ANALYSIS OF LAND SUITABILITY AND ENVIRONMENTAL FACTORS AFFECTING SEAWEED (GRACILARIA VERRUCOSA) PRODUCTIVITY IN A POND AREAAgus Dharmawan, Nuddin Harahab, Muhammad Musa and Soemarno
In a pond system all integrated factors work as a whole in a holistic way. Each factor has a possibility to cause some changes in the pond waters environment resulting in the level of suitability and productivity of Gracilaria verrucosa. This study aims to analyze the suitability of land and environmental factors affecting the productivity of Gracilaria verrucosa seaweed in a pond area. The research sample consisted of 161 ponds which were systematically determined from 670 ponds. Environmental factors as observed variables include pH, surface current, water transparency, turbidity, depth, dissolved oxygen (DO), N Ratio (fertilization), salinity, pond substrate, water temperature, and wet basis of harvested seaweed per m2. The suitability analysis was carried out based on the range of tolerance of seaweed growth towards environmental factors which were grouped in three categories consisting of Category 3 (Suitable), Category 2 (Less Suitable), and Category 1 (Not Suitable). The statistical analysis was done by employing multiple regression to determine the effect of measured variables on productivity. The results indicated that the measured variables in the dry season were nearly in less suitable and not suitable category compared to the rainy season which tended to be in suitable category. The average measurement result of seaweed wet basis per m2 in the rainy season was also higher than the result in the dry season. The overall environmental factors observed affected the productivity of seaweed (Gracilaria verrucosa) with a contribution of 73.6% in the dry season and 97.6% in the rainy season. The most dominant environmental factors affecting the productivity of Gracilaria verrucosa in the dry season were water temperature (26.8%), depth (22.6%), and DO (22.5%), while in the rainy season were fertilization (25.2%), DO (24.0%), and water transparency (18.6%).