Diel oscillations of the photosynthesis-irradiance (P-I) relationship in natural assemblages of phytoplankton

Harding, Lawrence W.; Prézelin, Barbara B.; Sweeney, Beatrice M.; Cox, James L.

doi:10.1007/bf00401282

Cited by 93 publications

(61 citation statements)

References 37 publications

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“…Taguchi, 1976;Platt et al, 1980) or in the afternoon (e.g. Harding et al, 1982;PreH zelin et al, 1987). Diel variability in photosynthesis appears to be regulated by complex interactions between photoperiod, cell nutritional status and taxonomical composition of the microalgal assemblages, and therefore it is di$cult to assess the extent to which it has a!ected our productivity estimates.…”

Section: Phytoplankton Growth In the Oligotrophic Regionsmentioning

confidence: 99%

Basin-scale variability of phytoplankton biomass, production and growth in the Atlantic Ocean

Marañón

Holligan

Varela

et al. 2000

Deep Sea Research Part I: Oceanographic Research Papers

199

157

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The latitudinal distributions of phytoplankton biomass, composition and production in the Atlantic Ocean were determined along a 10,000-km transect from 503N to 503S in October 1995, May 1996 and October 1996. Highest levels of euphotic layer-integrated chlorophyll a (Chl a) concentration (75}125 mg Chl m\ ) were found in North Atlantic temperate waters and in the upwelling region o! NW Africa, whereas typical Chl a concentrations in oligotrophic waters ranged from 20 to 40 mg Chl m\ . The estimated concentration of surface phytoplankton carbon (C) biomass was 5}15 mg C m\ in the oligotrophic regions and increased over 40 mg C m\ in richer areas. The deep chlorophyll maximum did not seem to constitute a biomass or productivity maximum, but resulted mainly from an increase in the Chl a to C ratio and represented a relatively small contribution to total integrated productivity. Primary production rates varied from 50 mg C m\ d\ at the central gyres to 500}1000 mg C m\ d\ in upwelling and higher latitude regions, where faster growth rates ( ) of phytoplankton ( '0.5 d\ ) were also measured. In oligotrophic waters, microalgal growth was consistently slow [surface averaged 0.21$0.02 d\ (mean$SE)], representing (20% of maximum expected growth. These results argue against the view that the subtropical gyres are characterized by high phytoplankton turnover rates. The latitudinal variations in were inversely correlated to the changes in the depth of the nitracline and positively correlated to those of the integrated nitrate concentration, supporting the case for the role of nutrients in controlling the large-scale distribution of phytoplankton growth rates. We observed a large degree of temporal 0967-0637/00/$ -see front matter 2000 Elsevier Science Ltd. All rights reserved. PII: S 0 9 6 7 -0 6 3 7 ( 9 9 ) 0 0 0 8 7 -4 variability in the phytoplankton dynamics in the oligotrophic regions: productivity and growth rates varied in excess of 8-fold, whereas microalgal biomass remained relatively constant. The observed spatial and temporal variability in the biomass speci"c rate of photosynthesis is at least three times larger than currently assumed in most satellite-based models of global productivity.

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Section: Phytoplankton Growth In the Oligotrophic Regionsmentioning

confidence: 99%

Basin-scale variability of phytoplankton biomass, production and growth in the Atlantic Ocean

Marañón

Holligan

Varela

et al. 2000

Deep Sea Research Part I: Oceanographic Research Papers

199

157

View full text Add to dashboard Cite

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“…A variação nictemeral da fotossíntese pode influir decisivamente sobre dois eventos de significância concernente a um ecossistema aquático: 1) sobre a determinação da produção primária quando se considerar a amplitude do ritmo, assim como o período do dia escolhido para conduzir as medidas da produção primária afetando, por conseguinte, os cálculos da mesma; 2) com relação à amplitude e/ou fase do ritmo da fotossíntese, poder refletir também o estado fisiológico e, em particular o status do fitoplâncton em relação aos nutrientes (Harding et al, 1982).…”

Section: Contr N(l 723 Dounclassified

Variação nictemeral da clorofila α, produção primária do fitoplâncton e fatores ambientais da região de Ubatuba (Lat. 23º30'S Long. 45º06'W)

Teixeira

Gaeta

1991

Bol. Inst. Oceanogr.

