Data

The Measurement of Seagrass Photosynthesis Using PAM Fluorometry - Comparison of photosynthetic rates and meadow characteristics of two 'visually' different meadows

Australian Ocean Data Network
Horn, Lotte, Dr
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ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rfr_id=info%3Asid%2FANDS&rft_id=https://catalogue.aodn.org.au:443/geonetwork/srv/api/records/afeaf560-4a37-11dc-85e1-00188b4c0af8&rft.title=The Measurement of Seagrass Photosynthesis Using PAM Fluorometry - Comparison of photosynthetic rates and meadow characteristics of two 'visually' different meadows&rft.identifier=https://catalogue.aodn.org.au:443/geonetwork/srv/api/records/afeaf560-4a37-11dc-85e1-00188b4c0af8&rft.description=Two sites with apparent differences, west and east Mangles Bay, Cockburn Sound, W.A., on 4 June 2005 were examined in terms of seagrass photosynthetic activity and meadow characteristics. Variables measured include maximum electron transport rate, effective quantum yield, potential quantum yield, canopy height, shoot density, leaf area index, epiphyte biomass and sediment grain size.Maintenance and Update Frequency: notPlannedStatement: - Chlorophyll fluorescence measurements - The sites selected (Mangles Bay West and East) are shown in the large thumbnail. The east site was approximately 120 m from the beach in 1.8 m of water. Visual examination revealed the meadow was patchy with clumps of seagrasses and epiphytes at this site appeared thick and smothering, although easily removed by hand. The west site was directly exposed to the Indian Ocean and was approximately 20 - 30 m from the beach in 2.6 m of water. Visual examination suggested a thicker meadow than the east site. The epiphytes appeared less dense although harder to remove than at the east site. Dark-acclimated potential quantum yield (six minutes dark-acclimation), light-acclimated effective quantum yield and RLCs (rapid light curve) were carried out as described in section 4.2.1 of thesis on 4 June 2005 between 0940 and 1330 h. Visible epiphytic growth at the measurement sites was easily removed by rubbing the leaf with a finger. Ten replicate measurements of potential quantum yield and eight replicate measurements of effective quantum yield and ETR (RLCs) were made on seperate leaves at each site.Statement: - Meadow characteristics - Canopy height Ten replicate canopy height measurements were made randomly within 5 m of the sampling site, measuring the minimum and maximum canopy height under the prevailing conditions. These were averaged to give canopy height. Shoot density Shoot counts (shoots per m2) were carried out for nine replicate 25 x 25 cm quadrats to determine shoot density. Leaf area index The leaf area index was calculated after clearing a 25 cm x 25 cm quadrat. Leaf length and width (base, middle and tip) were measured. Leaf area index (m2 leaf m-2 ground area) was calculated as the product of the average shoot area (length x width) and the shoot density, and was doubled to allow for both sides of the leaf. Epiphyte biomass Ten replicate leaves were arbitrarily selected to determine the epiphyte biomass (mg dw cm-2 leaf area) and to examine this in terms of base and tip epiphyte loading. Leaves were divided into base (15 cm from leaf sheath) sections, because reading of photosynthetic rates were measured at the base of the leaves. All visible epiphytes were scraped off with a razor blade and oven-dried at 80 degrees Celsius for 24 h to determine epiphyte fry weight cm-2 leaf area. Sediment grain size Five replicate surface sediment samples were collected to compare sediment grain size at each site. The sediment samples were oven-dried at 80 degrees Celsius for 48 h before grading into seven categories (greater than 2 mm to less than 0.063 mm), using a mechanical shaker for fifteen minutes and standard laboratory sieves (Endecotts Ltd London, England: 2 mm, 1 mm, 0.5 mm, 0.25 mm, 0.125 mm, >0.063 mm and &rft.creator=Horn, Lotte, Dr &rft.date=2007&rft.coverage=westlimit=115.69; southlimit=-32.28; eastlimit=115.71; northlimit=-32.26&rft.coverage=westlimit=115.69; southlimit=-32.28; eastlimit=115.71; northlimit=-32.26&rft.coverage=uplimit=3; downlimit=1&rft.coverage=uplimit=3; downlimit=1&rft_rights=Photographs in thumbnail are not to be used without author's permission&rft_subject=oceans&rft_subject=Oceans | Marine Biology | Marine Plants&rft_subject=PHOTOSYNTHESIS&rft_subject=EARTH SCIENCE&rft_subject=BIOSPHERE&rft_subject=ECOLOGICAL DYNAMICS&rft_subject=ECOSYSTEM FUNCTIONS&rft_subject=Seagrass&rft_subject=Posidonia australis&rft_subject=63 617002&rft_subject=Posidonia sinuosa&rft_subject=63 617003&rft_subject=Halophila ovalis&rft_subject=63 605002&rft_subject=Chlorophyll fluorescence&rft_subject=Canopy height&rft_subject=Shoot density&rft_subject=Leaf area index&rft_subject=Epiphyte biomass&rft_subject=Sediment grain size&rft.type=dataset&rft.language=English Access the data
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Brief description

