Changes to the structure and productivity of a Posidonia sinuosa meadow during and after imposed shading

Gordon, D.; Grey, K.A.; Chase, S.C.; Simpson, Carl

doi:10.1016/0304-3770(94)90057-4

Cited by 86 publications

(66 citation statements)

References 13 publications

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“…This is in agreement with the hypothesis that smaller seagrasses are less able to survive adverse conditions than larger ones, because the latter have more extensive rhizome systems which allow more carbohydrates to be stored (Onuf, 1996;Brun et al, 2003). Reported survival times of seagrasses under light deprivation vary widely from as short as two weeks (Zostera marina, no light, Cabello-Pasini et al, 2002) to 24 months (Posidonia sinuosa, 10% of surface irradiance, Gordon et al, 1994). Studies where plants were subjected to (near) darkness showed that the dark incubation period tested here is the longest reported for a seagrass so far (Table 3).…”

Section: Growth Rates and Biochemical Compositionmentioning

confidence: 72%

Recovery of <i>Cymodocea nodosa</i> (Ucria) Ascherson photosynthesis after a four-month dark period

Malta¹,

Brun²,

Vergara³

et al. 2006

Sci. Mar.

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SUMMARY: Cymodocea nodosa plants were dark incubated for four months. The potential of reactivating photosynthesis was tested in an experiment in which half of the plants were reilluminated (HL) while the other half were grown under very low irradiance levels (LL). Photosynthesis was measured using PAM fluorescence and tissue nutrient and carbohydrate contents were analysed. Photosynthetic efficiency (F v /F m ) in HL plants increased from 0 to 0.58, whereas LL plants remained inactive. Photosynthetic parameters also increased, resulting in a final I k of 97.5 µmol m -2 s -1. Leaf shedding led to a negative mean RGR in HL plants. Tissue C and N dropped considerably during dark incubation in both rhizomes and shoots. Starch content was nearly equal for rhizomes and shoots (4.3 mg /g DW) and was not affected by dark incubation. In contrast, sucrose content dropped from 40.0 mg /g DW to zero in shoots and from 240 to 40.0 mg /g DW in rhizomes in HL plants. We conclude that C. nodosa is capable of recovering photosynthetic activity after four months darkness, which is considerably longer than the 80 d recorded so far for a seagrass. Stored carbohydrates, more specifically sucrose, play an important role in both survival and reactivation.Keywords: Cymodocea nodosa, chlorophyll fluorescence, light, carbohydrates, survival. RESUMEN: RECUPERACIÓN FOTOSINTÉTICA DE CYMODOCEA NODOSA (UCRIA) ASCHERSON DESPUÉS UN PERIODO DE CUATRO MESES EN OSCURIDAD. -La capacidad de recuperación de la fotosíntesis se ha investigado en la fanerógama marina Cymodocea nodosa. Para ello, se diseñó un experimento en el que la mitad de las plantas se cultivaron en condiciones de luz saturante (HL) y la otra mitad en condiciones de luz muy baja (LL), tras un precultivo de 4 meses en oscuridad. Se examinó la actividad fotosintética mediante la señal de fluorescencia del PAM y se determinó el contenido interno en nutrientes y de hidratos de carbono. La eficacia fotosintética (F v /F m ) se incrementó desde 0 hasta 0,58 en las plantas de HL, mientras las plantas de LL permanecieron fotosintéticamente inactivas. Los parámetros fotosintéticos también se incrementaron, obteniéndose valores finales para I k de 97,5 µmol fotones m -2 s -1 . Las plantas de HL mostraron valores medios negativos de la tasa de crecimiento relativo, atribuible al desprendimiento de hojas. El contenido interno de carbono y nitrógeno disminuyó considerablemente durante el periodo de oscuridad tanto en la biomasa epigea como hipogea. El contenido interno en almidón permaneció constante en ambos tejidos (4,3 mg /g DW), no estando afectado por el periodo de oscuridad. El contenido interno de sacarosa mostró un patrón opuesto, disminuyendo desde 40 mg /g DW a valores cercanos a cero en haces, y en rizomas desde 240 a 40 mg /g DW, en plantas de HL. En conclusión, C. nodosa recuperó la actividad fotosintética tras 4 meses en oscuridad, un periodo considerablemente mayor al registrado anteriormente para otras especies de fanerógamas (80 días). Los carbohidratos de reserva, y más concre...

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Section: Growth Rates and Biochemical Compositionmentioning

confidence: 72%

Recovery of <i>Cymodocea nodosa</i> (Ucria) Ascherson photosynthesis after a four-month dark period

Malta¹,

Brun²,

Vergara³

et al. 2006

Sci. Mar.

