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Open Access Publications from the University of California

Tracing Anthropogenic Nutrient Inputs Using δ15N Levels in Algae Tissue


With the pressure on coral reefs increasing, effective mapping of tropical coastal areas affected by anthropogenic nutrient input is essential in conserving existing reefs and to also restore reefs that may already be degraded. However, it is often difficult to detect the source of nutrients entering the reef ecosystem due to the rapid dilution and mixing of nutrients through currents, wave activity and other general mixing events. It is therefore recommended for water quality assessments that biological assays (bioassays) and chemical data are collected as well as biological and habitat data. A bioassay involves the use of a biological organism to test for the relative strength of a substance within the natural environment. This study attempts to quantify the amount, and find the source, of nutrient inputs into the marine environment on a developing tourist island in Thailand. Chemical data in the form of nutrient concentrations are used as an indication of the amount of nutrients present; while δ15N values in algae tissue are used to indicate the source of nutrients and whether or not they are of anthropogenic origin. A more detailed review of the current literature on tracing anthropogenic nutrient inputs using these methods is given below. Also reviewed is the current knowledge of the effects of nutrients on a coral reef ecosystem along with the various mechanisms involved.

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