Diel abundance and productivity patterns of autotrophic picoplankton in the lower Chesapeake Bay

Affronti, Lewis F.; Marshall, Harold G.

doi:10.1093/plankt/15.1.1

Cited by 21 publications

(16 citation statements)

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“…Net changes in PCY biomass were also found by others to be low, despite growth rates in the order of 1 division per day (Liu et al 1995, Olsen et al 2006. μ in our study were lower than those reported by Affronti & Marshall (1994), but in agreement with the average specific growth rate of 0.41 d -1 found by Lavallée & Pick (2002). Most literature values of μ are from temperate and subtropical regions, where average sea temperatures are higher than 12°C (ambient temperature during the present study).…”

Section: Biomass and Growth Rates Of Picocyanobacteriasupporting

confidence: 85%

Trophic cascades mediated by copepods, not nutrient supply rate, determine the development of picocyanobacteria

Sundt-Hansen¹,

Ôlsen²,

Stibor³

et al. 2006

Aquat. Microb. Ecol.

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We studied the effect of nutrient supply rate (resources) and concentrations of copepods (top predator) on picocyanbacteria (PCY) in experimental ecosystems (mesocosms) using gradients of both nutrients and predators. The biomass and production of PCY, and the biomass and predation rates of their predators were determined by epifluorescence microscopy, X-ray microanalysis (XRMA), the 14 C method, and cell counting by microscopy. PCY biomass did not change significantly with increased supply of nutrients, but it was positively correlated with copepod biomass. A lack of variation in PCY growth rates, and nutrient saturation of cells as suggested by nutrient analysis and XRMA measurements, indicate that PCY grew close to their maximum growth rate during the experiment. Appendicularia and ciliates were the main predators on PCY when copepod biomass was normal or low, whereas heterotrophic nanoflagellates were significant predators on PCY when copepod biomass was high. Based on a negative effect of copepod biomass on the biomass of PCY predators, we conclude that predation had a stronger effect on the development of PCY than did nutrient supply rate. The only effect of nutrient supply was negative and indirect, implemented through stimulation of predatory ciliates. Copepods had a profound effect by structuring the food web, and thus directly and indirectly regulating the abundances of predators of PCY (top-down control). Therefore, copepods indirectly controlled the abundance of PCY through trophic cascades.

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Section: Biomass and Growth Rates Of Picocyanobacteriasupporting

confidence: 85%

Trophic cascades mediated by copepods, not nutrient supply rate, determine the development of picocyanobacteria

Sundt-Hansen¹,

Ôlsen²,

Stibor³

et al. 2006

Aquat. Microb. Ecol.

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“…The vertical distribution of picophytoplankton also varies considerably, with surface maxima (e.g., Waterbury et al 1979;Hall & Vincent 1990;Affronti & Marshall 1993), subsurface maxima (e.g., Takahashi & Hori 1984;Murphy & Haugen 1985), and uniform distributions (e.g., Olson et al 1990) having been reported. In this study 12 out of 14 profile stations had the maximum picophytoplankton concentrations within the mixed layer.…”

Section: Discussionmentioning

confidence: 99%

Vertical and horizontal structure of the picophytoplankton community in a stratified coastal system off New Zealand

Hall

Vincent

1994

New Zealand Journal of Marine and Freshwater Research

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“…Most of the published studies concern phycoerythrin-rich cyanobacteria (Waterbury et al 1979, Glover et al 1986), which are ubiquitous and dominant. There are few data on the phycocyanin-rich group, which seems to be confined Aquat hlicrob Ecol 10: 149-163, 1996 --p p ---mainly to estuaries (Campbell et al 1983, Affronti & Marshall 1992, or on small eucaryotes. Procaryotes are generally more abundant in coastal waters than offshore (Xltlrphy & Haugen 1985, Olson et al 1.990) and also at low latitudes where water temperature is high (Murphy & Haugen 1985) Their range of abundance is 1 order of m a g n~t u d e larger than that of eucaryotes (Glover et al 1985, Joint 19861, especially in coastal waters.…”

Section: Introductionmentioning

confidence: 99%

Dynamics of size-fractionated phytoplankton and trophic pathways on the Scotian Shelf and at the shelf break, Northwest Atlantic

Mousseau¹,

Legendre²,

Fortier³

1996

Aquat. Microb. Ecol.

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Composition of ultraplankton ( c 5 pm) and of biomass and primary production of size-fractionated phytoplankton (<5 or > S pm) were determined during 1 yr at 2 stations off Nova Scotia, eastern Canada. Water temperature was a major factor regulating the abundance of ultraplankton cells, whereas nutrient concentrations and irradiance mainly controlled the relative proportions of procaryotes to eucaryotes. Procaryotes (mainly phycoerythrin-rich cyanobacteria) clearly dominated the ultraplankton throughout the year. Eucaryotes were more severely affected by low nutrient concentrations and high irradiances than procaryotes. The study indicates that ultraplankton assemblages were highly dynamic, with succession among groups in response to seasonal variations in environmental conditions. The spring bloom was dominated by large phytoplankton and ended upon exhaustion of nitrate and silicate. During the remainder of the year, nutrient concentrations were low (although non-limiting) and ultraplankton were the main primary producers. In summer, sporadically enhanced production of large phytoplankton was likely caused by inputs of nutrients and seeding of the euphotic zone by local vertical mixing. This mechanism was effective at the shallow shelf station only. The size structure of the grazer assemblage controlled the fate of primary production, i.e. sinking to depth or export to higher trophic levels. Hence, primary production and standing stock were controlled by bottom-up (nutrient input and seeding of the euphotic zone) and top-down (grazlng pressure by micro-or mesozooplankton) processes, respectively. Interactions between these processes determined the nature of the trophic web in the euphotic zone. Differences in hydrodynamics and grazer communities between the 2 sampling sites led to the following model: (1) at the 2 sites, year round, there was a microbial food web, in quasi-steady state; (2) on the shelf, year round, herbivorous and microbial components coex~sted, leading to efficient transfer from large and small phytoplankton to large metazoans; and ( 3 ) at the shelf break, because of scarcity of mesozooplankton, the microbial food web dominated year round and most of the large spring-bloom phytoplankton could be lost to sedimentation.

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Diel abundance and productivity patterns of autotrophic picoplankton in the lower Chesapeake Bay

Cited by 21 publications

References 0 publications

Trophic cascades mediated by copepods, not nutrient supply rate, determine the development of picocyanobacteria

Trophic cascades mediated by copepods, not nutrient supply rate, determine the development of picocyanobacteria

Vertical and horizontal structure of the picophytoplankton community in a stratified coastal system off New Zealand

Dynamics of size-fractionated phytoplankton and trophic pathways on the Scotian Shelf and at the shelf break, Northwest Atlantic

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