Exploring the trophic pathway of organic matter within the Mauguio lagoon (southern France, westernMediterranean), we found spatial differences in the isotopic composition (both d13C and d15N values) oforganic matter sources (primary producers, particulate and sedimentary organic matter), which weremirrored in the upper trophic levels (invertebrates and fish). On average, d13C was heavier by about 1.5–2&in the location under marine influence than in the sites influenced by freshwater discharge. The oppositetrend was found for d15N, which attained maximum values in the north-central zone influenced byfreshwater delivery. For both C and N stable isotope ratios, the highest spatial variability was found inorganic matter sources (2–3&), while invertebrates and fish exhibited less variability (1–2&). The differencesobserved may be related to both anthropogenic (wastewater input) and natural (marine vs. terrestrialinputs) factors. Discharge of wastewater, which affects the innermost location, generally determinesan increase in the relative abundance of 15N. In addition, terrestrially derived nutrients and organic matter,which also affect the innermost location, are known to determine a shift towards 13C-depleted values. Ourresults substantiate the finding that the analysis of carbon and nitrogen stable isotopes can help in elucidatingorigin and fate of organic matter in coastal lagoons, which are characterised by a great spatialvariability and complexity.
|Numero di pagine||10|
|Stato di pubblicazione||Published - 2005|
All Science Journal Classification (ASJC) codes
- Aquatic Science