Wastewater discharge, seagrass decline and algal proliferation on the côte d'Azur

• Published in: Marine pollution bulletin Vol. 34; no. 2; pp. 78 - 84
• Main Authors: Chisholm, John R.M., Fernex, François E., Mathieu, Daniel, Jaubert, Jean M.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 1997; Elsevier
• Subjects: Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; Caulerpa taxifolia; Ecotoxicology, biological effects of pollution; Fundamental and applied biological sciences. Psychology; Marine; Marine and brackish environment; Posidonia oceanica; proliferation; seagrass; sediment biogeochemistry; wastewater; Mediterranean Sea; West Mediterranean; sediment biogeochemistry; wastewater; proliferation; seagrass; Caulerpa taxifolia; Algae; Chlorophycophyta; Environmental factor; Biogeochemical cycle; Proliferation; Sediments; Population decline; Invasion; Marine environment; Ammonia; Nitrogen cycle; Correlation analysis; Urban waste water; Seagrass bed; Waste water discharge; Thallophyta
• ISSN: 0025-326X; 1879-3363
• DOI: 10.1016/S0025-326X(96)00072-0

The green alga, Caulerpa taxifolia, has recently proliferated in areas of the N-W Mediterranean that were previously dominated by the seagrass Posidonia oceanica. Sediments in areas of proliferation had high exoenzyme activities, NH + 4 concentrations and production rates, but very low capacities to transform organic-N into NH + 4 relative to the quantity of organic material available. All sediments supporting C. taxifolia contained large quantities of precipitated phosphorus and exhibited extremely low capacities to transform NH + 4 into NO − 2 and NO − 3. Low transformative capacities and high phosphate concentrations are characteristic of sediments that have been polluted by urban wastewater. Where C. taxifolia did not exist, or where growth had stabilized, sediments had exoenzyme activities, NH + 4 concentrations and NH + 4 production rates that were proportional to organic-N transformative potential. All sediments contained significant concentrations of non-crystalline sulphide. Caulerpa taxifolia proliferation may be linked to enrichment of substrata by urban wastewater and dead or dying seagrass vegetation.