Distribution and Biomass of Ruppia Filifolia (Phil.) Skottsberg, (Ruppiaceae) in Skyring Sound, Sub-Antarctic Ecoregion of Magallanes, Chile

Abstract

RESUMENRuppia filifolia es el pasto marino con la distribución más austral del planeta y del que se desconoce incluso los aspectos más básicos de su biología y ecología. Se evalúa la presencia, distribución batimétrica y biomasa alcanzada por las praderas R. filifolia en seno Skyring (ecoregión subantártica de Magallanes, Chile) mediante prospección remota con una cámara de video, y verificación directa y muestreo por buceadores. El litoral del seno Skyring está rodeado por praderas fragmentadas de R. filifolia hasta una profundidad de 5,3 m en bandas de 100-160 m de anchura. R. filifolia alcanza una biomasa de 80 g peso seco m -2 con una asignación relativa de biomasa a rizomas más raíces frente a hojas de 1,6 a 1,9 y una densidad de 2.000 haces foliares m -2 . Se discute la importancia de este pasto marino en el funcionamiento del ecosistema costero somero del seno Skyring.Palabras clave: pastos marinos, ambientes sub-antárticos. ABSTRACTRuppia filifolia is the seagrass with the world's southernmost distribution and a species about which even the most fundamental aspects of its biology and ecology are not known. Presence, bathymetric distribution, and biomass of R. filifolia meadows in Skyring sound (sub-antarctic ecoregion of Magallanes, Chile) were evaluated through a remotely operated vehicle (ROV) survey, and direct verification and sampling by divers. The littoral of Skyring sound is surrounded by patchy R. filifolia meadows to a depth of 5.3 m in bands 100-160 m wide. R. filifolia achieved a biomass of 80 g dry weight m -2 , a rhizomes plus roots to leaves biomass ratio of 1.6 to 1.9 and a density of 2.000 shoots m -2 . Possible relevance of meadows formed by this seagrass species in the functioning of the shallow coastal ecosystem of Skyring sound is discussed.

Phenology, biomass and productivity of sub-Antarctic Ruppia filifolia

“…The high RSR suggests that R. filifolia might have a higher potential for carbon burial in the sediment than other Ruppia species. Indeed, we observed the presence of a rhizome mat (i.e., a 5-10-cm-thick, compacted layer of rhizomes, roots and sediment) of this species in several meadows at Skyring Sound during a previous survey (Mansilla et al 2013) and erosional morphologies (scarps, blowouts;Patriquin 1975;Clarke and Kirkman 1989) in the edges of some meadows. Also such meadow features suggest that R. filifolia might play an important role in sediment stabilization in Skyring Sound.…”

“…The annual average air temperature is 6°C, with a strong gradient of west-to-east rainfall ([6600 to \1000 mm year -1 ) and dominant, strong winds from the west (annual average speed 3.7 m s -1 , average maximum speed 13.4-8.8 m s -1 ; Schneider et al 2003). The eastern shores of Skyring Sound harbor patchy meadows of R. filifolia to a depth of 4.5-5.3 m with biomass of 80 g dry weight (DW) m -2 (Mansilla et al 2013), and it is the locality where the species was first described (Skottsberg 1916). Air temperature in this part of the fjord varies between 1.5 and 8.6°C (average daily minima and maxima, respectively), the average daily solar radiation is 116 W m -2 , and the annual rainfall is 988 mm year -1 (Schneider et al 2003).…”

“…Although debated (den Hartog and Kuo 2006), Ruppia species living in marine environments are regularly included in comprehensive seagrass treaties (Short and Coles 2001;Green and Short 2003). The name R. filifolia was proposed by Skottsberg (1916), and it has been used since then to refer to Ruppia plants living in freshwater and brackish coastal lagoons of southern Patagonia, Tierra del Fuego and the Falkland (or Malvinas) Islands, as well as the fjords and channels surrounding the Strait of Magellan (Moore 1973(Moore , 1983Alvarez et al 2010;Ito et al 2010;San Martín et al 2011;Mansilla et al 2013). The names Ruppia sp.…”

An update on morphology and distribution of Ruppia filifolia (Philippi) Skottsberg in the Magellan region, southern Chile

“…Ruppia filifolia has also been described in marine, hyposaline waters of the Patagonian Fjords Ecosystem in the Magellan region of Chile's Subantarctic archipelago, including the species phenology and biomass (Mansilla et al, 2013;Murcia et al, 2015). But continued monitoring and assessment of new niche distributions for Ruppiaceae communities in the region, and their molecular phylogenies is paramount to gather baseline information to identify future environmental and community changes (e.g., Coles et al, 2011) in the Magellan region.…”

“…1), a brackish (18) water body (Kilian et al, 2007) from the Magellan region, where this taxon is abundant according to ancient (Hagstrom, 1911;Skottsberg, 1916) and recent reports (Mazzella & Gambi, 1993, Mansilla et al, 2013, Murcia et al, 2015. These collections of R. filifolia include also 20 plants sampled in Tierra del Fuego areas reported by Moore (1983), as well as non-systematic collections of 31 plants in total from different shallow water bodies throughout the archipelago (see Results).…”