The origin of a metalimnetic chrysophyte peak

The annual record of fossil pigments and zooplankton was compared with detailed contemporaneous records from two manipulated lakes from 1940 to 1986. Annually resolved sedimentary records accurately monitored known changes in plankton communities, identified periods of trophic change, and proved a powerful tool for examining long-term, complex interactions. Both Paul and Peter Lakes underwent the same three complete changes in their fish assemblages (trout, cyprinid, bass), and Peter Lake received repeated inputs of lime. Alterations in fish community composition produced long-lived changes in zooplankton communities that cascaded to the microbial level of the food web. Liming, in concert with trophic changes, caused distinctive phytoplankton dynamics in Peter Lake.Paleolimnological data recorded all major plankton dynamics known from coeval limnological data. Specifically, the sediment record showed transitions in cladoceran size structure and species composition, changes in water clarity resulting from both food web and chemical manipulations that affected vertical zonation of primary producers, and changes in absolute abundance of all algal divisions except dinoflagellates. Undegraded Chl a indicated deep blooms and, in conjunction with Chl c, fucoxanthin and P-carotene, indicated metalimnetic chrysophytes. Transient (2-3 yr) nonselective increases in sedimentation corresponded with increases in grazing rates. Isorenieratene indicated overlap of photic and anoxic zones, revealing changes in transparency and conditions for pigment preservation.

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“…3). Metalimnetic chrysophyte populations are sensitive to alterations in light penetration (Pick et al 1984).…”

Section: Resultsmentioning

confidence: 99%

“…Changes in water clarity regulate the presence of deep bloom-forming algae (Pick et al 1984) and bacteria (Brown et al 1984). These blooms are well preserved in lacustrine deposits (McIntosh 1983;Brown et al 1984).…”

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confidence: 99%

Whole‐lake experiments: The annual record of fossil pigments and zooplankton

Leavitt

Carpenter

Kitchell

1989

Limnology & Oceanography

217

146

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“…In contrast, large metalimnetic populations occur deep in the water column, tend to have simpler plankton compositions, and are sometimes dominated by a single species (e.g. Pick et al 1984). Under the latter scenario, differential losses of Chl a are reduced.…”

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confidence: 99%

Aphotic pigment degradation in the hypolimnion: Implications for sedimentation studies and paleolimnology

Leavitt

Carpenter

1990

Limnology & Oceanography

107

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Reversed‐phase high pressure liquid chromatography was used to quantify carotenoid and Chl degradation resulting from bacterial and microfaunal action during aphotic, hypolimnetic incubations of natural phytoplankton assemblages and detrital material in three lakes. Decay of carotenoids (to −0.0870 d−1) and chlorophylls (to −0.1226 d−1was potentially rapid but site‐specific. Chl a decay spanned a wide range (to −0.1226 d−1) with greatest losses in circumneutral, unstained Peter Lake and least in acidic, stained Tuesday Lake. The usefulness of Chl a as an indicator of algal sedimentation was compromised by its rapid degradation, lack of compensatory production of recognizable derivatives, and an abundance of unknown, chlorophyllous compounds. β‐carotene degraded less rapidly and variably (to −0.0167 d−1) and is a useful addition to both sedimentation and paleolimnological studies. Differences among ca rotenoids in decay pose difficulties in reconstructing accurate estimates of former algal community composition, especially dinoflagellates, whose peridinin decays rapidly (−0.0843 d−1). Changes in the relative (within‐core) abundance of individual pigments may be combined, however, with changes in Chl a : β‐carotene ratios to differentiate between periods of enhanced productivity (or pigment preservation) and changes in the vertical zonation of algal communities.

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“…During summer in temperate regions, the daily average of photon flux density (PAR) at the 1 O/ O depth is equivalent to 4 to 5 pm01 m-2 S-' of continuous light (Geider et al 1986). However, several investigations show that natural phytoplankton population~ grow and may develop an extensive biomass at the 1 % (Fee 1976, Pick et al 1984 and even lower light level (Vennck et al 1973), provided that the light climate is stable over days and weeks so that long-term shade adaptation can occur as in non-mixed depth strata of a stabilized water column (Richardson et al 1983). Recent laboratory work has shown growth of microalgae at even lower photon flux densities of 0.1 to 1 pm01 m-2 S-' (Geider et al 1985(Geider et al , 1986, and references therein) stressing that the 1 % light level should b e used as a point of reference and not as a lower limit to growth (Richardson et al 1983).…”

Section: Introductionmentioning

confidence: 99%

Minimum light requirement for growth in Ulva lactuca

Sand‐Jensen

1988

Mar. Ecol. Prog. Ser.

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Growth and photoadaptation were measured in Ulva lactuca discs kept in the laboratory at cont~nuous photon flux densities between 0 and 55 km01 m-' S-' at 7 "C. The light compensation point for growth (I,) was ca 2.5 pm01 m-'s-' and was similar to the minimum hght compensation point for photosynthesis of U. lactuca. I, corresponded to only 0.5 % of surface light In Danish waters during summer and 2 to 4 % at 7°C in autumn. Photoadaptation was regulated mainly by changes in Light absorptance and dark respiration rates whereas quantum efficiency was approximately constant. Absorptance was highest at intermedate light levels (2.5 to 8.8 pm01 m-'s-') and coincided with maximum efficiencies for growth (ca 0.024 m01 C fixed per m01 incident photon and 0.056 m01 C fixed per m01 photon absorbed). Dark respiration rates were linearly related to growth rate and doubled from low to hlgh Light accllmated plants. Respiratory maintenance costs, estimated from the carbon growth balance of non-growing U. lactuca in very weak light (<0.3 pm01 m-' S-'), were low at 0.0094 to 0.012 molC respired (m01 cell C ) -' d -' (half-life of cellular carbon = 58 to 74 d) and corresponded to the experlmentally denved values. These low maintenance costs are essential to maintain a low I, value and would also allow U lactuca to survive extended periods in the dark. The results do not conform with the previous vlew of Ulva lactuca as a classic ruderal sun species, but show a high capacity for growth In the shade.

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The origin of a metalimnetic chrysophyte peak

Abstract: A metalimnetic chlorophyll peak (40-70 pg.liter-*) in Jacks Lake, Ontario, was due primarily to a colonial chrysophyte, Chrysosphaerella longispina. The peak was not the result of in situ

Cited by 60 publications

References 21 publications

Whole‐lake experiments: The annual record of fossil pigments and zooplankton

Whole‐lake experiments: The annual record of fossil pigments and zooplankton

Aphotic pigment degradation in the hypolimnion: Implications for sedimentation studies and paleolimnology

Minimum light requirement for growth in Ulva lactuca

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