able to withstand 2 to 10 cm of oil with only slight, short-term, 

 floral composition changes. Apparently, most of the toxic fractions 

 had been lost from the Torrey Canyon oil, since it had been weathered 

 at sea for 2 to 18 days. Stebbings noted that oil appeared to form an 

 impervious layer on the substrate preventing gaseous interchange 

 between soil and air, causing reducing conditions in the mud, and 

 ultimately chlorotic symptoms in plants. Stands of Agropyron pungens 

 (Pers. ) R. and S. , Festuca rubra L. , Juncus maritimus Lam., and 

 Scirpus maritimus L. were extremely vigorous and seemed to derive some 

 nutritional benefit from the breakdown products of this Torrey Canyon 

 oil. Cowell and Baker (1969) noted that populations of annuals such as 

 Suaeda maritima (L. ) Dum. and Salicornia spp. near Pembroke, Southwest 

 Wales, were reduced initially but were recovering a year after oiling 

 from the Chryssi P. Goulandris. Halimione portulacoides (L.) Aell. was 

 the plant most badly damaged. In June 1968 the plant species with the 

 greatest coverage in the upper, middle, and lower marsh ( Festuca rubra , 

 Puccinellia maritima , and Spartina townsendii , respectively) had 

 recovered completely (Cowell and Baker, 1969). Baker (1971a-i) 

 reported on several aspects of the effects of oil pollution on salt 

 marsh and concluded that single oil spillages do not cause long-term 

 damage to marsh vegetation (Baker, 1971a). 



These studies indicate that marsh vegetation is resilient and 

 often can recover from single oil spills. Baker (1971e) suggests that 

 it is best to let an oiled marsh recover naturally. However, 

 persistent oil pollution has killed Spartina marsh at Southampton Water 

 (Ranwell, 1968). Such sites may develop extremely anaerobic conditions 

 in the mud so that higher plants can no longer grow on them. Cowell 

 (1969) states that repeated contamination is likely to have 

 increasingly serious effects if anaerobic conditions are created due to 

 bacterial use of oxygen in the biological oxidation of the oil. We 

 found no account of marsh recovery after removal of the upper layer of 

 marsh substrate and vegetation. 



Study Sites 



The lie Grande site is a relatively protected estuary with a mean 

 tide range of ca . 6 m, a spring tide range of ca. 8 m, and a mean tide 

 level of ca. 5 m. Our first visit to lie Grande was in December 1978. 

 Our NOAA liason representative, Douglas Wolfe, indicated that the marsh 

 west of the bridge at lie Grande was to be our primary study site (Fig. 

 1 ) . There were extensive stands of Juncus maritimus on both sides of 

 the estuary with lesser stands composed of a mixture of species 

 including Puccinellia maritima , Triglochin maritima L., Limonium 

 vulgare Mill., Spartina maritima (Curtis) Fern., and Halimione 

 portulacoides . There were vast areas with no vegetation cover, the 

 result of cleanup operations by the French military to rid the marsh 

 of Amoco Cadiz oil. In many areas only the aboveground marsh 

 vegetation and associated oil had been removed and in other areas the 

 entire marsh surface including the root mat had been removed to a depth 

 of over 30 cm. The intertidal creek banks were almost completely 

 lacking in vegetation cover. A limited number of substrate samples 

 from the disturbed sites were taken which subsequently indicated a 



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