ABSTRACT
Aims: Spatial variability and temporal dynamics of benthic seaweeds using the field investigation and Landsat Thematic Mapper images Place and Duration of Study: Al-Shoaiba area, Saudi Arabia, Red Sea was investigated and the study area was divided into four sites extending about 10 km. The study period extended seasonally from summer 2011 to spring 2012. Methodology: The assessment of seaweeds abundance and distribution were performed using quadrate method. Methodology includes analyses of the Enhanced Landsat Thematic Mapper (ETM+) images. Results: A total of 46 seaweed taxa were collected from Al-Shoaiba region belonging to three different algal phyla to extend on reef flat to hundreds of yards to open sea. The field observations showed the broad macroalgal groups as optically mixture. The main confusion was distinguished between macroalgal groups. The contribution of seaweeds varied significantly not only between seasons, but also between sites. The physical parameters showed a close relationship between air and sea water temperatures. Generally, the weather tends to be warm at the selected sites. The pH values were slightly alkaline. Water salinity was relatively high especially in summer and autumn. Diverse of macroalgal communities was shown pronounced seasonal changes. Image classifications of remote sensing data showed large visual appearance of algal vegetation in summer and autumn on the reef flat than in winter and spring. High temperature and evaporation during summer and autumn may causes decline in sea water level. In contrary, low temperature leads to increasing the sea water level to cover most of the reef flat in winter and spring. Conclusion: This study emphasizes the significant impact of seasonal variations, especially temperature, on the spatial and temporal distribution of seaweeds in Al- Shoaiba coast, Saudi Arabia, Red Sea.