Stable carbon and nitrogen isotopic characterization and tracing nutrient sources of Ulva blooms around Jeju coastal areas

The present investigation was aimed to characterize the Ulva blooms and to identify the probable sources for Ulva blooms along the Jeju Island coast for pertinent control measures. Algal isotope signatures (delta C-13, delta N-15 and delta O-18) and tissue nitrogen and carbon were analyzed to map nutrient sources around the Jeju coastal areas. The algal delta C-13 values were ranged from -20.52 to -439 parts per thousand, while delta N-15 and delta O-18 values ranged from 4.26 to 8.29 parts per thousand and 12.80-17.34 parts per thousand, respectively. Moreover, site-specific significant differences were observed in algal stable isotope (delta C-13, delta N-15 and delta O-18) values. The bi-plot (delta N-15 vs delta O-18) diagram indicated four dominant nitrogen sources along the Jeju coast, with 1) soil organic nitrogen mixed with livestock wastes (spring water samples and E), the 2) synthetic fertilizer input (A3 and B2), 3) sewage discharge (D1, D2 and 13) and 4) aquaculture waste (fish farm samples, A4, A5, B1, G and 12). Present findings revealed the different potential nitrogen sources for localized increase of algal growth along the Jeju coast. Finally, the present findings could be used as baseline data for efficient nutrient management to remediate Ulva blooms along Jeju coastal environment. (C) 2019 Elsevier Ltd. All rights reserved.