Effects of pretreated domestic wastewater supplies on leaf pigment content, photosynthesis rate and growth of mangrove trees: A field study from Mayotte Island, SW Indian Ocean

Abstract

International audienceAfter 12 and 18 months of daily wastewater discharge into mangrove plots in Mayotte Island, SW Indian Ocean, leaf pigment content, photosynthesis rate and growth of Rhizophora mucronata and Ceriops tagal mangrove trees were evaluated and compared with similar individuals from control plots. Chlorophyll and carotenoid contents, measured using an HPLC analyser, were significantly higher in leaves of mangrove trees receiving wastewater discharges. Photosynthesis and transpiration rates, analysed using an LCi portable system, increased significantly for mangrove trees in impacted plots. Measurements of leaf areas, young branch length and propagule length showed significant increases in plots receiving wastewater. These results suggest a beneficial effect of domestic wastewater on R. mucronata and C. tagal mangrove tree functioning. Analyses and observations on mangrove ecosystems as a whole - taking into account water and sediment compartments, crab populations and nitrogen and phosphorus cycles - are nevertheless necessary for evaluation of bioremediation capacities of mangrove ecosystems

Inhibitory effect of municipal sewage on symbiosis between mangrove plants and arbuscular mycorrhizal fungi

“…This inhibition would greatly reduce the potentially beneficial effects of AMF on mangrove ecosystems. The effects of sewage discharge on the growth of mangrove plants have been evaluated in several studies (Wong et al 1995, Herteman et al 2011), but no congruent view has been reached. The results of the present study provide knowledge important for managing the conservation and restoration of mangrove forests, especially those subject to human disturbance.…”

“…Information on the impacts of municipal sewage discharge on mangrove plants (Herteman et al 2011), ciliate communities (Chen et al 2009), crab and mollusc assemblages (Cannicci et al 2009) and soil enzymes (Yang et al 2008) have previously been published; however, the impact of wastewater on the symbiosis between AMF and mangrove plants remains unexplored. In terrestrial ecosystems, the inhibitory effects of high levels of phosphorus (P) and/or nitrogen (N) on the symbiosis between AMF and plants have been widely studied (van Diepen et al 2011, Lin et al 2012.…”

Mangrove microbial diversity and the impact of trophic contamination

“…In the Chirongui bay mangrove, Lambs et al (2011) andHerteman et al (2011) first reported results at the vegetation and crab community scale, showing that their growth was boosted as a result of changes in the nutrient load in the mangrove sediments. However, analyses and observations of mangrove ecosystems as a whole are necessary to evaluate their bioremediation capacities as vegetative buffers against anthropogenic N-loading in coastal waters.…”

Tracing sewage water by 15N in a mangrove ecosystem to test its bioremediation ability

“…[27][28][29][30] In general, however, the mangrove sediments remain poor in N-and P-containing compounds, [31] due to low upland inflow and Table 3. Retention/immobilization of applied wastewater N in the mangrove biomass washing out by the ocean tide.…”