Seaweed Cultivation Techniques Gracillariaverrucosa in Pond Ujungpangkah District, Gresik East Java using Broadcast Method

Seaweed is one of the sea cultivation commodities that are easy to be cultivated and have a good market prospect in improving coastal community empowerment. Moreover, the technology used to cultivate seaweed is also simple and inexpensive so it is suitable and easily adapted by coastal communities.Type of seaweed that has been cultivated in brackish water isGracilaria sp.One of the methods used for seaweed cultivation Gracilaria verrucosa is the broadcast method or spread.This method provides an increase in the growth length from 5 cm to 5.8 cm for 42 days and the weight of Gracilaria verrucosa seaweed from 10 grams to 14.1 gr for 42 days. This growth was influenced by ambient temperature including temperature 28-33 º C, salinity 5-17 ppt and degree of acidity (pH) 5-8.


INTRODUCTION
Gracilaria is a species of seaweed that increased production from 1990 to 2010 [1], the world market demand for seaweed continues to increase by 3-5% per year [2]. Intensification of Gracilaria cultivation continues to be encouraged to meet the needs of industry, one of them by expanding the production area. Gracilaria verrucosa is mostly cultivated in ponds because it can live in waters of 15-30 ppt [3].
Seaweed cultivation business (Gracilaria sp.) Often fails due to lack of attention to several factors that can affect the growth rate of seaweed in cultivation, including: location of cultivation, management, seeds, season, location and especially selected cultivation method. Factors mentioned above, greatly affect the level (productivity) production of seaweed cultivated [4].
Gracilaria verrucosa can be cultivated by several methods, one of them using the broadcast method or spread. The method is a method commonly chosen by the farmer's community because the technology is easy, cheap, without the need for extra care [5]. The results of this study are expected to contribute as one source of information in an effort to support the development of seaweed cultivation Gracilaria verrucossa with the use of the broadcast method or spread in the pond.

II.
MATERIALS AND METHODS Time and place.The study was conducted for 42 days. In March to May 2018, in the brackish water ponds of Pangkah Wetan Village, Ujungpangkah District, Gresik Regency, East Java Province. Land preparation. Preparation of land by preparing waring for happa to be made for seaweed cultivation in ponds. Happa is made of black waring with size 3 x 4 x 0.5 with four sides, which on each side are given bamboo as a rebuttal. Procurement and Selection of Seedlings . Seeds used are good seeds with the following criteria: • cylindrical rod/tallus appearance, clean, fresh, hard, not slimy, no fishy smell, and not pale • Seeds with many branches and grow centered from one part of the base and spread • Seed should be homogeneous not mixed with other types • Selecting seeds with elongated talus ranges from 15-30 cm Seedling. Seeds that have been obtained in pieces weighing 10 grams and then in stocking by using the method of spread (broadcast method).
Seedling maintenance and water quality. Seed maintenance is done once every week, for 42 days of research. Water quality monitoring, such as temperature, pH, and salinity, is also carried out. Gracilariaverrucosa seaweed growth. Growth and weight of Gracilaria verrucosa using formula [6]: Weight (g) = final weight -initial weight

III. RESULTS AND DISCUSSION Growth
Based on existing data from figure 1, the growth of seaweed each week has increased. The initial length was only 5 cm at the beginning of the spread to 5.8 cm. The scattering method used has a weakness that is seaweed is only spread and located in the bottom of the pond less sunlight, thallus many of which are covered in silt deposits resulting in inhibition of long growth in seaweed and also less current. According to [7] the role of the current is to avoid the accumulation of silt and epiphytes attached to the thallus, with the presence of mud attached to the seaweed thallus indicating that the movement of water at the depth is not good because it cannot clean the dirt and the sediment attached to thallus that can block the growth of seaweed itself.

Weight
Based on the graph figure 2 obtained results that indicate that the growth of weight in Gracilaria verrucosa seaweed in ponds increased weight (g) every week. The initial weight of spreading using seed seaweed weighing 10 grams increased to 14.1 gr. The lack of growth in this study can be influenced by environmental factors ie temperature. Temperatures in the waters exceed the normal limits of seaweed maintenance that is 20-28ºC [8]. In addition, factors that affect the growth of seaweed is the intensity of sunlight, depth, current, weather and climate. Environmental factor.
Temperature. Water temperature during the study is between 28-33 ° C.
[9] states that seaweed grows and develops well in waters that have a temperature range of 20-28° C. Temperature affects the process of seaweed breeding because it helps the process of photosynthes is in the waters. If in temperatures the water does not match will inhibit the growth process.
Salinity.Based on the results of the average pH measurement at the seaweed cultivation pond-Gracilaria verrucosa ranged from 5-17 ppt. The good salinity condition for seaweed growth is between 15-34 ppt A degree of acidity (pH). The degree of acidity (pH) of the waters during the study ranged from pH 5-8, the pH range still qualified as a process of cultivation in ponds. As in [9] seaweed growth requires optimal sea water pH ranging from 6-9. According to SNI 7579.1 (2010) that the pH of waters required for seaweed cultivation ranges from 7-8.5.

IV.
CONCLUSION The method used in seedling distribution using the spread method. However, by using this method the growth of seaweed is <3%. Long growth increased from 5 cm at baseline to 5.8 cm at the end of the study. The initial weight of the spreading using the seaweed seeds weighing 10 grams increased to 14.1 g until the end of the study for 42 days. Environmental factors include water temperature during the study of 28-33 ° C, salinity 5-17 ppt and pH 5-8.