Comparative Analysis of The Two Sites of Lahe (Caulerpa sp.) Growth for Determine The Range of Atmospheric, Physical and Chemical Water Conditions

Abstract

Background Ecological conditions determine the growth and productivity of lahe (Caulerpa Sp.). We conduct a comparative study of ecological conditions that affected differences in growth and productivity of lahe in two locations, in the Batunderang village area and the Lapango village area, Sangihe Regency. The ecological factors that we examined include atmospheric, chemical and physical factors. Atmospheric variables include radiation intensity, duration of irradiation, the air temperature above sea level. The physical and chemical parameters of water studied include current velocity, seawater temperature, salinity, current strength, pH, dissolved oxygen, and nitrate concentrations. Results The indicator of lahe growth are: chain length, stem diameter, meristem diameter. The productivity indicator is the wet weight of the lahe harvested by farmers within 90 days. Comparative analysis between locations and measurement positions summarizes the range of ecological conditions for natural growth. The seabed for lahe is 0.8 m − 1.4 m lower than the surface of a coral reef and is not exposed at the lowest tide. The air temperature range at position 20 cm above sea level is 250C − 31.60C, while the temperature of seawater varies between 250C to 28.40C. Daily fluctuations in current velocity at high tides range from 0.09 cm/sec to 2 cm/sec. The salinity range between 27.8 ppt to 28.6 ppt. The pH range of seawater for natural growth is 7.6–8.12, while the dissolved oxygen range is 6 ppm to 6.25 ppm. Nitrate concentrations in lahe growth positions vary between 1.8 ppm − 1.96 ppm. Conclusion This ecological condition guarantees that the productivity of lahe varies between 20–30 kg/m2 for a 90-day harvest period.