Phytoplankton biomass in the sub-Antarctic area of the Straits of Magellan (53°S), Chile during spring-summer 1997/1998

Iriarte, José Luis; Kusch, Alejandro; Osses, Josefa; Ruiz, Milena

doi:10.1007/s003000000189

Cited by 45 publications

(42 citation statements)

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“…Certain species are able to completely dominate a phytoplankton community (Legrand et al, 2003). 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).…”

Section: __________________mentioning

confidence: 99%

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

Montero

Daneri

Tapia

et al. 2017

lajar

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ABSTRACT.Here we report on the seasonal productivity cycle at a fixed station in the Puyuhuapi Channel (44ºS, 73ºW), Chilean Patagonia. The analysis of in situ water column data and longer-term records of satellitederived surface ocean color (Chl-a) highlighted two contrasting seasons. A more productive period occurred between August and April, where depth-integrated gross primary production (GPP) estimates ranged from 0.1 to 2.9 g C m -2 d -1, and a shorter, less-productive season lasted from May to July with GPP ranging from 0.03 to. Diatoms of the genera Pseudo-nitzschia, Skeletonema and Chaetoceros dominated the phytoplankton, and showed a pronounced seasonality greatly influenced by prevailing environmental conditions. Warmer waters were associated with high concentrations of Pseudo-nitzschia spp., while high abundances of Skeletonema spp. and Chaetoceros spp. were associated with fresher silicate-rich waters. A marked Skeletonema spp. bloom characterized the onset of the productive season in August 2008, and with some exceptions, the highest levels of GPP (1.5 to 2.9 g C m -2 d -1) were measured when Skeletonema dominated the phytoplankton community. Reduced production (low GPP) was observed during periods of increased discharge from the Cisnes River, whereas the "spring" diatom bloom (or late winter bloom in Puyuhuapi Channel) observed during August 2008 coincided with a ~50% drop in the freshwater discharge. We therefore suggest that periods of intensive freshwater Input, that increase the silicic acid concentrations in the upper layers, provide ideal growing conditions for diatoms as the freshwater flow subsequently recedes. Principal component analysis (PCA) suggests that a decrease in salinity, increase in silicic acid concentration, and growth of Skeletonema spp. and Chaetoceros spp., are probably key factors in the annual cycle of GPP in Puyuhuapi Channel.

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confidence: 99%

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

Montero

Daneri

Tapia

et al. 2017

lajar

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“…Maximum P. micans abundances occurred simultaneously with the lowest Si(OH) 4 levels observed during the present study, whereas diatom blooms were positively related to high Si(OH) 4 :NO 3 periods. The relative concentrations of Si(OH) 4 and NO 3 have been highlighted as the main factor determining phytoplankton composition in the fjords of southern Chile (Alves-de-Souza et al 2008, Torres et al 2011, with low Si(OH) 4 :NO 3 ratios favoring the development of non-diatom blooms (Iriarte et al 2001(Iriarte et al , 2007.…”

Section: Evolution Of Phytoplankton Assemblagesmentioning

confidence: 99%

Infection dynamics of Amoebophryidae parasitoids on harmful dinoflagellates in a southern Chilean fjord dominated by diatoms

Alves‐de‐Souza¹,

Varela²,

Iriarte³

et al. 2012

Aquat. Microb. Ecol.

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Parasitoids belonging to Amoebophryidae (Marine ALVeolate Group II or MALV II) infecting dinoflagellates were investigated in Reloncaví Fjord (southern Chile) in the austral summer 2009. Of the 12 dinoflagellate species recorded during monthly sampling, Prorocentrum micans, Dinophysis acuminata, and Phalacroma rotundata were infected by Amoebophrya spp. To assess parasitoid control of host populations, the short-term dynamics of Amoebophrya spp. were followed for 21 d during a bloom of P. micans. Host mortality induced by Amoebophrya spp. (% hosts killed per day) was estimated by dividing prevalence by the generation time of these parasitoids. Parasitism by Amoebophrya spp. was responsible for ~10% of P. micans mortality between 8 and 17 March. The small subunit rDNA genes of individual parasitoids infecting different host cells were sequenced, and like most environmental sequences retrieved from this ecosystem in January and February, all belonged to the MALV II Clade 4. However, as soon as the P. micans bloom was detected, the MALV II genetic composition changed drastically, with the detection of Clades 1, 4 (a different sub-cluster than before), 5, 6, and 12. Our results suggest that different types of parasitoids belonging to Amoebophryidae likely infect dinoflagellates in Reloncaví Fjord, offering the first demonstration of the presence of important genetic diversity in MALV II inhabiting an ecosystem where dinoflagellate hosts are not the usual dominant phytoplanktonic organisms.

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“…In the northern area of the Chilean fjords (41 to 48°S), PP and chlorophyll a (chl a) ranged from 1 to 26 mgC m -3 h -1 and from 1 to 12 mg chl a m -3 respectively (Pizarro et al 2000, Iriarte et al 2007). In addition, reports have shown that pico-and nanophytoplankton are dominant in the Strait of Magellan (53°S) after the spring bloom, whereas microphytoplankton contributes the bulk (> 50%) of the pigment biomass in spring (Iriarte et al 2001). Since spring blooms in middle and high latitude coastal regions play a pivotal role in carbon flows and ecosystem functioning (Tian et al 2001), a better comprehension of the fate of PP is needed.…”

Section: Introductionmentioning

confidence: 99%

Primary production and plankton dynamics in the Reloncaví Fjord and the Interior Sea of Chiloé, Northern Patagonia, Chile

González

Calderón²,

Castro³

et al. 2010

Mar. Ecol. Prog. Ser.

117

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), respectively, from winter to spring. In addition, the bacterial secondary production to primary production (BSP:PP) ratio decreased from 3.7 to 0.2 in Reloncaví Fjord, suggesting a transition from microbial to classical pelagic food webs. The higher solar radiation and extended photoperiod of springtime promoted the growth of diatoms in a nutrient-replete water column. Allochthonous (river discharge) and autochthonous (phytoplankton exudates) organic matter maintained high year-round bacteria biomass and secondary production. In spring, grazing pressure from zooplankton on the microplankton (largely diatoms) resulted in the relative dominance of the classical food web, with increased export production of zooplankton faecal pellets and ungrazed diatoms. Conversely, in winter, zooplankton grazing, mainly on nanoplankton, resulted in a relative dominance of the microbial loop with lower export production than found in spring. Carbon fluxes and fjord-system functioning are highly variable on a seasonal basis, and both the multivorous trophic webs and the carbon export were more uncoupled from local PP than coastal areas.

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Phytoplankton biomass in the sub-Antarctic area of the Straits of Magellan (53°S), Chile during spring-summer 1997/1998

Cited by 45 publications

References 0 publications

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

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

Infection dynamics of Amoebophryidae parasitoids on harmful dinoflagellates in a southern Chilean fjord dominated by diatoms

Primary production and plankton dynamics in the Reloncaví Fjord and the Interior Sea of Chiloé, Northern Patagonia, Chile

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