英语翻译

英语翻译
Light limiting thresholds for submerged aquatic vegetation in a blackwater river
Dean R.Dobberfuhl
St.Johns River Water Management District,4049 Reid Street,Palatka,FL 32178,United States
Received 19 January 2006; received in revised form 16 November 2006; accepted 3 January 2007
Abstract
Field-based monitoring data were used to estimate the limiting light threshold for Vallisneria americana,the dominant species,in the St.Johns River,Florida.There was a considerable range of threshold estimates (0.5–35% of surface light) among individual observations.Light threshold calculations were divided into low- and high-salinity groups of sites.The field-based mean threshold for 1998–2004 was 9% for low-salinity (0.5 ppt annual mean) had a higher mean light threshold of 14%.A separate analysis of the freshwater Crescent Lake suggested a light threshold of 9%.Increased epiphyte biomass during the drought may have accounted for the majority of the higher light requirements in the freshwater reach of the river.Light requirement values in this study were similar to other studies focusing on V.americana.
# 2007 Elsevier B.V.All rights reserved.
Keywords:Vallisneria americana; Minimum light threshold; Salinity effect; Epiphyte burden; Drought