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• Abstract: A series of experiments with natural phytoplankton populations was carried out to study the diel variation of chlrophyll a, primary production and some environmental factors. Samples were collected from surface over a period of 24 hours and always from one fixed station located in Flamengo Inlet, Ubatuba region, southem Brazil The experiments were performed in situ and simulated conditions to verify the patterns of diel cycies of both biotic and abiotic factors; The results obtained showed that diel variations were markedly pronounced mainly in relation to primary production and chlorophyll a. Diel variations of biological factors seems to be due to exogenous and endogenous phenomena.• DeScriptoTS: Photosynthesis, Chlorophyll a, Diel variation, Primary production, Environmental conditions, Ubatuba: SP.• DescritoTes: Fotossíntese, CloroIDa a, Variação nictemeral, Produção primária, Fatores ambientais, Ubatuba: SP. IntroduçãoUm dos aspectos fundamentais para a obtenção de dados sobre a produção primária de um ecossistema marinho com maior acurácia e de alto significado para a confecção de modelos, refere-se aos conhecimentos obtidos a partir dos estudos e da determinação da periodicidade nictemeral (atividades cíclicas de 24 h compreendidas pelo dia e noite), não só do fúoplâncton, como também das características ambientais. Os ritmos biológicos caracterizam-se pela recorrência, a intervalos regulares, de eventos bioquímicos, fisiológicos e comportamentais (Aschoff, 1981).Desde o trabálho de Doty & Oguri (1957), sugerindo a existência do ritmo nictemeral na atividade fotossintética do fitoplâncton marinho, têm sido ápresentados inúmeros estudos de campo e de laboratório, documentando o fenômeno. V árias pesquisas têm demonstrado que a capacidade fotossintética (F max) assim como a eficiência fotossintética (a) do fitoplâncton natural variam durante o dia geralmente com valores máximos e com valores mínimos ocorrendo a noite (Gargas et al., 1979; Prezelin & Ley, 1980; Teixeira, 1980;1982, etc.). Muito embora seja reconhecido e) Professor Associado do Centro de Biologia Marinha -USP. Contr. n(lque as oscilações nictemerais periódicas da capacidade fotossintética sejam em parte controladas pelo "relógio biológico" da célula (Hastingset al., 1961, etc.), os fatores ambientais podem também alterar significativamente a natureza deste ritmo.A variação nictemeral da fotossíntese pode influir decisivamente sobre dois eventos de significância concernente a um ecossistema aquático: 1) sobre a determinação da produção primária quando se considerar a amplitude do ritmo, assim como o período do dia escolhido para conduzir as medidas da produção primária afetando, por conseguinte, os cálculos da mesma; 2) com relação à amplitude e/ou fase do ritmo da fotossíntese, poder refletir também o estado fisiológico e, em particular o status do fitoplâncton em relação aos nutrientes (Harding et al., 1982).O desenvolvimento deste trabalho objetiva determinar o comportamento das populações naturais do fúoplâncton em termos das ...

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“…m '~. h " ) dépend de la biomasse de phytoplancton présente (B, = mg C H L~.~.~) et du flux de photons transmis (Iz) selon une relation de la forme (Talling, 1957 ;Vollenweider, 1965 ;Fee, 1973) : (1) Les valeurs de P' max et de cxB qui caractérisent l'activité photosynthétique du phytoplancton de Pareloup se situent dans la gamme des valeurs correspondant au phytoplancton de lacs de différents statuts trophiques (p. ex Williams, 1978;Gelin & Rippl, 1978 ;Fee et al, 1987) ; elles sont par contre très nettement infé-rieures aux valeurs publiées pour le phytoplancton marin (Platt & Jassby, 1976 ;Harding et al, 1982;Coté & Platt, 1983; Bannister & Weideman, 1 984).…”

