Macro and micro nutrients of tropical seagrasses, Halophila ovalis, H. spinulosa and Halodule uninervis in Johore, Malaysia

The present study determined and compared contents of macro- (nitrogen-n, phosphorus-p, potassium-k, calcium-ca, magnesium-mg) and micro- (zinc-zn, iron-fe, manganese-mn, cupper-cu) nutrients in four seagrass species; big-leaved (bl) halophila ovalis (r. br.) hook. f., small-leaved (sl) h. ovalis (r. br.) ascherson, h. spinulosa (r. br.) aschers. in neumayer and halodule uninervis (forssk.) aschers from three locations; merambong shoal, seluyong shoal-1 and seluyong shoal-2, johore, malaysia on march 2013. dried seagrass samples were subjected to wet digestion method and concentration determined using a perkin elmer 5100 pc atomic absorption spectrophotometer. macro and micro-nutrients varied with species and locations. observed macro-nutrient contents were high for n (17320 mg kg-1) in big-leaved (bl) h. ovalis from seluyong shoal-2, p (2921.33 mg kg-1) in big-leaved (bl) h. ovalis from seluyong shoal-1, and for k (10942.67 mg kg-1) in h. uninervis from merambong shoal and for ca (10576 mg kg-1) in small-leaved (sl) h. ovalis from merambong shoal. mg (3534.67 mg kg-1) was comparatively higher in h. spinulosa from merambong shoal. micro-nutrients such as zn ranged from 138.67 mg kg-1 to 212 mg kg-1 and cu from 13.33 mg kg-1 to17.33 mg kg-1 with no discernible differences between species. fe concentration was consistently higher in all species. hierarchically macro and micro-nutrients contents did not show a consistent ordered pattern according to species and location. based on biplots generated by principle component analysis (pca), there were clear separation of seagrass species based on the micro- and macro-nutrient contents with locations from malaysia and other regions.