Two sites with apparent differences, west and east Mangles Bay, Cockburn Sound, W.A., on 4 June 2005 were examined in terms of seagrass photosynthetic activity and meadow characteristics. Variables measured include maximum electron transport rate, effective quantum yield, potential quantum yield, canopy height, shoot density, leaf area index, epiphyte biomass and sediment grain size.

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Maintenance and Update Frequency: notPlanned
Statement: - Chlorophyll fluorescence measurements - The sites selected (Mangles Bay West and East) are shown in the large thumbnail. The east site was approximately 120 m from the beach in 1.8 m of water. Visual examination revealed the meadow was patchy with clumps of seagrasses and epiphytes at this site appeared thick and smothering, although easily removed by hand. The west site was directly exposed to the Indian Ocean and was approximately 20 - 30 m from the beach in 2.6 m of water. Visual examination suggested a thicker meadow than the east site. The epiphytes appeared less dense although harder to remove than at the east site. Dark-acclimated potential quantum yield (six minutes dark-acclimation), light-acclimated effective quantum yield and RLCs (rapid light curve) were carried out as described in section 4.2.1 of thesis on 4 June 2005 between 0940 and 1330 h. Visible epiphytic growth at the measurement sites was easily removed by rubbing the leaf with a finger. Ten replicate measurements of potential quantum yield and eight replicate measurements of effective quantum yield and ETR (RLCs) were made on seperate leaves at each site.
Statement: - Meadow characteristics - Canopy height Ten replicate canopy height measurements were made randomly within 5 m of the sampling site, measuring the minimum and maximum canopy height under the prevailing conditions. These were averaged to give canopy height. Shoot density Shoot counts (shoots per m2) were carried out for nine replicate 25 x 25 cm quadrats to determine shoot density. Leaf area index The leaf area index was calculated after clearing a 25 cm x 25 cm quadrat. Leaf length and width (base, middle and tip) were measured. Leaf area index (m2 leaf m-2 ground area) was calculated as the product of the average shoot area (length x width) and the shoot density, and was doubled to allow for both sides of the leaf. Epiphyte biomass Ten replicate leaves were arbitrarily selected to determine the epiphyte biomass (mg dw cm-2 leaf area) and to examine this in terms of base and tip epiphyte loading. Leaves were divided into base (<=15 cm from leaf sheath) and tip (>15 cm from leaf sheath) sections, because reading of photosynthetic rates were measured at the base of the leaves. All visible epiphytes were scraped off with a razor blade and oven-dried at 80 degrees Celsius for 24 h to determine epiphyte fry weight cm-2 leaf area. Sediment grain size Five replicate surface sediment samples were collected to compare sediment grain size at each site. The sediment samples were oven-dried at 80 degrees Celsius for 48 h before grading into seven categories (greater than 2 mm to less than 0.063 mm), using a mechanical shaker for fifteen minutes and standard laboratory sieves (Endecotts Ltd London, England: 2 mm, 1 mm, 0.5 mm, 0.25 mm, 0.125 mm, >0.063 mm and <0.063 mm). Each fraction was weighed enabling a size fraction distribution to be calculated.

Notes

Purpose
To determine whether "visual" appearance can be used to determine whether a seagrass meadow is "healthy" or "unhealthy".

Created: 10 08 2007

Data time period: 2005-06-04 to 2005-06-04

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115.71,-32.26 115.71,-32.28 115.69,-32.28 115.69,-32.26 115.71,-32.26

115.7,-32.27

text: westlimit=115.69; southlimit=-32.28; eastlimit=115.71; northlimit=-32.26

text: uplimit=3; downlimit=1

Subjects
63 605002 | 63 617002 | 63 617003 | BIOSPHERE | Canopy height | Chlorophyll fluorescence | EARTH SCIENCE | ECOLOGICAL DYNAMICS | ECOSYSTEM FUNCTIONS | Epiphyte biomass | Halophila ovalis | Leaf area index | Oceans | Marine Biology | Marine Plants | Photosynthesis | Posidonia australis | Posidonia sinuosa | Seagrass | Sediment grain size | Shoot density | oceans |

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global : be3a7d90-46ed-11dc-9f4a-00188b4c0af8

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  • global : afeaf560-4a37-11dc-85e1-00188b4c0af8