The Relationships Between Weight, Length, Age and Intensity of Photosynthesis and Organotrophy of Macrophytes in the Barents Sea

Abstract

For Ascophyllum nodosum, Fucus vesiculosus, Fucus inflatus and Rhodymenia palmata in the Barents Sea a quantitative description isgiven of the relationship between length (L) and weight (W) ofthe thallus, and for/4. nodosum also between weight (W) and age (7"). The weight of the thallus has also been related to the intensity of two physiological functions -photosynthesis (/*,·) and the consumption of organic substances (P0) dissolved in the water. According to the value of linear growth per unit of weight and the intensity of P,·, the different species form the series: Rhodymenia palmata > Fucus inflatus > Fucus vesiculosus > Ascophyllum nodosum, From the W-T relationship a lag phase ("early youth"), a logarithmic phase ("youth"), and the beginning of a stationary phase ("maturity") have been disclosed in the ontogenesis of A. nodosum. It has been shown that the photosynthesis and Organotrophy of the thallus diminish with the increase of its weight. This dependence is approximated by a power equation, which parameters have been determined. In two species A. nodosum and F. vesiculosus the weight {HO ratios of tissues of different age (t) have been determined. On the basis of these data, stages of youth, maturity and senescence of tissues have been determined in A. nodosum. The comparison of the w-t curves of A. nodosum and F. vesiculosus shows that a different strategy of thallus formation is innerem in them.The knowledge of functional morphology of higher organisms -especially animals -has developed very purposefully and successfully. At the same time the functional morphology of marine plants has been represented by investigations which, even if numerous, are uncoordinated, and no purposeful development of such research has been observed äs yet. Marine marcrophytes, however, with their perennial, usuaUy veiy ramified thalli and strongly expressed basic function (photosynthesis) could doubtlessly provide a wealth of data for the comparison of form and function. In our opinion one of the main causes for the lagging of functional morphology of marine macrophytes depends on the absence of a quantitative approach, a systematic measurement of at least the principal morphological parameters ofthe thallus -length and weight. If such measurements were paralleled by simultaneous measurements of physiological functions, primarily photosynthesis, the functional morphology of marine plants would be given the necessary foundation. An analysis of the literature devoted to marine macrophytes shows that even for the best studied species ofthe northern seas, asA nodosum, (Baardseth 1970), despite a relatively great variety of Information, very littie quantitative data are available on growth and relationship of morphological and physiological characters. The aim of this work is to make a morpho-physiological anaJysis of the thalli of two species of macrophytes ocurring in masses ~ Ascophyllum nodosum and Fucus vesiculosus. We have less data on the third species studied -Fucus inflatus.

Seasonal Growth and Photosynthetic Performance of the Antarctic Macroalga Desmarestia menziesii (Phaeophyceae) Cultivated under Fluctuating Antarctic Daylengths

“…However, even under the low irradiance of 2pmol photons rn-, s-l, D. anceps had maximum rates close to 2% d-l. Therefore it seems that other factors such as age and size of the plants also influence growth rates, as has been found in other studies using temperate macroalgae (Khailov, 1976;Khailov et al, 1978). For example, plants used in the present study were 2-year-old whereas Wiencke used approximately 1-year-old D. anceps plants.…”

Regrowth of Ascophyllum nodosum and Fucus vesiculosus under Various Harvesting Regimes in Maine, U.S.A.

“…The reasons for these declining yields are not known but may be related to a loss of regenerative capacity and normal senescence (Khailov 1976). The declining yields with repeated annual harvests strongly indicates that annual reharvests should be avoided in Maine.…”

Variations in photosynthetic characteristics of the Antarctic marine brown algaAscoseira mirabilisin relation to thallus age and size

“…large thalli with a relatively high proportion of structural and non-photosynthetic tissues have lower photosynthesis rates than thalli consisting mostly of photosynthetically active cells (Littler, 1980;Littler & Littler, 1980). These differences have also been seen among tissues of a single thallus from perennial macroalgae (Khailov, 1976;Khailov & Firsow, 1978;Arnold & Manley, 1985). In our study, net photosynthetic rates and photosynthetic efficiencies, measured in terms of flesh weight (Figs 5, 6), were always higher in the 2-year-old plants, which may be related to differences in tissue characteristics.…”