Canopy characteristics of the brown alga Sargassum muticum (Fucales, Phaeophyta) in Lake Grevelingen, southwest Netherlands

Abstract

The present distribution of the invasive brown alga Sargassum muticum in the southwest Netherlands is updated . Populations of the alga were found to remain at their 1985 level in Lake Grevelingen, with a small eastward expansion into the Eastern Scheldt estuary . A new population for the brackish, non-tidal Lake Veere is reported . Within Lake Grevelingen S . muticum forms a persistent, extensive canopy of 100% cover (4,442 .5 ± 525 .6 g fresh wt m -2 ; 640 .3 ± 75 .8 g dry wt m -2) that has a marked effect upon the penetration of photosynthetically active radiation (PAR) (reduced by 97 % at 0 .1 m) . Surface sea water temperatures can be elevated by 2 .7 °C above water not associated with a Sargassum canopy ; furthermore, the dense canopy shades and hence reduces water temperatures below 0 .1 m depth. Productivity studies indicate that assimilation occurs in the upper levels of the canopy (57 .09 pg C mg dry wt -' m -2 at a mean PAR rate of 106 .7 J cm -2 h -') . Self-shading and a resultant decrease in the rate of assimilation was evident below the canopy .

Comparative Phenology of Sargassum muticum and Halidrys siliquosa (Phaeophyceae: Fucales) in Limfjorden, Denmark

“…75 cm (DeWreede 1978, Espinoza 1990, Givernaud et al 1991 to ca. The maximum mean biomass of S. muticum in Limfjorden (27 g DW ind Ϫ1 ) was lower than the range 60Ϫ80 g DW ind Ϫ1 reported by Yamauchi (1984) from Japan (in culture) and Critchley et al 1990 a from the Netherlands, but corresponded well to the ca. The maximum mean biomass of S. muticum in Limfjorden (27 g DW ind Ϫ1 ) was lower than the range 60Ϫ80 g DW ind Ϫ1 reported by Yamauchi (1984) from Japan (in culture) and Critchley et al 1990 a from the Netherlands, but corresponded well to the ca.…”

“…When disregarding the generally small seasonal variations in FW:DW, mean values for both Sargassum muticum (4.4Ϫ9.7) and Halidrys siliquosa (4.6Ϫ6.0) are in the proximity of 4.8Ϫ6.9 found in earlier studies of Sargassum muticum , Yamauchi 1984, Critchley et al 1990 and other Fucales [Fucus vesiculosus L.: 6.1, Ascophyllum nodosum (L.) LeJol. : 4.5 (Brinkhuis 1977)].…”

“…Sargassum muticum (Yendo) Fensholt is indigenous to South East Asia (Yendo 1907) but it has been introduced to and invaded the American west coast for more than 50 years and European waters from the Mediterranean Sea to Scandinavia for about 30 years (Scagel 1956, Deysher and Norton 1982, Rueness 1989, Critchley et al 1990b, Wernberg-Møller et al 1998a, Karlsson and Loo 1999, Staehr et al 2000. The invasive nature of S. muticum has resulted in a tremendous research effort (the bibliography of Critchley et al 1990 b lists 314 publications and numerous others have been published since) covering almost every facet of the species' biology.…”

High-value products from macroalgae: the potential uses of the invasive brown seaweed, Sargassum muticum

“…muticum is a relatively high water content biomass (80-90 %) (Critchley et al 1990;Milledge et al 2015;Wernberg et al 2001) compared to terrestrial crops (sugarcane *75 %, grain maize 14-31 %) (European Commission 2014; McLaren 2009). It also has a high ash content of between 27 and 42 % dry weight (Hardouin et al 2014;Shekhar et al 2012).…”

Light climate and energy flow in the seagrass canopy of Amphibolis griffithii (J.M. Black) den Hartog

“…It suggests that the canopy is a functional unit. Brown algal canopies (Sargassum muticum) have been recorded to cause higher (5°C) differences in water temperature under calm conditions (Critchley et al 1990). Temperature is known to have large effects on photosynthetic (and therefore production) rates in many seagrass species (Evans et al 1986;Marsh et al 1986;Perez and Romero 1992;Walker and Cambridge 1995).…”