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Titolo:
A Halodule-dominated community in a subtropical embayment: physical environment, productivity, biomass, and impact of dugong grazing
Autore:
Masini, RJ; Anderson, PK; McComb, AJ;
Indirizzi:
Univ Calgary, Dept Biol Sci, Calgary, AB T2N 1N4, Canada Univ Calgary Calgary AB Canada T2N 1N4 l Sci, Calgary, AB T2N 1N4, Canada Dept Environm Protect, Perth, WA 6000, Australia Dept Environm Protect Perth WA Australia 6000 , Perth, WA 6000, Australia Murdoch Univ, Inst Environm Sci, Perth, WA 6150, Australia Murdoch Univ Perth WA Australia 6150 ironm Sci, Perth, WA 6150, Australia
Titolo Testata:
AQUATIC BOTANY
fascicolo: 3, volume: 71, anno: 2001,
pagine: 179 - 197
SICI:
0304-3770(200111)71:3<179:AHCIAS>2.0.ZU;2-H
Fonte:
ISI
Lingua:
ENG
Soggetto:
SEAGRASS HALOPHILA-OVALIS; PAPUA-NEW-GUINEA; SHARK BAY; WESTERN-AUSTRALIA; QUEENSLAND; ABUNDANCE; HABITATS;
Keywords:
seagrass; Halodule; Penicillus; Dugong; Australia; temperature; salinity; biomass; productivity; herbivore impact;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Agriculture,Biology & Environmental Sciences
Citazioni:
42
Recensione:
Indirizzi per estratti:
Indirizzo: Anderson, PK Univ Calgary, Dept Biol Sci, 2500 Univ Dr 1 NW, Calgary, AB T2N 1N4, Canada Univ Calgary 2500 Univ Dr 1 NW Calgary AB Canada T2N 1N4 nada
Citazione:
R.J. Masini et al., "A Halodule-dominated community in a subtropical embayment: physical environment, productivity, biomass, and impact of dugong grazing", AQUATIC BOT, 71(3), 2001, pp. 179-197

Abstract

Physical variables, standing crop and dugong activity were monitored over 14 months in a subtidal community dominated by the tropical seagrass Halodule uninervis and the green alga Penicillus nodulosus in a small cove in subtropical Shark Bay, Western Australia. Water temperature ranged from 14.5 (June) to 30.5 degreesC (February), salinity from 48 (August) to 62 parts per thousand (March). Attenuation coefficients were 0.18-0.32 m(-1) in February and 0.10 m(-1) in June. Mean daily PAR at the sea bed was 200 mu mol m(-2) s(-1) in September and 400 mu mol m(-2) s(-1) in January. Visually, Halodule appeared dominant, but Penicillus biomass exceeded Halodule biomass byapproximate to3% on ridges and averaged approximate to nine times higher in gullies. Total Halodule biomass on ridges was 46.5 g m(-2) in May and 69.8 g m(-2) in March, rhizome biomass (40-65 g dry weight m(-2)) was four to six times leaf biomass (7-16 g dry weight m(-2)). Productivity on the ridges, measured over 4-6 week intervals was 0.12 g dry weight m(-2) per day in August-October and 1.56 g dry weight m(-2) per day in March-April. Growth persisted throughout the year, and was not limited to temperatures of greater than or equal to 21 degreesC. Productivity was estimated as 295 g dry weight m(-2) per year. The plastochrone interval in productivity did not coincide with peak insolation, but did coincide with high temperatures and high and continuous dugong activity. Statistical analysis indicated that light and temperature influenced leaf productivity more than they did rhizome, root, or total productivity. Dugongs (Dugong dugon) rooted in the community from January through April, raising levels of suspended sediments and attenuation coefficients and reducing PAR. Halodule biomass in dugong exclosures at the end of the grazing season was 1.8 times that in adjacent unprotected areas. Dugongs departed when autumn temperatures fell below 19 degreesC. During the grazing season loss of biomass resulting from dugong activity exceeded 50% of production. (C) 2001 Elsevier Science B.V. All rights reserved.

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Documento generato il 05/04/20 alle ore 21:22:37