ECOLOGY OF SEAGRASSES IN NORTHEASTERN SAUDI-ARABIA ONE-YEAR AFTER THEGULF-WAR OIL-SPILL

Approximately 1 year after the Gulf War oil spill we examined the dist ribution, species composition, abundance and productivity of seagrasse s in several oil contaminated bays along the northeastern coastline of Saudi Arabia. The most abundant seagrass, Halodule uninervis, grew fr om the intertidal down to depths of 10 m with a standing crop ranging from 2 to 32 gdw m-2. Specific leaf productivity in a heavily oiled sh allow site (1.5 m depth) was 2.2% d-1 and areal production was 0.172 g dw M-2 d-1. Specific productivity was similar to other reported rates for healthy populations of Halodule species but the low areal producti vity reflected late winter water temperatures which were between 16 an d 19-degrees-C. Halophila ovalis was intermediate in abundance followe d by Halophila stipulacea. Leaf morphology and indicators of vegetativ e growth suggested that all three species were healthy, despite the re cent history of oiling. Morphometric analyses indicated the seagrasses were experiencing a seasonal transition and initializing a normal gro wth pattern from lower winter temperatures to spring conditions. All t hree species grew in monospecific and mixed species meadows. The highe st diversity and biomass of vegetation occurred on a mixture of hard a nd soft substrates where species of brown macroalgae were dominant. Ba sed on these observations we conclude that seagrasses in the northwest ern Gulf have not experienced acute or long-term degradation as a dire ct result of the Gulf War oil spill.