Seasonal variability of primary production in a fjord ecosystem of the Chilean Patagonia: Implications for the transfer of carbon within pelagic food webs

Diatom blooms and primary production in a channel ecosystem of central Patagonia

“…Montero et al (2011) reported that the onset of the productive season in the Reloncaví Fjord (41°S, 72°W) coincided with a late winter relaxation of prevailing poleward winds. This seasonal shift in predominant winds and improved light conditions has been shown to influence the productivity of fjord and channel ecosystems (Iriarte & González, 2008;Montero et al, 2011). More locally, hydrodynamic patterns within a given fjord are strongly modulated by freshwater discharges, which can either intensify or weaken an estuarine type of circulation, and may modulate the occurrence and spatial extent of phytoplankton blooms (Goebel et al, 2005;González et al, 2013;Iriarte et al, 2014;Jacob et al, 2014).…”

“…The productivity cycle within a number of Patagonian channels and fjords (41-51ºS) has been typically described in terms of two contrasting seasons: a productive season characterized by a marked spring diatom bloom followed by pulsed productivity events dominated by a sequence of different phytoplankton species, and then a non-productive season that predominantly features small phytoplankton cells (Iriarte et al, 2007;Iriarte & González, 2008;Czypionka et al, 2011;Montero et al, 2011;Paredes & Montecinos, 2011). Despite considerable recent research, uncertainty remains regarding the factors that modulate the seasonal phase change within Chilean fjords system, from non-productive in late autumn-winter to highly productive in late winter-autumn.…”

“…In Chilean fjords ecosystems, diatoms are known to represent a significant component of the overall phytoplankton biomass (Iriarte et al, 2001;Cassis et al, 2002;Alves-de-Souza et al, 2008;Iriarte & González, 2008). In addition to efficiently transferring energy to higher trophic levels, diatoms make a significant contribution to the downward transfer of organic carbon (Iriarte et al, 2007;González et al, 2010;Montero et al, 2011;Iriarte et al 2013). Diatoms occur in highest abundance during the Patagonian fjord spring bloom, and are generally dominated by Skeletonema spp.…”

“…Diatoms occur in highest abundance during the Patagonian fjord spring bloom, and are generally dominated by Skeletonema spp. and associated with high levels of primary production (Iriarte et al, 2007;Montero et al, 2011). Despite the significant contribution that diatoms make to overall fjord productivity, important questions remain unanswered: for example, which are the main factors that trigger diatom blooms in specific fjords and channels, and which are the key species in terms of significance to annual productivity.…”

“…Montero et al (2011) reported that the onset of the productive season in the Reloncaví Fjord (41°S, 72°W) coincided with a late winter relaxation of prevailing poleward winds. This seasonal shift in predominant winds and improved light conditions has been shown to influence the productivity of fjord and channel ecosystems (Iriarte & González, 2008;Montero et al, 2011).…”