Section: Relations Photosynthèse-lumièreunclassified

“…Plusieurs travaux (Platt & Jassby, 1976 ; Harding et al, 1982;Coté & Platt, 1983 ;Fee et al 1987 (3) La capacité photosynthétique optimale (pB max) est inversement corrélée à la biomasse de phytoplancton ( fig. 5).…”

Section: Relations Photosynthèse-lumièreunclassified

Production du phytoplancton et du bactérioplancton dans le lac de retenue de Pareloup

1994

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Résumé. -La biomasse et la production du phytoplancton ont été étudiées parallèlement à la biomasse et à la production du bactérioplancton hétérotrophe dans le réservoir de Pareloup. Les productions phytoplanctoniques et bactériennes ont été respectivement mesurées à partir des taux d'incorporation de 14C bicarbonate et de % thymidine.Au cours de l'année, la moyenne des concentrations en chlorophylle a dans la zone euphotique varie de 2 mg.m-3 (juin-août) à 20 mg.m-3 (printemps). La production brute moyenne annuelle du phytoplancton est d'environ 80-85 g C.m*, valeur typique des lacs oligo-mésotrophes. La transparence de l'eau et les paramètres de la relation photosynthèse-lumière (PB max, c/.') sont inversement corrélés à la biomasse du phytoplancton de sorte que les effets antagonistes des variations de biomasse et d'irradiance journalière se compensent en partie. La comparaison des taux d'assimilation du C et des taux de variation de biomasse phytoplanctonique indique un couplage étroit entre les processus de fixation et de perte de carbone. Au cours d'un cycle nycthéméral, les pertes moyennes par respiration représenteraient de 33% à 82% du C incorporé selon les rapports RB/PB max appliqués (0,03 à 0,l pour les diatomées; 0,07 à 0,15 pour le phytoplancton estival).Sur toute la colonne d'eau, la densité des bactéries planctoniques varie de 2,3.109 a 4,6.109 cellules.l~', et la biomasse carbonée de 37 à 68 pg C.1.'. Les taux d'incorporation de thymidine tritiée dans le précipité TCA froid varient de 0,8 à 17,2 picomoles.l-'.h-' ; ils correspondent à une production bactérienne nette inférieure à 0,2 yg C.1-'.j-' en hiver et supérieure à 4,5 pg C.1-'.j-' en été; environ 55% de la production a lieu dans la zone euphotique. La production bactérienne brute représente 7% de la production photosynthétique brute au printemps et plus de 70% à la fin de l'été. Au cours d'un cycle annuel et en considérant l'ensemble du lac, le carbone nécessaire à la production bactérienne représente environ 113 de la production brute autotrophe.Mot-clés. -Phytoplancton, production primaire, bactérioplancton, production secondaire. J. Capblancq et al.Abstract. -Biomass and primary production of phytoplankton were cornpared with biomass and production of heterotrophic bacterioplankton in the reservoir of Pareloup. Phytoplankton and bacterioplankton productions were estimated from 14C bicarbonate and 3H thymidine incorporation rates respectively. Over the year, mean euphotic zone concentrations of chlorophyll a ranged from 2 mg.ma (june-august) to 20 mg.m~3 (spring diatom bloom). Gross annual phytoplankton production was about 80-85 g C.m-', a value typical for slightly meso-eutrophic lakes. Water transparency and parameters of the photosynthesis-irradiance relationship (PB max, clB) were inversely correlated with phytoplankton biomass; accordingly, the effects of seasonal variations of biomass and mean daily radiance fluxes on integral photosynthesis can to a significant extent be compensated for. Comparison of carbon fixation rates and a...

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Diel oscillations of the photosynthesis-irradiance (P-I) relationship in natural assemblages of phytoplankton

Cited by 93 publications

References 37 publications

Basin-scale variability of phytoplankton biomass, production and growth in the Atlantic Ocean

Basin-scale variability of phytoplankton biomass, production and growth in the Atlantic Ocean

Variação nictemeral da clorofila α, produção primária do fitoplâncton e fatores ambientais da região de Ubatuba (Lat. 23º30'S Long. 45º06'W)

Production du phytoplancton et du bactérioplancton dans le lac de retenue de Pareloup

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