Abstract
Carbon, nitrogen content and stable carbon isotope abundance (δ13C) were measured in mangrove leaves collected from seven species as well as in mangrove and canal sediments. The C/N ratio in the senescent leaves is 103±20 which is quite different from the ratio of 15.2±1.4 in mangrove sediments. Thus, it is difficult to explain the source of organic matter in the sediments using C/N data. On the other hand,(δ13C values in the senescent leaves and mangrove sediments were-30.2±1.3 and-26.3±1.0‰, respectively. The δ13C values in sediments were several units more positive than those in the leaves. However, the source of organic matter in the sediments is assumed to be in the leaves because isotopic fractionation in sediments takes place and the value becomes several units more positive. Waste water from shrimp ponds flows through the canals. The δ13C values in the canal sediments were -26.4± 1.0‰ which is close to the value in mangrove sediments, indicating that the canal sediments will not be affected by shrimp feed δ13C=-22.5±0.4‰).
