LINKING NUTRIENTS, METALS AND PRODUCTIVITY IN GULF OF MANNAR MANGROVE ISLANDS, INDIA

摘要

Influence of metals (Fe, Mn, Zn, Cu, Cd, Pb & Ni) and nutrients (N, P & K) on mangrove productivity (net canopy photosynthesis - NCP & complex index - CI) were investigated in Mandappam, Keelakarai and Tuticorin island groups in Gulf of Mannar (GoM), India. Tuticorin was less diverse, lower NCP (1.23+0.3 gCm~(-2)d~(-1)) and Cl (420±56), but with higher salinity (55.0±5.2). Mandappam was more diverse, highest NCP and Cl (2.89±0.8 gC/m~2/d & 2737±145) but lower salinity (21.2±2.1). The nutrients (kg ha~(-1)) varied significantly; N (121±12 -22±3), P (15.6±2.9 - 6.2±0.8) and K (259±23.9 - 57±8.6) were maximum in Mandappam and minimum in Tuticorin. The concentration (μg g~(-1)) of Fe (1653 - 481), Mn (750 - 115), Zn (95 -11), Cu (156 - 19), Cd (2.12 - 0.53), Pb (137 - 0.5) and Ni (15.21 - 2.36) were higher in Tuticorin and lower in Mandappam. NCP and CI exhibited positive correlation with nutrients (N, P & K) but negative correlation with salinity and Cu, Pb & Zn. Principal component ordination, BIOENVI and Global BEST match tests revealed salinity, Cu and Pb are most influential parameters on NCP. Results indicate GoM mangroves are under degradation due to environmental and anthropogenic stress.