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“…Since the compensation irradiance for seagrass growth is higher than for most ephemeral macroalgae (Enriquez et al 1996), such light reduction may result in a negative carbon balance. The capacity to accumulate carbohydrates in the rhizomes allows seagrasses to support brief periods of shading (Peralta et al 2002, Brun et al 2003a), but these reserves cannot impede mortality when light reduction occurs over longer time spans (Gordon et al 1994, Onuf 1996, specially in 'small' seagrasses with a low storage capacity (i.e.…”

Section: Introductionmentioning

confidence: 99%

Effect of shading by Ulva rigida canopies on growth and carbon balance of the seagrass Zostera noltii

Brun¹,

Vergara²,

Navarro³

et al. 2003

Mar. Ecol. Prog. Ser.

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The effects of macroalgae blooms on seagrasses were assessed by shading Zostera noltii Hornem. with Ulva rigida C. Agardh mats under laboratory and field conditions. In the laboratory, where there was no direct contact between U. rigida and Z. noltii, leaf, rhizome, and root elongation rates, as well as gross production, declined as a function of U. rigida layers, causing a mobilization of non-structural carbohydrates in both above-and belowground tissues to meet carbon demands. However, when shading was performed in the field, where direct contact exists between Z. noltii and U. rigida, Z. noltii responses were not proportional to the number of Ulva layers. Elongation rates and gross production were reduced by U. rigida shading, with the lowest values under 2 Ulva layers, while there were no significant differences between controls and 4 U. rigida layers. This suggests another Ulva effect occurs besides shading. To test the likely effect of dissolved organic carbon (DOC) derived from U. rigida, Z. noltii plants were cultured under light limitation with radioactive dissolved organic carbon (DO 14 C) released by U. rigida. Plants cultured under a full DO 14 C load showed a significant enhancement of growth. The DO 14 C disappeared from the culture medium during the first 4 d of culture as a linear function of external DO 14 C concentration. This was coupled to a linear increase of radioactive particulate organic carbon (PO 14 C) in aboveground tissues, while a substantial part of this PO 14 C was allocated in belowground tissues. Overall, the PO 14 C incorporated in Z. noltii plants represented ca. 20 to 25% of the DO 14 C which had disappeared. Therefore, a net transfer of DO 14 C from U. rigida to Z. noltii has been documented. Other additional possibilities, such as a light quality effect or other kind of signals (i.e. growth factors), are discussed.KEY WORDS: Eutrophication · Heterotrophic DOC uptake · Dissolved organic carbon · Seagrass · Non-structural carbohydrates · Light reduction Resale or republication not permitted without written consent of the publisher

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“…Shading due to excessive growth of epiphytes or free-living macroalgae, has been the suggested cause of major declines of Posidonia spp. in Cockburn Sound (Cambridge 1979, Cambridge et al 1986, Silberstein et al 1986, Shepherd et al 1989) and in Albany Harbours (Bastyan 1986, Gordon et al 1994 in Western Australia and around Adelaide, South Australia (Neverauskus 1987).…”

Section: Introductionmentioning

confidence: 99%

“…In addition to studies which have demonstrated correlation between reduced light and seagrass decline (Cambridge et al 1986, Silberstein et al 1986, Giesen et al 1990a, there have been some manipulative field expenments which investigated the relationships between the distribution and growth of seagrasses and light (Backman & Barilotti 1976, Congdon & McComb 1979, Dennison & Alberte 1982, 1985, Bulthuis 1983, 1984, Neverauskas 1988, Gordon et al 1994). These studies have provided evidence of causal relationships between light reduction and reduction in the growth and biomass of seagrasses.…”

Section: Introductionmentioning

confidence: 99%

Effects of prolonged shading stress on growth and survival of seagrass Posidonia australis in Jervis Bay, New South Wales, Australia

Fitzpatrick¹,

Kirkman²

1995

Mar. Ecol. Prog. Ser.

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Experimental shading reduced the light reaching a shallow Posidon~a australis meadow in Jervis Bay, New South Wales, Australia, to less than 10% of incident light. Shaded seagrass had significantly lower leaf growth rate, shoot density, shoot weight and epiphyte weight than seagrass in control plots. The structure of the epiphyte community also changed under shade as the fleshy macroalgae disappeared during the first month of shading and the leaves were dominated by encrusting invertebrates The magnitude of the decrease in shoot number and leaf growth varied among 3 experiments at different times of year. Shading in early summer had a more severe effect on the seagrass than shading at the end of summer. There was no significant recovery of P. australis in the shaded plots during 17 mo following removal of the shades.

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Changes to the structure and productivity of a Posidonia sinuosa meadow during and after imposed shading

Cited by 86 publications

References 13 publications

Recovery of <i>Cymodocea nodosa</i> (Ucria) Ascherson photosynthesis after a four-month dark period

Recovery of <i>Cymodocea nodosa</i> (Ucria) Ascherson photosynthesis after a four-month dark period

Effect of shading by Ulva rigida canopies on growth and carbon balance of the seagrass Zostera noltii

Effects of prolonged shading stress on growth and survival of seagrass Posidonia australis in Jervis Bay, New South Wales, Australia

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