller growth of microthalli.?rom 2 cm produced rhizoidsand smaller disc than the former. The spores released from 6 cm show the greatestgrowth. The spores with a greater density of fixation ss from this region arenot necessarily applicable to the alga in other temperate and boreal regions.Furthermore, much of the work on ssp. tomentosoides is unrelated to the invasionecology of this alga, and many authors remain unaware of its exotic origins. In thisreview, I examine the ecological differences among and within subspecies andevaluate their relative invasiveness. Variation among subspecies of C. fragileoccurs in the following attributes: (a) sexual reproduction v. parthenogenesis, (b)apparent ploidy level of the macroscopic adult thallus, (c) salinity tolerance, and (d) thallus buoyancy in germs both of tissue density and propensity to trap gases.There is little reported evidence, however, that subspecies vary substantially inlength of their reproductive period, growth, phenology, vegetative propagation,physiological ecology, herbivore palatability, competitive ability, host-epiphyteinteractions, or natural products production. Comparative studies are needed tounderstand the variable invasiveness of the three introduced subspecies and thenon-invasiveness of indigenous forms as well as geographic variation in ecologicalattributes of ssp. tomentosoides.