Sea grape (Caulerpa lentillifera) cultivation in artificial seawater closed system

Abstract

In the present study, the daily relative growth rates of the green macroalga (sea grape, Caulerpa lentillifera) in artificial seawater closed system with cement ponds was evaluated. Cultivation in artificial seawater was investigated for the combined impact of three significant aspects: algal productivity, water quality and nutritional value. Sea grape was cultured for 30 days and important factors were analyzed weekly, and the results showed that the fastest growth rate (productivity rate) was recorded in the second week at 23.27 g.day-1. After that, biomass yield was steadily decreased to 11.67 g.day-1 in the fourth week. The ranges of the experimental cultivation conditions were salinity (29.13 - 31.54 ppt), pH (8.42 - 9.41), air temperature (12.14 - 35.13ºC), water temperature (21.02 - 24.64ºC), light intensity (0 - 35,350.00 lux), electrical conductivity, EC (46.67 - 48.62 ms.cm-1), total dissolved solids, TDS (25.22 - 26.14 g.l-1) and alkalinity (74.00 - 106.67 mg.l-1). During cultivation, the EC was high and the values were quite stable. The amount of ammonia-nitrogen, nitrite-nitrogen, nitrate-nitrogen ranged were 0.17 - 7.20, 2.04 - 8.51 and 2.06 - 3.60 mg.l-1, respectively. The amount of inorganic phosphorus (phosphate phosphorus) was between 0.58 - 0.91 mg.l-1. The nutritional value of cultivated sea grape was performed by dry algal weight and the amount of protein, fat, moisture, ash, fiber and carbohydrate were 24.44 ± 4.329, 2.07 ± 0.13, 8.53 ± 0.40, 38.99 ± 0.30, 14.50 ± 1.28 and 11.47%, respectively. This artificial seawater grown algae contained a high amount of protein (24.44%), and our study results show that artificial seawater cultivation presents positive production of nutritions.