Evaluation for values of ecosystem service functions of cultivated seaweeds in Guangdong Province, China

Abstract

Based on the yields of cultivated seaweeds of Guangdong Province in the past 20 years, this study evaluated the values of ecosystem service functions, including carbon sink and oxygen release, removal of N and Pi nutrients, and absorption of heavy metals. The results indicated that all the ecological values of cultivated seaweeds showed a rising trend from 2000 to 2019. The total ecosystem service value increased from $2.50 million in 2000 to $10.36 million in 2019 at an average annual growth rate of 8.41%. The values of carbon sink and oxygen release, removal of N and Pi nutrients and absorption of heavy metals increased from $10.71 million, $12.98 million and $1.25 million in 2000 to $41.76 million, $56.64 million and $5.25 million in 2019 respectively. Besides, the value of carbon sink and oxygen release and removing N and Pi nutrients contributed significantly to the total ecosystem service value, accounting for 41.36% and 53.15%, while the annual average value of absorption of heavy metals only accounted for 5.49%. In addition, since the market price of Saccharina japonica, Gracilaria spp. and Eucheuma denticulaturn is low, their economic profits are less than the ecological services. They should be given ecological compensations of $1.39/kg, $1.50/kg, and $1.27/kg respectively based on the market price in China. This study illustrates clearly huge ecological values of cultivated seaweeds in carbon emission reduction and improving coastal eutrophication. On the other hand, ecological compensations can promote the healthy development of seaweed cultivation industry and maximize the ecosystem service functions of seaweeds.