Release of Dissolved Organic Matter by Marine Seaweeds and Distribution of Their Total Organic Production to Inshore Communities1

Abstract

Under controlled experimental conditions, release rates of organic matter were estimated for five species of Barents Sea macrophytes and for thirteen species of Black Sea macrophytes. The release rates of different species from the Barents Sea were bctwccn 0.9 and 2.9 mg of organic matter per gram (dry wt) of plants per hour (mg g-l hr-") in March and between 1.7 and 9.8 mg 6-l hr-' in June. The release rates of different species from the Black Sea were between 1.25 and 6.1 mg g-l hrzL in fast growing plants and bctwccn 0.5 and 1.6 mg 8-l hr-' in slowly growing plants. Approximate quantities of total dissolved organic matter rclcased per year have been calculated to bc about 39% of gross production in brown algae, about 38% in red algae, and about 23% in green algae. The rest of the organic matter was released during decomposition of that part of standing stock not consumed by herbivorous animals. About 30% of gross production may be released in this way. Thus, the total flow of dissolved organic matter from seaweeds during growth and after death may be as much as 70% of their gross production. The ecological significance of external organic mctabolitcs rclcased in the surrounding water is discussed. 'A paper on this subject by J. McN. Sieburth will appear in the J. Exp. Mar, Biol. Ecol., 3. 2 The authors are very indeb,ted to Dr. J. D. 1-I. Strickland for his valuable and cordial help in retranslating the paper into contemporary American-English from our Russian-English,

International Helgoland Symposium: Convener's report on the Informal Session on biomass and productivity of microorganisms in planktonic ecosystems

“…The amount of primary productivity that must go rather quickly to DOC to support this bacterioplankton is an example. When Khailov & Burlakova (1969) and Sieburth (1969) reported that up to 40 ~ of the photosynthesis of the large browns is released during the early spring, this was challenged by Mann (1974) and Moe:bus & Johnson (1974) among others. However, current work at Dalhousie by Mann and a Ph.D. student and by Johnston et al (1977) using independent methods show that for Larninaria a release of 30 to 40 % of production occurs when photosynthesis occurs but growth has not yet begun, so that the plants dump the excess.…”

Effect of shading by Ulva rigida canopies on growth and carbon balance of the seagrass Zostera noltii

“…A second explanation involves some kind of resource/signal interaction between Zostera noltii and Ulva rigida canopies. Macroalgae can release a variable amount of their daily fixed carbon as DOC (Khailov & Burlakova 1969, Otsuki & Wetzel 1974, Pregnall 1983). This DOC is usually composed of low molecular weight molecules like carbohydrates, organic nitrogen, polyphenols and halocarbons (Sieburth 1969, Wetzel & Penhale 1979, Nightingale et al 1995, which can be used as a source for plant growth.…”

Flow cytometry for observing the distribution of adsorption sites on particles

“…This stock solution was assumed to represent natural yellow substance produced in the ocean. Exudates from Norwegian seaweeds have been reported to contain yellow substance that is indistinguishable from that in seawater (Sieburth and Jensen 1969) and Khailov and Burlakova (1969) have shown that release from seaweeds can be a significant contribution to inshore waters. Clay was obtained from shelf mud (courtesy of J. Christensen) at 43"N, 68"W in the Gulf of Maine during a cruise in July 1987.…”