Dispersal and colonization in Sargassum muticum (Yendo) Fensholt

Deysher, Lawrence; Norton, Trevor A.

doi:10.1016/0022-0981(81)90188-x

Cited by 213 publications

(189 citation statements)

References 9 publications

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“…Other studies of spore dispersal in marine algae have found a much more restricted dispersal: on the order of five meters from the parent plant (Anderson & North, 1966;Dayton, 1973;Paine, 1979;Deysher & Norton, 1981). The observed rate of spread of Sargassum muticum suggested that this species possessed a long distance dispersal mechanism in addition to the short distance dispersal observed for germlings (Deysher & Norton, 1981}.…”

Section: Dispersalmentioning

confidence: 87%

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Genetic differentiation among populations of marine algae

Innes

1984

Helgoländer Meeresunters

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Most of the information for genetic differentiation among populations of marine algae is from studies on ecotypic variation. Physiological ecotypes have been described for individuals showing different responses to temperature and salinity conditions. Morphological ecotypes have also been found associated with areas differing in wave exposure or different intertidal positions. Little is known on how genetic variation is organized within and between populations of marine algae. The occurrence of ecotypic variation in some species is evidence for genetic differentiation among populations resulting from selection by the local environment. The rate of dispersal and subsequent gene flow will also affect the level of differentiation among populations. In species with low dispersal, differentiation can arise through chance founder events or random genetic drift. The few studies available have shown that species of algae exhibit a range of dispersal capabilities. This information can be useful for predicting the potential level of genetic differentiation among populations of these species. Crossing experiments with several species of algae have shown that populations separated by a considerable distance can be inteffertile. In some cases individuals from these populations have been found to be morphologically distinct. Crosses have been used to study the genetic basis of this variation and are evidence for genetic differentiation among the populations sampled. Genetic variation of enzyme proteins detected by electrophoresis provides an additional method for measuring genetic variation within and between populations of marine algae. Etectrophoretic methods have previously been used to study systematic problems in algae. However, there have been few attempts to use electrophoretic variation to study the genetic structure of populations of marine algae. This approach is outlined and includes some of the potential problems associated with interpreting electrophoretic data. Studies of electrophoretic variation in natural populations of Enteromorpha linza from Long Island Sound are used as an example. This species was found to reproduce only asexually. Despite a dispersing spore stage, genetic differentiation was found on a microgeographic scale and was correlated with differences in the local environment of some of the populations. Similar studies on other species, and especially sexually reproducing species, will add to a growing understanding of the evolutionary genetics of marine algae.

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Section: Dispersalmentioning

confidence: 87%

“…The observed rate of spread of Sargassum muticum suggested that this species possessed a long distance dispersal mechanism in addition to the short distance dispersal observed for germlings (Deysher & Norton, 1981}. It was postulated that detached vegetative fragments could be carried by wind and water currents.…”

Section: Dispersalmentioning

confidence: 99%

Genetic differentiation among populations of marine algae

Innes

1984

Helgoländer Meeresunters

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“…Once propagules are released into the water, a plume of spore cloud may drift downstream (Deysher and Norton 1982) and can be displaced laterally by currents and progressively diluted by turbulent mixing (Norton 1992). Zoospores can, therefore, be suspended within the euphotic layer of the water column for a period of time.…”

Section: Introductionmentioning

confidence: 99%

Exposure to ultraviolet radiation delays photosynthetic recovery in Arctic kelp zoospores

Roleda

Hanelt²,

Wiencke

2006

Photosynth Res

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Seasonal reproduction in some Arctic Laminariales coincides with increased UV-B radiation due to stratospheric ozone depletion and relatively high water temperatures during polar spring. To find out the capacity to cope with different spectral irradiance, the kinetics of photosynthetic recovery was investigated in zoospores of four Arctic species of the order Laminariales, the kelps Saccorhiza dermatodea, Alaria esculenta, Laminaria digitata, and Laminaria saccharina. The physiology of light harvesting, changes in photosynthetic efficiency and kinetics of photosynthetic recovery were measured by in vivo fluorescence changes of Photosystem II (PSII). Saturation irradiance of freshly released spores showed minimal I k values (photon fluence rate where initial slope intersects horizontal asymptote of the curve) values ranging from 13 to 18 lmol photons m )2 s )1 among species collected at different depths, confirming that spores are low-light adapted. Exposure to different radiation spectra consisting of photosynthetically active radiation (PAR; 400-700 nm), PAR+UV-A radiation (UV-A; 320-400 nm), and PAR+ UV-A+UV-B radiation (UV-B; 280-320 nm) showed that the cumulative effects of increasing PAR fluence and the additional effect of UV-A and UV-B radiations on photoinhibition of photosynthesis are species specific. After long exposures, Laminaria saccharina was more sensitive to the different light treatments than the other three species investigated. Kinetics of recovery in zoospores showed a fast phase in S. dermatodea, which indicates a reduction of the photoprotective process while a slow phase in L. saccharina indicates recovery from severe photodamage. This first attempt to study photoinhibition and kinetics of recovery in zoospores showed that zoospores are the stage in the life history of seaweeds most susceptible to light stress and that ultraviolet radiation (UVR) effectively delays photosynthetic recovery. The viability of spores is important on the recruitment of the gametophytic and sporophytic life stages. The impact of UVR on the zoospores is related to the vertical depth distribution of the large sporophytes in the field.

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“…We define propagule both as microscopic and as the product of a specialized reproductive structure or cell. Clearly, macroalgae are also propagated and dispersed by other mechanisms such as dislodged or fragmented plants (which may or may not release propagules as we have defined them; e.g., Russell, 1967;Hay, 1979;Deysher & Norton, 1982;Amsler, 1984;van den Hoek, 1987;Neushul et al, in press). Although a propagule by this definition can be of vegetative origin, [for example, the specialized branches which are released by Sphacelaria (van den Hoek & Flinterman, 1968)], most macroalgal propagules are unicellular spores, gametes, or zygotes and, in some cases, germlings which develop from them before or during dispersal.…”

mentioning

confidence: 99%