Seasonal Ecological Study for Community of Hydrilla Verticillata in Al-Masehb Marsh, Southern Iraq.

This study was performed in Al-Masehb Marsh, Southern Iraq after its restoration processes during 2007, seasonally. Hydrilla verticillata was identified for the first time in this marsh, then its standing crop biomass and vegetation cover percentage were studied. In addition to some physical and chemical water properties. Whereas, its standing crop biomass was with its peak in summer, its value was 213.5 gm/m2, while the lowest value was 42.7 gm/m2 in winter. Also, the vegetation cover percentage was with its peak in summer, its value was 80 %, while the lowest value was 20 % in winter. T-test program was applied to study the significant differences in the growth between seasons at significance levels (P-value 0.01) and (P-value 0.05). Pearson’s product moment correlation coefficient (r) was done to study the relationships between the growth and the studied environmental variables. Statistically, significant differences were shown in the growth between some seasons (winter and summer, winter and autumn, spring and summer; thus spring and autumn). Positive relationships for water temperature and salinity with the growth were observed, while negative relationships were observed for water depth, calcium, magnesium, nitrite, nitrate, and phosphate with Hydrilla verticillata growth.