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Titolo:
ECOLOGY OF EUTROPHIC WATERBODIES IN A COASTAL GRAZING MARSH
Autore:
SAMUELS AJ; MASON CF;
Indirizzi:
UNIV ESSEX,DEPT BIOL SCI,WIVENHOE PK COLCHESTER CO4 3SQ ESSEX ENGLAND
Titolo Testata:
Hydrobiologia
, volume: 346, anno: 1997,
pagine: 203 - 214
SICI:
0018-8158(1997)346:<203:EOEWIA>2.0.ZU;2-M
Fonte:
ISI
Lingua:
ENG
Keywords:
COASTAL GRAZING MARSH; EUTROPHICATION; NUTRIENTS; PLANKTON;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
16
Recensione:
Indirizzi per estratti:
Citazione:
A.J. Samuels e C.F. Mason, "ECOLOGY OF EUTROPHIC WATERBODIES IN A COASTAL GRAZING MARSH", Hydrobiologia, 346, 1997, pp. 203-214

Abstract

The ecology of a mainly interconnected, complex system of small waterbodies on a coastal grazing marsh in the Greater Thames estuary, north-east of London, England, is described. Sixteen sites were sampled on a regular basis over a two-year period while 37 sites were sampled once in May to develop a site classification. Most sites were brackish and alkaline but, following re-wetting after drying out, the pH in some waterbodies decreased sharply (minimum pH 2.7). All sites had high concentrations of phosphorus but there were large differences; some, withgood growths of submerged aquatic macrophytes, having lower phosphorus than other sites, which were devoid of macrophytes. Internal loadingwith phosphorus was important. Nitrate levels were low. Waters were mostly turbid, Secchi depths sometimes falling as low as 2 cm, while chlorophyll a was very high, indicating extreme hypertrophy. Diatoms andeuglenoids were characteristic members of the phytoplankton; cyanobacterial blooms did not occur. The zooplankton was dominated by copepods, while Cladocera were much less numerous, largely due to predation byshrimps in waterbodies without macrophytes. The classification of sites was influenced primarily by water depth, some waterbodies drying out, while phosphorus and turbidity were also important in differentiating sites. Animal guano is the likely cause of the hypertrophic state but livestock grazing is an essential management tool for grazing marshes. The dredging of waterbodies (with removal of sediments from the site) and the instigation of a flushing regime, requiring a new system of sluices, should reduce nutrient loading and assist the establishmentof submerged macrophytes, providing refuges for cladocerans from predation.

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Documento generato il 14/08/20 alle ore 15:33:08